Stable drug encapsulation in micelles and microemulsions.

Oral absorption of hydrophobic drugs can be significantly improved using lipid-based non-particulate drug delivery systems, which avoid the dissolution step. Micellar and microemulsion systems, being the most dispersed of all, appear the most promising. While these systems show high drug entrapment and release under sink conditions, the improvement in oral drug bioavailability is often unpredictable. The formulation and drug-related biopharmaceutical aspects of these systems that govern oral absorption have been widely studied. Among these, preventing drug precipitation upon aqueous dilution could play a predominant role in many cases. Predictive ability and quick methods for assessment of such problems could be very useful to the formulators in selecting lead formulations. This review will attempt to summarize the research work that could be useful in developing these tools.