Formulation and evaluation of nitrendipine buccal films

Buccal films: A review of therapeutic opportunities, formulations & relevant evaluation approaches

The potential of the mucoadhesive film technology is hard to ignore, owing to perceived superior patient acceptability versus buccal tablets, and significant therapeutic opportunities compared to conventional oral drug delivery systems, especially for those who suffer from dysphagia. In spite of this, current translation from published literature into the commercial marketplace is virtually non-existent, with no authorised mucoadhesive buccal films available in the UK and very few available in the USA. This review seeks to provide an overview of the mucoadhesive buccal film technology and identify key areas upon which to focus scientific efforts to facilitate the wider adoption of this patient-centric dosage form. Several indications and opportunities for development were identified, while discussing the patient-related factors influencing the use of these dosage forms. In addition, an overview of the technologies behind the manufacturing of these films was provided, highlighting manufacturing methods like solvent casting, hot melt extrusion, inkjet printing and three-dimensional printing. Over thirty mucoadhesive polymers were identified as being used in film formulations, with details surrounding their mucoadhesive capabilities as well as their inclusion alongside other key formulation constituents provided. Lastly, the importance of physiologically relevant in vitro evaluation methodologies was emphasised, which seek to improve in vivo correlations, potentially leading to better translation of mucoadhesive buccal films from the literature into the commercial marketplace.

Current Status of Mucoadhesive Gel Systems for Buccal Drug Delivery

BACKGROUND

Buccal drug delivery is a fascinating research field. Gel-based formulations present potent characteristics as buccal systems since they have great physicochemical properties.

METHODS

Among the various gels, in situ gels are viscous colloidal systems consisting of polymers; when physiological conditions change (pH, temperature, ion activation), they are transformed into the gel phase. These systems can improve bioavailability. Other systems, such as nanogels or emulgels can also be applied for buccal delivery with promising results. Polymeric gel-based systems can be produced by natural, semisynthetic, and synthetic polymers. Their main advantage is that the active molecules can be released in a sustained and controllable manner. Several gels based on chitosan are produced for the entrapment of drugs demonstrating efficient retention time and bioavailability due to chitosan mucoadhesion. Besides polysaccharides, poloxamers and carbopol are also used in buccal gels due to their high swelling ability and reversed thermal gelation behavior.

RESULTS

Herein, the authors focused on the current development of mucoadhesive gel systems used in buccal drug delivery. After explaining buccal drug delivery and mucoadhesion, various studies with hydrogels, in situ gels, and nanogels were analyzed as buccal gel systems. Various mucoadhesive gel studies with mucoadhesive polymers have been studied and summarized. This review is presented as valuable guidance to scientists in formulating buccal mucoadhesive drug delivery systems.

CONCLUSION

This review aimed to assist researchers working on buccal drug delivery by summarizing buccal drug delivery, mucoadhesion, and buccal mucoadhesive gel systems recently found in the literature.

Development and characterization of sublingual films for enhanced bioavailability of selegiline hydrochloride

Low oral bioavailability of selegiline hydrochloride (SH) is primarily due to extensive first-pass metabolism and hence the need for an alternative pathway of administration. Herein, we report the development of sublingual SH films. The films were formulated with varying polymer composition (F1-F6) and evaluated for physicochemical characteristics, in vitro drug release and ex vivo permeation studies. The film F2 demonstrated satisfactory weight (10.60 mg), folding endurance (>200), drug content (11.44 mg/cm²), disintegration time (68 s), mucoadhesive strength (47.7 N/cm²), and controlled release for 30 min. The permeation studies exhibited a higher ex vivo sublingual flux than that of the plain drug. This study concludes that the SH film can provide a potential opportunity for sublingual drug delivery.

Vitamin B12-Loaded Buccoadhesive Films as a Noninvasive Supplement in Vitamin B12 Deficiency: In Vitro Evaluation and In Vivo Comparative Study With Intramuscular Injection

This study aimed to formulate and evaluate vitamin B12-loaded buccal mucoadhesive hydrogel films. Various film formulations were prepared using chitosan and polyvinyl alcohol. The prepared films were characterized for thickness, weight variation, drug content, percentage moisture uptake and moisture content, surface pH, mechanical properties, in vitro release, and mucoadhesion. Vitamin B12 bioavailability from the optimized formulation was studied on rabbits by the aid of enzyme-linked immunosorbent assay. Neuroton^® I.M. injection was used for comparison. The films had acceptable mechanical and mucoadhesion properties. The percentages of moisture content of the optimized formulation were 3.2 ± 0.95, whereas the percentage drug released was 98.59 ± 1.41% at the end of 40 min. FTIR revealed the incidence of drug/polymer interaction. Differential scanning calorimetry revealed the possibility of the dispersion of cyanocobalamin in a molecular state with complete amorphization in the polymers. The estimated AUC_0-8h showed 1.5-fold increases in the bioavailability of cyanocobalamin from the optimized formulation compared with the marketed I.M. injection. These findings warrant that vitamin B12 buccal film formulation can be considered as an effective alternative portal with noninvasive and more convenient characteristics compared with the I.M. injection dosage form.

