Control of blood pressure in hypertensive patients with felodipine extended release or nifedipine retard.

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Abstract
This multicentre hospital study compared the antihypertensive efficacy and the tolerability of once daily felodipine extended release (ER) with twice daily nifedipine retard (R) in hypertensive patients inadequately controlled on metoprolol monotherapy. One hundred patients, aged 20-70 years, whose seated diastolic blood pressure was 100-115 mmHg after 4 to 6 weeks of metoprolol (200 mg day-1) monotherapy, were randomised, double-blind, to receive felodipine ER 10 mg once daily or nifedipine R 20 mg twice daily for 8 weeks. The dosage of felodipine or nifedipine was doubled if seated diastolic blood pressure exceeded 95 mmHg, 2 or 4 weeks after randomisation. Metoprolol 200 mg once daily was taken throughout the trial. Fifty-one patients received felodipine ER and 49 nifedipine R; 46 and 45 respectively completed the 8 week trial. About half of patients on each treatment needed the higher dose. The baseline characteristics of the felodipine and nifedipine groups were generally well balanced. Seated diastolic blood pressure was reduced by 17 mmHg for felodipine (24 h post-dose) and by 9 mmHg for nifedipine (12 h post-dose), a difference between treatments of 8 mmHg (95% confidence interval 5 to 12 mmHg, P < 0.0001). The attained blood pressures at the end of the study (felodipine 90 .+-. 10, mmHg, mean .+-. s.d.; nifedipine 95 .+-. 10) were also significantly idfferent (95% confidence interval for the 5 mmHg difference, -9 to -1 mmHg, P < 0.01). In contrast, 3 h post-dose, the reduction in diastolic blood pressure was similar for both drugs; felodipine 17 mmHg, nifedipine 14 mmHg (difference 3 mmHg, 95% confidence interval -3 to +7 mmHg, P > 0.2). The attained blood pressures were also similar (felodipine 81 .+-. 9; nifedipine 83 .+-. 8 mmHg). The pattern and prevalence of adverse events were similar for the two drugs, with the most common adverse events being ankle oedema, flushing and headache. In response to a questionnaire, ''vasodilator'' adverse events were reported by 31% of patients on metoprolol alone and increaesd to over 50% during treatment with the calcium antagonists. In this trial felodipine ER produced a greater reduction in blood pressure than nifedipine R when blood pressure was measured at the end of the dose interval. Felodipine had a more even effect at 3 and 24 h post-dose than did nifedipine 3 and 12 h post-dose. This trial supports the view that felodipine is suitable for once daily use as an addition to .beta.-adrenoceptor blocker therapy. The short duration of the trial gives no guidance on long-term tolerability.