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Liu J, Zhu L, Bao Y, Du Z, Shi L, Hong X, Zou Z, Peng G. Injectable dexamethasone-loaded peptide hydrogel for therapy of radiation-induced ototoxicity by regulating the mTOR signaling pathway. J Control Release 2024; 365:729-743. [PMID: 38065412 DOI: 10.1016/j.jconrel.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/19/2023] [Accepted: 12/02/2023] [Indexed: 12/17/2023]
Abstract
Radiation-induced ototoxicity is associated with inflammation response and excessive reactive oxygen species in the cochlea. However, the effectiveness of many drugs in clinical settings is limited due to anatomical barriers in the inner ear and pharmacokinetic instability. To address this issue, we developed an injectable hydrogel called RADA32-HRN-dexamethasone (RHD). The RHD hydrogel possesses self-anti-inflammatory properties and can self-assemble into nanofibrous structures, ensuring controlled and sustained release of dexamethasone in the local region. Flow cytometry analysis revealed that the uptake of FITC-conjugated RHD gel by hair cells increased in a time-dependent manner. Compared to free dexamethasone solutions, dexamethasone-loaded RHD gel achieved a longer and more controlled release profile of dexamethasone. Additionally, RHD gel effectively protected against the inflammatory response, reduced excessive reactive oxygen species production, and reversed the decline in mitochondrial membrane potentials induced by ionizing radiation, leading to attenuation of apoptosis and DNA damage. Moreover, RHD gel promoted the recovery of outer hair cells and partially restored auditory function in mice exposed to ionizing radiation. These findings validated the protective effects of RHD gel against radiation-induced ototoxicity in both cell cultures and animal models. Furthermore, RHD gel enhanced the activity of the mammalian target of rapamycin (mTOR) signaling pathway, which was inhibited by ionizing radiation, thereby promoting the survival of hair cells. Importantly, intratympanic injections of RHD gel exhibited excellent biosafety and do not interfere with the anti-tumor effects of radiotherapy. In summary, our study demonstrates the therapeutic potential of injectable dexamethasone-loaded RHD hydrogel for the treatment of radiation-induced hearing loss by regulating the mTOR signaling pathway.
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Affiliation(s)
- Jingyu Liu
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China
| | - Lisheng Zhu
- The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China
| | - Yuqing Bao
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China
| | - Zhouyuan Du
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China
| | - Liangliang Shi
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China
| | - Xiaohua Hong
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China
| | - Zhenwei Zou
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China.
| | - Gang Peng
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei, China; Hubei Key Laboratory of Precision Radiation Oncology, Wuhan 430022, China; Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong, University of Science and Technology, Wuhan 430022, China.
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Mohammed Y, Holmes A, Kwok PCL, Kumeria T, Namjoshi S, Imran M, Matteucci L, Ali M, Tai W, Benson HA, Roberts MS. Advances and future perspectives in epithelial drug delivery. Adv Drug Deliv Rev 2022; 186:114293. [PMID: 35483435 DOI: 10.1016/j.addr.2022.114293] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 04/09/2022] [Indexed: 12/12/2022]
Abstract
Epithelial surfaces protect exposed tissues in the body against intrusion of foreign materials, including xenobiotics, pollen and microbiota. The relative permeability of the various epithelia reflects their extent of exposure to the external environment and is in the ranking: intestinal≈ nasal ≥ bronchial ≥ tracheal > vaginal ≥ rectal > blood-perilymph barrier (otic), corneal > buccal > skin. Each epithelium also varies in their morphology, biochemistry, physiology, immunology and external fluid in line with their function. Each epithelium is also used as drug delivery sites to treat local conditions and, in some cases, for systemic delivery. The associated delivery systems have had to evolve to enable the delivery of larger drugs and biologicals, such as peptides, proteins, antibodies and biologicals and now include a range of physical, chemical, electrical, light, sound and other enhancement technologies. In addition, the quality-by-design approach to product regulation and the growth of generic products have also fostered advancement in epithelial drug delivery systems.
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Li H, Suh MW, Oh SH. Dual Viscosity Mixture Vehicle for Intratympanic Dexamethasone Delivery Can Block Ototoxic Hearing Loss. Front Pharmacol 2021; 12:701002. [PMID: 34776942 PMCID: PMC8581269 DOI: 10.3389/fphar.2021.701002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/11/2021] [Indexed: 11/17/2022] Open
Abstract
Clinically there is no effective method to prevent drug induced hearing loss in patients undergoing chemotherapy and anti-tuberculosis therapy. In this study, we developed an intratympanic (IT) local drug delivery vehicle featuring hyaluronic acid-based dual viscosity mixture encapsulation of dexamethasone (D), named dual-vehicle + D, and assessed its protective effect in ototoxic hearing loss. We assessed the residence time, biocompatibility, and treatment outcome of the novel vehicle compared with the current standard of care vehicle (saline) and control conditions. The hearing threshold and hair cell count were significantly better in the dual-vehicle + D group compared to the other two groups. The final hearing benefit in the dual-vehicle group was approximately 25–35 dB, which is significant from a clinical point of view. Morphologic evaluation of the cochlear hair cells also supported this finding. Due to the high viscosity and adhesive property of the vehicle, the residence time of the vehicle was 49 days in the dual-vehicle + D group, whereas it was less than 24 h in the saline + D group. There was no sign of inflammation or infection in all the animals. From this study we were able to confirm that dual viscosity mixture vehicle for IT D delivery can effectively block ototoxic hearing loss.
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Affiliation(s)
- Hui Li
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, South Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, South Korea
| | - Myung-Whan Suh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, South Korea
| | - Seung Ha Oh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, South Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, South Korea
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Hearing Changes After Intratympanic Steroids for Secondary (Salvage) Therapy of Sudden Hearing Loss: A Meta-Analysis Using Mathematical Simulations of Drug Delivery Protocols. Otol Neurotol 2019; 39:803-815. [PMID: 29995001 DOI: 10.1097/mao.0000000000001872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The use of glucocorticoids for secondary (salvage/rescue) therapy of idiopathic sudden hearing loss (ISSHL), including controlled and uncontrolled studies with intratympanic injections or continuous, catheter mediated applications, were evaluated by means of a meta-analysis in an attempt to define optimal local drug delivery protocols for ISSHL. STUDY DESIGN A total of 30 studies with 33 treatment groups between January 2000 and June 2014 were selected based on sufficiently detailed description of application protocols. Cochlear drug levels were calculated by a validated computer model of drug dispersion in the inner ear fluids based on the concentration and volume of glucocorticoids applied, the time drug remained in the middle ear, and on the specific timing of injections. Various factors were compared with hearing outcome, including baseline data, individual parameters of the application protocols, calculated peak concentration (Cmax), and total dose (area under the curve, AUC). RESULTS There was no dependence of hearing outcome on individual parameters of the application protocol, Cmax or AUC. Hearing gain and final hearing thresholds were independent of treatment delay. CONCLUSION Based on the available data from uncontrolled and controlled randomized and non-randomized studies no clear recommendation can be made so far for a specific application protocol for either primary or secondary (salvage) intratympanic steroid treatment in patients with ISSHL. For meta-analyses, change in pure tone average (PTA) may not be an adequate outcome parameter to assess effectiveness of the intervention especially with inhomogeneity of patient populations. Final PTA might provide a better outcome parameter.
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A Polymer-Based Extended Release System for Stable, Long-term Intracochlear Drug Delivery. Otol Neurotol 2019; 39:1195-1202. [PMID: 30199502 DOI: 10.1097/mao.0000000000001977] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Investigate a new polymer-based drug coating suitability for safe intracochlear delivery and ability to maintain long-term physiologically active levels of the corticosteroid fluticasone propionate. STUDY DESIGN In vitro dissolution study to evaluate release profiles of polymer-coated drug particles and in vivo studies using a guinea pig model to measure perilymph drug concentrations at specific time points after implantation with polymer-coated drug particles and evaluate their effect on hearing function. METHODS Polymer-coated fluticasone propionate (FP) particles were surgically implanted in guinea pigs through the round window membrane into the cochlear scala tympani. In the pilot study, pre- and post-op hearing thresholds were conducted on days 7, 14, and 42. In a second study, post-op hearing thresholds were conducted on days 90, 120, and 180. Perilymph drug concentrations were measured on the same time points. RESULTS In 15 of 16 animals from day 7 through day 90, drug levels were within the targeted range, with no initial burst release detected. Drug was present in all animals on day 90 and was detected in some animals at 120 and 180 days. Hearing was tested and compared with non-implanted ears. Very good hearing preservation was observed in ears implanted with intracochlear particles when compared with contralateral ears. CONCLUSIONS The polymer-based extended release system is effective in providing long-term, stable drug delivery for at least 90 days with good hearing outcomes. The results of this study support the potential for achieving long-term drug delivery with a single intracochlear administration.
