Rescuing a Troubled Tolcapone with PEGylated PLGA Nanoparticles: Design, Characterization, and Hepatotoxicity Evaluation

Tolcapone is an orally active catechol-O-methyltransferase (COMT) inhibitor used as adjuvant therapy in Parkinson's disease. However, it has a highly hepatotoxic profile, as recognized by the U.S. Food and Drug Administration. As a possible solution, nanoscience brought us several tools in the development of new functional nanomaterials with tunable physicochemical properties, which can be part of a solution to solve several drawbacks, including drug's short half-life and toxicity. This work aims to use PEGylated poly(lactic-co-glycolic acid) (PLGA) nanoparticles as a stable carrier with lower hydrodynamic size and polydispersity to encapsulate tolcapone in order to overcome its therapeutic drawbacks. Using the nanoprecipitation method, tolcapone-loaded nanoparticles with a DLC% of 5.7% were obtained (EE% of 47.0%) and subjected to a lyophilization optimization process to obtain a final shelf-stable formulation. Six different cryoprotectants in concentrations up to 10% (w/v) were tested. A formulation of PLGA nanoparticles with 3% hydroxypropyl-β-cyclodextrin (HPβCD) as a cryoprotectant (PLGA-HP@Tolc), presenting sub-200 nm sizes and low polydispersity (PdI < 0.200) was selected. Cytotoxicity assays, namely, MTT and SRB, were used to study the metabolic activity and cell density of tolcapone and PLGA-HP@Tolc-treated cells. In both assays, a hepatocarcinoma cell line (HepG2) growing in glucose or glucose-free media (galactose-supplemented medium) was used. The results demonstrated that the treatment with the PLGA-HP@Tolc formulation led to a decrease in cytotoxicity in comparison to free tolcapone-treated cells in both media tested. Moreover, the elected formulation also counteracted ATP-depletion and excessive ROS production induced by tolcapone. The results suggest that HPβCD might have a dual function in the formulation: cryoprotectant and anticytotoxic agent, protecting cells from tolcapone-induced damage. Using an in vitro COMT inhibition assay, the PLGA-HP@Tolc formulation demonstrated to inhibit COMT as efficiently as free tolcapone. Overall, the results suggest that tolcapone-loaded PLGA NPs could be an interesting alternative to free tolcapone, demonstrating the same in vitro efficacy in inhibiting COMT but with a safer cytotoxic profile.

The Effect of Systemic Parameters and Baseline Characteristics in Short-Term Response Analysis with Intravitreal Ranibizumab in Treatment-Naive Patients with Neovascular Age-Related Macular Degeneration

Anti-vascular endothelial growth factor drugs keep being the main therapy for neovascular age-related macular degeneration (AMD). Possible predictive parameters (demographic, biochemical and/or inflammatory) could anticipate short-term treatment response with ranibizumab. 46 treatment-naive patients were included in a prospective observational study. They underwent three monthly injections of intravitreal ranibizumab for neovascular AMD and the clinical examination was made at baseline and one month after the third injection. Demographic characteristics, co-morbidities and concomitant treatments were recorded at the baseline visit. Biochemical parameters, complete blood count and inflammation biomarkers were also measured at these times. Uric Acid was found to be statistically significant with a one-point difference between good and poor responders in both basal and treated patients, but only in basal parameters was statistical significance reached (p = 0.007 vs. p = 0.071 in treated patients). Cholesterol and inflammatory parameters such as white blood cell count and neutrophils were significantly reduced over time when treated with intravitreal ranibizumab. On the other hand, women seemed to have a worse prognosis for short-term response to intravitreal ranibizumab treatment. Uric acid may help identify possible non-responders before initial treatment with ranibizumab, and cholesterol and white blood cells could be good candidates to monitor short-term response to ranibizumab treatment.

Cysteamine Eye Drops in Hyaluronic Acid Packaged in Innovative Single-Dose Systems, Part II: Long-Term Stability and Clinical Ocular Biopermanence

BACKGROUND

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in several tissues and organs causing, among others, severe eye symptoms. The high instability of cysteamine eye drops makes it difficult to develop formulations with an acceptable shelf life to be prepared in hospital pharmacy departments. Previously, a new compounded formulation of cysteamine eye drops in hyaluronic acid (HA) packaged in innovative single-dose systems was developed.

METHODS

Long-term stability at -20 °C of this formulation was studied considering the content of cysteamine, pH, osmolality, viscosity, and microbiological analysis. The oxygen permeability of single-dose containers was also studied and an ocular biopermanence study was conducted in healthy volunteers measuring lacrimal stability and volume parameters.

RESULTS

Data confirm that cysteamine concentration remained above 90% for 120 days, all parameters remaining within the accepted range for ophthalmic formulations. The permeability of the containers was reduced over time, while ocular biopermanence was maintained despite the freezing process and storage time.

CONCLUSIONS

0.55% cysteamine hydrochloride formulation in HA and packaged in single-dose containers preserved at -20 °C is stable for 120 days protected from light, presenting high potential for its translation into clinical practice when commercial presentations are not available.

Intravitreal implants manufactured by supercritical foaming for treating retinal diseases

Chronic retinal diseases, such as age-related macular degeneration (AMD), are a major cause of global visual impairment. However, current treatment methods involving repetitive intravitreal injections pose financial and health burdens for patients. The development of controlled drug release systems, particularly for biological drugs, is still an unmet need in prolonging drug release within the vitreous chamber. To address this, green supercritical carbon dioxide (scCO2) foaming technology was employed to manufacture porous poly(lactic-co-glycolic acid) (PLGA)-based intravitreal implants loaded with dexamethasone. The desired implant dimensions were achieved through 3D printing of customised moulds. By varying the depressurisation rates during the foaming process, implants with different porosities and dexamethasone release rates were successfully obtained. These implants demonstrated controlled drug release for up to four months, surpassing the performance of previously developed implants. In view of the positive results obtained, a pilot study was conducted using the monoclonal antibody bevacizumab to explore the feasibility of this technology for preparing intraocular implants loaded with biologic drug molecules. Overall, this study presents a greener and more sustainable alternative to conventional implant manufacturing techniques, particularly suited for drugs that are susceptible to degradation under harsh conditions.

Design and biopharmaceutical preclinical characterisation of a new thermosensitive hydrogel for the removal of gastric polyps

BACKGROUND AND AIMS

Submucosal injection agents are widely used solutions in gastric polyp resection techniques. Currently, many different solutions are used in clinical practice, but most are not authorised for this use or are not biopharmaceutical characterised. The objective of this multidisciplinary work is to test the efficacy of a novel thermosensitive hydrogel designed specifically for this indication.

