The acute hypotensive effect of nifedipine was evaluated, and the possibility of its long-term use in hypertensives over 60 years of age was studied. Sublingual nifedipine in a dose of 20 mg was given to 28 patients, mean age 73.1 yrs, and blood pressure, heart rate, and plasma drug concentration were monitored at 15 min, and every 30 min thereafter for 3 hrs. Systolic and diastolic blood pressure decreased at 15 min by 22.1 and 7.0 mmHg, respectively, reaching a maximal decrease two hours after drug administration. The decrease in blood pressure level did not correlate with nifedipine plasma concentration, but only with the initial systolic blood pressure. Long-term treatment with nifedipine was initiated in 60 patients, with 45 patients completing the study. Mean age was 66.2 years. An initial dose of 30 mg daily had to be increased to 60-80 mg in one-third of the patients. Monotherapy was not satisfactory in some patients. Blood pressure gradually decreased from 173/99 to 148/85 mmHg at three months, and to 141/84 mmHg at six months. Drug tolerance was fairly good. Nifedipine was withdrawn due to a considerable increase in heart rate in three patients and skin allergy in one. The most frequent adverse symptoms were: rash, headache, and leg oedema. Laboratory tests revealed no changes in urea and creatinine, and an increase in fasting glycaemia. Lipid parameters did not change significantly. These data proved that a single dose of 20 mg of nifedipine produced therapeutic plasma concentration of the drug and good hypotensive effect, positively correlating with initial systolic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)