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Dexamethasone-loaded chitosan-based genipin-cross-linked hydrogel for prevention of cisplatin induced ototoxicity in Guinea pig model. Int J Pediatr Otorhinolaryngol 2019; 122:60-69. [PMID: 30974336 DOI: 10.1016/j.ijporl.2019.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 04/01/2019] [Accepted: 04/01/2019] [Indexed: 01/05/2023]
Abstract
OBJECTIVES The aim of this study was to investigate the protective effects of a sustained release form of dexamethasone (dex) loaded chitosan-based genipin-cross-linked hydrogel (CBGCH) in a guinea pig model of cisplatin (CP) induced hearing loss. METHODS Implantation of CBGCH was made by intratympanic (IT) injection. Ototoxicity was produced by intraperitoneal (IP) single dose of 14 mg/kg CP. Animals were randomly divided into four groups with 6 guinea pigs in each. Group 1 received only IP CP; group 2 received only IT dex-loaded CBGCH injections. Group 3 and group 4 received IP CP, plus IT nondrug CBGCH and IT dex-loaded CBGCH respectively 24 h prior to IP CP injections. Distortion product otoacoustic emissions (DPOAEs) and auditory brainstem response (ABR) measurements were obtained before the treatments and solely ABR measurements were done after 3 and 10 days. The ultrastructural effects were investigated by scanning electron microscopy (SEM) analysis. RESULTS The postCP ABR thresholds at 4, 8, 12, 16, 32 kHz frequencies were significantly better in group 4 than groups 1 and 3 (p < 0.05). The comparison of time effective ABR thresholds between groups 1 and 4 and between groups 3 and 4 showed significantly lower ABR thresholds in group 4 (p < 0.05). The SEM analysis showed that stereocilia of inner and outer hair cells were preserved in group 4, almost like group 2, whereas cytotoxic degenerations were noted in groups 1 and 3. CONCLUSIONS Intratympanic administration of dex-loaded CBGCH has been shown to provide functional and structural protection against CP-induced ototoxicity.
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Aykal K, Ardıç FN, Tümkaya F, Yücel E, Akarsu M, Kara CO, Erdem E. Preliminary Results of a New Experimental Model for Intratympanic Treatment. Turk Arch Otorhinolaryngol 2018; 56:188-192. [PMID: 30701112 PMCID: PMC6340320 DOI: 10.5152/tao.2018.3467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 08/14/2018] [Indexed: 03/23/2024] Open
Abstract
OBJECTIVE Corticosteroids have been applied via transtympanic route for a long time to treat the inner ear disorders. A few animal models were used to answer the questions, "How much drug goes into the inner ear?" and "How far does the drug reach through the scala tympani and/or scala vestibuli?" However, the cerebrospinal fluid contamination poses a major problem. The aims of this study were to create a new sampling model showing the dexamethasone distribution in the inner ear and to provide more reliable data about drug concentrations. METHODS Ten Hartley strain albino guinea pigs that weighted between 400 and 600 g were used. After dexamethasone application to the left ear, they were sacrificed at two time points: after 0.5 hours (Exp 1) and after 2 hours (Exp 2). The temporal bones were immediately dissected and put into liquid nitrogen for freezing. The apex, second turn, and basal turns of the cochlea and vestibule were separated, while the bone was in the frozen state. The samples were prepared and measured with ultraviolet (UV) spectroscopy. RESULTS The total amount of dexamethasone was statistically higher in the left ear than the control ear. Although the basal turn and vestibule were the most prominent parts, there was no statistical difference between the different parts of the inner ear at 0.5 hours. The vestibule and the apex showed the highest level of dexamethasone at 2 hours. CONCLUSION Although the model has some limitations, it can measure dexamethasone concentrations and show the time variability in the inner ear.
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Affiliation(s)
- Kamil Aykal
- Department of Otorhinolaryngology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Fazıl Necdet Ardıç
- Department of Otorhinolaryngology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Funda Tümkaya
- Department of Otorhinolaryngology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Emrah Yücel
- Department of Otorhinolaryngology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Mehri Akarsu
- Department of Chemistry, Pamukkale University School of Medicine, Denizli, Turkey
| | - Cüneyt Orhan Kara
- Department of Otorhinolaryngology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Emin Erdem
- Department of Chemistry, Pamukkale University School of Medicine, Denizli, Turkey
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Liu X, Li M, Smyth H, Zhang F. Otic drug delivery systems: formulation principles and recent developments. Drug Dev Ind Pharm 2018; 44:1395-1408. [PMID: 29659300 DOI: 10.1080/03639045.2018.1464022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Disorders of the ear severely impact the quality of life of millions of people, but the treatment of these disorders is an ongoing, but often overlooked challenge particularly in terms of formulation design and product development. The prevalence of ear disorders has spurred significant efforts to develop new therapeutic agents, but perhaps less innovation has been applied to new drug delivery systems to improve the efficacy of ear disease treatments. This review provides a brief overview of physiology, major diseases, and current therapies used via the otic route of administration. The primary focuses are on the various administration routes and their formulation principles. The article also presents recent advances in otic drug deliveries as well as potential limitations. Otic drug delivery technology will likely evolve in the next decade and more efficient or specific treatments for ear disease will arise from the development of less invasive drug delivery methods, safe and highly controlled drug delivery systems, and biotechnology targeting therapies.
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Affiliation(s)
- Xu Liu
- a College of Pharmacy , The University of Texas at Austin , Austin , TX , USA
| | - Mingshuang Li
- b Department of Communication Sciences and Disorders , The University of Texas at Austin , Austin , TX , USA
| | - Hugh Smyth
- a College of Pharmacy , The University of Texas at Austin , Austin , TX , USA
| | - Feng Zhang
- a College of Pharmacy , The University of Texas at Austin , Austin , TX , USA
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Lai D, Zhao F, Jalal N, Zheng Y. Intratympanic glucocorticosteroid therapy for idiopathic sudden hearing loss: Meta-analysis of randomized controlled trials. Medicine (Baltimore) 2017; 96:e8955. [PMID: 29390288 PMCID: PMC5815700 DOI: 10.1097/md.0000000000008955] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Glucocorticoids are the standard treatment for idiopathic sudden sensorineural hearing loss (ISSNHL), but whether intratympanic or systemic therapy is superior remains controversial. Previous meta-analyses of this question have omitted key clinical trials or included observational studies. METHODS English-language randomized controlled trials in OvidSP, PubMed, Embase, CINAHL, and the Cochrane Library comparing intratympanic versus systemic glucocorticoid therapy for ISSNHL were meta-analyzed using RevMan 5.3. The primary outcome of interest was improvement in pure tone average (PTA) threshold. RESULTS Six trials involving 248 patients receiving intratympanic steroids and 236 receiving systemic steroids were meta-analyzed. PTA thresholds were similar between the 2 groups at 3 months after therapy initiation (mean difference, 0.24; 95% confidence interval [CI] -2.43 to 2.91, P = .86; I = 54%, P = .07, random-effects model). PTA thresholds were also similar at 6 months (mean difference, 4.69, 95% CI -5.84 to 15.22, P = .38), although the results showed extremely high heterogeneity (I = 98%). Sensitivity analysis indicated that a single trial containing 250 patients provided the strongest evidence for equivalence between the 2 types of therapy. Rates of recovery within 3 months (defined as PTA improvement >10 dB) were similar between the 2 types of therapy (odds ratio 0.92, 95% CI 0.59-1.43, P = .70), with no significant heterogeneity in the pooled data (I = 1%, P = .40). CONCLUSION Intratympanic and systemic steroids' therapies appear to show similar short-term efficacy for restoring hearing in patients with ISSNHL. Intratympanic therapy may reduce systemic side effects associated with steroid use.
