Oral nifedipine for the treatment of patients with severe hypertension.

Ten mg of nifedipine was administered to 19 patients with severe hypertension (mean blood pressure 187 +/- 17/122 +/- 12 mm Hg) without intensive care monitoring. Patients were instructed to bite and swallow the contents of the capsule. Blood pressure declined significantly to a mean of 149 +/- 17/92 +/- 10 mm Hg. No adverse side effects or hypotension occurred. Ten patients required an additional dose 30 to 60 minutes after the initial dose. Mean heart rate increased from 79 to 95 beats per minute without symptomatic consequences. Laboratory parameters measured before and after the four-hour study did not change significantly, although peripheral renin activity rose transiently. Urinary sodium excretion increased 43 percent over four hours after therapy in three patients in whom it was measured. Cardiac output, which was measured noninvasively in seven patients, rose nonsignificantly whereas systemic vascular resistance declined from 2,070 dynes/second/cm-5 to 1,271 dynes/second/cm-5 (statistically significant difference) in 20 minutes. These results indicate that oral nifedipine, when bitten and swallowed, effectively lowers blood pressure in patients with severe hypertension without the occurrence of adverse side effects or hypotension. Oral nifedipine may be used safely in an outpatient setting when urgent intervention is required.