Buccal Dosage Forms: General Considerations for Pediatric Patients

The development of an appropriate dosage form for pediatric patients needs to take into account several aspects, since adult drug biodistribution differs from that of pediatrics. In recent years, buccal administration has become an attractive route, having different dosage forms under development including tablets, lozenges, films, and solutions among others. Furthermore, the buccal epithelium can allow quick access to systemic circulation, which could be used for a rapid onset of action. For pediatric patients, dosage forms to be placed in the oral cavity have higher requirements for palatability to increase acceptance and therapy compliance. Therefore, an understanding of the excipients required and their functions and properties needs to be particularly addressed. This review is focused on the differences and requirements relevant to buccal administration for pediatric patients (compared to adults) and how novel dosage forms can be less invasive and more acceptable alternatives.

Cellulose Buccoadhesive Film Bearing Glimepiride: Physicomechanical Characterization and Biophysics of Buccoadhesion

The present study aimed to develop buccoadhesive film of glimepiride with unique combination of polymers and to investigate its effect(s) on physicomechanical parameters, drug-release, and permeation of films. Drug-polymer interaction was examined by FTIR and DSC analysis. Films were prepared by solvent casting technique and characterized for film strength (320 ± 8.5 g, 28.98 ± 2.00 mJ), buccoadhesive strength (28.8 ± 1.37 g, 3.04 ± 0.32 mJ), and tensile strength (260 ± 6.88 g, 18.00 ± 0.44 mJ) by new instrumental techniques. Increase in polymer concentration augmented zeta potential of polymeric matrix-mucin mixture and exhibited strong buccoadhesion (electrical theory). Buccoadhesion was also influenced by particle size (adsorption theory) and swelling (wetting theory). Erosion behavior of films was observed in swelling and SEM studies. Film GM4 exhibited 98 ± 2% in vitro drug release and 85 ± 8% ex vivo drug permeation in 12 h with controlled diffusion mechanism. Films were compatible with oral probiotic microorganisms. Stability studies revealed no significant (P < 0.05) variation in physicomechanical characteristics.

Comparative Study of Different Combinational Mucoadhesive Formulations of Sumatriptan-Metoclopramide

PURPOSE

Sumatriptan succinate (Sum) is a Serotonin 5- HT1 receptor agonist, used in the treatment of migraine. It is absorbed rapidly but incompletely when taken orally and underwent first - pass metabolism, resulting in a low bioavailability of about 15%. The aim was to design mucoadhesive buccal discs and sublingual films of Sum and metoclopramide (Met) combined to improve their bioavailability.

METHODS

In the current study, the microparticles and films were prepared by emulsion solvent diffusion (ESD) and solvent casting methods, respectively. Buccal-mucoadhesive microparticles and films with different drug to polymer ratios were prepared and characterized by encapsulation efficiency, particle size, DSC (Differential Scanning Calorimetric), folding endurance, mucoadhesive property and drug release studies.

RESULTS

The best drug/s to polymer ratios in films and microparticles were 1:2.7:8 (SM2) and 1:4:6 (SM4), respectively. The film of SM2 showed 11.01 mg weight, 123 µm thickness and 300 folding endurance. The production yield was 107.33% for SM4 microparticles, 323.59 µm for mean particle size and 94.53% for loading efficiency (for Sum) and 104.18% (for Met). The DSC showed no stable characteristic of Sum and Met in the drug loaded films/discs and revealed amorphous form and transition of hydrate to anhydrous form for Met. The films exhibited very good mucoadhesive properties and shorter retention time (15-30 s) in comparison with the discs (130 min). The results showed that the discs prepared had slower release than the films (p<0.05).

CONCLUSION

Films and discs of Sum-Met combinations were successfully prepared with improved release and mucoadhesive properties.

