“Herbal viagra” pills may contain viagra or other designer PDE5 inhibitors

An increasing number of dietary supplements sold in the US, UK, and beyond as “sexual enhancement” products are being found to contain prescription medications used to treat male erectile dysfunction, or similar chemical analogues.

Often sold in online shops or on ebay, these products are typically touted as containing all natural ingredients, but FDA analysis reveals that they contain synthetic drugs that are known as PDE5 inhibitors. These are prescription-only medications – though demand for them is so high that they are commonly bought and sold on the black market, counterfeited, and found in adulterated dietary supplements.

Fig 1. Chemical structure of sildenafil

There are three prescription drugs in this class: sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra), however analysis of many of the misbranded products on the market reveals that they often contain chemically similar ingredients that have not undergone the same pre-market safety checks that licensed medicines have. How well these novel analogues work – and how toxic they are – has not been established.

Fig 2. Chemical structure of hydroxythiohomosildenafil

As recently as today the FDA announced the discovery of sildenafil and hydroxythiohomosildenafil (a related analogue) in the mislabelled dietary supplement “X-rock” by CRM Laboratories. Any consumers who have X-Rock in their possession are advised to stop using this product immediately and throw it away. Consumers who have experienced any negative side effects should consult a health care professional as soon as possible. [1]

Analogues of sildenafil have been detected in supplements since at least 2006, [2] though the particular drug in this case (hydroxythiohomosildenafil) was first discovered in the herbal supplements in 2009. [3] Since then an increasing number of products have been found to be “spiked” with these untested drugs.
In some cases the courts have successfully removed the offending products from sale, [4] though it’s feared in many cases the product may simply be repackaged and reintroduced to the market under a new name.

Other products found to have been adulterated with undeclared drug ingredients include: [5]

“African Black Ant” – sildenafil and tadalafil
“Stree Overlord” – sildenafil
“France T253” – sildenafil
“Hard Ten Days” – sildenafil
“Black Ant” – sildenafil
“ViaXtreme” – sulfoaildenafil
“Rock Hard Extreme” – sulfoaildenafil
“Passion Coffee” – sulfoaildenafil
“Man King” – sildenafil

References:
[1] FDA Public Notification: “X-Rock” Contains Undeclared Drug Ingredient
[2] J Toxicol Environ Health A. 2006 Nov;69(21):1951-8.
[3] Food Additives and Contaminants Vol. 26, No. 2, February 2009, 145–151
[4] Forensic Sci Int. 2008 May 20;177(2-3):e25-7.
[5] FDA: Tainted Sexual Enhancement Products