Herbal erection pills may be spiked.

Some pills marketed as herbal remedies for erectile dysfunction contain drugs that should be available only by prescription, researchers report.

Sildenafil (Viagra) and tadalafil (Cialis), known as phosphodiesterase inhibitors, improve erections in some men by increasing blood flow to the penis during arousal. But the prescription compounds can cause fatal complications if used at the same time as certain drugs that have effects on the heart and blood vessels.

Neil Fleshner of Princess Mary Hospital in Toronto and his colleagues found substantial quantities of sildenafil or tadalafil in two of seven nonprescription brands of purported erectile enhancers they tested. None of the samples contained vardenafil (Levitra), a third phosphodiesterase inhibitor.

The team chemically analyzed a dozen pills of each herbal brand. The researchers reported their findings on May 10 at a meeting of the American Urological Association in San Francisco. They didn't release the products' brand names.

In previous studies, other herbal supplements have been found to vary considerably in composition, suggesting quality control problems (SN: 6/7/03, p. 359). Since phosphodiesterase inhibitors aren't natural compounds, the new analyses suggest that some manufacturers are deliberately spiking their products, Fleshner and his colleagues say.--B.H.