The costs and effects of switching calcium channel blockers: evidence from Medicaid claims data

This study used Medicaid claims data from Pennsylvania to examine the costs and effects of changing calcium channel blocker therapies. Specifically, we compared Procardia XL® with Adalat® CC. They are the only once-daily-dosed, extended-release forms of nifedipine available. These drugs were interesting to compare for several reasons. First, because the frequency of treatment regimens has been shown to be the most important determinant of long-term compliance with calcium channel blocker medications, it was desirable to compare drugs having identical dosing regimens. Second, switching from one to the other should be quite feasible in most patients. Third, Adalat CC is priced (ie, average wholesale price) less than Procardia XL. The results indicate that prescription prices were lower when patients were switched from Procardia XL to Adalat CC, with no apparent effects on blood pressure control, the incidence of adverse drug reactions, or nonprescription health care costs. The potential savings to Medicaid from switching patients from Procardia XL to Adalat CC appears to be large, more than $2.5 million annually for Procardia XL-treated Medicaid patients in the state of Pennsylvania. Our study also demonstrates that large retrospective databases can be used to evaluate economic and clinical outcomes for specific therapy alternatives. Such evaluations are increasingly relevant to third-party payers, health maintenance organizations, and other parties involved in managed care.