Meeting expectations for FDA nasal spray Q3 structural equivalence

Establishing bioequivalence based on pharmacokinetic (PK) and clinical endpoint studies is challenging, given systemic drug concentrations may not correlate with local therapeutic response. The United States Food and Drug Administration’s (FDA’s) Generic Drug User Fee Amendments (GDUFA) initiatives support advancing regulatory science to determine equivalence of complex and locally acting topical dosage forms. These activities lend themselves to a new weight of evidence approach for ophthalmic, topical cream and ointment, inhalation and nasal spray drug products in that they may allow approval based on in vitro testing alone through the concept of Q3 structural equivalence.