The list of potentially fatal interactions with Viagra continues to grow.
According to a recent review, Viagra (sildenafil) is known to react with organic nitrates to cause acute hypotension. Manufacturer Pfizer recommends that concurrent use of sildenafil with organic nitrates or nitric oxide donors is contraindicated.
This contraindication begs other questions, however, since nitrates are not just in medicines. For instance, can men who ingest large amounts of nitrates in the form of pesticides or food preservatives also be adversely affected when using Viagra? In this form, nitrates have been shown to produce many of the symptoms associated with medical nitrates, especially low blood pressure and other circulatory problems.
Comments Andy Burrows of Pfizer: “We have actually looked at the question of organic nitrates as used in foodstuffs, and our conclusion was that the amount of nitrates likely to be present in foods was so small that there would be no contraindication for individuals taking Viagra.”
Drugs are not tested for cross reactions with foodstuffs since foodstuffs are considered non pharmacological. There have been no reported interactions of this type with Viagra. However, the 28 studies from which safety data on Viagra have been pooled are known to have excluded data on nitrates or nitric oxide donors, such as sodium nitroprusside or amyl nitrite (“poppers”) (Drugs Ther Bull, 1998, 36: 81-4).