Foam - rediscovered drug form

Abstract

Foam is a multiphase system consisting mainly of gas dispersed in a liquid or solid. The continuous phase creates a very large surface with a small thickness, which is very thermodynamically unfavorable, and thus causes high instability of the system. This system is very widespread in nature, but also in our daily lives. We meet with her starting from the morning espresso, where the foam should constitute 10% of the volume, and ending with the evening foam bath. In the technology of the drug form, foams were initially used mainly for the local treatment of skin lesions of various origin. Dermatological drugs in the form of foam are well accepted by patients. In biopharmaceutical terms, foams also show better properties compared to the ointment because the drug substance is in liquid form, which significantly increases its absorption through the outer layers of the skin. Dermatological foams have pharmacopoeial monographs. However, the specific properties of multiphase systems, which is foam, have made it increasingly used to create drug carriers administered by various routes to obtain modifications of action. One of the development directions is the use of foams in oral medications. The use of foam-like carriers allows for a significant increase in the surface of the drug - which is equivalent to an increase in its solubility. To achieve release modification, it is possible to place a significant amount of drug substance in the pores of the foam carrier. In addition, foam carriers are characterized by low density, which allows them to stay longer in the upper part of the gastrointestinal tract, and thus longer release of the drug substance. In this case, either solid carriers with a high gas content in their structure are used, or liquid foams produced in situ are used. Foams are also used in parenteral administration, such as bone implants made of hydroxyapatite or biodegradable carriers for antibiotics. This work is a review of some of the ways to use foam systems in modern drug form technology.

Keywords

• foam
• modified drug form
• target released