Nasal mucociliary clearance as a factor in nasal drug delivery

Nasal Vaccine Delivery

The mucosal surfaces represent the major site of entry of many pathogens, and major challenges in vaccine development include safety and stability in a suitable dosage form. Micro- and nanocarrier-based delivery systems as nasal vaccines induce humoral, cellular, and mucosal immunity. The nasal route of vaccination could also offer immunity at several distant mucosal sites (oral, rectal, vaginal, and pulmonary), which is considered a simplified and cost-effective mode of vaccination with enhanced patient compliance. Most of the nasal vaccine delivery systems in the form of microparticulates, nanoparticulates, and liposomes are currently under development and prove to offer immunity in animal models. The importance and potential of the nasal route of administration for vaccines is unexplored, and this chapter outlines the opportunities, challenges, and potential delivery solutions to facilitate the development of improved nasal vaccines for infectious diseases.

Nasal drug delivery: Design of a novel mucoadhesive and in situ gelling polymer

The aim of the present study was to establish a novel polymeric excipient for liquid nasal dosage forms exhibiting viscosity increasing properties, improved mucoadhesion and stability towards oxidation in solution. In order to achieve this goal, 2-mercaptonicotinic acid was first coupled to l-cysteine by disulfide exchange reaction and after purification directly attached to the polymeric backbone of xanthan gum by carbodiimide mediated amide bond formation. The resulting conjugate was characterized with respect to the amount of coupled ligand, the in situ gelling behavior, mucoadhesive properties and stability towards oxidation. Furthermore, the influence of preactivated polymers on ciliary beat frequency (CBF) of porcine nasal epithelial cells was investigated. Results showed, that 252.52±20.54μmol of the ligand was attached per gram polymer. No free thiol groups could be detected on the polymeric backbone indicating entire preactivation. Rheological investigations of polymer mucus mixtures revealed a 1.7-fold and 2.5-fold enhanced mucoadhesion of entirely preactivated xanthan (Xan-Cys-MNA) compared to thiolated xanthan (Xan-Cys) and unmodified xanthan (Xan). Tensile force evaluation reported a 2.87 and 5.11-fold higher total work of adhesion (TWA) as well as a 1.63 and 2.41-fold higher maximum detachement force of Xan-Cys-MNA compared to Xan-Cys and Xan. In the presence of H₂O₂ as an oxidizing agent Xan-Cys-MNA showed unlike Xan-Cys no increase in viscosity, indicating high stability towards oxidation. Addition of CaCl₂ to Xan-Cys-MNA solutions caused a decrease in viscosity at nevertheless higher total viscosity. Results from CBF studies proved nasal safety for the novel conjugate. According to these results, entirely preactivated thiolated xanthan gum seems to be a promising excipient for nasal dosage forms in order to improve drug bioavailability.

Heterotopic Mucosal Grafting Enables the Delivery of Therapeutic Neuropeptides Across the Blood Brain Barrier

BACKGROUND

The blood-brain barrier represents a fundamental limitation in treating neurological disease because it prevents all neuropeptides from reaching the central nervous system (CNS). Currently, there is no efficient method to permanently bypass the blood-brain barrier.

OBJECTIVE

To test the feasibility of using nasal mucosal graft reconstruction of arachnoid defects to deliver glial-derived neurotrophic factor (GDNF) for the treatment of Parkinson disease in a mouse model.

METHODS

The Institutional Animal Care and Use Committee approved this study in an established murine 6-hydroxydopamine Parkinson disease model. A parietal craniotomy and arachnoid defect was repaired with a heterotopic donor mucosal graft. The therapeutic efficacy of GDNF (2 μg/mL) delivered through the mucosal graft was compared with direct intrastriatal GDNF injection (2 μg/mL) and saline control through the use of 2 behavioral assays (rotarod and apomorphine rotation). An immunohistological analysis was further used to compare the relative preservation of substantia nigra cell bodies between treatment groups.

RESULTS

Transmucosal GDNF was equivalent to direct intrastriatal injection at preserving motor function at week 7 in both the rotarod and apomorphine rotation behavioral assays. Similarly, both transmucosal and intrastriatal GDNF demonstrated an equivalent ratio of preserved substantia nigra cell bodies (0.79 ± 0.14 and 0.78 ± 0.09, respectively, P = NS) compared with the contralateral control side, and both were significantly greater than saline control (0.53 ± 0.21; P = .01 and P = .03, respectively).

CONCLUSION

Transmucosal delivery of GDNF is equivalent to direct intrastriatal injection at ameliorating the behavioral and immunohistological features of Parkinson disease in a murine model. Mucosal grafting of arachnoid defects is a technique commonly used for endoscopic skull base reconstruction and may represent a novel method to permanently bypass the blood-brain barrier.

Nasal drug absorption from powder formulations: The effect of three types of hydroxypropyl cellulose (HPC)

Despite the numerous advantages of powder formulations, few studies have described their nasal drug absorption. The first aim of this study was to compare the drug absorption from powder formulation with that from a liquid formulation in rats. Since pharmaceutical excipients are usually added to most powder formulations, the second aim of the study was to investigate the effect of hydroxypropyl cellulose (HPC) on nasal drug absorption from the powder. Three types of HPC with different polymerization degrees were used: HPC(SL), HPC(M), and HPC(H). The model drugs were warfarin (BCS Class I), piroxicam (BCS Class II), and sumatriptan (BCS Class III). The absorption of these model drugs in the powder form was higher than that from the solution. All HPCs failed to enhance warfarin absorption, while the piroxicam absorption was enhanced only by HPC(M). Sumatriptan absorption was not enhanced by HPC(SL), but by HPC(M) and HPC(H). The differences in nasal absorption of the three model drugs promoted by HPCs depend on the permeability and solubility of the drug. Moreover, the nasal retention of different formulations was increased by HPCs. Because HPCs showed no toxic effect on the nasal epithelium. These findings indicate that powder formulations supplemented with HPC are a valuable and promising approach to increase the nasal absorption of highly soluble and poorly permeable drugs.

Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption

The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules.

