Development and evaluation of rapidly dissolving buccal films of naftopidil: in vitro and in vivo evaluation

Objectives: Development and evaluation of rapidly dissolving film for intra-oral administration of naftopidil. Methods: Rapidly dissolving film utilized hydroxypropyl methylcellulose E5 and polyvinylpyrrolidone K30 as the main components. The drug was loaded in pure form or after co-grinding with citric and/or tartaric acid. A solution of naftopidil in plurol oleique, labrasol, and tween 80 self-microemulsifying drug delivery systems (SMEDDS) was also loaded. The interactions of the drug with the excipients were monitored using thermal analysis, Fourier transform infrared spectroscopy, and X-ray diffraction. Naftopidil dissolution was monitored and selected films were used to assess the bioavailability after buccal administration to rabbit. Unprocessed drug suspension was administered orally and used as a reference. Results: Incorporation of naftopidil in the film developed a new crystalline structure. The crystallinity of drug was abolished in the presence of organic acids or SMEDDS. The rapidly dissolving films showed fast liberation of the drug irrespective to the composition. Those films enhanced the bioavailability of naftopidil compared to orally administered suspension with SMEDDS containing film being superior. Conclusion: The study introduced rapidly dissolving buccal film for enhanced dissolution and bioavailability of naftopidil.