Drug Groups

approved

Description

A plant alkaloid with alpha-2-adrenergic blocking activity. Yohimbine has been used as a mydriatic and in the treatment of impotence. It is also alleged to be an aphrodisiac. [PubChem]

Indication

Indicated as a sympatholytic and mydriatic. Impotence has been successfully treated with yohimbine in male patients with vascular or diabetic origins and psychogenic origins.

Pharmacology

Yohimbine is an indolalkylamine alkaloid with chemical similarity to reserpine. Yohimbine blocks presynaptic alpha-2 adrenergic receptors. Its action on peripheral blood vessels resembles that of reserpine, though it is weaker and of short duration. Yohimbine's peripheral autonomic nervous system effect is to increase parasympathetic (cholinergic) and decrease sympathetic (adrenergic) activity. It is to be noted that in male sexual performance, erection is linked to cholinergic activity and to alpha-2 adrenergic blockade which may theoretically result in increased penile inflow, decreased penile outflow or both. Yohimbine exerts a stimulating action on the mood and may increase anxiety. Such actions have not been adequately studied or related to dosage although they appear to require high doses of the drug. Yohimbine has a mild anti-diuretic action, probably via stimulation of hypothalmic center and release of posterior pituitary hormone. Reportedly Yohimbine exerts no significant influence on cardiac stimulation and other effects mediated by (beta)-adrenergic receptors. Its effect on blood pressure, if any, would be to lower it; however, no adequate studies are at hand to quantitate this effect in terms of Yohimbine dosage.

Affected Organisms

Biotransformation

Yohimbine appears to undergo extensive metabolism in an organ of high flow such as the liver or kidney, however, the precise metabolic fate of yohimbine has not been fully determined.

Absorption

Rapidly absorbed following oral administration. Bioavailability is highly variable, ranging from 7 to 87% (mean 33%).

Half Life

Elimination half-life is approximately 36 minutes.

External Links