Papaverine/phentolamine Disease Interactions

The use of papaverine and papaverine derivatives is contraindicated in patients with complete AV heart block. When conduction is depressed, these agents can induce transient ectopic rhythms of ventricular origin, either premature beats or paroxysmal tachycardia. Therapy with these agents should be administered cautiously in patients with conduction disturbances, including sinus bradyarrhythmia and partial or first-degree AV block.

The use of phentolamine is contraindicated in patients with myocardial infarction, or a history of myocardial infarction, coronary artery disease or insufficiency, or angina. Hypotension due to decreased peripheral vascular resistance results from direct relaxation of vascular smooth muscle and/or alpha adrenergic blockade. Heart rate and cardiac output are increased due to beta adrenergic agonist properties. Acute and prolonged hypotensive episodes with reflex tachycardia and arrhythmia have also occurred during phentolamine therapy.

The use of papaverine derivatives has been associated with an increase in intraocular pressure. Therapy with papaverine derivatives should be administered cautiously in patients with glaucoma.

Cerebrovascular spasms and occlusions have occurred as a result of marked hypotension during phentolamine therapy. Therapy with phentolamine should be administered cautiously in patients with or a history of cerebrovascular disorders.

The pharmacokinetic disposition of phentolamine has not been fully determined. Limited data suggest that phentolamine is metabolized by the liver. Phentolamine is eliminated by the kidney and approximately 13% is excreted unchanged in the urine. Therapy with phentolamine should be administered cautiously in patients with severe liver and/or renal function. Clinical monitoring of hepatic and/or renal function is recommended.