METHODS

A mixture design of various components (Pluronic®, hyaluronic acid and sodium alginate) was carried out to select the combination with optimal properties for this use. Three final thermosensitive hydrogels were selected on which biopharmaceutical characterisation was performed and stability and biocompatibility were analysed. Efficacy in maintaining elevation was tested ex vivo on pig mucosa and in vivo in pigs RESULTS: The mixture design allowed selection of the ideal combinations of agents for the characteristics sought. The thermosensitive hydrogels studied showed high values of hardness and viscosity at 37 °C, maintaining good syringeability. One of them demonstrated superiority in maintaining polyp elevation in the ex vivo assay and non-inferiority in the in vivo assay.

CONCLUSION

The thermosensitive hydrogel specifically designed for this use is promising both for its biopharmaceutical characteristics and for its demonstrated efficacy. This study lays the foundation for evaluating the hydrogel in humans.

Monitoring dexamethasone skin biodistribution with ex vivo MALDI-TOF mass spectrometry imaging and confocal Raman microscopy

Two of the most promising techniques in terms of ex vivo skin imaging and quantifying are confocal Raman microscopy and MALDI-TOF mass spectrometry imaging (MALDI-TOF MSI). Both techniques were set up, and the semiquantitative skin biodistribution of previously developed dexamethasone (DEX) loaded lipomers was compared using Benzalkonium chloride (BAK) as a tracer of the nanoparticles. In MALDI-TOF MSI, DEX was derivatised with GirT (DEX-GirT) and the semiquantitative biodistribution of both DEX-GirT and BAK was successfully obtained. The amount of DEX measured by confocal Raman microscopy was higher than that measured by MALDI-TOF MSI, but MALDI-TOF MSI proved to be a more suitable technique for tracing BAK. An absorption-promoting tendency of DEX loaded in lipomers versus a free-DEX solution was observed in confocal Raman microscopy. The higher spatial resolution of confocal Raman microscopy (350 nm) with respect to MALDI-TOF MSI (50 μm) allowed to observe specific skin structures like hair follicles. Nevertheless, the faster sampling rate of MALDI-TOF-MSI, permitted the analysis of larger tissue regions. In conclusion, both techniques allowed to simultaneously analyze semiquantitative data together with qualitative images of biodistribution, which is a very helpful tool when designing nanoparticles that accumulate in specific anatomical regions.

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Efficacy and Safety of Inhaled Ethanol in Early-Stage SARS-CoV-2 Infection in Older Adults: A Phase II Randomized Clinical Trial

BACKGROUND

Inhaled ethanol in the early stages of SARS-CoV-2 infection may reduce the viral load, decreasing progression and improving prognosis. The ALCOVID-19 trial was designed to study the efficacy and safety of inhaled ethanol in older adults at initial phases of infection.

METHODS

Randomized, triple-blind, placebo-controlled phase II clinical trial. Experimental group (n = 38) inhaled 65° ethanol through an oxygen flow, while in the control group (n = 37), water for injection was used. General endpoint was to evaluate disease progression according to the modified World Health Organization (WHO) Clinical Progression Scale. Specific effectiveness endpoints were body temperature, oxygen saturation, viral load assessed by cycle threshold (Ct) on real-time polymerase chain reaction (RT-PCR), analytical biomarkers and use of antibiotics or corticosteroids. Specific safety outcomes were the absence of ethanol in plasma, electrographic, analytical, or respiratory alterations.

RESULTS

In the intention-to-treat population, no differences were found regarding disease progression. Mean Ct values increased over time in both groups, being numerically higher in the ethanol group, reaching a value above 33 only in the ethanol group on day 14, a value above which patients are considered non-infective. No differences were found in the other specific effectiveness endpoints. Inhaled ethanol was proven to be safe as no plasma ethanol was detected, and there were no electrocardiographic, analytical, or respiratory alterations.

CONCLUSIONS

The efficacy of inhaled ethanol in terms of the progression of SARS-CoV-2 infection was not demonstrated in the present trial. However, it is positioned as a safe treatment for elderly patients with early-stage COVID-19.

Cysteamine Eye Drops in Hyaluronic Acid Packaged in Innovative Single-Dose Systems: Stability and Ocular Biopermanence

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs causing, among other symptoms, severe ocular manifestations. Cysteamine eye drops are prepared in hospital pharmacy departments to facilitate access to treatment, for which vehicles that provide adequate biopermanence, as well as adaptable containers that maintain its stability, are required. Difficulties related to cysteamine preparation, as well as its tendency to oxidize to cystamine, show the importance of conducting rigorous galenic characterization studies. This work aims to develop and characterize an ophthalmic compounded formulation of cysteamine prepared with hyaluronic acid and packaged in innovative single-dose systems. For this task, the effect of different storage temperatures and the presence/absence of nitrogen on the physicochemical stability of the formulation and its packaging was studied in a scaled manner, until reaching the optimal storage conditions. The results showed that 0.55% cysteamine, prepared with hyaluronic acid and packaged in single-dose containers, is stable for 30 days when stored at −20 °C. In addition, opening vials every 4 h at room temperature after 30 days of freezing maintains the stability of the cysteamine formulation for up to 16 h. Moreover, ocular biopermanence studies were conducted using molecular imaging, concluding that the biopermanence offered by the vehicle is not affected by the freezing process, where a half-life of 31.11 min for a hyaluronic acid formulation stored for 30 days at −20 °C was obtained, compared with 14.63 min for 0.9% sodium chloride eye drops.

Preparation and ex vivo investigation of an injectable microparticulate formulation for gastrointestinal mucosa polyp resection

Endoscopic submucosal dissection (ESD) and endoscopic submucosal resection (EMR) are non-invasive endoscopic techniques. They allow an early excised gastrointestinal (GI) mucosal precancerous lessions. For their application is necessary use of a submucosal injection that lift area to excise. The main objective of this study was the preparation of microparticulate-based fluid for injection in the GI submucosa. Alginate microparticles (MPs) were developed by the solvent displacement technique and characterized by particle size, surface electrical properties, swelling, degradation, rheology, adhesion and leakage, syringeablity and stability. Furthermore, their potential to form a submucosal cushion was assayed in porcine stomach mucosa and porcine colon mucosa. Results showed MPs sizes below 160 μm, negative surface charge around -50 mV at pH=6, high rates of swelling and good adhesion. The microparticulate-based fluid exhibited pseudoplastic behavior following the Ostwald-de Waele rheological model. A brief force is sufficient for its injection through a syringe. Finally, formulations were able to provide a submucosa elevation of 1.70 cm for more than 90 min and 120 min in the porcine stomach and colon, respectively.

