Controlled-release injectable microemulsions: recent advances and potential opportunities

Controlled-release injectable (CRI) formulations hold significant value for several indications. However, there have been very few successful developments and approvals due to various challenges that include limited polymer options, drug-excipient process incompatibility and complex scale-up/validation processes. Microemulsion technology, as reviewed in this article, promises to resolve many of these challenges.

In addition to its development and manufacturing advantages, feasibility to engineer microemulsion formulations by choosing its constituents and nature of formulation vis-à-vis drug candidate demonstrates capability of microemulsion to modulate in-vivo drug release and thereby optimize drug pharmacokinetics and pharmacodynamics. This potential of microemulsion has been used in a few studies to prolong in vivo drug residence time resulting in a more favorable benefit/risk profile for various drugs. Virtues of injectable microemulsion, results related to prolonged-release injectable microemulsion, impact on drug safety and efficacy and possible opportunities have been discussed. A detailed review of research work on microemulsions as well as other parenteral controlled-release formulations was conducted using PubMed, Science Direct and Google Scholar.

The fact that microemulsion formulations administered through subcutaneous or intramuscular route would undergo significantly prolonged elimination should be leveraged to develop novel CRI drug products. Such products will find enormous application for several drug candidates which have poor oral pharmacokinetics resulting into poor treatment outcome.