Understanding the Role of Excipients in Topical Semi-Solid Microstructure and Critical Performance Parameters

Topical semi-solids, like creams, lotions and ointments are comprised of a complex mixture of microstructures or colloidal phases, frequently referred to as the Q3. These microstructures may include micelles, lamellar phases, polymer matrices, liquid crystalline and crystalline states of wax excipients, as well as the solid states of active pharmaceutical ingredients. Different topical medicated semi-solid formulations, spanning a range of treatment indications, reveal a variety of different microstructures.