Biomineralized vaccine nanohybrid for needle-free intranasal immunization

Frequent outbreaks and the rapid global spread of infectious diseases have increased the urgent need for massive vaccination especially in countries with limited resources. Intranasal vaccination facilitates the mass vaccination via needle-free delivery of vaccine through nasal mucosal surfaces. Inspired by the strong capability of calcium phosphate (CaP) materials to adhere to cells and tissues, we propose to improve nasal vaccination by using a biomineralization-based strategy. The vaccine nanohybrid was obtained by covering the viral surface with CaP nanoshell, which changed the physiochemical properties of original vaccine, resulting in the increase of mucosal adhesion to the nasal tissues. The core-shell structure was beneficial for the receptor-independent uptake and the induction of elevated local IgA response within the nasal cavity. Moreover, the vaccine complex elicited enhanced systemic antibody response that neutralized wild type of dengue virus and promoted the systemic cellular immune responses. This achievement presents the potential of CaP based vaccine biomineralization for the fabrication of needle-free vaccine formulation.

Application of RPMI 2650 nasal cell model to a 3D printed apparatus for the testing of drug deposition and permeation of nasal products

The aim of this study was to incorporate an optimized RPMI2650 nasal cell model into a 3D printed model of the nose to test deposition and permeation of drugs intended for use in the nose. The nasal cell model was optimized for barrier properties in terms of permeation marker and mucus production. RT-qPCR was used to determine the xenobiotic transporter gene expression of RPMI 2650 cells in comparison with primary nasal cells. After 14days in culture, the cells were shown to produce mucus, and to express TEER (define) values and sodium fluorescein permeability consistent with values reported for excised human nasal mucosa. In addition, good correlation was found between RPMI 2650 and primary nasal cell transporter expression values. The purpose-built 3D printed model of the nose takes the form of an expansion chamber with inserts for cells and an orifice for insertion of a spray drug delivery device. This model was validated against the FDA glass chamber with cascade impactors that is currently approved for studies of nasal products. No differences were found between the two apparatus. The apparatus including the nasal cell model was used to test a commercial nasal product containing budesonide (Rhinocort, AstraZeneca, Australia). Drug deposition and transport studies on RPMI 2650 were successfully performed. The new 3D printed apparatus that incorporates cells can be used as valid in vitro model to test nasal products in conditions that mimic the delivery from nasal devices in real life conditions.

A review of intranasal formulations for the treatment of seizure emergencies

Epileptic seizure emergencies are life-threatening conditions, which in their most severe form, status epilepticus, have a high mortality rate if not quickly terminated. Treatment requires rapid delivery of anti-epileptics such as benzodiazepines to the brain. The nasal route is attractive due to its non-invasiveness, potential for direct nose to brain delivery, high vascularity, relatively large absorptive surface area, and avoidance of intestinal/liver metabolism. However, the limited volume of the nasal cavity and poor water solubility of anti-epileptics restrict absorption, leading to insufficient therapeutic brain levels. This review covers various formulation approaches adopted to improve nasal delivery of drugs, especially benzodiazepines, used to treat seizure emergencies. Other general topics such as nasal anatomy, challenges to nasal delivery, and drug/formulation considerations for nose to brain delivery are also discussed.

An open-label randomised controlled trial on the efficacy of adding intranasal fentanyl to intravenous tramadol in patients with moderate to severe pain following acute musculoskeletal injuries

INTRODUCTION

The use of intranasal fentanyl as an alternative type of analgesia has been shown to be effective in paediatric populations and prehospital settings. There are a limited number of studies on the use of intranasal fentanyl in adult patients in emergency settings.

METHODS

An open-label study was conducted to evaluate the effectiveness of the addition of 1.5 mcg/kg intranasal fentanyl to 2 mg/kg intravenous tramadol (fentanyl + tramadol arm, n = 10) as compared to the administration of 2 mg/kg intravenous tramadol alone (tramadol-only arm, n = 10) in adult patients with moderate to severe pain due to acute musculoskeletal injuries.

RESULTS

When analysed using the independent t-test, the difference between the mean visual analogue scale scores pre-intervention and ten minutes post-intervention was 29.8 ± 8.4 mm in the fentanyl + tramadol arm and 19.6 ± 9.7 mm in the tramadol-only arm (t[18] = 2.515, p = 0.022, 95% confidence interval 1.68-18.72 mm). A statistically significant, albeit transient, reduction in the ten-minute post-intervention mean arterial pressure was noted in the fentanyl + tramadol arm as compared to the tramadol-only arm (13.35 mmHg vs. 7.65 mmHg; using Mann-Whitney U test with U-value 21.5, p = 0.029, r = 0.48). There was a higher incidence of transient dizziness ten minutes after intervention among the patients in the fentanyl + tramadol arm.

CONCLUSION

Although effective, intranasal fentanyl may not be appropriate for routine use in adult patients, as it could result in a significant reduction in blood pressure.

Ion activated in situ gel of gellan gum containing salbutamol sulphate for nasal administration

Nasal delivery is the promising approach for rapid onset of action and avoids the first pass metabolism. The main aim of present study was to develop a novel mucoadhesive in situ gel of salbutamol sulphate using gellan gum and hydroxylpropyl methyl cellulose (HPMC) for nasal administration. The formulations were prepared so as to have gelation at physiological ion content after nasal administration. Developed formulations were evaluated for gelation, viscosity, drug content, in vitro mucoadhesion, in vitro drug release study, ex vivo permeation, and histopathology. Formulations showed pH in the range of nasal cavity and optimum viscosity for nasal administration. The mucoadhesive force depends upon concentration of HPMC and drug release was found to be 97.34% in 11h. The histopathology did not detect any damage during ex vivo permeation studies. Hence, in situ gel system of gellan gum may be a promising approach for nasal delivery of salbutamol sulphate for therapeutic improvement.

