In vitro–in vivo correlation of microsphere formulations: recent advances and challenges

Background Microsphere formulations prepared using biodegradable polymers are among the most common strategies used for controlled-release drug delivery. These formulations can be loaded with a wide array of drugs, including chemicals and peptides, enabling prolonged release periods. However, establishing a standardized release profile for microsphere formulations is challenging because of their complexity and diversity. For this reason, there is no official method for in vitro–in vivo correlation (IVIVC) of microspheres. Area covered This review outlines a method for developing IVIVC of microsphere formulations based on the United States Food and Drug Administration guidance for extended-release oral dosage forms. It briefly provides definitions and summarizes each stage of the method. In addition, we discuss the findings of recent studies on obstacles and influencing factors in developing IVIVC of microspheres. Expert opinion IVIVC is an effective model for quality control during manufacturing and an indicator of in vivo performance. Ultimately, it can serve as a surrogate for costly and time-consuming human bioequivalence studies. The IVIVC of microspheres has become an important concern as the microsphere drug market grows. This review provides a plethora of examples for microsphere IVIVC to enhance predictability.