Matrix tablets based on a novel poly (magnesium acrylate) hydrogel for the treatment of inflammatory bowel diseases

The objective of this work was to evaluate the potential use of a new polymer (PAMgA) in the development sustained release matrix tablets for the treatment of bowel inflammatory diseases. For this purpose, budesonide, a highly lipophilic compound, was used as model drug. Tablets with two reticulation grades of PAMgA (PAMgA 5 and 40) and with 9 mg of budesonide were developed and characterized. All the studies were carried out using biorelevant media (FaSSGF and FaSSIF). Swelling and erosion of PAMgA tablets was influenced by the reticulation grade of the polymer and the biorelevant media assayed, being water uptake higher for PAMgA 40 tablets in intestinal fluid, whereas PAMgA 5 showed more intense erosion in this biorelevant medium. Budesonide was released slowly from PAMgA tablets, both in gastric and intestinal environment, following Super case II transport kinetics (relaxation-controlled delivery), with a lag time of around 1-2 h. When the dissolution medium was changed sequentially throughout the trial, 75% of the budesonide dose was released in a sustained manner between 4 and 20 h of testing from PAMgA tablets, showing a more controlled budesonide release than Entocort® and Budenofalk® (commercially available sustained release formulations of budesonide). In conclusion, PAMgA polymer allows controlling the release of highly lipophilic drugs as budesonide, being an useful excipient for the development of sustained release matrix tablets.

Current Situation and Challenges in Vitreous Substitutes

Vitreo-retinal disorders constitute a significant portion of treatable ocular diseases. These pathologies often require vitreo-retinal surgery and, as a consequence, the use of vitreous substitutes. Nowadays, the vitreous substitutes that are used in clinical practice are mainly divided into gases (air, SF₆ , C₂ F₆ , C₃ F₈ ) and liquids (perfluorocarbon liquids, silicone oils, and heavy silicone oils). There are specific advantages and drawbacks to each of these, which determine their clinical indications. However, developing the ideal biomaterial for vitreous substitution continues to be one of the most important challenges in ophthalmology, and a multidisciplinary approach is required. In this sense, recent research has focused on the development of biocompatible, biodegradable, and injectable hydrogels (natural, synthetic, and smart), which also act as medium and long-term internal tamponade agents. This comprehensive review aims to cover the main characteristics and indications for use of the extensive range of vitreous substitutes that are currently used in clinical practice, before going on to describe the hydrogels that have been developed recently and which have emerged as promising biomaterials for vitreous substitution.

In situ forming and mucoadhesive ophthalmic voriconazole/HPβCD hydrogels for the treatment of fungal keratitis

Fungal keratitis is a severe infectious corneal disease. At present, no voriconazole ophthalmic formulations are approved by the FDA or EMA. This lack of therapeutic options leads to the reformulation of intravenous voriconazole preparations (VFEND®) by the hospital pharmacy departments to prepare the appropriate ophthalmic formulations (pharmacy compounding). However, the limited residence time of these formulations leads to an intensive treatment posology that may increase the occurrence of side effects. In the present study, two different hydrogels were developed and characterized in order to improve the voriconazole's ophthalmic solubility, permanence, and security. Voriconazole-cyclodextrin (HPβCD or HPɣCD) inclusion complexes in aqueous solutions were characterized by NMR and molecular modeling. Complexes were formed by encapsulation of voriconazole into the cyclodextrin's internal cavity which considerably increases its water solubility. Ocular safety was proven by ocular irritation studies. Permeability studies suggest both hydrogels have good corneal permeability. Furthermore, in vivo ocular permanence study by PET/CT showed a longer permanence time on the ocular surface (t_1/2 = 58.91 ± 13.4 min and 96.28 ± 49.11 min for VZHAH and VZISH 0.65 respectively) compared to the voriconazole control formulation (VFEND® t_1/2 = 32.27 ± 15.56 min). Results suggest these formulations are a good alternative for the treatment of fungal keratitis.

Development and Characterization of a Tacrolimus/Hydroxypropyl-β-Cyclodextrin Eye Drop

Uveitis is a vision inflammatory disorder with a high prevalence in developing countries. Currently, marketed treatments remain limited and reformulation is usually performed to obtain a tacrolimus eye drop as a therapeutic alternative in corticosteroid-refractory eye disease. The aim of this work was to develop a mucoadhesive, non-toxic and stable topical ophthalmic formulation that can be safely prepared in hospital pharmacy departments. Four different ophthalmic formulations were prepared based on the tacrolimus/hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complexes’ formation. Phase solubility diagrams, Nuclear Magnetic Resonance (NMR) and molecular modeling studies showed the formation of 1:1 and 1:2 tacrolimus/HPβCD inclusion complexes, being possible to obtain a 0.02% (w/v) tacrolimus concentration by using 40% (w/v) HPβCD aqueous solutions. Formulations also showed good ophthalmic properties in terms of pH, osmolality and safety. Stability studies proved these formulations to be stable for at least 3 months in refrigeration. Ex vivo bioadhesion and in vivo ocular permanence showed good mucoadhesive properties with higher ocular permanence compared to the reference pharmacy compounding used in clinical settings (t_1/2 of 86.2 min for the eyedrop elaborated with 40% (w/v) HPβCD and Liquifilm^® versus 46.3 min for the reference formulation). Thus, these novel eye drops present high potential as a safe alternative for uveitis treatment, as well as a versatile composition to include new drugs intended for topical ophthalmic administration.

Characterization of New Proteomic Biomarker Candidates in Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis type IVA (MPS IVA) is a lysosomal storage disease caused by mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Skeletal dysplasia and the related clinical features of MPS IVA are caused by disruption of the cartilage and its extracellular matrix, leading to a growth imbalance. Enzyme replacement therapy (ERT) with recombinant human GALNS has yielded positive results in activity of daily living and endurance tests. However, no data have demonstrated improvements in bone lesions and bone grow thin MPS IVA after ERT, and there is no correlation between therapeutic efficacy and urine levels of keratan sulfate, which accumulates in MPS IVA patients. Using qualitative and quantitative proteomics approaches, we analyzed leukocyte samples from healthy controls (n = 6) and from untreated (n = 5) and ERT-treated (n = 8, sampled before and after treatment) MPS IVA patients to identify potential biomarkers of disease. Out of 690 proteins identified in leukocytes, we selected a group of proteins that were dysregulated in MPS IVA patients with ERT. From these, we identified four potential protein biomarkers, all of which may influence bone and cartilage metabolism: lactotransferrin, coronin 1A, neutral alpha-glucosidase AB, and vitronectin. Further studies of cartilage and bone alterations in MPS IVA will be required to verify the validity of these proteins as potential biomarkers of MPS IVA.

Recent Research in Ocular Cystinosis: Drug Delivery Systems, Cysteamine Detection Methods and Future Perspectives

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs. Although renal damage prevails during initial stages, the deposition of cystine crystals in the cornea causes severe ocular manifestations. At present, cysteamine is the only topical effective treatment for ocular cystinosis. The lack of investment by the pharmaceutical industry, together with the limited stability of cysteamine, make it available only as two marketed presentations (Cystaran® and Cystadrops®) and as compounding formulations prepared in pharmacy departments. Even so, new drug delivery systems (DDSs) need to be developed, allowing more comfortable dosage schedules that favor patient adherence. In the last decades, different research groups have focused on the development of hydrogels, nanowafers and contact lenses, allowing a sustained cysteamine release. In parallel, different determination methods and strategies to increase the stability of the formulations have also been developed. This comprehensive review aims to compile all the challenges and advances related to new cysteamine DDSs, analytical determination methods, and possible future therapeutic alternatives for treating cystinosis.