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Affiliation(s)
- Dan Lai
- Hearing Center/Hearing and Speech Science Laboratory, Department of Otolaryngology Head and Neck Surgery, West China Hospital of Sichuan University, Chengdu
- Department of Otolaryngology Head and Neck Surgery, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Fei Zhao
- Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, England
- Department of Hearing and Speech Science, Xinhua College, Sun Yat-Sen University, Guangzhou, China
| | - Nasim Jalal
- Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, England
| | - Yun Zheng
- Hearing Center/Hearing and Speech Science Laboratory, Department of Otolaryngology Head and Neck Surgery, West China Hospital of Sichuan University, Chengdu
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Intratympanic Triamcinolone and Dexamethasone in the Treatment of Ménière's Syndrome. Otol Neurotol 2017; 38:386-391. [DOI: 10.1097/mao.0000000000001311] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Li L, Chao T, Brant J, O'Malley B, Tsourkas A, Li D. Advances in nano-based inner ear delivery systems for the treatment of sensorineural hearing loss. Adv Drug Deliv Rev 2017; 108:2-12. [PMID: 26796230 DOI: 10.1016/j.addr.2016.01.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/03/2016] [Accepted: 01/04/2016] [Indexed: 01/31/2023]
Abstract
Sensorineural hearing loss (SNHL) is one of the most common diseases, accounting for about 90% of all hearing loss. Leading causes of SNHL include advanced age, ototoxic medications, noise exposure, inherited and autoimmune disorders. Most of SNHL is irreversible and managed with hearing aids or cochlear implants. Although there is increased understanding of the molecular pathophysiology of SNHL, biologic treatment options are limited due to lack of noninvasive targeted delivery systems. Obstacles of targeted inner ear delivery include anatomic inaccessibility, biotherapeutic instability, and nonspecific delivery. Advances in nanotechnology may provide a solution to these barriers. Nanoparticles can stabilize and carry biomaterials across the round window membrane into the inner ear, and ligand bioconjugation onto nanoparticle surfaces allows for specific targeting. A newer technology, nanohydrogel, may offer noninvasive and sustained biotherapeutic delivery into specific inner ear cells. Nanohydrogel may be used for inner ear dialysis, a potential treatment for ototoxicity-induced SNHL.
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Affiliation(s)
- Lilun Li
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA; New York University School of Medicine, New York, NY 10016, USA
| | - Tiffany Chao
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Jason Brant
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Bert O'Malley
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Andrew Tsourkas
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daqing Li
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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Lavigne P, Lavigne F, Saliba I. Sustained Inner Ear Steroid Delivery via Bioabsorbable Stent. Otolaryngol Head Neck Surg 2016; 155:649-53. [DOI: 10.1177/0194599816651262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/03/2016] [Indexed: 11/17/2022]
Abstract
Objective To determine the feasibility and tolerability of a steroid-eluting middle ear device on an animal model. Study Design Prospective experimental. Setting Experimental animal study. Subjects and Method Mometasone furoate (MF)–eluting miniature sticks were implanted through a myringotomy incision into the middle ear of 10 guinea pigs. Two additional ears of 2 animals served as controls. Fourteen days after implantation, perilymphatic fluid was collected through an endaural cochleostomy. MF concentrations were measured with high-performance liquid chromatography, and the middle ear mucosal inflammation was graded with hematoxylin and eosin colorations. Results Fourteen days after implantation, all tympanic membranes had fully healed. An average of 165 ng/mL of MF was detected in the perilymphatic fluid of the experimental ears, and none was measured in control ears. Microscopic residues of the ministicks were found in 90% of the samples, confirming the bioabsorbable properties of this device. Histologic analysis of the middle ear mucosa found similar inflammation profiles in both groups, thereby suggesting middle ear tolerability. Conclusion MF-coated bioabsorbable miniature stick allows for prolonged delivery over 14 days without injuring the middle ear mucosa. Middle ear–sustained steroid delivery may prove to be beneficial in numerous neurotologic conditions.
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Affiliation(s)
- Philippe Lavigne
- Division of Otolaryngology–Head and Neck Surgery, Montreal University Hospital Center, University of Montreal, Montreal, Canada
| | - François Lavigne
- Division of Otolaryngology–Head and Neck Surgery, Montreal University Hospital Center, University of Montreal, Montreal, Canada
| | - Issam Saliba
- Division of Otolaryngology–Head and Neck Surgery, Montreal University Hospital Center, University of Montreal, Montreal, Canada
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Zhang Y, Su H, Wen L, Yang F, Chen G. Mathematical modeling for local trans-round window membrane drug transport in the inner ear. Drug Deliv 2016; 23:3082-3087. [PMID: 26934165 DOI: 10.3109/10717544.2016.1149745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The structure and composition of the round window membrane (RWM) make it a particularly effective pathway for drug delivery to the inner ear. Therefore, predicting the efficiency of RWM transport would provide useful information for enhancing local application. In the present study, a mathematical model was established to achieve this goal. A series of drugs with different physicochemical properties were introduced in the inner ear cavity of guinea pigs via RWM by intratympanic application. The perilymphatic drug concentration (C) data were used to calculate the permeability coefficient (Kp) of different drugs diffusing through the RWM. The experimental data were fitted using the Matlab software to set up the numerical model based on Fick's diffusion law and the single-compartment model following extravascular administration, which facilitated the prediction of the permeation profiles of different drugs while trans-RWM. In summary, this mathematical model is a contribution toward developing potentially useful RWM administration simulating tools.
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Affiliation(s)
- Yue Zhang
- a School of Pharmacy, Guangdong Pharmaceutical University , Guangzhou , China
| | - Huanpeng Su
- a School of Pharmacy, Guangdong Pharmaceutical University , Guangzhou , China
| | - Lu Wen
- a School of Pharmacy, Guangdong Pharmaceutical University , Guangzhou , China
| | - Fan Yang
- a School of Pharmacy, Guangdong Pharmaceutical University , Guangzhou , China
| | - Gang Chen
- a School of Pharmacy, Guangdong Pharmaceutical University , Guangzhou , China
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Staecker H, Schlecker C, Kraft S, Praetorius M, Hsu C, Brough DE. Optimizing atoh1-induced vestibular hair cell regeneration. Laryngoscope 2014; 124 Suppl 5:S1-S12. [PMID: 24938696 DOI: 10.1002/lary.24775] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2014] [Indexed: 01/20/2023]
Abstract
OBJECTIVES/HYPOTHESIS Determine the optimal design characteristics of an adenoviral (Ad) vector to deliver atoh1 and induce regeneration of vestibular hair cells. STUDY DESIGN Evaluation of a mouse model of intralabyrinthine gene delivery. Tissue culture of mouse and human macular organs. METHODS Macular organs from adult C57Bl/6 mice were treated with binding modified and alternate adenovectors expressing green fluorescent protein (gfp) or luciferase (L). Expression of marker genes was determined over time to determine vector transfection efficiency. The inner ear of adult mice was then injected with modified vectors. Expression of gfp and distribution of vector DNA was followed. Hearing and balance function was evaluated in normal animals to ensure safety of the novel vector designs. An optimized vector was identified and tested for its ability to induce hair cell regeneration in a mouse vestibulopathy model. Finally, this vector was tested for its ability to induce hair cell regeneration in human tissue. RESULTS Ad5 serotype-based vectors were identified as having a variety of different binding capacities for inner ear tissue. This makes it difficult to limit the dose of vector due to entry into nontargeted cells. Screening of rare adenovector serotypes demonstrated that Ad-based vectors were ideally suited for delivery to supporting cells; therefore, they were useful for hair cell regeneration studies. Utilization of an Ad28-based vector to deliver atoh1 to a mouse model of vestibular loss resulted in significant functional recovery of balance. This vector was also capable of transfecting human macular organs and inducing regeneration of human vestibular hair cells in vitro. CONCLUSIONS Improvement in vector design can lead to more specific cell-based delivery and reduction of nonspecific delivery of the trans gene, leading to the development of optimized molecular therapeutics to induce hair cell regeneration. LEVEL OF EVIDENCE N/A. Laryngoscope 124:S1-S12, 2014.
