Association Between Market Competition and Prices of Generic Topical Dermatology Drugs

During the last decade, increases in drug prices for commonly prescribed dermatologic medications have outpaced the rate of inflation, national health care growth, and reimbursements. Among nondermatologic medications, studies have shown a role for robust generic market competition in reducing drug prices. The association between competition and the costs of topical dermatologic generic drugs has not been evaluated.

To characterize the association between changes in drug price and the number of US Food and Drug Administration (FDA)-approved manufacturers among the most commonly used topical dermatologic generic products.

This retrospective cost analysis of the most commonly prescribed topical dermatologic generic drugs used cumulative annual claims data from the Medicare Part D Prescriber Public User File to identify 597 dermatologist-prescribed drugs with more than 10 claims. The number of manufacturers and the price per unit were identified from the FDA Orange Book and the National Average Drug Acquisition Cost (NADAC) database, respectively, for 2013 through 2016. Drugs that were nondermatologic, were not topically administered, were missing NADAC data, were lacking a generic formulation, or had fewer than 400 claims were excluded.

Primary outcomes included per-unit drug price and number of FDA-approved manufacturers. Pricing measures were adjusted for inflation and are reported in 2016 dollars.

The present analysis included 116 topical dermatologic generic formulations, representing 70.5% of the total Medicare Part D dermatologist-coded claims from 2015. Drug formulations with 1 to 2 manufacturers during the study period sustained a median percentage increase in price of 12.7%, whereas those with more than 6 manufacturers had a median percentage decrease in price of 20.5%. Formulations with 1 to 2 manufacturers had a 20.6%, 19.5%, and 33.2% higher percentage increase in price than those with 3 to 4 manufacturers, 5 to 6 manufacturers, and more than 6 manufacturers, respectively. There was a statistically significant inverse association between the percentage change in drug price and median number of manufacturers (Spearman correlation coefficient, -0.26; P = .005).

The negative association between the change in drug price and the median number of manufacturers of generic topical dermatologic drugs indicates a role for market competition in controlling the costs of generic drug prices within dermatology. These findings support policies that facilitate robust market competition among topical dermatologic generic drugs produced by a limited number of manufacturers.