3D Printed Tacrolimus Rectal Formulations Ameliorate Colitis in an Experimental Animal Model of Inflammatory Bowel Disease

The aim of this study was to fabricate novel self-supporting tacrolimus suppositories using semisolid extrusion 3-dimensional printing (3DP) and to investigate their efficacy in an experimental model of inflammatory bowel disease. Blends of Gelucire 44/14 and coconut oil were employed as lipid excipients to obtain suppository formulations with self-emulsifying properties, which were then tested in a TNBS (2,4,6-trinitrobenzenesulfonic acid) induced rat colitis model. Disease activity was monitored using PET/CT medical imaging; maximum standardized uptake values (SUVmax), a measure of tissue radiotracer accumulation rate, together with body weight changes and histological assessments, were used as inflammatory indices to monitor treatment efficacy. Following tacrolimus treatment, a significant reduction in SUVmax was observed on days 7 and 10 in the rat colon sections compared to non-treated animals. Histological analysis using Nancy index confirmed disease remission. Moreover, statistical analysis showed a positive correlation (R2 = 71.48%) between SUVmax values and weight changes over time. Overall, this study demonstrates the effectiveness of 3D printed tacrolimus suppositories to ameliorate colitis and highlights the utility of non-invasive PET/CT imaging to evaluate new therapies in the preclinical area.

Bone-Specific Drug Delivery for Osteoporosis and Rare Skeletal Disorders

PURPOSE OF REVIEW

The skeletal system provides an important role to support body structure and protect organs. The complexity of its architecture and components makes it challenging to deliver the right amount of the drug into bone regions, particularly avascular cartilage lesions. In this review, we describe the recent advance of bone-targeting methods using bisphosphonates, polymeric oligopeptides, and nanoparticles on osteoporosis and rare skeletal diseases.

RECENT FINDINGS

Hydroxyapatite (HA), a calcium phosphate with the formula Ca10(PO4)6(OH)2, is a primary matrix of bone mineral that includes a high concentration of positively charged calcium ion and is found only in the bone. This unique feature makes HA a general targeting moiety to the entire skeletal system. We have applied bone-targeting strategy using acidic amino acid oligopeptides into lysosomal enzymes, demonstrating the effects of bone-targeting enzyme replacement therapy and gene therapy on bone and cartilage lesions in inherited skeletal disorders. Virus or no-virus gene therapy using techniques of engineered capsid or nanomedicine has been studied preclinically for skeletal diseases. Efficient drug delivery into bone lesions remains an unmet challenge in clinical practice. Bone-targeting therapies based on gene transfer can be potential as new candidates for skeletal diseases.

PET study of ocular and blood pharmacokinetics of intravitreal bevacizumab and aflibercept in rats

Intravitreal injections are the standard procedure in the treatment of retinal pathologies, such as the administration of the anti-VEGF antibodies in age-related macular degeneration. The aim of this study is to evaluate the intraocular and blood pharmacokinetics after an intravitreal injection of ⁸⁹Zr-labelled bevacizumab and ⁸⁹Zr-labelled aflibercept in Sprague-Dawley rats using Positron Emission Tomography. First, both antibodies were radiolabelled to zirconium-89 with a maximum specific activity of 15 Mbq/mg for bevacizumab and 10 Mbq/mg for aflibercept. Four µL containing 1-1.2 Mq of ⁸⁹Zr-labelled compound were injected into the vitreous through a 35 G needle. A microPET acquisition was carried out immediately after the injection and at different time points through a 12-day study and blood samples were obtained through the tail vein. Radiolabelling was successfully performed with a radiochemical purity after ultrafiltration above 95% for both agents. Both antibodies ocular curves followed a two-compartment model in which an intraocular elimination half-life of 16.44 h was found for ⁸⁹Zr-bevacizumab and 4.51 h for ⁸⁹Zr-aflibercept, considering the alpha phase as the elimination phase. Regarding the beta phase, a half-life of 3.23 days for ⁸⁹Zr-bevacizumab and 4.69 days for ⁸⁹Zr-aflibercept were observed. With regards to blood concentration, ⁸⁹Zr-bevacizumab showed a blood half-life of 7.08 days, whereas ⁸⁹Zr-aflibercept's was 3.18 days, by a one-compartment model with first-order absorption kinetics. In conclusion, this study shows for the first time the ocular and blood pharmacokinetic analysis after intravitreal injection of aflibercept and bevacizumab in rats.

Novel Polymeric Formulation for Removal of Gastrointestinal Polyps by Digestive Endoscopy

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are two techniques used in the resection of gastrointestinal mucosal polyps. The aim of this work is the development and evaluation of an innovative polymeric solution containing sodium carboxymethylcellulose and hyaluronic acid. For this purpose, several mixtures of these two main components, as well as other components such as fructose, citric acid, and zinc, are evaluated in terms of physicochemical and microbiological properties, rheological behavior, extensibility, syringeability, and stability at different storage conditions. Furthermore, the potential production of mucosal elevation and duration is also studied by an ex vivo model using porcine stomach and colon. Results show that the developed polymeric solutions possess optimal values of pH, from 4.58 to 6.63, for their use in the gastrointestinal tract. The formulations exhibit both Newtonian and pseudoplastic behaviors with different viscosity values as a function of their composition. All formulations exhibit high stability properties and no bacterial or fungal growth is detected. MCS01 and MCS05 are the polymeric solutions with the best syringeability results. In this line, MCS05 is the formulation that provides the highest, 2.20 ± 0.18 cm and 1.40 ± 0.11 cm, and longest-lasting, for more than 120 min, elevation effect on porcine submucosal stomach and colon tissues, respectively. Thus, it can be concluded that polymeric solution MCS05 might be considered as a promising tool for use in human EMR and ESD.

Drug Delivery to the Posterior Segment of the Eye: Biopharmaceutic and Pharmacokinetic Considerations

The treatment of the posterior-segment ocular diseases, such as age-related eye diseases (AMD) or diabetic retinopathy (DR), present a challenge for ophthalmologists due to the complex anatomy and physiology of the eye. This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. This review article gives an overview of pharmacokinetic and biopharmaceutics aspects for the most commonly-used ocular administration routes (intravitreal, topical, systemic, and periocular), including information of the absorption, distribution, and elimination, as well as the benefits and limitations of each one. This article also encompasses different conventional and novel drug delivery systems designed and developed to improve drug pharmacokinetics intended for the posterior ocular segment treatment.