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Affiliation(s)
- Hinrich Staecker
- Department of Otolaryngology, Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
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Haghpanahi M, Gladstone MB, Zhu X, Frisina RD, Borkholder DA. Noninvasive technique for monitoring drug transport through the murine cochlea using micro-computed tomography. Ann Biomed Eng 2013; 41:2130-42. [PMID: 23636576 DOI: 10.1007/s10439-013-0816-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/17/2013] [Indexed: 11/28/2022]
Abstract
Local delivery of drugs to the inner ear has the potential to treat inner ear disorders including permanent hearing loss or deafness. Current mathematical models describing the pharmacokinetics of drug delivery to the inner ear have been based on large rodent studies with invasive measurements of concentration at few locations within the cochlea. Hence, estimates of clearance and diffusion parameters are based on fitting measured data with limited spatial resolution to a model. To overcome these limitations, we developed a noninvasive imaging technique to monitor and characterize drug delivery inside the mouse cochlea using micro-computed tomography (μCT). To increase the measurement accuracy, we performed a subject-atlas image registration to exploit the information readily available in the atlas image of the mouse cochlea and pass segmentation or labeling information from the atlas to our μCT scans. The approach presented here has the potential to quantify concentrations at any point along fluid-filled scalae of the inner ear. This may permit determination of spatially dependent diffusion and clearance parameters for enhanced models.
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Affiliation(s)
- Masoumeh Haghpanahi
- Department of Electrical and Microelectronic Engineering, Rochester Institute of Technology, 79 Lomb Memorial Drive, Rochester, NY 14623, USA
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Li ML, Lee LC, Cheng YR, Kuo CH, Chou YF, Chen YS, Yao CM, Chen PR, Hsu CJ, Song YL, Lee CF. A novel aerosol-mediated drug delivery system for inner ear therapy: intratympanic aerosol methylprednisolone can attenuate acoustic trauma. IEEE Trans Biomed Eng 2013; 60:2450-60. [PMID: 23613018 DOI: 10.1109/tbme.2013.2258154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We developed a novel aerosol-mediated drug delivery system for inner ear therapy by using a silicon-based multiple-Fourier horn nozzle. Intratympanic aerosol (ITA) methylprednisolone (MP) delivery can protect hearing after acoustic trauma. The highest concentration of MP (38.9 ± 5.47 ppm) appeared at 2 h and declined rapidly within 10 h. The concentrations of MP remained at a relatively low level for more than 10 h. Compared to the baseline, the auditory brainstem response (ABR) thresholds shifted markedly at 1 h after noise exposure in all groups (p < 0.05). From the cochleograms, it can be noted that the main lesions encompassed the 2-20 kHz frequency range. Significant differences ( ) were observed for the range between 5 and 8 kHz in the cell loss of outer hair cells (OHCs). The losses for IHCs were lower than for OHCs. The MP movement in the middle ear was simulated by a convection diffusion equation with a relaxation time. The relaxation time was 0.5 h, and the concentration threshold of MP on the round window membrane (RWM) in the middle ear (C T) was 8900 ppm. Using the unit hydrograph (UH) method, we obtained a proper boundary concentration on the RWM at the cochlea, which resulted in a well-fit concentration. Finally, a linking mechanism between the middle ear and the cochlea was established by the RWM. The adjustable permeability and concentration threshold provide the flexibility to match the peak times and peak values of the concentration on the RWM in the middle ear and the cochlea.
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Affiliation(s)
- Ming-Lung Li
- National Center for High-Performance Computing and National Applied Research laboratories, Hsinchu 30076, Taiwan.
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Dexamethasone levels and base-to-apex concentration gradients in the scala tympani perilymph after intracochlear delivery in the guinea pig. Otol Neurotol 2012; 33:660-5. [PMID: 22588238 DOI: 10.1097/mao.0b013e318254501b] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS To determine whether intracochlearly applied dexamethasone will lead to better control of drug levels, higher peak concentrations, and lower base-to-apex concentration gradients in the scala tympani (ST) of the guinea pig than after intratympanic (round window [RW]) application. BACKGROUND Local application of drugs to the RW results in substantial variation of intracochlear drug levels and significant base-to-apex concentration gradients in ST. METHODS Two microliters of dexamethasone-phosphate (10 mg/ml) were injected into ST either through the RW membrane, which was covered with 1% sodium hyaluronate gel or through a cochleostomy with a fluid tight seal of the micropipette. Perilymph was sequentially sampled from the apex at a single time point for each animal, at 20, 80, or 200 min after the injection ended. Results were mathematically interpreted by means of an established computer model and compared with previous experiments performed by our group with the same experimental techniques but using intratympanic applications. RESULTS Single intracochlear injections of 20 minutes resulted in approximately 10 times higher peak concentrations (on average) than 2 to 3 hours of intratympanic application to the RW niche. Intracochlear drug levels were less variable and could be measured for over 220 minutes. Concentration gradients along the scala tympani were less pronounced. The remaining variability in intracochlear drug levels was attributable to perilymph and drug leak from the injection site. CONCLUSION With significantly higher, less variable drug levels and smaller base-to-apex concentration gradients, intracochlear applications have advantages to intratympanic injections. For further development of this technique, it is of importance to control leaks of perilymph and drug from the injection site and to evaluate its clinical feasibility and associated risks.
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Perilymph pharmacokinetics of markers and dexamethasone applied and sampled at the lateral semi-circular canal. J Assoc Res Otolaryngol 2012; 13:771-83. [PMID: 22968908 DOI: 10.1007/s10162-012-0347-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/13/2012] [Indexed: 10/27/2022] Open
Abstract
Perilymph pharmacokinetics was investigated by a novel approach, in which solutions containing drug or marker were injected from a pipette sealed into the perilymphatic space of the lateral semi-circular canal (LSCC). The cochlear aqueduct provides the outlet for fluid flow so this procedure allows almost the entire perilymph to be exchanged. After wait times of up to 4 h the injection pipette was removed and multiple, sequential samples of perilymph were collected from the LSCC. Fluid efflux at this site results from cerebrospinal fluid (CSF) entry into the basal turn of scala tympani (ST) so the samples allow drug levels from different locations in the ear to be defined. This method allows the rate of elimination of substances from the inner ear to be determined more reliably than with other delivery methods in which drug may only be applied to part of the ear. Results were compared for the markers trimethylphenylammonium (TMPA) and fluorescein and for the drug dexamethasone (Dex). For each substance, the concentration in fluid samples showed a progressive decrease as the delay time between injection and sampling was increased. This is consistent with the elimination of substance from the ear with time. The decline with time was slowest for fluorescein, was fastest for Dex, with TMPA at an intermediate rate. Simulations of the experiments showed that elimination occurred more rapidly from scala tympani (ST) than from scala vestibuli (SV). Calculated elimination half-times from ST averaged 54.1, 24.5 and 22.5 min for fluorescein, TMPA and Dex respectively and from SV 1730, 229 and 111 min respectively. The elimination of Dex from ST occurred considerably faster than previously appreciated. These pharmacokinetic parameters provide an important foundation for understanding of drug treatments of the inner ear.
