Saquinavir is a protease inhibitor. Protease inhibitors are a class of anti-HIV drugs that work by blocking a part of HIV called protease. When protease is blocked, or inhibited, 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. Anti-HIV drug combinations, sometimes called cocktails, can reduce the amount of HIV in your body.

The trade name for saquinavir is Fortovase. Fortovase is a new version of saquinavir. The old version was approved in 1995 and had the trade name Invirase. The Invirase version of saquinavir wasn't well absorbed by the body and had a very weak anti-HIV effect compared to other protease inhibitors. Because Fortovase is better absorbed by the body, it has a stronger anti-HIV effect than Invirase. The anti-HIV effect of Fortovase seems to be similar to other available protease inhibitors. The other approved protease inhibitors are amprenavir (trade name Agenerase), indinavir (Crixivan), nelfinavir (Viracept) and ritonavir (Norvir).

Taking the drug: Fortovase comes in 200 mg pills. The recommended dose of Fortovase is six pills (1,200 mg) taken three times a day with with food. The total daily dose is 18 pills (3,600 mg). If Fortovase is not taken at the same time as a meal, it should be taken within two hours afterwards.

Protease inhibitor combinations: Both Fortovase and the first version of saquinavir, Invirase, have been studied in combination with other protease inhibitors. A study of Invirase with ritonavir (Norvir) has been going on for over a year. When taken together, ritonavir increases the amount of both versions of saquinavir in the body. Because the level is higher than usual, the dose of both drugs is lowered. When taken together, the doses are 400 mg of Fortovase and 400 mg of ritonavir twice a day. This combination, along with one or two nucleoside analog drugs (AZT, ddI, ddC, d4T, 3TC) is listed as a possible first HIV treatment in the new Public Health Service guidelines on the best use of HIV drugs.

Fortovase is also being studied in combination with the protease inhibitor nelfinavir (Viracept). Nelfinavir also increases levels of Fortovase in the body. The doses being used in studies are 800 mg of Fortovase and 750 mg of nelfinavir taken three times a day. The combination of Fortovase and nelfinavir hasn't been studied very long and is not generally recommended at this time.

Drug interactions: Fortovase can block the processing other drugs in your body, causing them to get backed up to dangerously high levels. The following drugs should NOT to be taken with Fortovase as these interactions can be life threatening: terfenadine (Seldane), astemizole (Hismanal), cisapride (Propulsid), midazolam (Versed), triazolam (Halcion), and drugs known as ergot derivatives.

The antibiotics rifampin and rifabutin (Mycobutin) should not be taken with Fortovase, as they greatly lower the amount of Fortovase in your body. The NNRTI anti-HIV drug delavirdine (Rescriptor) can boost the levels of Fortovase, and people taking this combination should be closely monitored for signs of liver toxicity. Other drugs that are processed by the liver can also increase Fortovase levels, including ketoconazole (Nizoral) and clarithromycin (Biaxin).

Side effects: The most common side effects of Fortovase are diarrhea, nausea, stomach upset and heartburn. Other less common side effects caused by Fortovase 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.

Some people taking combination anti-HIV drugs are also experiencing swollen bellies, and losing fat from their face, arms and legs. These side effects have been given the general name lipodystrophy. Tell your doctor if you experience these symptoms while taking Fortovase.

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.

Hoffman-La Roche, the company that makes Fortovase, has an assistance program for people that need help getting the drug. The number to call is (800) 282-7780. The company will continue to provide the first version of saquinavir, Invirase, to people who are already taking it and doing well. Most people will be encouraged to switch to Fortovase.

Last modified: 8/15/2006
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