Development of an optimized avanafil-loaded invasomal transdermal film: Ex vivo skin permeation and in vivo evaluation.

Avanafil (AVA) is a recent FDA approved selective phosphodiesterase type 5 inhibitor used for oral treatment of erectile dysfunction. The oral bioavailability of the drug is challenged by its reduced water solubility, considerable presystemic metabolism, and altered absorption in the presence of food. Accordingly, this work aimed to surmount the aforementioned challenges through the development of optimized nanosized AVA invasomes with enhanced transdermal delivery. AVA invasomes were prepared according to a Box-Behnken experimental design to explore the impact of the following formulation factors: phospholipid % (X), ethanol % (X), terpene % (X), and terpene type (X) on vesicle size (Y) and entrapment efficiency (Y). The three numerical variables were used at three levels, while the categorical variable was used at two levels. The optimized formulation with vesicular size of 109.92 nm and entrapment efficiency of 96.98% was incorporated into a hydroxypropyl methyl cellulose-based transdermal film and characterized for its ex vivo permeation behavior and in vivo performance in rats. The optimized AVA invasomal film showed enhanced ex vivo permeation with an enhancement factor of 2.514 and a more than four-fold increase in relative bioavailability compared to the raw AVA film. These results provide insight into the capability of the optimized invasomal film to enhance the transdermal permeation and bioavailability of AVA.