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Intratympanic dexamethasone perfusion versus injection for treatment of refractory sudden sensorineural hearing loss. Eur Arch Otorhinolaryngol 2012; 270:861-7. [DOI: 10.1007/s00405-012-2061-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 05/15/2012] [Indexed: 11/26/2022]
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Krenzlin S, Vincent C, Munzke L, Gnansia D, Siepmann J, Siepmann F. Predictability of drug release from cochlear implants. J Control Release 2011; 159:60-8. [PMID: 22233971 DOI: 10.1016/j.jconrel.2011.12.032] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 12/19/2011] [Accepted: 12/22/2011] [Indexed: 11/17/2022]
Abstract
A simplified mathematical theory is presented allowing for in silico simulation of the effects of key parameters of miniaturized implants (size and composition) on the resulting drug release kinetics. Such devices offer a great potential, especially for local drug treatments, e.g. of the inner ear. However, the preparation and characterization of these systems is highly challenging, due to the small system dimensions. The presented mathematical theory is based on Fick's second law of diffusion. Importantly, theoretical predictions do not require the knowledge of many system-specific parameters: Only the "apparent" diffusion coefficient of the drug within the implant matrix is needed. This parameter can be easily determined via drug release measurements from thin, macroscopic films. The validity of the theoretical model predictions was evaluated by comparison with experimental results obtained with a cochlear implant. The latter consisted of miniaturized electrodes, which were embedded in a silicone matrix loaded with various amounts of dexamethasone. Importantly, independent experimental results confirmed the theoretical predictions. Thus, the presented simplified theory can help to significantly speed up the optimization of this type of controlled drug delivery systems, especially if long release periods are targeted (e.g., several months or years). Straightforward experiments with thin, macroscopic films and computer simulations can allow for rapid identification of optimal system design.
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Affiliation(s)
- S Krenzlin
- University of Lille, College of Pharmacy, 3 Rue du Prof. Laguesse, Lille, France
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Abstract
INTRODUCTION Advances in molecular biology and in the basic understanding of the mechanisms associated with sensorineural hearing loss and other diseases of the inner ear are paving the way towards new approaches for treatments for millions of patients. However, the cochlea is a particularly challenging target for drug therapy, and new technologies will be required to provide safe and efficacious delivery of these compounds. Emerging delivery systems based on microfluidic technologies are showing promise as a means for direct intracochlear delivery. Ultimately, these systems may serve as a means for extended delivery of regenerative compounds to restore hearing in patients suffering from a host of auditory diseases. AREAS COVERED Recent progress in the development of drug delivery systems capable of direct intracochlear delivery is reviewed, including passive systems such as osmotic pumps, active microfluidic devices and systems combined with currently available devices such as cochlear implants. The aim of this article is to provide a concise review of intracochlear drug delivery systems currently under development and ultimately capable of being combined with emerging therapeutic compounds for the treatment of inner ear diseases. EXPERT OPINION Safe and efficacious treatment of auditory diseases will require the development of microscale delivery devices, capable of extended operation and direct application to the inner ear. These advances will require miniaturization and integration of multiple functions, including drug storage, delivery, power management and sensing, ultimately enabling closed-loop control and timed-sequence delivery devices for treatment of these diseases.
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Affiliation(s)
- Jeffrey T Borenstein
- Biomedical Engineering Center, Draper Laboratory, Cambridge, MA 02139, United States.
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Round window perfusion dynamics: implications for intracochlear therapy. Curr Opin Otolaryngol Head Neck Surg 2011; 18:377-85. [PMID: 20808222 DOI: 10.1097/moo.0b013e32833d30f0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW The treatments for inner ear diseases are evolving as the systemic administration of medication is replaced by novel intratympanic and intracochlear drug delivery. The current review explores the background and recent developments in this field. RECENT FINDINGS Although still in various stages of clinical development, novel drug delivery techniques such as the Silverstein MicroWick, the round window microcatheter, biodegradable hydrogels, biopolymers, nanoparticles, newly designed cochlear implant arrays, osmotic mini/micro pumps, and reciprocating perfusion systems hold significant promise. Animal data suggest that sustained delivery systems have more reliable inner ear pharmacokinetics than both systemic administration and intratympanic injections. SUMMARY As research scientists advance technologies for treating inner ear diseases, drug delivery techniques must keep pace. Viable treatment options for sensorineural hearing loss, tinnitus, and vestibular disorders are on the horizon and may usher in a new golden age for otology.
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Salt AN, Hartsock J, Plontke S, LeBel C, Piu F. Distribution of dexamethasone and preservation of inner ear function following intratympanic delivery of a gel-based formulation. Audiol Neurootol 2010; 16:323-35. [PMID: 21178339 DOI: 10.1159/000322504] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 10/29/2010] [Indexed: 01/11/2023] Open
Abstract
Intratympanic (IT) delivery of drugs to the ear is increasingly used for both clinical and research purposes. One limitation of IT delivery is that drugs are rapidly lost from the middle ear by a number of processes, so that prolonged delivery of drug is technically difficult. In the present study, the delivery characteristics of a poloxamer hydrogel formulation containing dexamethasone (dex) were evaluated. The gel is liquid at room temperature, allowing IT injection, but transitions to a gel at body temperature, providing a prolonged residence time in the middle ear. A 50-μl volume of control or dex-containing gel (dex-gel) was injected through the tympanic membrane of guinea pigs. Cochlear function was assessed with cochlear action potential and acoustic emission thresholds measured immediately, 6 or 24 h after IT gel injection. After 6- or 24-hour treatment with dex-gel, perilymph drug gradients along the cochlea were assessed by taking samples sequentially from the apex, and endolymph was sampled from the basal turn. Control gel injections caused small changes in sound field calibrations and functional measures for low-frequency stimuli, consistent with an induced conductive loss. Within 24 h, responses returned to normal. Twenty-four hours after dex-gel injection, low-frequency changes remained as the dex-gel was retained better in the middle ear, but there was no indication of high-frequency loss. While perilymph sample data showed that dex gradients were substantially lower than after single injections of dex solution, quantitative analysis of this result suggests that some dex may have entered the perilymph through the thin bone in the apical region of the cochlea. Endolymph levels of dex remained lower than those in the perilymph. This study confirms that a poloxamer hydrogel-based dex formulation provides an effective method for a prolonged delivery, providing a more uniform distribution of drug in the inner ear.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Mo., USA. salta @ ent.wustl.edu
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Plontke SK, Löwenheim H, Koitschev A, Zenner HP. Response toRandomized, Double Blind, Placebo Controlled Trial on the Safety and Efficacy of Continuous Intratympanic Dexamethasone Delivered Via a Round Window Catheter for Severe to Profound Sudden Idiopathic Sensorineural Hearing Loss After Failure of Systemic Therapy(Laryngoscope119:359â369, 2009). Laryngoscope 2009. [DOI: 10.1002/lary.20596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Salt AN, Plontke SK. Principles of local drug delivery to the inner ear. Audiol Neurootol 2009; 14:350-60. [PMID: 19923805 DOI: 10.1159/000241892] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 07/17/2009] [Indexed: 01/03/2023] Open
Abstract
As more and more substances have been shown in preclinical studies to be capable of preventing damage to the inner ear from exposure to noise, ototoxic drugs, ischemia, infection, inflammation, mechanical trauma and other insults, it is becoming very important to develop feasible and safe methods for the targeted delivery of drugs to specific regions in the inner ear. Recently developed methods for sampling perilymph from the cochlea have overcome major technical problems that have distorted previous pharmacokinetic studies of the ear. These measurements show that drug distribution in perilymph is dominated by passive diffusion, resulting in large gradients along the cochlea when drugs are applied intratympanically. Therefore, in order to direct drugs to specific regions of the ear, a variety of delivery strategies are required. To target drugs to the basal cochlear turn and vestibular system while minimizing exposure of the apical cochlear turns, single one-shot intratympanic applications are effective. To increase the amount of drug reaching the apical cochlear turns, repeated intratympanic injections or controlled-release drug delivery systems, such as biodegradable biopolymers or catheters and pumps, are more effective. However, if the applied substance does not easily pass through the round window membrane, or if a more widespread distribution of drug in the ear is required, then intralabyrinthine injections of the substance may be required. Intralabyrinthine injection procedures, which are currently in development in animals, have not yet been proven safe enough for human use.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA. salta @ ent.wustl.edu
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Plontke SK, Löwenheim H, Mertens J, Engel C, Meisner C, Weidner A, Zimmermann R, Preyer S, Koitschev A, Zenner HP. Randomized, double blind, placebo controlled trial on the safety and efficacy of continuous intratympanic dexamethasone delivered via a round window catheter for severe to profound sudden idiopathic sensorineural hearing loss after failure of systemic therapy. Laryngoscope 2009; 119:359-69. [PMID: 19172627 DOI: 10.1002/lary.20074] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES To study the safety and efficacy of continuous intratympanic dexamethasone-phosphate (Dex-P) for severe to profound sudden idiopathic sensorineural hearing (ISSHL) or sudden idiopathic anacusis after failure of systemic therapy. STUDY DESIGN Randomized, double-blind, placebo controlled multicenter trial. METHODS Patients with ISSHL and insufficient recovery (mean 4PTA = 97 dB HL) after systemic high dose glucocorticoid therapy received either Dex-P (4 mg/ml) or placebo (NaCl 0.9%) continuously applied for 14 days into the round window niche via a temporarily implanted catheter. For ethical reasons, intratympanic treatment was continued with Dex-P in all patients for another 14 days after the placebo-controlled study period. According to a two-step adaptive study design an interim analysis was performed after inclusion of 23 patients. RESULTS Intention-to-treat analysis for the primary outcome criterion (4PTA: 0.5-3 kHz) during the placebo controlled study period (14 days) showed an average hearing improvement in the treatment group of 13.9 dB (SD: 21.3) and in the placebo group of 5.4 dB (SD: 10.4). This difference in hearing improvement between the two groups (mean: 8.4 dB, SD: 17.0, 95% CI: -7.1-24.1) was statistically not significant (p = .26). Of the secondary outcome parameters, the largest benefit of local salvage therapy was found for maximum speech discrimination with an improvement of 24.4% (SD: 32.0) in the treatment and 4.5% (SD: 7.6) in the placebo group (p = 0.07). After a 3 month follow-up period (i.e. after all patients received intratympanic Dex-P) hearing improvement in the two groups was very similar. No serious adverse events were observed. Sample size calculation after the interim analysis resulted in stopping of the trial. CONCLUSIONS The tendency toward better hearing improvement in the treatment group, the rather conservative inclusion criteria, the limited placebo-controlled observation period and the absence of serious adverse events supports further investigation local inner ear drug delivery as a first or second line treatment option for ISSHL.
