Intravenous nicardipine: an effective new agent for the treatment of severe hypertension. Fifty-six patients with severe hypertension were treated with intravenous nicardipine for infusion periods of eight to twenty-four hours. Each patient achieved satisfactory blood pressure control during the infusion period with a mean controlling dose of 7.85 mg/hr. The dose of nicardipine needed for sustained blood pressure control correlated with untreated diastolic blood pressure but not with untreated systolic blood pressure. These results demonstrate the potential usefulness of intravenous nicardipine for the treatment of severe hypertension requiring rapid lowering, and they suggest also that the severity of pretreatment diastolic hypertension might be a useful indicator of the dose required for blood pressure control. 