Dynamic view on affordability of fixed-dose combination antihypertensive drug therapy

The use of fixed-dose combinations (FDCs) has been increasing since the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommended using ≥2 drugs as the first-line drug therapy for patients with stage 2 hypertension. FDCs simplify the drug therapy regimen and reportedly lower the drug therapy cost compared with the free combination (FC) of 2 single-agent drugs. This study hypothesized that the affordability of FDCs over FCs would change over time depending on the availability of generic single-agent drugs.

This study used the 2009 Medical Expenditure Panel Survey. Antihypertensive drugs were identified based on the Food and Drug Administration national drug directory. Based on the 2 databases, regression models were run to predict average monthly drug cost as well as out-of-pocket cost for each prescription along with their 95% confidence intervals (CIs).

Overall, FDCs (n = 26) had average monthly drug costs similar to respective FCs when FCs were not generically available. However, when FCs were generically available, FDCs (n = 11) had average drugs costs much higher than their respective FCs. For example, Lotrel as an FDC had an average monthly drug cost of $115.97 (95% CI = $96.59-$135.36), whereas its counterpart FC had an average monthly drug cost of $21.00 (95% CI = $18.23-$23.79).

The cost advantage of FDCs over FCs was reversed when FCs were generically available. The finding of this study informs patients, health-care providers, and drug plans of the importance of making dynamic decisions on preferred drug therapy options depending on the availability of generic drugs.