Yohimbine hydrochloride

Yohimbine hydrochloride has been associated with high blood pressure, increased heart rate, headache, anxiety, dizziness, nausea, vomiting, tremors, and sleeplessness. It can be dangerous if taken in large doses or for long periods of time. It should not be taken in combination with monoamine oxidase (MAO) inhibitors, as effects may be additive.
Yohimbe should be used with caution when taken with medicines for high blood pressure, tricyclic antidepressants, or phenothiazines. People with kidney problems and people with psychiatric conditions should not use yohimbe. Women who are pregnant or breastfeeding should not take yohimbe.
The Journal of Medical Toxicology reports an instance of refractory priapism associated with ingestion of yohimbe extract, and there are other scattered reports of adverse reactions. However, may studies report it to be generally well tolerated.

Yohimbine hydrochloride is a pre-synaptic alpha 2-adrenergic blocking agent. The exact mechanism for its use in impotence has not been fully elucidated. However, yohimbine may exert its beneficial effect on erectile ability through blockade of central alpha 2-adrenergic receptors producing an increase in sympathetic drive secondary to an increase in norepinephrine release and in firing rate of cells in the brain noradrenergic nuclei.Yohimbine-mediated norepinephrine release at the level of the corporeal tissues may also be involved. In addition, beneficial effects may involve other neurotransmitters such as dopamine and serotonin and cholinergic receptors.

Yohimbine hydrochloride—an α2-adrenoceptor antagonist that is approved for treatment of erectile dysfunction—may increase BP.1,2,In normal volunteers and in patients with panic disorders, oral administration at doses used clinically may slightly increase BP.1 However, in hypertensive patients oral yohimbine was reported to induce a significant increase in mean arterial pressure.The magnitude of the pressor response was related to baseline norepinephrine levels and to the yohimbine-induced increment in plasma norepinephrine levels.Thus yohimbine increases BP by stimulation of the sympathetic nervous outflow, and the drug should be administered with caution to patients with evidence for increased basal sympathetic outflow or those undergoing concurrent treatment with tricyclic antidepressants or other drugs that interfere with neuronal uptake or metabolism of norepinephrine.