Nelfinavir (trade name Viracept) is one of a new class of anti-HIV drugs called protease inhibitors. These drugs work by blocking a part of HIV called protease. When protease is blocked, HIV makes copies of itself that can't infect new cells. Protease inhibitors are almost always used in combination with at least two other anti-HIV drugs.

Taking the drug: The standard dose of nelfinavir is 750 mg taken three times a day with food. Doctors recommmend that you don't leave a gap of more than 12 hours between any two doses. A new twice-daily dose of nelfinavir has now also been approved. The approved twice-daily dose is 1,250 mg taken every 12 hours. Nelfinavir should generally be taken in combination with other anti-HIV drugs. If you've been taking anti-HIV drugs for a while, doctors recommend starting at least one new anti-HIV drug when starting a protease inhibitor. Nelfinavir is also available in a sprinkle formulation for children.

Side effects: The major side effect of nelfinavir is diarrhea. Most people that take nelfinavir get diarrhea, which has been described as mild. According to nelfinavir's manufacturer, mild diarrhea is two to six bowel movements a day. In studies, about 20% of participants experienced more serious diarrhea that was called moderate to severe. Less than 2 out of every 100 people (1.6%) actually stopped taking the drug because of diarrhea. Over-the-counter antidiarrheal medications can be used to help try and control this side effect. One recent study reported good results using a digestive supplement called Ultrase (pancreatic enzymes) to prevent nelfinavir-related diarrhea.

Other less common side effects caused by nelfinavir include increases in liver function tests, which can indicate toxicity to the liver. Anyone taking a protease inhibitor should have their liver function closely monitored. People that have hepatitis are at greater risk for getting elevated liver function tests when taking protease inhibitors. Your doctor should test for hepatitis infections before starting a protease inhibitor. There have also been reports of allergic-type reactions to nelfinavir, leading to a rash. If you get a rash from nelfinavir it may be possible to stop and then try the drug again, building up to the full dose over a few days. This is called "desensitization." One case of abnormal heartbeats (a condition called bradycardia) after starting nelfinavir has very recently been reported. This individual had to stop nelfinavir and use an alternative anti-HIV drug.

Some people taking combination anti-HIV drugs are experiencing swollen bellies, and losing fat from their face, arms and legs. These side effects have been given the name lipodystrophy. One of the most serious lipodystrophy-related problems is high levels of fats (cholesterol and triglycerides) in the blood. High levels of fats in the blood can increase the risk of heart attacks. Because of these risks it's important to have your cholesterol and triglyceride levels checked regularly if you're taking nelfinavir.

Drug interactions: The drugs terfenadine (Seldane), astemizole (Hismanal), cisapride (Propulsid), triazolam (Halcion), midazolam (Versed), amiodarone (Cordarone), quinidine (Quinidex), and drugs known as ergot derivatives should not be taken with nelfinavir as the interactions could be life-threatening.

The TB drug rifampin should not be taken with nelfinavir as it greatly reduces the levels of nelfinavir in the body. The drug rifabutin (Mycobutin) should be avoided if possible when taking nelfinavir. If rifabutin must be taken with nelfinavir, the dose of rifabutin should be cut in half.

The antifungal drug ketoconazole (Nizoral) can increase the levels of nelfinavir in the body, but it is not yet known whether this will mean that the dose of the drug will have to be changed. Levels of the oral contraceptive ethinyl estradiol are reduced by 50% by nelfinavir, and alternative methods of contraception should be used.

Warnings: There has been a government warning about protease inhibitors causing high blood sugar and diabetes. Symptoms to watch out for include increased thirst and hunger, unexplained weight loss, increased urination, fatigue, and dry, itchy skin. There have been 83 cases of this problem reported so far, usually 10-11 weeks after starting the protease inhibitor, although in one case symptoms started just four days afterwards. There are also reports of protease inhibitors causing high levels of fats (called cholesterol and triglycerides) in the blood. Because this can lead to heart problems, fat levels should be closely monitored in people taking protease inhibitors.

Availability: Nelfinavir is approved for prescription for both adults and children. The manufacturer, Agouron Pharmaceuticals, has set up a patient assistance program for people having difficulty accessing the drug. Call (888) 777-6637 for more information.

The Network has a fact sheet on nutritional considerations and Viracept from the AIDS Project Los Angeles. Call us for a copy, or call APLA at (213) 993-1612. Also available on the Web at aidsinfonyc.org/apla/

The Simple Facts Project is a program of The Network. If you need help finding out whether or not a specific drug or therapy is covered by private or public insurance, contact The Network at (800) 734-7104. This information does not intend to promote or endorse any specific treatment for any health related condition.

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Last modified: 12/6/1999 The Network copyright © 1999 The Network