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VIAGRA « Warnings
Protease Inhibitors & POPPeRs

By John S. James
Publisher, AIDS Treatment News

viagrahiv.gif - 6.68 K VIAGRA(R) (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 an April 21 "Backgrounder for HIV Treatment Advocates" from Pfizer Inc., "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."

There are several other medications which require caution if used with sildenafil (and some which must not be combined at all); patients should obtain this information from a medical professional, or from a recent copy of the official labeling of the drug.

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[Note: The current labeling, dated February 1999, is considerably less cautious than the Pfizer backgrounder quoted above.

The backgrounder is conservative because discussions with the FDA are ongoing, and it is not known what the final recommendations will be. Technical information will be posted by the National AIDS Treatment Advocacy Project,]

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 and Poppers

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.
AIDS Treatment News
Published twice monthly

Subscription and Editorial Office:

P.O. Box 411256
San Francisco, CA 94141
800/TREAT-1-2 toll-free U.S. and Canada
415/255-0588 regular office number
Fax: 415/255-4659

Editor and Publisher: John S. James
Associate Editor: Tadd T. Tobias
Reader Services: Tom Fontaine and Denny Smith
Operations Manager: Danalan Richard Copeland

Statement of Purpose:
AIDS TREATMENT NEWS reports on experimental and standard treatments, especially those available now. We interview physicians, scientists, other health professionals, and persons with AIDS or HIV; we also collect information from meetings and conferences, medical journals, and computer databases. Long-term survivors have usually tried many different treatments, and found combinations which work for them. AIDS Treatment News does not recommend particular therapies, but seeks to increase the options available.

ISSN # 1052-4207
Copyright 1999 by John S. James.

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