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Affiliation(s)
- Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Tübingen, Tübingen, Germany.
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Rapid clearance of methylprednisolone after intratympanic application in humans. Comment on: Bird PA, Begg EJ, Zhang M, et al. Intratympanic versus intravenous delivery of methylprednisolone to cochlear perilymph. Otol Neurotol 2007;28:1124-30. Otol Neurotol 2009; 29:732-3; author reply 733. [PMID: 18451748 DOI: 10.1097/mao.0b013e318173fcea] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dexamethasone concentration gradients along scala tympani after application to the round window membrane. Otol Neurotol 2008; 29:401-6. [PMID: 18277312 DOI: 10.1097/mao.0b013e318161aaae] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Local application of dexamethasone-21-dihydrogen-phosphate (Dex-P) to the round window (RW) membrane of guinea pigs produces a substantial basal-apical concentration gradient in scala tympani (ST) perilymph. BACKGROUND In recent years, intratympanically applied glucocorticoids are increasingly being used for the treatment of inner ear disease. Although measurements of intracochlear concentrations after RW application exist, there is limited information on the distribution of these drugs in the inner ear fluids. It has been predicted from computer simulations that substantial concentration gradients will occur after RW application, with lower concentrations expected in apical turns. Concentration gradients of other substances along the cochlea have recently been confirmed using a sequential apical sampling method to obtain perilymph. METHODS Dexamethasone-21-dihydrogen-phosphate (10 mg/ml) was administered to the RW membrane of guinea pigs (n = 9) in vivo for 2 to 3 hours. Perilymph was then collected using a protocol in which 10 samples, each of approximately 1 mul, were taken sequentially from the cochlear apex into capillary tubes. Dexamethasone-21-dihydrogen-phosphate concentration of the samples was analyzed by high-performance liquid chromatography. Interpretation of sample data using a finite element model allowed the longitudinal gradients of Dex-P in ST to be quantified. RESULTS The Dex-P content of the first sample in each experiment (dominated by perilymph from apical regions) was substantially lower than that of the third and fourth sample (dominated by basal turn perilymph). These findings qualitatively demonstrated the existence of a concentration gradient along ST. After detailed analysis of the measured sample concentrations using an established finite element computer model, the mean basal-apical concentration gradient was estimated to be 17,000. Both absolute concentrations of Dex-P in ST and the basal-apical gradients were found to vary substantially. CONCLUSION The existence of substantial basal-apical concentration gradients of Dex-P in ST perilymph were demonstrated experimentally. If the variability in peak concentration and gradient is also present under clinical conditions, this may contribute to the heterogeneity of outcome that is observed after intratympanic application of glucocorticoids for various inner ear diseases.
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Plontke SK, Zimmermann R, Zenner HP, Löwenheim H. Technical note on microcatheter implantation for local inner ear drug delivery: surgical technique and safety aspects. Otol Neurotol 2008; 27:912-7. [PMID: 17006340 DOI: 10.1097/01.mao.0000235310.72442.4e] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS Despite its invasiveness, the temporary implantation of a microcatheter into the middle ear cavity is an appropriately safe method for providing continuous drug delivery to the inner ear. BACKGROUND For the application of drugs to the inner ear, different delivery strategies are available ranging from intratympanic injections to temporarily implanted microcatheters. It has recently been demonstrated that the choice of the drug delivery system influences the pharmacokinetics in the inner ear. If a continuous drug application over several weeks is required, a secure placement of the delivery device (i.e., the microcatheter) is necessary to guarantee efficient drug delivery and to avoid unwanted side effects. STUDY DESIGN Retrospective chart review. MATERIALS AND METHODS During 2000 to 2005, 25 patients with acute unilateral severe-to-profound hearing loss or anacusis and failure of systemic high-dose glucocorticoid and rheological therapy were offered an intratympanic delivery of glucocorticoids via a temporarily implanted catheter and an external pump for up to 4 weeks as a salvage treatment option. The standardized surgical implantation and fixation technique developed for the microcatheter were characterized by six elements: 1) a medial and a lateral tunnel connected by a groove in the posterior wall of the bony ear canal, 2) stabilization of the catheter with bone wax and soft tissue plugs in the tunnels, 3) an ear canal packing, 4) a series of fixating sutures along the catheter, 5) an adhesive dressing, and 6) additional tapes at the connecting line between pump and catheter. At the end of the implantation period, the catheter was removed by a second surgical procedure allowing for evaluation of the catheter position and the condition of the middle ear space. RESULTS Adverse events included catheter dislocation, catheter obstruction, formation of mild granulation tissue in the middle ear cavity, tympanic membrane defects, and ear canal skin defects. With introduction of an improved implantation and fixation technique, the number of catheter dislocations could be significantly reduced. No complications were observed on long-term follow-up. CONCLUSION If the pharmacokinetics or pharmacodynamics of a specific local inner ear therapy approach requires a continuous intratympanic drug application (e.g., to restore hearing in patients with severe or profound hearing loss), the temporary implantation of a microcatheter by a standardized surgical technique is a feasible and appropriately safe method for providing continuous drug delivery to the inner ear.
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Affiliation(s)
- Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery and Tübingen Hearing Research Center, University of Tübingen, Germany.
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Plontke SK, Siedow N, Wegener R, Zenner HP, Salt AN. Cochlear pharmacokinetics with local inner ear drug delivery using a three-dimensional finite-element computer model. Audiol Neurootol 2006; 12:37-48. [PMID: 17119332 PMCID: PMC1779502 DOI: 10.1159/000097246] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Accepted: 08/02/2006] [Indexed: 11/19/2022] Open
Abstract
HYPOTHESIS Cochlear fluid pharmacokinetics can be better represented by three-dimensional (3D) finite-element simulations of drug dispersal. BACKGROUND Local drug deliveries to the round window membrane are increasingly being used to treat inner ear disorders. Crucial to the development of safe therapies is knowledge of drug distribution in the inner ear with different delivery methods. Computer simulations allow application protocols and drug delivery systems to be evaluated, and may permit animal studies to be extrapolated to the larger cochlea of the human. METHODS A finite-element 3D model of the cochlea was constructed based on geometric dimensions of the guinea pig cochlea. Drug propagation along and between compartments was described by passive diffusion. To demonstrate the potential value of the model, methylprednisolone distribution in the cochlea was calculated for two clinically relevant application protocols using pharmacokinetic parameters derived from a prior one-dimensional (1D) model. In addition, a simplified geometry was used to compare results from 3D with 1D simulations. RESULTS For the simplified geometry, calculated concentration profiles with distance were in excellent agreement between the 1D and the 3D models. Different drug delivery strategies produce very different concentration time courses, peak concentrations and basal-apical concentration gradients of drug. In addition, 3D computations demonstrate the existence of substantial gradients across the scalae in the basal turn. CONCLUSION The 3D model clearly shows the presence of drug gradients across the basal scalae of guinea pigs, demonstrating the necessity of a 3D approach to predict drug movements across and between scalae with larger cross-sectional areas, such as the human, with accuracy. This is the first model to incorporate the volume of the spiral ligament and to calculate diffusion through this structure. Further development of the 3D model will have to incorporate a more accurate geometry of the entire inner ear and incorporate more of the specific processes that contribute to drug removal from the inner ear fluids. Appropriate computer models may assist in both drug and drug delivery system design and can thus accelerate the development of a rationale-based local drug delivery to the inner ear and its successful establishment in clinical practice.
