Bracketed Stability Evaluation of Topical Minoxidil and Finasteride in Foamil®

Many commercial scalp solutions contain propylene glycol and high quantities of alcohols which can irritate the scalp and cause additional undesirable side effects. Foamil®, a propylene glycol-free and alcohol-reduced foam vehicle, was previously developed to reduce these side effects and increase patient compliance. Two concentrations of combined minoxidil and finasteride (5% Minoxidil/0.1% Finasteride and 12.5% Minoxidil/0.25% Finasteride) in Foamil were extemporaneously compounded and studied to evaluate chemical, physical, and microbial stability over 180 days. An HPLC analysis method was developed and validated to assess chemical stability. Additionally, pH measurement and observation of organoleptic properties was assessed throughout storage. Physical and chemical stability testing was performed at predetermined timepoints (0, 30, 60, 90, 120, and 180 days). Antimicrobial testing was conducted per USP <51> guidelines after 180 days of storage. Together, these results show that the compounded minoxidil and finasteride preparations in Foamil are considered stable for 180 days when stored at room temperature in tightly closed, light resistant plastic containers.