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Background: This retrospective study compared the efficacy, tolerability, and cost of two dihydropyridine calcium channel blockers., Methods: Charts of patients who had been on continuous antihypertensive therapy with amlodipine or felodipine for at least 6 months were reviewed. Analyses include mean changes in blood pressure, percentage of patients achieving blood pressure (BP) < 140/90 mm Hg, average dose, and cost per day of the two calcium channel blockers, average cost of additional medication, total medication cost per day, and cost to achieve BP control., Results: Eighty-seven percent of amlodipine-treated patients achieved BP control compared with 33% of felodipine-treated patients. Total medication cost to achieve BP control was 0.87 dollars per day for patients on amlodipine compared with 1.79 dollars per day for patients on felodipine., Conclusions: Amlodipine produced BP control in a greater percentage of patients than did felodipine at a lower total cost to achieve BP control. When evaluating the total cost of antihypertensive treatment, the cost of a drug alone can be misleading.

The cost of treating hypertension represents a substantial percentage of total pharmacy expenditures at medical centers and by managed care organizations in the United States. The present study evaluated improvements in blood pressure control and cost savings achieved by switching 543 hypertensive patients from nifedipine gastrointestinal therapeutic system (GITS) to amlodipine and concurrently instituting an educational program directed at prescribers, nursing and pharmacy staff, and patients and family members. Before the switch, 543 patients were being treated with nifedipine GITS: 259 with 30 mg/d, 209 with 60 mg/d, and 75 with 90 mg/d. The total annual cost of primary antihypertensive therapy for this patient population was $184,698. All patients were switched from nifedipine GITS to 5 mg of amlodipine. The pharmacist saw patients at the time of the switch and at 2, 4, and 6 to 8 weeks after the change in antihypertensive therapy. Patients who did not achieve systolic blood pressure < or = 140 mm Hg or diastolic blood pressure < or = 90 mm Hg by 6 to 8 weeks after the switch were titrated to 10 mg/d amlodipine. After the conversion, 417 patients were receiving amlodipine 5 mg/d and 126 patients were ultimately titrated to 10 mg/d. Measurements made during the first 6 to 8 weeks of treatment indicated that amlodipine therapy significantly reduced blood pressure. Overall, amlodipine produced further mean reductions in blood pressure, from 140/82 to 130/76 mm Hg (p < 0.00005). The mean reduction from the time of the switch to 6 to 8 weeks was from 138/81 to 129/74 mm Hg for the patients who received 5 mg/d amlodipine (p < 0.00001) and from 147/85 to 133/79 mm Hg for the patients ultimately titrated to 10 mg/d amlodipine (p < 0.05). The total annual cost for primary antihypertensive therapy after the conversion was $136,854. We observed that conversion from nifedipine GITS to amlodipine enhanced blood pressure control and saved $47,844 in the annual cost of primary antihypertensive medication. For the 543 patients undergoing the switch, annual cost savings was $47,844. When the cost of additional antihypertensive agents discontinued after the switch to amlodipine was added to the analysis, the net annual cost savings increased to $49,578, a 27% reduction in yearly drug costs.