Chemical and Microbiological Stability Supporting Extended BUDs in Pentravan® Based Transdermal Preparations

Transdermal drug delivery represents an important strategy in personalized medicine, offering advantages such as avoidance of first-pass metabolism, improved adherence, and sustained plasma concentrations. In compounding practice, the assignment of scientifically justified beyond-use dates (BUDs) requires robust evidence of both physicochemical stability and microbiological quality. This study evaluated the chemical and antimicrobial stability of compounded transdermal formulations containing dehydroepiandrosterone (DHEA, 0.1-10.0%), estradiol hemihydrate (0.01-2.0%), progesterone (1.0-20.0%), and propranolol hydrochloride (0.1-5.0%) prepared in Pentravan®. Stability-indicating UHPLC methods were developed and validated for each active pharmaceutical ingredient (API), and forced-degradation studies confirmed method specificity. Formulations were stored at room temperature and analyzed over 180 days, with acceptance criteria defined as 90-110% of labeled content. Antimicrobial effectiveness testing (AET) was performed according to USP <51> at initial and final stability time points. All analytical methods met validation criteria for specificity, linearity (r > 0.99), precision (CV < 5%), and accuracy (98-102%). Estradiol (0.01% and 2.0%), progesterone (1.0% and 20.0%), propranolol hydrochloride (0.1% and 5.0%), and DHEA 10.0% remained within specification for 180 days. DHEA 0.1% demonstrated significant potency loss at 180 days, supporting a BUD of 150 days. No relevant physical instability was observed, and all formulations complied with USP <51> antimicrobial effectiveness requirements throughout their assigned BUDs. These findings demonstrate that Pentravan® supports extended BUDs of up to 180 days for multiple clinically relevant transdermal APIs while maintaining chemical stability and preservative efficacy. Concentration-dependent stability was observed for DHEA, reinforcing the importance of formulation-specific evaluation when assigning BUDs in compounded preparations.