Optimization of Drug Permeation from 8% Ciclopirox Cyclodextrin/Poloxamer-Soluble Polypseudorotaxane-Based Nail Lacquers

Cyclodextrin/poloxamer-soluble polypseudorotaxane-based nail lacquers have demonstrated significant capacity for promoting the permeation of drugs into the nail plate. Furthermore, previous studies have shown that the use of hydroalcoholic blends as vehicles promotes drug permeation. The work described herein studies the effect of the type of alcohol used in the lacquer preparation, and the composition of the vehicle is optimized to obtain soluble doses of 8% and to promote the diffusion of ciclopirox base and olamine across the nail. Permeation studies on different types of alcohols show that optimum results are achieved with short-chain alcohols, and that results become less satisfactory the higher the number of alcohol carbons. In addition, solubility and penetration studies on the bovine hoof have enabled the composition of the lacquer to be optimized for both forms of ciclopirox. The results suggest that optimized lacquers have better ciclopirox diffusion and penetration properties than the commercial reference lacquer. Lastly, in vivo studies in which optimized ciclopirox olamine lacquer was applied for 45 days to the nails of healthy volunteers showed that it caused no negative effects or changes to the nail surface. These results demonstrate the significant potential of cyclodextrin/poloxamer-soluble polypseudorotaxane-based nail lacquers for the ungual administration of drugs.

Intravitreal anti-VEGF drug delivery systems for age-related macular degeneration

Age-related macular degeneration is the most common cause of vision loss in elderly people in developed countries. Nowadays, in clinical practice, three anti-VEGF drugs are commonly used (bevacizumab, aflibercept and ranibizumab), requiring repeated intravitreal injections. In order to minimise the number of injections, research on intravitreal drug delivery systems (DDSs) is needed. In this review, the DDSs developed up to date regarding intravitreal anti-VEGF drugs have been summarised, which include systems as hydrogels, liposomes, microparticles, nanoparticles or implants. Most of the studies have focused on the extended in vitro release behaviour of the developed DDSs, but data as antibody bioactivity, biocompatibility or in vivo stability is sometimes scarce. Moreover, as DDS development relies on in vivo pharmacokinetic analyses to evaluate the extended drug release, all the information regarding anti-VEGF intravitreal pharmacokinetics in different animal species have been compiled.

Evaluation of the therapeutic activity of melatonin and resveratrol in Inflammatory Bowel Disease: A longitudinal PET/CT study in an animal model

Inflammatory Bowel Disease (IBD) is a group of chronic disorders of the gastrointestinal tract, which two main types are Crohn's disease and ulcerative colitis. Although conventional therapeutic strategies have demonstrated to be effective in the IBD treatment, it is necessary to incorporate novel therapeutic agents that target other mechanisms involved in the pathogenesis of the disease, such as oxidative stress. For this reason, the efficacy in vivo of two antioxidant compounds, melatonin and resveratrol, has been investigated in an animal model of TNBS (2, 4, 6-trinitrobenzenesulfonic acid) induced colitis. PET/CT (Positron emission tomography/Computer Tomography) scans were performed to assess disease activity and evaluate treatment response. SUV_max (Standardized Uptake Value) values, body weight changes and histological evaluation were used as inflammatory indices to measure the efficacy of both treatments. SUV_max values increased rapidly after induction of colitis, but after the beginning of the treatment (day 3) a statistically significant decrease was observed on days 7 and 10 in treated animals compared to the non-treated group. This remission of the disease was also confirmed by histological analysis of the colon tissue using the Nancy histological index (p value < 0.05 for differences between non-treated and both groups of treated animals). Moreover, statistical analysis showed a correlation (R² = 65.52%) between SUV_max values and weight changes throughout the treatment. Overall, this study demonstrates the potential of resveratrol, and melatonin in lower extent, as therapeutic agents in the IBD treatment.

Proteomic Analysis in Morquio A Cells Treated with Immobilized Enzymatic Replacement Therapy on Nanostructured Lipid Systems

Morquio A syndrome, or mucopolysaccharidosis type IVA (MPS IVA), is a lysosomal storage disease due to mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Systemic skeletal dysplasia and the related clinical features of MPS IVA are due to disruption of cartilage and its extracellular matrix, leading to an imbalance of growth. Enzyme replacement therapy (ERT) with recombinant human GALNS, alpha elosulfase, provides a systemic treatment. However, this therapy has a limited impact on skeletal dysplasia because the infused enzyme cannot penetrate cartilage and bone. Therefore, an alternative therapeutic approach to reach the cartilage is an unmet challenge. We have developed a new drug delivery system based on a nanostructure lipid carrier with the capacity to immobilize enzymes used for ERT and to target the lysosomes. This study aimed to assess the effect of the encapsulated enzyme in this new delivery system, using in vitro proteomic technology. We found a greater internalization of the enzyme carried by nanoparticles inside the cells and an improvement of cellular protein routes previously impaired by the disease, compared with conventional ERT. This is the first qualitative and quantitative proteomic assay that demonstrates the advantages of a new delivery system to improve the MPS IVA ERT.

Pharmacokinetics of Intravitreal Anti-VEGF Drugs in Age-Related Macular Degeneration

Intravitreal administration of anti-vascular endothelial growth factor (VEGF) antibodies has become the standard treatment for Age-Related Macular Degeneration; however, the knowledge of their pharmacokinetics is limited. A comprehensive review of the preclinical and clinical pharmacokinetic data that were obtained in different studies with intravitreal bevacizumab, ranibizumab, and aflibercept has been conducted. Moreover, the factors that can influence the vitreous pharmacokinetics of these drugs, as well as the methods that were used in the studies for analytical determination, have been exposed. These anti-VEGF drugs present different charge and molecular weights, which play an important role in vitreous distribution and elimination. The pharmacokinetic parameters that were collected differ depending on the species that were involved in the studies and on physiological and pathological conditions, such as vitrectomy and lensectomy. Knowledge of the intravitreal pharmacokinetics of the anti-VEGF drugs that were used in clinical practice is of vital importance.

Ocular Biodistribution Studies using Molecular Imaging

Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.

