July 1999 Cover
|
 |
Viagra (sildenafil) doses must be low when the drug is used with HIV protease inhibitors (especially ritonavir), because these antiretrovirals reduce the metabolism
of sildenafil in the liver, resulting in abnormally high blood levels which can cause adverse effects. The combination apparently does not affect blood levels of
protease inhibitors.
Sildenafil, used to treat erectile dysfunction, is supplied as tablets in three doses: 25, 50, and 100 mg, and is taken half an hour to four hours before
intercourse; physicians often start with 50 mg and then lower or raise the dose if needed. But according to manufacturer Pfizer, "Given the magnitude of the interaction
between sildenafil and protease inhibitors, ongoing discussions with the FDA indicate that a maximum single dose of 25 mg of sildenafil in a 48 hour period should not
be exceeded in patients receiving these agents concurrently."
The labeling also warns that anyone with an erection lasting more than four hours needs medical assistance immediately, because of the risk of tissue damage to
the penis which could cause permanent loss of potency.
Viagra must not be combined with nitrite inhalants ("poppers") or any form of nitrates, because the combination may result in dangerously low blood
pressure, which could be fatal.
Editor's Note: from AIDS Treatment News
You are not logged in.
No comments yet, but
click here to be the first to comment on this
HIV Digest!
|
