WHAT IS YOHIMBINE?
Yohimbine is an indole alkaloid derived from the bark of West African evergreen (pausinystalia yohimbine). It is widely available over the counter (OTC) but is also available as a pharmaceutical-grade powder for pharmacy compounding.
A LITTLE HISTORY…
Prior to the approval of PDE-5 inhibitors (i.e., Viagra®), yohimbine was FDA-approved for impotence and prescribed regularly. It has, however, since been removed from the market due to potential deleterious cardiac and neurologic adverse effects. Despite being removed from the market, yohimbine still remains readily available as an OTC supplement. In addition to impotence, yohimbine is now commonly marketed as an athletic performance aid, stimulant, and weight loss aid.
**BEWARE: OTC supplements are not regulated in the same way as prescription products. Federal law does not require dietary supplements to be proven safe to FDA's satisfaction before they are marketed. This means these products can contain any number (and quantity) of ingredients. In a study by Cohen and colleagues published in 2016, 49 brands of yohimbine supplements sold at seven major retail chains were analyzed to assess pharmaceutical quantity. Ultimately, only 4.1% (2/49) provided consumers with accurate information about the quantity of yohimbine.
WHY SO DANGEROUS?
Yohimbine blocks pre-and post-synaptic alpha-2 adrenergic receptors; blockade of these receptors, in turn, leads to an increase in the release of norepinephrine and dopamine. This increase in norepinephrine and dopamine can manifest as the sympathomimetic toxidrome characterized by tachycardia, hypertension, hyperthermia, diaphoresis, tremor, seizures, and psychosis. Cardiac collapse with sudden death has been reported in multiple case reports. The exact dose at which adverse effects occur is unknown. There is no antidote; treatment is supportive care.
1. Anderson C, et al. J Anal Toxicol. 2013;37(8):611-614.
2. Giampreti A, et al. Clin Toxicol (Phila). 2009;47(8):827-9.
3. Cohen PA, et al. Drug Test Anal. 2016;8(3-4):357-69.
This question prepared by L. Montana Fleenor, PharmD; PGY-2 Critical Care Pharmacy Resident, VUMC
It's always good to review OTC supplements and the potential adverse effects they can cause. One of the main concerns is the lack of consistency in the constituents of each capsule. The adage that “it’s over the counter, it must be safe” is still a strong belief among public consumers. I wish it were so. Ds
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