Effect of Penetration Enhancers on Drug Nail Permeability from Cyclodextrin/Poloxamer-Soluble Polypseudorotaxane-Based Nail Lacquers

Nail delivery has interest for local treatment of nail diseases. Nevertheless, the low permeability of drugs in the nail plaque precludes the efficacy of local treatments. The use of penetration enhancers can increase drug permeability and improve the efficacy of the treatment of nail pathologies. In this work, different chemical substances have been evaluated as potential penetration enhancers. With this aim, the effect of different substances such as sodium lauryl sulfate (SLS), polyethylene glycol 300 (PEG 300), carbocysteine, N-acetylcysteine, lactic acid, potassium phosphate, Labrasol® and Labrafil® in the microstructure, nail surface and drug permeability has been evaluated. The models obtained by mercury intrusion porosimetry and PoreXpert™ software show a more porous structure in nails treated with different enhancers. Permeation studies with bovine hooves and nails revealed that all the hydroalcoholic lacquers developed, and particularly those prepared with SLS, provide better nail penetration of the drugs ciclopirox olamine and clobetasol propionate. Results have shown that the increase of the drug penetration in the nail is caused by the formation of a porous random microstructure and by the decrease of the contact angle between lacquers and the surface or the nail plaque. The presence of SLS produces an improvement in the spreading of the solution on the nail surface and promotes the penetration of the solution into the nail pores. The hydroalcoholic lacquer, elaborated with cyclodextrin/poloxamer soluble polypseudorotaxane and sodium lauryl sulfate as an enhancer, allowed the rate of diffusion and penetration of the active ingredient within the nail to be significantly higher than obtained with the reference lacquers when using either ciclopirox olamine or clobetasol propionate as the active ingredient.

Polyurethanes as New Excipients in Nail Therapeutics

Onychomycosis affects about 15% of the population. This disease causes physical and psychosocial discomfort to infected patients. Topical treatment (creams, solutions, gels, colloidal carriers, and nail lacquers) is usually the most commonly required due to the high toxicity of oral drugs. Currently, the most common topical formulations (creams and lotions) present a low drug delivery to the nail infection. Nail lacquers appear to increase drug delivery and simultaneously improve the effectiveness of treatment with increased patient compliance. These formulations leave a polymer film on the nail plate after solvent evaporation. The duration of the film residence in the nail constitutes an important property of nail lacquer formulation. In this study, a polyurethane polymer was used to delivery antifungals drugs, such as terbinafine hydrochloride (TH) and ciclopirox olamine (CPX) and the influence of its concentration on the properties of nail lacquer formulations was assessed. The nail lacquer containing the lowest polymer concentration (10%) was the most effective regarding the in vitro release, permeation, and antifungal activity. It has also been demonstrated that the application of PU-based nail lacquer improves the nail plate, making it smooth and uniform and reduces the porosity contributing to the greater effectiveness of these vehicles. To conclude, the use of polyurethane in nail formulations is promising for nail therapeutics.

PEGylated PLGA Nanoparticles As a Smart Carrier to Increase the Cellular Uptake of a Coumarin-Based Monoamine Oxidase B Inhibitor

Despite research efforts to discover new drugs for Parkinson treatment, the majority of candidates fail in preclinical and clinical trials due to inadequate pharmacokinetic properties, namely blood-brain barrier permeability. Within the high demand to introduce new drugs to market, nanotechnology can be used as a solution. Accordingly, PEGylated PLGA nanoparticles (NPs) were used as a smart delivery carrier to solve the suboptimal aqueous solubility, which precludes its use in in vivo assays, of a potent, reversible, and selective monoamine oxidase B inhibitor (IMAO-B) (coumarin C75, IC₅₀ = 28.89 ± 1.18 nM). Long-term stable PLGA@C75 NPs were obtained by nanoprecipitation method, with sizes around 105 nm and a zeta potential of -10.1 mV. The encapsulation efficacy was around 50%, achieving the final C75 concentration of 807 ± 30 μM in the nanoformulation, which corresponds to a therapeutic concentration 27828-fold higher than its IC₅₀ value. Coumarin C75 showed cytotoxic effects at 50 μM after 48 and 72 h of exposure in SH-SY5Y, Caco-2, and hCMEC/D3 cell lines. Remarkably, no cytotoxic effects were observed after nanoencapsulation. Furthermore, the data obtained from the P-gp-Glo assay and the cellular uptake studies showed that C75 is a P-glycoprotein (P-gp) substrate having a lower uptake profile in intestinal and brain endothelial cells. Moreover, it was shown that this membrane transporter influences C75 permeability profile in Caco-2 and hCMEC/D3 cells. Interestingly, PLGA NPs inhibited P-gp and were able to cross intestinal and brain membranes allowing the successful transport of C75 through this type of biological barriers. Overall, this work showed that nanotechnology can be used to solve drug discovery related drawbacks.

Vaginal residence and pharmacokinetic preclinical study of topical vaginal mucoadhesive W/S emulsions containing ciprofloxacin

The aim of this work is to test the in vivo behavior of a mucoadhesive vaginal emulsion resistant to the clearance of vaginal fluids using ciprofloxacin (CPX) as an anti-infective model of drug. CPX is a broad-spectrum antibiotic used in the treatment of sexual tissues infections, as intravenous injection in a dose of 20 mg every 12 h. In this study, CPX was incorporated in water in silicone (W/S) mucoadhesive emulsions and the in vivo residence time and the CPX in vivo absorption and distribution to the sexual organs was studied using the rat as animal model. W/S emulsion shows excellent in vitro bioadhesion having high resistance to the vaginal fluids clearance. The drug release profiles show a constant release of CPX during at least 6 h according to a zero-order kinetics. In vivo computerized PET/CT Image Analysis after intravaginal administration to rats indicates that W/S emulsions remain in the vaginal area for a long time and shows a good absorption of the radiotracers used as markers through the vaginal mucosa. Ciprofloxacin pharmacokinetic studies developed after the single intravaginal administration of W/S emulsion shows a good absorption and distribution of CPX on the uterus and ovarian tissue. A significant concentration of CPX in the sexual tissues was observed after 24 h of administration of W/S emulsion. Therefore, W/S emulsions have a good in vivo residence and drug release in the vaginal mucosae showing a great potential for the treatment of sexual tissues infections, as vaginal bioadhesive delivery systems of antinfectious drugs.

Effect on Nail Structure and Transungual Permeability of the Ethanol and Poloxamer Ratio from Cyclodextrin-Soluble Polypseudorotaxanes Based Nail Lacquer

Aqueous-based nail lacquers have shown potential in promoting the diffusion of drugs into the nail. In our laboratory, we have recently developed a transungual delivery system based on an aqueous dispersion of cyclodextrin-poloxamer soluble polypseudorotaxanes, supramolecular host−guest assemblies that improves the drug permeation into the nail. However, the high-water content and the rheological and adhesive properties of this lacquer negatively affect properties that play a fundamental role in the patients’ acceptance such as stickiness, nail film formation or drying rate, properties. In this work, we have optimized the composition of these lacquers to improve these properties whilst maintaining good drug permeation profiles. Incorporating ethanol into the vehicle and reducing the proportion of Poloxamer 407 (PL), provided a good strategy. The use of hydro-ethanolic mixtures (>50% ethanol) and the reduction of the poloxamer concentration significantly improved the lacquer drying speed by reducing the stickiness and promoting film formation on the nail surface. Additionally, in a surprising way, the use of hydro-ethanolic vehicles further enhanced the permeation of ciclopirox olamine and clobetasol propionate, used for the treatment of onychomycosis and nail psoriasis respectively, into the nail and hooves.

