Basics of Sterile Compounding: Vehicles Used in Sterile Compounding.

The primary component of most compounded preparations is the vehicle. Vehicles are critical in delivering the active pharmaceutical ingredient to the patient. For liquid preparations, water is the most common vehicle followed by co-solvent systems containing water-miscible ingredients and then the non-miscible oils are used. There are different purposes and advantages for each vehicle in developing a formulation involving solutions of a drug. In developing a formulation, there are some characteristics that must be considered including pH, endotoxin load, sterility issues, and even the labeling of the vehicle being used. The vehicle has a direct impact on the delivery and stability of the finished preparation so they must be carefully evaluated for appropriateness in each specific formulation.