Salivary Oxytocin Concentrations in Males following Intranasal Administration of Oxytocin: A Double-Blind, Cross-Over Study

The use of intranasal oxytocin (OT) in research has become increasingly important over the past decade. Although researchers have acknowledged a need for further investigation of the physiological effects of intranasal administration, few studies have actually done so. In the present double-blind cross-over study we investigated the longevity of a single 24 IU dose of intranasal OT measured in saliva in 40 healthy adult males. Salivary OT concentrations were significantly higher in the OT condition, compared to placebo. This significant difference lasted until the end of testing, approximately 108 minutes after administration, and peaked at 30 minutes. Results showed significant individual differences in response to intranasal OT administration. To our knowledge this is the largest and first all-male within-subjects design study to demonstrate the impact of intranasal OT on salivary OT concentrations. The results are consistent with previous research in suggesting that salivary OT is a valid matrix for OT measurement. The results also suggest that the post-administration ‘wait-time’ prior to starting experimental tasks could be reduced to 30 minutes, from the 45 minutes typically used, thereby enabling testing during peak OT concentrations. Further research is needed to ascertain whether OT concentrations after intranasal administration follow similar patterns in females, and different age groups.

The effect of drugs and other compounds on the ciliary beat frequency of human respiratory epithelium

BACKGROUND

Cilia in the human respiratory tract play a critical role in clearing mucus and debris from the airways. Their function can be affected by a number of drugs or other substances, many of which alter ciliary beat frequency (CBF). This has implications for diseases of the respiratory tract and nasal drug delivery. This article is a systematic review of the literature that examines 229 substances and their effect on CBF.

METHODS

MEDLINE was the primary database used for data collection. Eligibility criteria based on experimental design were established, and 152 studies were ultimately selected. Each individual trial for the substances tested was noted whenever possible, including concentration, time course, specific effect on CBF, and source of tissue.

RESULTS

There was a high degree of heterogeneity between the various experiments examined in this article. Substances and their general effects (increase, no effect, decrease) were grouped into six categories: antimicrobials and antivirals, pharmacologics, human biological products, organisms and toxins, drug excipients, and natural compounds/other manipulations.

CONCLUSION

Organisms, toxins, and drug excipients tend to show a cilioinhibitory effect, whereas substances in all other categories had mixed effects. All studies examined were in vitro experiments, and application of the results in vivo is confounded by several factors. The data presented in this article should be useful in future respiratory research and examination of compounds for therapeutic and drug delivery purposes.

Nanotechnology for CNS delivery of bio-therapeutic agents

The current therapeutic strategies are not efficient in treating disorders related to the central nervous system (CNS) and have only shown partial alleviation of symptoms, as opposed to, disease modifying effects. With change in population demographics, the incidence of CNS disorders, especially neurodegenerative diseases, is expected to rise dramatically. Current treatment regimens are associated with severe side-effects, especially given that most of these are chronic therapies and involve elderly population. In this review, we highlight the challenges and opportunities in delivering newer and more effective bio-therapeutic agents for the treatment of CNS disorders. Bio-therapeutics like proteins, peptides, monoclonal antibodies, growth factors, and nucleic acids are thought to have a profound effect on halting the progression of neurodegenerative disorders and also provide a unique function of restoring damaged cells. We provide a review of the nano-sized formulation-based drug delivery systems and alternate modes of delivery, like the intranasal route, to carry bio-therapeutics effectively to the brain.

Hybrid nanosystems based on natural polymers as protein carriers for respiratory delivery: Stability and toxicological evaluation

Chitosan/carrageenan/tripolyphosphate nanoparticles were previously presented as holding potential for an application in transmucosal delivery of macromolecules, with tripolyphosphate demonstrating to contribute for both size reduction and stabilisation of the nanoparticles. This work was aimed at evaluating the capacity of the nanoparticles as protein carriers for pulmonary and nasal transmucosal delivery, further assessing their biocompatibility pattern regarding that application. Nanoparticles demonstrated stability in presence of lysozyme, while freeze-drying was shown to preserve their characteristics when glucose or sucrose were used as cryoprotectants. Bovine serum albumin was associated to the nanoparticles, which were successfully microencapsulated by spray-drying to meet the aerodynamic requirements inherent to pulmonary delivery. Finally, a satisfactory biocompatibility profile was demonstrated upon exposure of two respiratory cell lines (Calu-3 and A549 cells) to the carriers. A negligible effect on cell viability along with no alterations on transepithelial electrical resistance and no induction of inflammatory response were observed.

Mucoadhesive and enzymatic inhibitory nanoparticles for transnasal insulin delivery

AIM

To develop a novel nanocarrier with mucoadhesion and enzymatic inhibition for transnasal insulin delivery. METHODS & METHODS: The physicochemical characterization of the nanoparticles included size and morphology, as well as mucoadhesion and enzymatic inhibition. The in vitro release of insulin from the nanoparticles was evaluated in 3 mg/ml glucose medium. The cytocompatibility of the nanoparticles was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The interactions of the nanoparticles with Caco-2 cells and nasal epithelia, and the effect of the nanoparticles on transnasal insulin delivery were estimated.

RESULTS

The nanoparticles were spherical in shape, with an average size of 100 nm, and presented strong enzymatic inhibitory activity and high mucin adsorption ability. The insulinloaded nanoparticles showed the rapid insulin release in 3 mg/ml glucose medium. The nanoparticles were noncytotoxic to Caco-2 cells. Furthermore, the insulin-loaded nanoparticles overcame mucosal barriers and significantly decreased plasma glucose levels.

Gellan gum-based mucoadhesive microspheres of almotriptan for nasal administration: Formulation optimization using factorial design, characterization, and in vitro evaluation

Background:

Almotriptan malate (ALM), indicated for the treatment of migraine in adults is not a drug candidate feasible to be administered through the oral route during the attack due to its associated symptoms such as nausea and vomiting. This obviates an alternative dosage form and nasal drug delivery is a good substitute to oral and parenteral administration.

Materials and Methods:

Gellan gum (GG) microspheres of ALM, for intranasal administration were prepared by water-in-oil emulsification cross-linking technique employing a 2³ factorial design. Drug to polymer ratio, calcium chloride concentration and cross-linking time were selected as independent variables, while particle size and in vitro mucoadhesion of the microspheres were investigated as dependent variables. Regression analysis was performed to identify the best formulation conditions. The microspheres were evaluated for characteristics such as practical percentage yield, particle size, percentage incorporation efficiency, swellability, zeta potential, in vitro mucoadhesion, thermal analysis, X-ray diffraction study, and in vitro drug diffusion studies.