Preclinical characterization and clinical evaluation of tacrolimus eye drops

Severe allergic ocular diseases as atopic keratoconjunctivitis can induce corneal damage due to inflammatory substances released from giant papillae. Tacrolimus eye drops are one of the current therapeutic alternatives for its treatment. This work is aimed at developing and characterizing a 0.03% tacrolimus ophthalmic formulation, which was introduced in three types of vehicles (BBS, PVA and Hyaluronic Acid). For this, we have performed in vitro (stability studies) and in vivo assays (corneal permanence time measured directly by Positron Emission Tomography) of three potential formulations. Next, the best formulation was selected, and its toxicological profile and clinical effectiveness have been evaluated. The biopermanence studies (direct measurements and PET/CT) showed that the formulations with PVA and Hyaluronic Acid present more retention time on the ocular surface of rats than PBS. From the stability study, we have determined that tacrolimus with PVA in cold storage is the best option. Tacrolimus with PVA has shown lower cytotoxicity than cyclosporine at early times. On the other hand, the pilot study performed has shown significant improvements in patients, with no noticeable adverse reactions. Based on stability, biopermanence, safety and clinical effectiveness studies, we concluded that tacrolimus-PVA eye drops are a suitable candidate for its clinical application in inflammatory ophthalmology diseases.

Ophthalmic Econazole Hydrogels for the Treatment of Fungal Keratitis

Econazole is a feasible alternative treatment in the management of fungal keratitis. Nevertheless, its low water solubility is considered the main limitation to the incorporation into ophthalmic formulations. In this work, econazole nitrate is solubilized by using cyclodextrins to achieve an optimum therapeutic concentration. Phase solubility diagrams suggest α-cyclodextrin as the most effective cyclodextrin and later the inclusion complex formed with this one was characterized in solution by 1D, 2D-NMR, and molecular modeling. Econazole-α-cyclodextrin inclusion complex was included in 2 types of ocular hydrogels: a natural polysaccharides ion-sensitive hydrogel and a hyaluronic acid hydrogel. Both of them show no ocular irritation in the hen's egg test on chorioallantoic membrane assay and a controlled econazole release over time. Permeability studies suggest that hydrogels do not modify the econazole nitrate permeability through bovine cornea in comparison with an econazole-α-cyclodextrin inclusion complex solution. Finally, ocular biopermanence studies performed using positron emission tomography show these hydrogels present a high retention time on the eye. Results suggest the developed formulations have a high potential as vehicles for the econazole topical ocular administration as fungal keratitis treatment.

Pharmacokinetic model of florfenicol in turbot (Scophthalmus maximus): establishment of optimal dosage and administration in medicated feed

The pharmacokinetics of florfenicol (FF) in turbot (Scophthalmus maximus) was studied after single intravenous (10 mg kg^-1 ) and oral (100 mg kg^-1 ) administration. The plasma concentration-time data of florfenicol were described by an open one-compartment model. The elimination half-life (t_1/2 ) was estimated to be 21.0 h, and the total body clearance, Cl, was determined as 0.028 L kg h^-1 . The apparent volume distribution (V_d ) was calculated to be 0.86 L kg^-1 and the mean residence time (MRT_iv ) was 30.2 h. Following oral administration, the maximum plasma concentration (C_max ) of 55.4 μg mL^-1 was reached at 12 h (T_max ). The absorption constant (k_a ) was 0.158 h^-1 . The bioavailability was estimated to be 57.1%. The low bioavailability observed at higher doses was explained by the saturation of the mechanisms of absorption. The drug absorption process was limited by its inherent low solubility, which limited the amount of available FF absorbed in the gastrointestinal tract. Based on the pharmacokinetic data, an optimal dosing schedule for FF administration is hereby provided. Based on the minimum inhibitory concentration found for susceptible strains of Aeromonas salmonicida, oral FF administration of first, an initial dose of 30 mg FF kg^-1 , followed by 6 maintenance doses at 18 mg kg^-1 /daily could be effective against furunculosis in turbot.

Evaluation of the in vitro ocular toxicity of the fortified antibiotic eye drops prepared at the Hospital Pharmacy Departments

The use of parenteral antibiotic eye drop formulations with non-marketed compositions or concentrations, commonly called fortified antibiotic eye drops, is a common practice in Ophthalmology in the hospital setting. The aim of this study was to evaluate the in vitro ocular toxicity of the main fortified antibiotic eye drops prepared in the Hospital Pharmacy Departments. We have conducted an in vitro experimental study in order to test the toxicity of gentamicin, amikacin, cefazolin, ceftazidime, vancomycin, colistimethate sodium and imipenem-cilastatin eye drops; their cytotoxicity and acute tissue irritation have been evaluated. Cell-based assays were performed on human stromal keratocytes, using a cell-based impedance biosensor system [xCELLigence Real-Time System Cell Analyzer (RTCA)], and the Hen's Egg Test for the ocular irritation tests. All the eye drops, except for vancomycin and imipenem, have shown a cytotoxic effect dependent on concentration and time; higher concentrations and longer exposure times will cause a steeper decline in the population of stromal keratocytes. Vancomycin showed a major initial cytotoxic effect, which was reverted over time; and imipenem appeared as a non-toxic compound for stromal cells. The eye drops with the highest irritating effect on the ocular surface were gentamicin and vancomycin. Those antibiotic eye drops prepared at the Hospital Pharmacy Departments included in this study were considered as compounds potentially cytotoxic for the ocular surface; this toxicity was dependent on the concentration used.

Ocular safety comparison of non-steroidal anti-inflammatory eye drops used in pseudophakic cystoid macular edema prevention

Non-steroidal anti-inflammatory drug (NSAID) eye drops are widely used to treat ocular inflammatory conditions related to ophthalmic surgical procedures, such as pseudophakic cystoid macular edema, and they have been used for off-label treatments. The most commonly used NSAIDs are diclofenac and ketorolac and the new molecules bromfenac and nepafenac have also been used. We used primary human keratocytes in cell culture in combination with a novel technology that evaluates dynamic real-time cytotoxicity through impedance analysis. This study also included classic cell viability tests (WST-1(®) and AlamarBlue(®)), wound healing assay, Hen's Egg Test and an ex vivo histopathological assay. NSAIDs were shown to have important cytotoxicities and to retard the healing response. Furthermore, the new eye drops containing bromfenac and nepafenac were more cytotoxic than the more classical eye drops. Nevertheless, no immuno-histochemical changes or acute irritation processes were observed after the administration of any eye drops tested. Due to cytotoxicity and the total absence of discomfort and observable injuries after the administration of these drugs, significant corneal alterations, such as corneal melts, can develop without any previous warning signs of toxicity.

