The Crux of vehicle designations: The essence of topical dermatologic vehicles and their use

Topical therapies are essential in dermatology, accounting for over half of all prescriptions. These treatments are invaluable for managing various skin conditions due to their localized effect, ease of access and application, and generally favourable safety profiles. However, the diversity in vehicle designations to describe the topical preparations has led to confusion among healthcare professionals, patients and consumers. The challenges surrounding vehicle designations stem from a lack of universally accepted classifications and terminology, leading to widespread misconceptions about topical products. This paper examines and clarifies the complexities associated with vehicle designations. Key concepts discussed include the evolution of vehicle classifications, the role of vehicle components in affecting the bioavailability of active pharmaceutical ingredients, and the vehicle metamorphosis/transformation phenomenon that alters the product's formulation upon skin application. It is crucial to prioritize clinically relevant properties over designations. Understanding the relationship between product characteristics and clinical efficacy can help in the selection of appropriate treatments. Pharmaceutical qualities of the preparation (polarity, spreadability) and clinical qualities (skin condition, treatment area) should be considered, with the focus on empirical evaluation of products rather than on the designation of the vehicle. This is the only way to find the appropriate product vehicle in dialogue with the patients. It also emphasizes the importance of shared decision making in topical dermato-pharmacotherapy.