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Affiliation(s)
- Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), University of Tübingen, Tübingen, Germany.
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Praetorius M, Baker K, Brough DE, Plinkert P, Staecker H. Pharmacodynamics of adenovector distribution within the inner ear tissues of the mouse. Hear Res 2006; 227:53-8. [PMID: 17081711 DOI: 10.1016/j.heares.2006.07.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 06/03/2006] [Accepted: 07/09/2006] [Indexed: 10/24/2022]
Abstract
Recent studies have demonstrated that delivery of genes to the inner ear can achieve a variety of effects ranging from support of auditory neuron survival to protection and restoration of hair cells, demonstrating the utility of vector based gene delivery. Translation of these findings to useful experimental systems or even clinical applications requires a detailed understanding of the pharmacokinetics of gene delivery in the inner ear. Ideal gene delivery systems will employ a well tolerated vector which efficiently transduces the appropriate target cells within a tissue, but spare non-target structures. Adenovectors based on serotype 5 (Ad 5) are commonly used vectors, are easy to construct and have a long track record of efficacious gene transfer in the inner ear. In this study we demonstrate that distribution of Ad5 vector occurs in a basal to apical gradient with rapid distribution of vector to the vestibule after delivery via a round window cochleostomy. Transduction of the vector and expression of the delivered transgene occurs by 10 min post vector delivery. At 24 h post delivery only 16% of vector that was initially detectable within the inner ear by quantitative PCR remained. Perilymph sampling was used to determine that vector concentrations in perilymph peaked at 30 min post delivery and then declined rapidly. Understanding these basic distribution patterns and parameters for delivery are important for the design of gene delivery vectors and vital for modeling dose responses to achieve safe efficacious delivery of a therapeutic agent.
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Affiliation(s)
- Mark Praetorius
- Department of Otolaryngology, University of Heidelberg Medical Center, Heidelberg, Germany
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Plontke SK, Salt AN. Simulation of application strategies for local drug delivery to the inner ear. ORL J Otorhinolaryngol Relat Spec 2006; 68:386-92. [PMID: 17065834 PMCID: PMC1751485 DOI: 10.1159/000095284] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Local, rather than systemic, drug delivery to the inner ear is becoming more widely used to treat inner ear disorders. While many substances are undergoing preclinical and clinical studies, it is equally important to develop appropriate drug delivery systems. Pharmacokinetic studies are technically demanding in animals and almost impossible in humans. Computer simulations have helped establish the basic principles of drug distribution in the inner ear. The distribution of methylprednisolone in the guinea pig cochlea has been simulated for different drug delivery systems based on kinetic parameters established in prior studies. Results were compared for different rates of drug clearance from the middle ear. Absolute and relative drug levels in the perilymph were highly dependent on how long the drug remained in the middle ear. For a brief (30 min) application, the basal to apical drug gradient was higher than for longer delivery times. These findings show that controlling middle ear drug clearance is of critical importance.
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Affiliation(s)
- Stefan K Plontke
- Tubingen Hearing Research Center and Department of Otorhinolaryngology, Head and Neck Surgery, University of Tubingen, Tubingen, Germany.
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Plontke S. [Inquiries into local application of drugs on the inner ear. Innovation prize of the Working Group for German Speaking Audiologists and Neuro-otologists 2005]. HNO 2006; 53:837-44. [PMID: 16897837 DOI: 10.1007/s00106-005-1339-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- S Plontke
- Universitätsklinik für Hals,- Nasen-, Ohrenheilkunde, Kopf-und Halschirurgie Tübingen.
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Mynatt R, Hale SA, Gill RM, Plontke SK, Salt AN. Demonstration of a longitudinal concentration gradient along scala tympani by sequential sampling of perilymph from the cochlear apex. J Assoc Res Otolaryngol 2006; 7:182-93. [PMID: 16718612 PMCID: PMC1945159 DOI: 10.1007/s10162-006-0034-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 03/17/2006] [Indexed: 10/24/2022] Open
Abstract
Local applications of drugs to the inner ear are increasingly being used to treat patients' inner ear disorders. Knowledge of the pharmacokinetics of drugs in the inner ear fluids is essential for a scientific basis for such treatments. When auditory function is of primary interest, the drug's kinetics in scala tympani (ST) must be established. Measurement of drug levels in ST is technically difficult because of the known contamination of perilymph samples taken from the basal cochlear turn with cerebrospinal fluid (CSF). Recently, we reported a technique in which perilymph was sampled from the cochlear apex to minimize the influence of CSF contamination (J. Neurosci. Methods, doi: 10.1016/j.jneumeth.2005.10.008 ). This technique has now been extended by taking smaller fluid samples sequentially from the cochlear apex, which can be used to quantify drug gradients along ST. The sampling and analysis methods were evaluated using an ionic marker, trimethylphenylammonium (TMPA), that was applied to the round window membrane. After loading perilymph with TMPA, 10 1-muL samples were taken from the cochlear apex. The TMPA content of the samples was consistent with the first sample containing perilymph from apical regions and the fourth or fifth sample containing perilymph from the basal turn. TMPA concentration decreased in subsequent samples, as they increasingly contained CSF that had passed through ST. Sample concentration curves were interpreted quantitatively by simulation of the experiment with a finite element model and by an automated curve-fitting method by which the apical-basal gradient was estimated. The study demonstrates that sequential apical sampling provides drug gradient data for ST perilymph while avoiding the major distortions of sample composition associated with basal turn sampling. The method can be used for any substance for which a sensitive assay is available and is therefore of high relevance for the development of preclinical and clinical strategies for local drug delivery to the inner ear.
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Affiliation(s)
- Robert Mynatt
- Department of Otolaryngology, St. Louis University School of Medicine, St. Louis, MO 63110 USA
| | - Shane A. Hale
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8115, St. Louis, MO 63110 USA
| | - Ruth M. Gill
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8115, St. Louis, MO 63110 USA
| | - Stefan K. Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery and Tübingen Hearing Research Center (THRC), University of Tübingen, D-72076 Tübingen, Germany
| | - Alec N. Salt
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8115, St. Louis, MO 63110 USA
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Liu HJ, Dong MM, Chi FL. Dexamethasone Pharmacokinetics in Guinea Pig Inner Ear Perilymph. ORL J Otorhinolaryngol Relat Spec 2006; 68:93-8. [PMID: 16446554 DOI: 10.1159/000091210] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2005] [Accepted: 05/06/2005] [Indexed: 12/20/2022]
Abstract
AIM To study the dexamethasone pharmacokinetics in the inner ear perilymph of guinea pigs using high-pressure liquid chromatography. METHODS Sixty-five guinea pigs were divided into three groups. In the first group, the drug application protocol used an intra-abdominal dose of 0.5% dexamethasone 4 mg x kg(-1). In the second group, an intratympanic application dose of 0.5% dexamethasone 150 microl was used. The third group was the control group. The concentrations of dexamethasone in inner ear perilymph were determined by high-pressure liquid chromatography. RESULTS The perilymph concentration-time curves of dexamethasone conformed to a one-compartment open model after an intra-abdominal application. The Cmax was 0.927 +/- 0.008 mg x l(-1), the Tmax 1.47 +/- 0.04 h, the T(1/2K) 2.92 +/- 0.056 h, the AUC 5.533 +/- 0.05 mg x h x l(-1), the T(1/2Ka) 0.47 +/- 0.024 h. After an intratympanic application, the perilymph concentration-time curves of dexamethasone also conformed to a one-compartment open model. The Cmax was 0.201 +/- 0.006 mg x l(-1), the Tmax 0.117 +/- 0.06 h, the AUC 0.868 +/- 0.004 mg x h x l(-1), the T(1/2K) 2.918 +/- 0.089 h, the T(1/2Ka) 0.161 +/- 0.009 h. Compared to the intra-abdominal application, the intratympanic application resulted in similar levels of inner ear perilymph drug concentrations in 30 min. CONCLUSION Dexamethasone can penetrate the blood-labyrinthine barrier after intra-abdominal application. Dexamethasone can enter into perilymph after intratympanic application. Under the condition of the study, the intratympanic application resulted in a similar level of inner ear perilymph drug concentrations compared to the intra-abdominal application in 30 min.