Use of 1H NMR STD, waterLOGSY, and Langmuir monolayer techniques for characterization of drug-zein protein complexes

Zein is a protein based natural biopolymer containing a large amount of nonpolar amino acids, which has shown the ability to form aggregates and entrap solutes, such as drugs and amino acids to form stable protein-drug complexes. In this work, π-A isotherm, NMR, and Dynamic light scattering were used to detect the formation of protein aggregates and the affinity between zein and two different drugs: tetracycline and indomethacin. An effective interaction of zein and the two drugs was evidenced by means of liquid NMR reinforced by means of changes in the surface pressure by π-A isotherm. The effective interactions zein/drugs under air/water interface were evidenced as a change in the surface pressure of the π-A isotherm of zein in the presence of drug solutions. The presence of tetracycline in the subphase decreased the area occupied by the monolayer at the expanded region until pressures of 12 mN/m were the areas became similar, but indomethacin produces an increment of the area in both expanded and collapsed region. The feasible methodology employed, focused in the functionality of the protein-drug interaction, can be very promising in the drug delivery field.

Competitive displacement of drugs from cyclodextrin inclusion complex by polypseudorotaxane formation with poloxamer: implications in drug solubilization and delivery

The competitive interactions between the poly-[propylene oxide] (POO)-poly-[ethylene oxide] (PEO) block copolymer poloxamer 407 (Pluronic F127) and two drugs, triamcinolone acetonide and ciclopirox olamine, by the formation of inclusion complexes with two cyclodextrin hydrophilic derivatives, hydroxypropyl-β-cyclodextrin (HPβCD; molar substitution (MS) 0.65) and partially methylated-β-cyclodextrin (MβCD; MS 0.57), were studied by means of one-dimensional (1)H NMR, 2D ROESY experiments, solubility studies and drug release studies. 1D and 2D NMR and solubility studies indicate that both triamcinolone acetonide and ciclopirox olamine form stable inclusion complexes with the cyclodextrin derivatives. In the case of ciclopirox olamine the complex was more stable at pH 1. Effective complexation of poloxamer with the two cyclodextrins (CDs) was also evidenced by NMR analysis, and competitive displacement of the drugs from the CD cavity by the polymer was observed. Drug solubility in CD solutions was not modified by the addition of polymers, indicating that a decrease in solubility due to the competitive displacement is probably compensated by the solubilizing effect of polymer micellization. Finally, polypseudorotaxanes formation has a significant influence on the release of the drugs studied. Changes in the release rate depend on the stability of drug-CD inclusion complex and on cyclodextrin concentration in the bulk solution; so polypseudorotaxane formation can be employed to modulate drug controlled release from thermosensitive hydrogels.

Cyclodextrins: more than pharmaceutical excipients

Cyclodextrins are pharmaceutical excipients used to enhance the solubility, stability, safety and bioavailability of drugs. Recent findings have shown them to display adjuvant activity in vaccine therapy and prophylactic and therapeutic activity in the treatment of several host-pathogen infections. This article focuses on their activity and mechanism of action.

Fast and Controlled Release of Triamcinolone Acetonide from Extrusion-Spheronization Pellets Based on Mixtures of Native Starch with Dextrin or Waxy Maize Starch

Pellets composed chiefly of inexpensive starches allow modulation of the rate of release of the poorly soluble drug triamcinolone acetonide in media of pH 1.2-6.8. Wheat- or maize-starch-based pellets with 20% of white dextrin release the drug in vitro almost completely within 20 min, while maize-starch-based pellets with 5-35% of waxy maize starch sustain gradual release over periods of 9-12 hr or longer when prepared using appropriate amounts of granulation fluid.

Microscopic image analysis techniques for the morphological characterization of pharmaceutical particles: Influence of the software, and the factor algorithms used in the shape factor estimation

The present report highlights the difficulties of particle shape characterizations of multiparticulate systems obtained using different image analysis techniques. The report describes and discusses a number of shape factors that are widely used in pharmaceutical research. Using photographs of 16 pellets of different shapes, obtained by extrusion-spheronization, we investigated how shape factor estimates vary depending on method of calculation, and among different software packages. The results obtained indicate that the algorithms used (both for estimation of basic dimensions such as perimeter and maximum diameter, and for estimation of shape factors on the basis of these basic dimensions) have marked influences on the shape factor values obtained. These findings suggest that care is required when comparing results obtained using different image analysis programs.

Microscopic image analysis techniques for the morphological characterization of pharmaceutical particles: Influence of process variables

This study investigated the effects of various process variables on some of the shape factors most widely used in the morphological characterization of pharmaceutical particles (including circularity, aspect ratio, er, and the recently proposed Vr and Vp). After optimization of the illumination system and greyscale thresholds for discrimination of particle background, we evaluated the effects of process variables within the image capture and analysis system, including the image capture device (video or digital camera), image color information (24-bits-per-pixel RGB or 8-bits-per-pixel black and white), file type (JPG or TIFF), and JPG file compression ratio. A key aspect was evaluation of the effect of scaling factor (microm/pixel), dependent on real pixel size and optical magnification, on shape factor estimates. The results obtained indicate that accurate estimation of shape factors requires use of a scaling factor below a certain maximum; however, use of very low scaling factors will mean that the field of view is very small, so that it will contain very few particles, implying a time-consuming increase in the number of images that must be analyzed. Finally, we use statistical procedures to estimate the minimum number of particles that must be analyzed in order to provide accurate estimates of shape factors.

Image Analysis of the Shape of Granulated Powder Grains

This study presents and evaluates two new form factors for the characterization of pharmaceutical microparticles using image analysis techniques. The first factor, denoted Vr, is mean percentage variation in radial chord length (for a large number of radial chords drawn at small angular intervals) with respect to mean radial chord length. The second factor, denoted Vp, is percentage deviation of measured perimeter from the perimeter of a circle with radius equal to the mean radial chord length of the particle. Considering both ideal shapes and real pharmaceutical particle populations, these factors are compared with other form factors widely used in pharmaceutical technology. Our results indicate that Vr and Vp allow effective assessment of whether the particles of a given population show pharmaceutically significant deviations from sphericity. The two factors additionally facilitate identification of the basic shapes of particle outlines (notably ellipsoid, rectangular, and irregular). These factors may thus be of value for the characterization and monitoring of pharmaceutical pelleting processes.

Anticryptosporidial Activity of Furan Derivative G1 and Its Inclusion Complex with Beta-Cyclodextrin

The capacity of beta-cyclodextrin (betaCD) to form a complex with a new furanic derivative, G1, was investigated. Interactions of the drug and betaCD in solution and in the solid state were studied using phase solubility techniques, thermal methods, X-ray, and IR spectroscopy. Preparation of a kneaded mix of G1/betaCD increased both the aqueous solubility and the dissolution rate of the furan derivative. The anticryptosporidial efficacies of the drug and of the inclusion complex were evaluated using a suckling murine model. Oral administration of G1 considerably decreased the intensity of the infection, but betaCD showed similar anticryptosporidial activity to that of the betaCD-G1 complex and higher activity than G1 alone.