Fixed-dose combination and single active ingredient drugs: a comparative cost analysis.

Background: Fixed-dose combination (FDC) drugs are formulations of two or more active ingredients.

Objectives: To assess the pricing structure and price difference of all US FDA-approved FDCs and single drugs included in the combination.

Methods: Data were collected from the FDA Orange Book and Drugs@FDA. Average Wholesale Price (AWP) unit price data were derived from The Red Book.

Results: The FDA approved 117 FDC. The average AWP difference percentage between the FDC and the sum of the single drugs in the FDC is 84.9 ± 26.2%, and varied by therapeutic class (p < 0.001). The FDC AWP averaged 83.3 ± 23.4% of the single drug AWP sum when there are no generics, and 95.1 ± 42.3% (p < 0.01) when there are two generic single active ingredients in the FDC.

Conclusions: The price difference between FDC and single active ingredients in the combination is correlated with the therapeutic class, the year of FDC approval, and the number of single ingredients in the combination that have generics.