Abstract
Background and Objective: Erectile dysfunction (ED) is a common condition, especially in diabetic males. Alpha-lipoic acid (ALA) can protect endothelial cells from oxidative stress damage. The purpose of this study was to find a new treatment for ED in diabetic patients via combined ALA with tadalafil (TFL) in a transdermal patch to enhance the skin permeability of TFL and protect epithelia cells lined penile vessels from the oxidative stress induced by hyperglycemia. Materials and Methods: A solubility study was carried out for TFL and ALA, followed by nine formulae with different ratios of oil, surfactant and co-surfactant. TFL released from the formulated patch was compared with a raw TFL patch and afterward, permeation of the formulated TFL was imaged. The difference between the treatments was estimated using one way-analysis of variance test. Results: Anise oil and Tween 20 showed highest solubility for both drugs, while polyethylene glycol (PEG 200) solubilized 0.49 +/- 0.1 and 7.8 +/- 1.2 mg mL(-1) of TFL and ALA, respectively, Formula A4, achieved the lowest globular size (134.3 +/- 12.3 nm) according to ternary phase diagram. TFL released was enhanced significantly by about 2.83-fold in the transdermal patch in comparison with raw TFL after 12 h, images clearly confirm the efficacy of penetration of the formula within the skin layers. According to cell viability (EA. hy926) data to assess the role of ALA in improvement of resistance of endothelial cells to oxidative stress, ALA increased cell survival by about 1.3-fold. Conclusion: The combination of ALA and TFL in the form of a self-nano emulsion drug delivery system as a transdermal patch could be a successful strategy for treatment of ED in diabetic patients.