Results:

The shape and surface characteristics of the microspheres were determined by scanning electron microscopy, which revealed spherical nature and nearly smooth surface with drug incorporation efficiency in the range of 71.65 ± 1.09% – 91.65 ± 1.13%. In vitro mucoadhesion was observed the range of 79.45 ± 1.69% – 95.48 ± 1.27%. Differential scanning calorimetry and X-ray diffraction results indicated a molecular level dispersion of drug in the microspheres. In vitro drug diffusion was Higuchi matrix controlled and the release mechanism was found to be non-Fickian. Stability studies indicated that there were no significant deviations in the drug content, in vitro mucoadhesion and in vitro drug diffusion characteristics.

Conclusion:

The investigation revealed promising potential of GG microspheres for delivering ALM intranasally for the treatment of migraine.

Enhancing the buccal mucosal delivery of peptide and protein therapeutics

With continuing advances in biotechnology and genetic engineering, there has been a dramatic increase in the availability of new biomacromolecules, such as peptides and proteins that have the potential to ameliorate the symptoms of many poorly-treated diseases. Although most of these macromolecular therapeutics exhibit high potency, their large molecular mass, susceptibility to enzymatic degradation, immunogenicity and tendency to undergo aggregation, adsorption, and denaturation have limited their ability to be administered via the traditional oral route. As a result, alternative noninvasive routes have been investigated for the systemic delivery of these macromolecules, one of which is the buccal mucosa. The buccal mucosa offers a number of advantages over the oral route, making it attractive for the delivery of peptides and proteins. However, the buccal mucosa still exhibits some permeability-limiting properties, and therefore various methods have been explored to enhance the delivery of macromolecules via this route, including the use of chemical penetration enhancers, physical methods, particulate systems and mucoadhesive formulations. The incorporation of anti-aggregating agents in buccal formulations also appears to show promise in other mucosal delivery systems, but has not yet been considered for buccal mucosal drug delivery. This review provides an update on recent approaches that have shown promise in enhancing the buccal mucosal transport of macromolecules, with a major focus on proteins and peptides.

Effect of surface charge on the brain delivery of nanostructured lipid carriers in situ gels via the nasal route

The aim of this study was to investigate the influence of the nanocarrier surface charge on brain delivery of a model hydrophilic drug via the nasal route. Anionic and cationic nanostructured lipid carriers (NLCs) were prepared and optimized for their particle size and zeta potential. The optimum particles were incorporated in poloxamer in situ gels and their in vivo behavior was studied in the plasma and brain after administration to rats. Optimum anionic and cationic NLCs of size <200 nm and absolute zeta potential value of ≈ 34 mV were obtained. Toxicity study revealed mild to moderate reversible inflammation of the nasal epithelium in rats treated with the anionic NLCs (A7), and destruction of the lining mucosal nasal epithelium in rats treated with the cationic NLCs (C7L). The absolute bioavailability of both drug loaded anionic and cationic NLCs in situ gels was enhanced compared to that of the intranasal solution (IN) of the drug with values of 44% and 77.3%, respectively. Cationic NLCs in situ gel showed a non significant higher Cmax (maximum concentration) in the brain compared to the anionic NLCs in situ gel. Anionic NLCs in situ gel gave highest drug targeting efficiency in the brain (DTE%) with a value of 158.5 which is nearly 1.2 times that of the cationic NLCs in situ gel.

Nasal-nanotechnology: revolution for efficient therapeutics delivery

CONTEXT

In recent years, nanotechnology-based delivery systems have gained interest to overcome the problems of restricted absorption of therapeutic agents from the nasal cavity, depending upon the physicochemical properties of the drug and physiological properties of the human nose.

OBJECTIVE

The well-tolerated and non-invasive nasal drug delivery when combined with the nanotechnology-based novel formulations and carriers, opens the way for the effective systemic and brain targeting delivery of various therapeutic agents. To accomplish competent drug delivery, it is imperative to recognize the interactions among the nanomaterials and the nasal biological environment, targeting cell-surface receptors, drug release, multiple drug administration, stability of therapeutic agents and molecular mechanisms of cell signaling involved in patho-biology of the disease under consideration.

METHODS

Quite a few systems have been successfully formulated using nanomaterials for intranasal (IN) delivery. Carbon nanotubes (CNTs), chitosan, polylactic-co-glycolic acid (PLGA) and PLGA-based nanosystems have also been studied in vitro and in vivo for the delivery of several therapeutic agents which shown promising concentrations in the brain after nasal administration.

RESULTS AND CONCLUSION

The use of nanomaterials including peptide-based nanotubes and nanogels (NGs) for vaccine delivery via nasal route is a new approach to control the disease progression. In this review, the recent developments in nanotechnology utilized for nasal drug delivery have been discussed.

Intranasal administration of carbamazepine to mice: a direct delivery pathway for brain targeting

The currently available antiepileptic drugs are typically administered via oral or intravenous (IV) routes which commonly exhibit high systemic distribution into non-targeted tissues, leading to peripheral adverse effects and limited brain uptake. In order to improve the efficacy and tolerability of the antiepileptic drug therapy, alternative administration strategies have been investigated. The purpose of the present study was to assess the pharmacokinetics of carbamazepine administered via intranasal (IN) and IV routes to mice, and to investigate whether a direct transport of the drug from nose to brain could be involved. The similar pharmacokinetic profiles obtained in all matrices following both administration routes indicate that, after IN delivery, carbamazepine reaches quickly and extensively the bloodstream, achieving the brain predominantly via systemic circulation. However, the uneven biodistribution of carbamazepine through the brain regions with higher concentrations in the olfactory bulb and frontal cortex following IN instillation, in comparison with the homogenous brain distribution pattern after IV injection, strongly suggests the involvement of a direct transport of carbamazepine from nose to brain. Therefore, it seems that IN delivery represents a suitable and promising alternative route to administer carbamazepine not only for the chronically use of the drug but also in emergency conditions.