A novel dosage form for buccal administration of bupropion

Bupropion is an antidepressant used in the treatment of smoking. The purpose of this study was to prepare controlled-release hydrogel films for buccal administration of bupropion and investigate its physicochemical and cytotoxic properties. The films were prepared from ultrapure sodium carboxymethylcellulose, hydroxypropylmethylcellulose K4M, and medium-viscosity chitosan. Evaluation of film physicochemical characteristics was based on scanning electron microscopy, bupropion content, mechanical strength (burst strength, relaxation, resilience, and traction), and cytotoxicity. Bupropion content in bilayer films was 121 mg per 9 cm2. The presence of bupropion modified film mechanical strength, but did not compromise the use of this pharmaceutical form. As shown by the cytotoxicity results, films containing bupropion did not cause cellular damage. Bupropion administration in the form of hydrogel films is a potentially useful alternative in the treatment of smoking.

Effect of novel mucoadhesive buccal patches of carvedilol on isoprenaline-induced tachycardia

The main aim of the study was designed to develop bioadhesive buccal patches of carvedilol (CR) and evaluate for isoprenaline-induced tachycardia. Buccal patches of carvedilol were prepared by using chitosan (CH), sodium salt of carboxy methyl cellulose (NaCMC), and polyvinyl alcohol (PVA) as mucoadhesive polymers. The solvent evaporation method was used for the preparation of buccal patches. The patches were evaluated for their physical characteristics like patch thickness, weight variation, content uniformity, folding endurance, surface pH, residence time, in vitro drug release, and in vivo pharmacodynamic study. The swelling index of the patches was found to be proportional to the polymer concentration, whereas surface pH of all the formulated bioadhesive patches was found to lie between neutral ranges. In-vitro release study shows that 94.75% drug was release in 8 hours from the patch, which containing 2% w/v chitosan. The folding endurance result shows good elasticity in all the patches. Application of buccal patches on buccal mucosa of rabbit shows a significant result in % inhibition of isoprenaline-induced tachycardia. Prepared buccal patches of chitosan, NaCMC, and PVA containing Carvedilol meet the ideal requirement for the delivery of cardiovascular drugs and inhibit the isoprenaline tachycardia.

Formulation and in vitro evaluation of salbutamol sulphate in situ gelling nasal inserts

The aim of this study was to formulate salbutamol sulfate (SS), a model drug, as mucoadhesive in situ gelling inserts having a high potential as nasal drug delivery system bypassing the first-pass metabolism. In situ gelling inserts, each containing 1.4% SS and 2% gel-forming polymer, hydroxypropyl methylcellulose (HPMC), carboxymethylcellulose sodium (CMC Na), sodium alginate (AL), and chitosan (CH) were prepared. The inserts were investigated for their different physicochemical properties. The weight of inserts was 16-27 mg, drug content was 3.9-4.2 mg, thickness ranged between 15 and 28 μm and surface pH was 5-7. Cumulative drug released from the inserts exhibited extended release for more than 10 h following the decreasing order: CH>AL>CMC Na>HPMC. The drug release from CMC Na and AL inserts followed zero-order kinetics while HPMC and CH inserts exhibited non-Fickian diffusion mechanism. The inserts exhibited different water uptake (7-23%) with the smallest values for CH. Differential scanning calorimetry study pointed out possible interaction of SS and oppositely charged anionic polymers (CMC Na and AL). The mucoadhesive in situ gelling inserts exhibited satisfactory mucoadhesive and extended drug release characteristics. The inserts could be used for nasal delivery of SS over about 12 h; bypassing the hepatic first-pass metabolism without potential irritation.

Manufacture and characterization of mucoadhesive buccal films

The buccal route of administration has a number of advantages including bypassing the gastrointestinal tract and the hepatic first pass effect. Mucoadhesive films are retentive dosage forms and release drug directly into a biological substrate. Furthermore, films have improved patient compliance due to their small size and reduced thickness, compared for example to lozenges and tablets. The development of mucoadhesive buccal films has increased dramatically over the past decade because it is a promising delivery alternative to various therapeutic classes including peptides, vaccines, and nanoparticles. The "film casting process" involves casting of aqueous solutions and/or organic solvents to yield films suitable for this administration route. Over the last decade, hot-melt extrusion has been explored as an alternative manufacturing process and has yielded promising results. Characterization of critical properties such as the mucoadhesive strength, drug content uniformity, and permeation rate represent the major research areas in the design of buccal films. This review will consider the literature that describes the manufacture and characterization of mucoadhesive buccal films.