Nifedipine
The FDA approved nifedipine (Pfizer’s Procardia XL, Bayer’s Adalat CC, generics) (Figure 11) for the treatment of hypertension in 1986. Like amlodipine, the agent is a long-acting dihydropyridine that reduces blood pressure via inhibition of calcium entry into vascular smooth-muscle cells. A once-daily, controlled-release formulation of nifedipine known as Adalat-GITS (Gastrointestinal Therapeutic System) is now available. The controlled-release formulation is designed to provide constant delivery of a range of doses (30-90 mg) of nifedipine over 24 hours, thus providing more-regulated blood pressure control.
Many clinical investigations comparing nifedipine with other antihypertensive therapies have been carried out, both in patients with uncomplicated hypertension and in patients with cardiovascular comorbidities. In one randomized, 12-week trial, investigators compared the efficacy, safety, and tolerability of once-daily nifedipine-GITS (initial dose = 30 mg) with amlodipine (initial dose = 5mg) in 155 mild-to-moderate hypertensive patients (diastolic blood pressure 95-109 mm Hg). They found no significant differences in efficacy between the two groups. Mean diastolic blood pressure was 83.1 and 81.9 mm Hg in the nifedipine and amlodipine groups, respectively (p = 0.436). The mean reduction in systolic blood pressure was 28.5 ± 11.9 mm Hg in the nifedipine group and 28.2 ± 11.2 mm Hg in the amlodipine group. Although both drugs were well tolerated, there was a trend toward an increase in adverse events in the amlodipine group (10.1%) compared with the extended-release nifedipine group (7.9%).
The International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT) compared the effects of nifedipine-GITS with those of the diuretic coamilozide on cardiovascular mortality and morbidity in 6,321 hypertensive patients aged 80 years or older who had at least one additional cardiovascular risk factor. Patients received either 30 mg nifedipine-GITS (n = 3157) or coamilozide (25 mg hydrochlorothiazide plus 2.5mg amiloride [n = 3164]). The study’s primary outcomes were cardiovascular death, MI, heart failure, or stroke. Both treatment regimens were found to be equally effective in preventing overall cardiovascular and cerebrovascular complications in this patient group. There were 8% more withdrawals from the nifedipine group due to peripheral edema, but more serious adverse events occurred more frequently in the coamilozide group. The researchers assert that this study demonstrates the need for antihypertensive therapy to be tailored to the individual patient.
Bayer is conducting the ACTION trial to investigate the effects of nifedipine-GITS on slowing disease progression and improving endothelial function with respect to clinical outcomes
The ACTION trial investigated the effects of nifedipine-GITS on clinical outcomes in 7,665 patients with hypertension and stable angina, with up to six years follow-up. Patients also received “best practice” therapy including other antihypertensive drugs; 80% received a beta blocker concurrently. Nifedipine GITS significantly reduced the combined incidence of all-cause mortality, myocardial infarction, refractory angina, heart failure, stroke, and peripheral revascularization by 13% in patients with hypertension only (P < 0.05). Nifedipine significantly reduced the incidence of any stroke or transient ischemic attack by almost 30% and the need for coronary angiography by 16% in hypertensives; the incidence of new heart failure was also significantly reduced by 38% and of debilitating stroke by 33%.
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