Safety and efficacy of nifedipine 20 mg tablets in hypertension using electronic data collection in general practice.

Electronic data collection was used in this open study to survey the safety and efficacy of nifedipine when used in the treatment of 3972 patients with mild to moderate essential hypertension. The safety and efficacy results are presented and discussed as well as the advantages, disadvantages and reliability of electronic data collection. The validity of data collected electronically has not previously been tested, such data having been assumed to be reliable. The pattern of adverse events reported in this study is compared with the pattern of reports to the Committee on Safety of Medicine (CSM), to Bayer UK and in a large paper-based study of nifedipine, in order to test these assumptions. Reported adverse medical events pre-treatment, prior to entry to the study and noted at visit 1, were compared with reports during treatment in the study at visits 2 and 3. The expected incidence of flushing and headache was seen which diminished with continued treatment. Reductions were seen in dyspnoea and impotence. Ankle oedema was observed and was not reduced by time alone. After one month of treatment with nifedipine 20 mg tablets twice daily, 66.5% of patients had a sitting phase V diastolic blood pressure of 90 mmHg or below and 79% of 95 mmHg or below.