Suppression of cytokine release by fluticasone furoate vs. mometasone furoate in human nasal tissue ex-vivo

BACKGROUND

Topical glucocorticosteroids are the first line therapy for airway inflammation. Modern compounds with higher efficacy have been developed, but head-to-head comparison studies are sparse.

OBJECTIVE

To compare the activity of two intranasal glucocorticoids, fluticasone furoate (FF) and mometasone furoate (MF) with respect to the inhibition of T helper (Th)1, Th2 and Th17 cytokine release in airway mucosa.

METHODS

We used an ex-vivo human nasal mucosal tissue model and employed pre- and post- Staphylococcus aureus enterotoxin B (SEB)-challenge incubations with various time intervals and drug concentrations to mimic typical clinical situations of preventive or therapeutic use.

RESULTS

At a fixed concentration of 10-10 M, FF had significantly higher suppressive effects on interferon (IFN)-γ, interleukin (IL)-2 and IL-17 release, but not IL-5 or tumor necrosis factor (TNF)-α, vs. MF. While the maximal suppressive activity was maintained when FF was added before or after tissue stimulation, the cytokine suppression capacity of MF appeared to be compromised when SEB-induced cell activation preceded the addition of the drug. In a pre-challenge incubation setting with removal of excess drug concentrations, MF approached inhibition of IL-5 and TNF-α after 6 and 24 hours while FF maximally blocked the release of these cytokines right after pre-incubation. Furthermore, FF suppressed a wider range of T helper cytokines compared to MF.

CONCLUSION

The study demonstrates the potential of our human mucosal model and shows marked differences in the ability to suppress the release of various cytokines in pre- and post-challenge settings between FF and MF mimicking typical clinical situations of preventive or therapeutic use.

Effect of cigarette smoking on nasal mucociliary clearance: A comparative analysis using saccharin test

Background:

Nasal mucociliary clearance (NMC) system transports the mucus layer covering the nasal epithelium towards nasopharynx by ciliary beating at a frequency of 7-16 Hz. NMC is altered by septal deviations, upper respiratory infections, and drugs. Few studies have revealed significant depression of ciliary activity in smokers. We conducted this study to compare NMC and influence duration of smoking on NMC in adult smokers and nonsmokers using saccharin test.

Materials and Methods:

Our study included 30 nonsmokers and 30 smokers (21-40 years) who were not on any medications and had no history of any systemic illness. Time elapsing until the first experience of sweet taste at posterior nasopharynx, following placement of saccharin particle approximately 1 cm behind the anterior end of inferior turbinate was recorded as NMC time in minutes using standard method described by Anderson. Mean NMC of both groups were compared using Student's t-test and influence of duration was analyzed by one-way Analysis of variance (ANOVA).

Results:

NMC was significantly prolonged in smokers (481.2 ± 29.83; P < 0.01) in comparison to nonsmokers (300.32 ± 17.42 s). A statistically significant increase in NMC was observed with an increase in duration of smoking habit (NMC in smoking <1 year = 492.25 ± 79.93 s, 1-5 years = 516.7 ± 34.01 s, >5 years = 637.5 ± 28.49 s; F statistic = 20.8968, P = 0.0000).

Conclusions:

NMC measurement is a simple and useful index for the assessment of effect of smoking on the ciliary activity of respiratory mucosa. Prolonged clearance observed in smokers of our study may be due to slowed ciliary beat frequency or reduction in number of cilia and changes in viscoelastic properties of mucus.

Nasal in-situ gels for delivery of rasagiline mesylate: improvement in bioavailability and brain localization

Intranasal thermosensitive gel for rasagiline mesylate (RM) was developed for effective treatment of Parkinson's disease. Intranasal gels were prepared by combination of poloxamer 407 and poloxamer 188 (1:1) with mucoadhesive polymers (carbopol 934 P and chitosan). The formulations were evaluated for sol-gel transition temperature, in-vitro drug release and in-vivo mucociliary transit time. Further, optimal intranasal gel formulations were tested for in-vivo pharmacokinetic behavior, nasal toxicity studies and brain uptake studies. It was found that optimal formulations had acceptable gelation temperature (28-33 °C) and adequate in-vitro drug release profile. Pharmacokinetic study in rabbits showed significant (p < 0.05) improvement in bioavailability (four- to six-folds) of the drug from intranasal gels than oral solution. Chronic exposure studies in Wistar rats showed that these intranasal gels were non-irritant and non-toxic to rat nasal mucosa. Estimation of RM in rat brain tissue showed significant (p < 0.01) improvement in uptake of RM form intranasal gel formulations than nasal solution.

Development of thiolated poly(acrylic acid) microparticles for the nasal administration of exenatide

The purpose of this study was to develop a microparticulate formulation for nasal delivery of exenatide utilizing a thiolated polymer. Poly(acrylic acid)-cysteine (PAA-cys) and unmodified PAA microparticles loaded with exenatide were prepared via coprecipitation of the drug and the polymer followed by micronization. Particle size, drug load and release of incorporated exenatide were evaluated. Permeation enhancing properties of the formulations were investigated on excised porcine respiratory mucosa. The viability of the mucosa was investigated by histological studies. Furthermore, ciliary beat frequency (CBF) studies were performed. Microparticles displayed a mean size of 70-80 µm. Drug encapsulation was ∼80% for both thiolated and non-thiolated microparticles. Exenatide was released from both thiolated and non-thiolated particles in comparison to exenatide in buffer only within 40 min. As compared to exenatide dissolved in buffer only, non-thiolated and thiolated microparticles resulted in a 2.6- and 4.7-fold uptake, respectively. Histological studies performed before and after permeation studies showed that the mucosa is not damaged during permeation studies. CBF studies showed that the formulations were cilio-friendly. Based on these results, poly(acrylic acid)-cysteine-based microparticles seem to be a promising approach starting point for the nasal delivery of exenatide.

