saquinavir, Invirase (Fortovase - discontinued)

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GENERIC NAME: saquinavir

BRAND NAME: Invirase (Fortovase has been discontinued)

DRUG CLASS AND MECHANISM: Saquinavir is an oral medication that is used for treating infections with the human immunodeficiency virus (HIV). It is in a class of drugs called protease inhibitors which also includes indinavir (Crixivan), nelfinavir (Viracept) and ritonavir (Norvir). During infection with HIV, the HIV virus multiplies within the body's cells. Viruses are released from the cells and spread throughout the body where they infect other cells. In this manner, HIV infection is perpetuated among new cells that the body produces continually. During the production of the viruses, new proteins are made. Some of the proteins are structural proteins, that, is, proteins that form the body of the virus. Other proteins are enzymes which manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. Saquinavir blocks the activity of protease and results in the formation of defective viruses that are unable to infect the body's cells. As a result, the number of viruses in the body (the viral load) decreases. Nevertheless, saquinavir does not prevent the transmission of HIV among individuals, and it does not cure HIV infections or AIDS. Saquinavir was approved by the FDA in December 1995.



PREPARATIONS: Tablets: 500 mg; Capsules: 200 mg

STORAGE: Store Invirase capsules at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Saquinavir must be administered with ritonavir. The recommended dose is 1000 mg twice daily within 2 hours of a meal.

DOSING: The recommended dose of Invirase for adults is 600 mg three times daily. Invirase should be administered within 2 hours of a meal.

DRUG INTERACTIONS: Saquinavir interacts with many drugs. Some of the important interactions are mentioned below. Viewers should consult their health care provider before combining any drugs with saquinavir.

Saquinavir should not be used together with triazolam (Halcion), midazolam (Versed), sildenafil (Viagra) and ergotamine derivatives (for example, Ergostat) because saquinavir increases the concentration of these drugs in the body and this could cause serious side effects.

Saquinavir also may inhibit the break-down of the cholesterol-lowering drugs lovastatin (Mevacor), simvastatin (Zocor), atorvastatin (Lipitor) and cerivastatin (Baycol). Combining saquinavir with these drugs may increase the occurrence of muscle breakdown (rhabdomyolysis) which is seen when these drugs accumulate in the body.

Clarithromycin (Biaxin) and ketoconazole (Nizoral) may increase blood concentrations of saquinavir and cause increased severity or frequency of side effects from saquinavir. Saquinavir also increases the concentration of clarithromycin.

Rifampin (Rifadin) and rifabutin (Mycobutin) decrease blood concentrations of saquinavir and therefore could decrease the effectiveness of saquinavir.

The combination of saquinavir and ritonavir should not be combined with rifampin due to the risk of severe liver damage.

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