The red flag is up for those protease-takers who use Viagra (sildenafil) to get it up. The problem is that all five PIs inhibit the CYP 3A4 liver enzyme that breaks down the potency pill. This causes more Viagra to remain in the blood longer and to produce worse side effects, including abnormal vision, flushing, headache and drops in blood pressure. In a study by Viagra’s manufacturer, Pfizer, even the slightest inhibitor of CYP 3A4, saquinavir (Invirase), increased the maximum Viagra concentration in the blood by 140 percent, while the strongest inhibitor, ritonavir (Norvir), increased it by 400 percent. Pfizer now recommends that for anyone on a PI, the standard 50-milligram Viagra dose should be halved, and that no one on ritonavir should repeat the drug in fewer than 48 hours (24 hours for those on any other PI). And those seeking to spice up Viagra-spiked sex with a side of poppers (amyl or butyl nitrate) should beware: Since both Viagra and poppers cause blood vessel dilation, the combo can cause serious—even fatal—blood pressure decreases.
Viagra, Poppers and...