Recommendations for the standardisation of oxytocin nasal administration and guidelines for its reporting in human research

A series of studies have reported on the salubrious effects of oxytocin nasal spray on social cognition and behavior in humans, across physiology (e.g., eye gaze, heart rate variability), social cognition (e.g., attention, memory, and appraisal), and behavior (e.g., trust, generosity). Findings suggest the potential of oxytocin nasal spray as a treatment for various psychopathologies, including autism and schizophrenia. There are, however, increasing reports of variability of response to oxytocin nasal spray between experiments and individuals. In this review, we provide a summary of factors that influence transmucosal nasal drug delivery, deposition, and their impact on bioavailability. These include variations in anatomy and resultant airflow dynamic, vascularisation, status of blood vessels, mode of spray application, gallenic formulation (including presence of uptake enhancers, control release formulation), and amount and method of administration. These key variables are generally poorly described and controlled in scientific reports, in spite of their potential to alter the course of treatment outcome studies. Based on this review, it should be of no surprise that differences emerge across individuals and experiments when nasal drug delivery methods are employed. We present recommendations for researchers to use when developing and administering the spray, and guidelines for reporting on peptide nasal spray studies in humans. We hope that these recommendations assist in establishing a scientific standard that can improve the rigor and subsequent reliability of reported effects of oxytocin nasal spray in humans.

Design of experiments to optimize an in vitro cast to predict human nasal drug deposition

BACKGROUND

Previous studies showed nasal spray in vitro tests cannot predict in vivo deposition, pharmacokinetics, or pharmacodynamics. This challenge makes it difficult to assess deposition achieved with new technologies delivering to the therapeutically beneficial posterior nasal cavity. In this study, we determined best parameters for using a regionally divided nasal cast to predict deposition. Our study used a model suspension and a design of experiments to produce repeatable deposition results that mimic nasal deposition patterns of nasal suspensions from the literature.

METHODS

The seven-section (the nozzle locator, nasal vestibule, front turbinate, rear turbinate, olfactory region, nasopharynx, and throat filter) nylon nasal cast was based on computed tomography images of healthy humans. It was coated with a glycerol/Brij-35 solution to mimic mucus. After assembling and orienting, airflow was applied and nasal spray containing a model suspension was sprayed. After disassembling the cast, drug depositing in each section was assayed by HPLC. The success criteria for optimal settings were based on nine in vivo studies in the literature. The design of experiments included exploratory and half factorial screening experiments to identify variables affecting deposition (angles, airflow, and airflow time), optimization experiments, and then repeatability and reproducibility experiments.

RESULTS

We found tilt angle and airflow time after actuation affected deposition the most. The optimized settings were flow rate of 16 L/min, postactuation flow time of 12 sec, a tilt angle of 23°, nozzle angles of 0°, and actuation speed of 5 cm/sec. Neither cast nor operator caused significant variation of results.

CONCLUSION

We determined cast parameters to produce results resembling suspension nasal sprays in the literature. The results were repeatable and unaffected by operator or cast. These nasal spray parameters could be used to assess deposition from new devices or formulations. For human deposition studies using radiolabeled formulations, this cast could show that radiolabel deposition represents drug deposition. Our methods could also be used to optimize settings for other casts.

Thermally triggered mucoadhesive in situ gel of loratadine: β-cyclodextrin complex for nasal delivery

The aim of the present study was to increase the solubility of an anti-allergic drug loratadine by making its inclusion complex with β-cyclodextrin and to develop it's thermally triggered mucoadhesive in situ nasal gel so as to overcome first-pass effect and consequently enhance its bioavailability. A total of eight formulations were prepared by cold method and optimized by 2(3) full factorial design. Independent variables (concentration of poloxamer 407, concentration of carbopol 934 P, and pure drug or its inclusion complex) were optimized in order to achieve desired gelling temperature with sufficient mucoadhesive strength and maximum permeation across experimental nasal membrane. The design was validated by extra design checkpoint formulation (F9) and Pareto charts were used to help eliminate terms that did not have a statistically significant effect. The response surface plots and possible interactions between independent variables were analyzed using Design Expert Software 8.0.2 (Stat Ease, Inc., USA). Faster drug permeation with zero-order kinetics and target flux was achieved with formulation containing drug: β-cyclodextrin complex rather than those made with free drug. The optimized formulation (F8) with a gelling temperature of 28.6±0.47°C and highest mucoadhesive strength of 7,676.0±0.97 dyn/cm2 displayed 97.74±0.87% cumulative drug permeation at 6 h. It was stable for over 3 months and histological examination revealed no remarkable damage to the nasal tissue.

Mucoadhesive in situ nasal gelling drug delivery systems for modulated drug delivery

INTRODUCTION

The nasal route is an attractive target for administration of the drug of choice, particularly in overcoming disadvantages such as high first-pass metabolism and drug degradation in the gastrointestinal environment that are associated with the oral and other modes of administration. The major limitation associated is of rapid mucociliary clearance in the nasal delivery that results in low absorption and hence poor bioavailability. In order to overcome this, mucoadhesive in situ nasal gelling drug delivery systems have been explored to develop sustained/controlled delivery via nasal route.

AREAS COVERED

The present review critically evaluates the importance of in situ gel for the nasal delivery of drugs, and the polymers used in the formulation of in situ gel along with their mechanism of gelation. It also encompasses the research reports made in this arena of delivery system.

EXPERT OPINION

The challenges of drug delivery through nose has led to development of in situ nasal gelling systems using a myriad of polymers to deliver the drugs, proteins, amino acids, hormones, vaccines and plasmid DNA for the local, systemic and central nervous system effects. Though a range of preclinical reports are available, clinical intricacies need to be critically worked out.

