Phentolamine
Pharmacology. Phentolamine is a competitive presynaptic and postsynaptic alpha-adrenergic receptor blocker that produces peripheral vasodilation. By acting on both venous and arterial vessels, it decreases total peripheral resistance and venous return. It also may stimulate beta-adrenergic receptors, causing cardiac stimulation. Phentolamine has a rapid onset of action (usually 2 minutes) and a short duration of effect (approximately 15–20 minutes).
Indications
Hypertensive crisis associated with stimulant drug overdose (eg, amphetamines, cocaine, or ephedrine). Also an adjunct for cocaine-induced acute coronary syndrome to reverse coronary artery vasoconstriction.
Hypertensive crisis resulting from interaction between monoamine oxidase inhibitors and tyramine or other sympathomimetic amines.
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