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Affiliation(s)
- Hong-Jian Liu
- Department of Otorhinolaryngology, Eye and ENT Hospital of Fudan University, Shanghai City, China
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Salt AN, Hale SA, Plonkte SKR. Perilymph sampling from the cochlear apex: a reliable method to obtain higher purity perilymph samples from scala tympani. J Neurosci Methods 2005; 153:121-9. [PMID: 16310856 PMCID: PMC1769328 DOI: 10.1016/j.jneumeth.2005.10.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Revised: 10/03/2005] [Accepted: 10/13/2005] [Indexed: 10/25/2022]
Abstract
Measurements of drug levels in the fluids of the inner ear are required to establish kinetic parameters and to determine the influence of specific local delivery protocols. For most substances, this requires cochlear fluids samples to be obtained for analysis. When auditory function is of primary interest, the drug level in the perilymph of scala tympani (ST) is most relevant, since drug in this scala has ready access to the auditory sensory cells. In many prior studies, ST perilymph samples have been obtained from the basal turn, either by aspiration through the round window membrane (RWM) or through an opening in the bony wall. A number of studies have demonstrated that such samples are likely to be contaminated with cerebrospinal fluid (CSF). CSF enters the basal turn of ST through the cochlear aqueduct when the bony capsule is perforated or when fluid is aspirated. The degree of sample contamination has, however, not been widely appreciated. Recent studies have shown that perilymph samples taken through the round window membrane are highly contaminated with CSF, with samples greater than 2microL in volume containing more CSF than perilymph. In spite of this knowledge, many groups continue to sample from the base of the cochlea, as it is a well-established method. We have developed an alternative, technically simple method to increase the proportion of ST perilymph in a fluid sample. The sample is taken from the apex of the cochlea, a site that is distant from the cochlear aqueduct. A previous problem with sampling through a perforation in the bone was that the native perilymph rapidly leaked out driven by CSF pressure and was lost to the middle ear space. We therefore developed a procedure to collect all the fluid that emerged from the perforated apex after perforation. We evaluated the method using a marker ion trimethylphenylammonium (TMPA). TMPA was applied to the perilymph of guinea pigs either by RW irrigation or by microinjection into the apical turn. The TMPA concentration of the fluid sample was compared with that measured in perilymph prior to taking the sample using a TMPA-selective microelectrode sealed into ST. Data were interpreted with a finite element model of the cochlear fluids that was used to simulate each aspect of the experiment. The correction of sample concentration back to the perilymph concentration prior to sampling can be performed based on the known ST volume (4.7microL in the guinea pig) and the sample volume. A more precise correction requires some knowledge of the profile of drug distribution along the cochlear prior to sampling. This method of sampling from the apex is technically simple and provides a larger sample volume with a greater proportion of perilymph compared to sampling through the RW.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Box 8115, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Abstract
Several drugs that are applied directly to the inner ear are in widespread clinical use for the treatment of inner-ear disorders. Many new substances and drug delivery systems specific to the inner ear are under development and in some cases are being evaluated in animal experiments and in clinical studies. However, the pharmacokinetics of drugs in the inner ear is not well defined and the field is plagued by technical problems in obtaining pure samples of the inner-ear fluids for analysis. Nevertheless, a basic understanding of the mechanisms of drug dispersal in the inner ear has emerged, which facilitates the design and interpretation of future pharmacokinetic studies.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Plontke S, Löwenheim H, Preyer S, Leins P, Dietz K, Koitschev A, Zimmermann R, Zenner HP. Outcomes research analysis of continuous intratympanic glucocorticoid delivery in patients with acute severe to profound hearing loss: basis for planning randomized controlled trials. Acta Otolaryngol 2005; 125:830-9. [PMID: 16158529 DOI: 10.1080/00016480510037898] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
CONCLUSIONS The data presented herein form the basis for conducting randomized placebo-controlled clinical trials evaluating the safety and efficacy of salvage treatment in patients with idiopathic sudden severe sensorineural hearing loss (but not anacusis) refractory to initial systemic therapy. Comparison of different application protocols and drug delivery systems will allow assessment of the value of continuous versus intermittent intratympanic glucocorticoid drug delivery. OBJECTIVES To describe and critically evaluate the results of continuous intratympanic glucocorticoid delivery in patients with acute unilateral severe and profound sensorineural hearing loss refractory to initial systemic therapy and to compare the outcome with a historical control group. MATERIAL AND METHODS In a retrospective chart review, treatment results were analyzed in 23 patients with acute severe and profound hearing loss and failure of systemic standard therapy who received a continuous intratympanic delivery of glucocorticoids as a salvage treatment. Audiological results were compared within the local therapy group and with the results of an historical control group who did not receive salvage treatment. The study and control groups were matched with respect to hearing loss after initial systemic treatment failure. RESULTS The average pure-tone threshold after intratympanic salvage treatment showed a statistically significant improvement of 15 dB (95% CI 7-24 dB; p<0.001). After exclusion of patients with complete anacusis, i.e. a non-measurable hearing threshold, the local therapy group showed a significantly better improvement (mean 19 dB; 95% CI 6-32 dB) than the historical control group (mean 5 dB; 95% CI -2-11 dB; p<0.05).
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Affiliation(s)
- Stefan Plontke
- Department of Otorhinolaryngology--Head and Neck Surgery and Tübingen Hearing Research Center, University of Tübingen, Tübingen, Germany.
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Banerjee A, Parnes LS. The biology of intratympanic drug administration and pharmacodynamics of round window drug absorption. Otolaryngol Clin North Am 2005; 37:1035-51. [PMID: 15474109 DOI: 10.1016/j.otc.2004.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The application of therapeutic agents to the round window holds great promise in the treatment of inner ear disease. The primary benefit of this route of administration is the ability to achieve high inner ear concentrations of drugs without systemic side effects. Recent research has elucidated the anatomy and physiology of the round window and provided important information on the inner ear pharmacokinetics and the pharmacodynamics of drugs administered intratympanically. Although amino-glycosides and steroids have been most thoroughly studied, many other classes of pharmaceuticals, including otoprotective agents, other antibiotics,and topical anesthetics, have therapeutic potential in the inner ear and will probably be the subject of future studies. The authors believe that direct delivery approaches other than through the round window, perhaps with slow or sustained release formulations, may hold the key to the future treatment of inner ear disorders.
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Affiliation(s)
- Avik Banerjee
- Department of Otolaryngology, University of Western Ontario, London Health Sciences Centre, 339 Windermere Road, London, Ontario, N6A 5A5, Canada
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Abstract
Hearing loss can be caused by acoustic trauma, aging, ototoxic medications, and various other causes. At the cellular level hearing loss seems to be mediated by reactive oxygen species and ultimately through the activation of apoptotic mechanisms. This article explains the cellular and molecular mechanisms of hearing loss and presents medications that could be used in the intratympanic treatment of hearing loss.
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Affiliation(s)
- David M Barrs
- Department of Otolaryngology Head and Neck Surgery/Audiology, Mayo Clinic, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA.
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