In vitro evaluation of nasal mucociliary clearance using excised rat nasal septum

Mucus on the nasal mucosa is translocated to the pharynx by ciliary beating, which is an important nonspecific defense mechanism called mucociliary clearance (MC). MC is one of the important factors determining the rate and extent of drug absorption after nasal application. The purpose of this study is to evaluate MC using rat nasal septum under physiological condition in an in vitro system. The nasal septum was excised from rats anesthetized with urethane and the movement of fluorescent microspheres (FMS) applied on the nasal septum was observed with a fluorescence microscope. FMS were transported at a constant velocity in the same direction for a few minutes, but addition of 4% mucin solution on the nasal septum maintained MC for at least 90 min after excision. With our evaluation system established by modifying the method of Saldiva, MC was determined to be around 1 mm/min. Furthermore, the ciliostatic effect of benzalkonium chloride was observed, and it was confirmed that β-adrenergic antagonists and a cholinergic antagonist decreased MC, and that β-adrenergic agonists and a cholinergic agonist tended to increase MC, indicating that our system is valid and useful for evaluating MC function and the effect of drugs and pharmaceutical additives for nasal application on MC.

Design and application of locally delivered agonists of the adenosine A(2A) receptor

The broad spectrum anti-inflammatory actions of adenosine A(2A) receptor agonists are well described. The wide distribution of this receptor, however, suggests that the therapeutic potential of these agents is likely to reside in topical treatments to avoid systemic side effects associated with oral administration. Adenosine A(2A) receptor agonists have been assessed as topical agents: GW328267X (GSK; allergic rhinitis and asthma), UK-432097 (Pfizer; chronic obstructive pulmonary disease [COPD]) and Sonedenoson (MRE0094, King Pharmaceuticals; wound healing). All trials failed to achieve effects against the desired clinical end points. This broad-based review will discuss general principles of chemical design of topically applied agents and potential therapeutic topical applications of current adenosine A(2A) receptor agonists. Potential factors contributing to the lack of efficacy in the above clinical trials will be discussed together with design principles, which may influence efficacy in disease states. Our analysis suggests that adenosine A(2A) receptor agonists have a wide therapeutic potential as topical agents in a wide variety of diseases, such as neutrophil-dependent lung diseases (acute lung injury, exacerbations in asthma and COPD), allergic rhinitis, glaucoma and wound repair. Factors that will influence topical activity include formulation, tissue retention, compound potency, receptor kinetics and pharmacokinetics.

Effect of polymer molecular weight and of polymer blends on the properties of rapidly gelling nasal inserts

The objective was to investigate the potential of polymer molecular weight (MW) and polymer blends for the control of drug release from in situ gelling nasal inserts prepared by lyophilization of solutions of model drugs (oxymetazoline HCl, diprophyllin) and polymers. Drug release, polymer solution viscosity, water uptake and mass loss, mechanical properties, and bioadhesion potential were measured. Sonication was effective to reduce the viscosity/polymer MW of carrageenan solutions. Nasal inserts prepared from sonicated carrageenan showed an insignificant reduction in water uptake with sonication time and no disintegration of the gel matrix. In contrast, inserts of different MW Na-alginates revealed a reduced water uptake and an increased mass loss with lower MW. Inserts prepared from carrageenan/low MW Na-alginate blends took up more water at a higher low MW Na-alginate content. Sonicated carrageenan inserts released oxymetazoline HCl independent of the sonication time and diprophyllin with only a slight reduction in the release rate. Release of both drugs from Na-alginate inserts was slow from high MW inserts because no insert dissolution occurred. Increasing the Na-alginate content of inserts prepared from polymer blends accelerated the drug release enabling release rates over a broad range. The bioadhesion potential of Na-alginate inserts was strongly reduced for the low MW grades because of dissolution of the inserts. Xanthan gum and Carbopol 971 blended with Na-alginate formed inserts with poor bioadhesion. The use of polymer blends to control the drug release from nasal inserts was superior to the use of polymers of different MW.

Intranasal drug delivery: an efficient and non-invasive route for systemic administration: focus on opioids

Intranasal administration is a non-invasive route for drug delivery, which is widely used for the local treatment of rhinitis or nasal polyposis. Since drugs can be absorbed into the systemic circulation through the nasal mucosa, this route may also be used in a range of acute or chronic conditions requiring considerable systemic exposure. Indeed, it offers advantages such as ease of administration, rapid onset of action, and avoidance of first-pass metabolism, which consequently offers for example an interesting alternative to intravenous, subcutaneous, oral transmucosal, oral or rectal administration in the management of pain with opioids. Given these indisputable interests, fentanyl-containing formulations have been recently approved and marketed for the treatment of breakthrough cancer pain. This review will outline the relevant aspects of the therapeutic interest and limits of intranasal delivery of drugs, with a special focus on opioids, together with an in-depth discussion of the physiological characteristics of the nasal cavity as well as physicochemical properties (lipophilicity, molecular weight, ionisation) and pharmaceutical factors (absorption enhancers, devices for application) that should be considered for the development of nasal drugs.

Nasal route: an alternative approach for antiemetic drug delivery

INTRODUCTION

Antiemetic drugs are used in the treatment of nausea and emesis. Development of novel delivery systems for antiemetic drugs, as an alternative to conventional preparations, is important in terms of good patient compliance and improving bioavailability. The nasal route offers unique superiorities, such as fast and high drug absorption, and high patient compliance. Therefore, a considerable amount of research has been carried out on the development of nasal delivery systems for antiemetic drugs.

AREAS COVERED

This review deals with the importance of nasal delivery of antiemetic drugs and the studies performed on this subject. The first part of this review summarizes the properties of the nasal route, its advantages and limitations, parameters affecting drug absorption through nasal mucosa, nasal passage pathways and general approaches to improve nasal transport. The second part reviews the studies conducted on the development of nasal delivery systems.

EXPERT OPINION

Due to its superiorities, the nasal route could be considered as an attractive alternative to oral and parenteral routes. To overcome the barrier properties of the nasal epithelium and to enhance transport of antiemetic drugs, several approaches, including permeation enhancers, in situ gel formulations and micro- and nanoparticulate systems, have been evaluated. The results obtained are promising and indicate that nasal formulations of some antiemetic drugs may enter the market in the near future.

