Overdosage with a 600 mg single dose (15 to 30 times normal clinical dose) has been reported. Marked hypotension (blood pressure unobtainable) and bradycardia (heart rate 20 bpm in normal sinus rhythm) occurred, along with drowsiness, confusion and slurred speech. Supportive treatment with a vasopressor resulted in gradual improvement with normal vital signs approximately 9 hours post treatment.

Based on the results obtained in laboratory animals, overdosage may cause systemic hypotension, bradycardia (following initial tachycardia) and progressive atrioventricular conduction block. Reversible hepatic function abnormalities and sporadic focal hepatic necrosis were noted in some animal species receiving very large doses of nicardipine.

For treatment of overdose standard measures (for example, evacuation of gastric contents, elevation of extremities, attention to circulating fluid volume and urine output) including monitoring of cardiac and respiratory functions should be implemented. The patient should be positioned so as to avoid cerebral anoxia. Frequent blood pressure determinations are essential. Vasopressors are clinically indicated for patients exhibiting profound hypotension. Intravenous calcium gluconate may help reverse the effects of calcium entry blockade.

Nicardipine HCl is contraindicated in patients with hypersensitivity to the drug.

Because proof of the effect of nicardipine HCl is secondary to reduced afterload, the drug is also contraindicated in patients with advanced aortic stenosis. Reduction of diastolic pressure in these patients may worsen rather than improve myocardial oxygen balance.

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