General practice data derived tolerability assessment of antihypertensive drugs.

A large hypertensive population of patients in general practice was used to assess the tolerability of nifedipine in previously untreated patients and was compared with other antihypertensive drugs in previously treated patients. A total of 3972 patients with a sitting diastolic blood pressure between 95 and 115 mmHg were treated with 20 mg nifedipine twice daily for 1 month. In non-responders the dose was increased to 40 mg twice daily for a second month; responders continued to take 20 mg twice daily. A total of 2772 patients had been previously untreated for hypertension, whereas 857 had previously been treated with beta-blockers alone or in combination and 346 had received diuretics alone or in combination. Adverse events were recorded for 28 days prior to treatment being initiated with or changed to nifedipine and for two 28-day nifedipine treatment periods. Flushing and headache, which diminished with time, occurred during nifedipine treatment. Ankle oedema did not diminish with time. Reductions were seen in occurrences of dyspnoea, impotence, lethargy and cold extremities.