Formulation and evaluation of in situ gelling systems for intranasal administration of gastrodin

Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

The influence of AT1002 on the nasal absorption of molecular weight markers and therapeutic agents when co-administered with bioadhesive polymers and an AT1002 antagonist, AT1001

OBJECTIVES

The purpose of this study was to demonstrate the effects of the tight junction permeation enhancer, AT1002, on the nasal absorption of molecular weight markers and low bioavailable therapeutic agents co-administered with bioadhesive polymers or zonulin antagonist.

METHODS

The bioadhesive polymers, carrageenan and Na-CMC, were prepared with AT1002 to examine the permeation-enhancing effect of AT1002 on the nasal absorption of inulin, calcitonin and saquinavir after nasal administration to Sprague-Dawley rats. Blood samples were collected over a 6-hour period from a jugular cannula. In addition, we determined whether AT1002 exerts a permeation-enhancing effect via activation of PAR-2 specific binding to a putative receptor of zonulin. To examine this zonulin antagonist, AT1001, was administered 30 min prior to dosing with an AT1002/inulin solution and blood samples were collected over a 6-hour period.

KEY FINDINGS

The bioadhesive polymers did not directly increase the absorption of inulin, calcitonin and saquinavir, but promoted the permeation-enhancing effect of AT1002 when delivered nasally, thereby significantly increasing the absorption of each drug. Pre-treatment with AT1001 antagonized the zonulin receptor and significantly minimized the permeation-enhancing effect of AT1002.

CONCLUSION

These findings will assist in understanding the permeation-enhancing capability of and the receptor binding of AT1002. Further, combining AT1002 with carrageenan supports the development of the mucosal delivery of therapeutic agents that have low bioavailability even with bioadhesive agents.

Solubilizing agents in nasal formulations and their effect on ciliary beat frequency

The purpose of this study was to determine the concentration-dependent effect of selected solubilizers, used in common nasal drug formulations, on ciliary beat frequency (CBF) in human nasal epithelial cell cultures. CBF was measured by a high-speed digital imaging method. Excised ciliated human nasal epithelial cells were incubated for 60min with the solubilizers and determination of the half maximal inhibitory concentration (IC(50)), followed by a reversibility test. LDH test was performed on human nasal epithelial cells with the solubilizing agents. These were applied to nasal epithelial cells in IC(50) values. The following rank order in IC(50) values was obtained for the solubilizers: glycerol>propylene glycol>polyethylene glycol 300>N,N-dimethylacetamide>polyethylene glycol 400>ethanol>ethylendiamindihydrochloride>polyvinylpyrrolidon 25>polyvinylpyrrolidon 90. The highest reversibility of approximately 75% was shown by propylene glycol and polyethylene glycol 300 at a concentration of 30% (v/v). Results from the LDH test showed that N,N-dimethylacetamide displayed the highest cytotoxicity with 5.2% at a concentration of 14.5% (v/v). According to these results, several solubilizers can alter the CBF frequency and thus, have an impact on the nasal mucosa. Therefore, CBF studies with solubilizers used at a concentration relevant for nasal formulations are essential in the design of efficient and most notably safe nasal medicinal products.

Brain distribution of ribavirin after intranasal administration

Ribavirin has proved to be effective in vitro against several RNA viruses responsible for encephalitis in humans and animals. However, the in vivo efficacy towards the cerebral viral load seems to be limited by the blood-brain barrier. Since the nose-to-brain pathway has been indicated for delivering drugs to the brain, we investigated here the distribution of ribavirin in the central nervous system (CNS) after intranasal administration. We first tested in vitro ribavirin diffusion from an aqueous solution across a biological membrane, using Franz cells and rabbit nasal mucosa. About 35% of ribavirin permeated in 4 h across the mucosa, after reaching steady-state flux in less than 30 min. In the first in vivo experiment, ribavirin aqueous solution was administered intranasally to Sprague Dawley rats (10 mg/kg). Animals were sacrificed at 10, 20 or 30 min after administration to collect brain areas (cerebellum, olfactory bulb, cerebral cortex, basal ganglia and hippocampus) and biological fluids (cerebrospinal fluid and plasma). Ribavirin, quantified by LC-MS/MS spectrometry, was detected at each time point in all compartments with the highest concentration in olfactory bulb and decreasing in rostro-caudal direction. Two subsequent in vivo experiments compared the nasal route (ribavirin solution) with the intravenous one and the nasal administration of ribavirin solution with ribavirin powder (10 mg/kg). It was found that 20 min after administration, ribavirin concentration in olfactory bulb was similar after intravenous or nasal administration of the ribavirin solution, whereas the powder led to significantly higher levels. Ribavirin was also present in deeper compartments, such as basal ganglia and hippocampus. Even if the mechanisms involved in ribavirin nose-to-brain transport are not clear, these results suggest a rapid extracellular diffusive flux from the nasal epithelium to the olfactory bulb and different CNS areas.

Enhanced transbuccal salmon calcitonin (sCT) delivery: effect of chemical enhancers and electrical assistance on in vitro sCT buccal permeation

This study investigates the combined effect of absorption enhancers and electrical assistance on transbuccal salmon calcitonin (sCT) delivery, using fresh swine buccal tissue. We placed 200 IU (40 μg/mL) of each sCT formulation--containing various concentrations of ethanol, N-acetyl-L-cysteine (NAC), and sodium deoxyglycocholate (SDGC)--onto the donor part of a Franz diffusion cell. Then, 0.5 mA/cm(2) of fixed anodal current was applied alone or combined with chemical enhancers. The amount of permeated sCT was analyzed using an ELISA kit, and biophysical changes of the buccal mucosa were investigated using FT-IR spectroscopy, and hematoxylin-eosin staining methods were used to evaluate histological alteration of the buccal tissues. The flux (J(s)) of sCT increased with the addition of absorption enhancer groups, but it was significantly enhanced by the application of anodal iontophoresis (ITP). FT-IR study revealed that all groups caused an increase in lipid fluidity but only the groups containing SDGC showed statistically significant difference. Although the histological data of SDGC groups showed a possibility for tissue damage, the present enhancing methods appear to be safe. In conclusion, the combination of absorption enhancers and electrical assistance is a potential strategy for the enhancement of transbuccal sCT delivery.