Impact of Menthol Concentration on Ketoprofen Permeation and Photostability in Compounded Topical Preparations in a Pentravan Base

High Resolution Image Download MS PowerPoint Slide Background: Topical nonsteroidal anti-inflammatory drugs provide localized pain relief while reducing the risk of systemic adverse effects. Menthol is frequently used in topical formulations both as an analgesic agent and as a penetration enhancer. Objective: This study evaluated the effect of menthol concentration on ketoprofen permeation through Strat-M membranes and photostability in compounded topical formulations based on a Pentravan vehicle. Research design and methods: Semisolid formulations containing ketoprofen, lidocaine hydrochloride, and increasing concentrations of menthol were prepared using the Pentravan base. In vitro permeation experiments were performed using Franz diffusion cells with Strat-M membranes as a screening model. Ketoprofen concentrations were determined using UHPLC analysis. Photostability under UVA exposure (0–200 Wh/m 2 ) was also assessed. Results: Ketoprofen permeation increased with increasing menthol concentration. After 12 h, the cumulative amount detected in the acceptor phase ranged from 194.9 μg for the menthol-free formulation to 475.9 μg for the formulation containing 10% menthol. Photostability studies showed formulation-dependent degradation profiles. The menthol-free formulation retained the highest proportion of ketoprofen during UVA exposure, whereas the menthol-containing formulation and the commercial product showed more pronounced drug degradation. Conclusion: Menthol enhanced ketoprofen permeation in the applied in vitro model while also influencing the drug’s photodegradation behavior under UVA exposure, highlighting the importance of formulation composition in compounded topical preparations.