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# FDA Approves 1st Generic Drug Based on PBPK Model
- URL: https://www.fdaweb.com/fda-approves-1st-generic-drug-based-on-pbpk-model/
- Published: 2022-02-22T12:00:00.000Z
- Updated: 2026-09-14T17:33:39.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5151214

FDA says its approval of a generic diclofenac sodium topical gel 1% was the first ANDA approval for which a physiologically based pharmacokinetic (PBPK) model supported the bioequivalence assessment. An agency [paper](https://www.fda.gov/drugs/regulatory-science-action/how-modeling-was-used-support-fda-approval-topical-generic-drug-product?utm%5Fmedium=email&utm%5Fsource=govdelivery) says CDER researchers have been investigating how pharmacokinetic modeling can support a bioequivalence determination for topical drug products.

“The capability of the model to generate local and systemic diclofenac exposure predictions following the application of topical products that were sensitive to formulation differences was adequately validated,” FDA says. The paper also says some of the platform research was partially supported by GDUFA 1 and 2 grants.