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# FDA Tests New BE Method for Generic Topicals
- URL: https://www.fdaweb.com/fda-tests-new-be-method-for-generic-topicals/
- Published: 2019-08-09T12:00:00.000Z
- Updated: 2026-09-15T01:42:57.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5144734

A new FDA [*Impact Story*](https://www.fda.gov/drugs/science-research-drugs/impact-story-developing-new-ways-evaluate-bioequivalence-topical-drugs?utm%5Fcampaign=FDA%20CDER%20Impact%20Story%3A%20Developing%20New%20Ways%20to%20Evaluate%20Bioequivalence%20for%20Topical%20Drugs&utm%5Fmedium=email&utm%5Fsource=Eloqua) discusses new research the agency has undertaken to help would-be generic topical dermatological drug product developers demonstrate bioequivalence. “FDA collaborated with international researchers to evaluate a new method for monitoring the amount of a topical drug in the dermis,” it says. “In a procedure called dermal open-flow microperfusion (dOFM), a thin, hollow tube is inserted just under the skin surface, running through a section of the skin a few inches wide and then exiting. A liquid similar to body fluid is injected into the tubing; a portion of the tube under the skin is porous, so any drug that has been applied and absorbed through the skin's outer layer enters the flowing liquid, which is then collected for analysis.”

FDA says the [clinical study](https://www.ncbi.nlm.nih.gov/pubmed/27539717?ref=fdaweb.com) that evaluated whether dOFM could reliably measure the varying amounts of drug in the skin used a topical application of a U.S. brand name acyclovir cream to two locations and a European acyclovir cream that had a different formulation to a third location. Before dosing, the dOFM tubing was inserted under these three areas, and acyclovir concentrations in collected fluid was measured over 36 hours.

“The study demonstrated that the dOFM pharmacokinetic approach could accurately and reproducibly confirm that the U.S. brand name product was bioequivalent to itself at different anatomical sites,” the agency says. “Furthermore, the dOFM approach was sufficiently sensitive to discriminate between the pharmacokinetics of the U.S. and European versions of the creams, which were — as expected — confirmed not to be bioequivalent. Additional studies are being developed to determine whether dOFM may be broadly applicable to other topical dermatological drugs with different chemical characteristics.”