Aim: The present work intends to formulate and evaluate film forming solution of
diphenhydramine. Materials and Methods: Film forming solutions (FFS) for transdermal
delivery of Diphenhydramine HCl were prepared using different polymers (hydroxypropyl
cellulose, Eudragit L 100, polyvinylpyrollidone K30 and polyvinylpyrollidone K90), PEG
400 as plasticizer and ethyl alcohol as solvent. Results: The film forming solutions were
found to display an acceptable drying time ranging from 2 to 5 min.
In-vitro release
studies indicated percentage drug released by the end of 8 h from FFS of HPC-EF,
Eudragit L 100 and PVP K 30 was found to be 41.31 ± 2.1%, 14.81 ± 1.2 % and
25.7 ± 1.9 % respectively. FFS of HPC-EF that readily released drug were considered
for further development by incorporating penetration enhancers like azone, isopropyl
myristate and oleic acid. Steady state flux of drug across shed snake skin used as a
barrier in vertical Franz diffusion cell was found to be 42.27 ±3.5 mg/cm2/hr, 51.18
±4.9 mg/cm2/hr and 57.91 ± 7.2 mg/cm2/hr for FFS containing isopropyl myristate,
oleic acid and azone as permeation enhancers respectively. Conclusion: Considering the
plasma clearance of the drug and transdermal steady state flux, it can be inferred that
FFS containing azone as enhancer needs to be spread across an application area of
0.5 cm2 to elicit a therapeutic response.