What is Saquinavir (Invirase) Used For? Side Effects and Dosage

What is Saquinavir (Invirase) Used For? Side Effects and Dosage

What is Saquinavir (Invirase, Fortovase)?

Saquinavir, also referred to by the trade names Invirase and Fortovase, is a medication used in the treatment of human immunodeficiency virus (HIV), the virus responsible for the development of acquired immunodeficiency syndrome (AIDS) in the human body. This medication is a protease inhibitor (PI), a class of antiretroviral medications used to halt the spread of the infection by ceasing the virus’ use of the enzyme protease in its reproduction cycle.

Saquinavir was introduced in 1995 and is produced and marketed by the Swiss pharmaceutical company Roche. Due to its age, it is less commonly prescribed as of 2019, having been overshadowed by the development of other classes of antiretroviral medications such as integrase inhibitors. Nevertheless, it remains an effective treatment when used in combination with other medications to successfully combat HIV.

What is It Used For?

As mentioned above, Saquinavir, in combination with other antiretroviral drugs, is used in the treatment of both HIV-1 (Type 1) and HIV-2 (Type 2). It is used to treat patients who are treatment naïve, meaning they have not yet received any prior HIV medications for their infection. As a protease inhibitor, its mechanism of action is to bind to the protease molecule, an enzyme responsible for the process of proteolysis, the cleaving of large protein chains into smaller chains, called peptides. Proteolysis is used by the virus to transform ribonucleic acid in viral DNA, increasing the patient’s viral load. The efficacy of Saquinavir results from its ability to attach itself to specific locations of the protease molecule, thus halting the enzyme’s cleaving behavior.

How to Take Invirase

Saquinavir, when branded as Invirase, is available in either a 200 mg opaque gelatin capsule form or a 500 mg orange tablet, both intended to be ingested orally by being swallowed whole. The tablets should not be crushed, chewed, or broken, while the capsules may have their contents emptied into a dish and mixed with 30 to 45 mL (two or three tablespoons) of sweetened syrup or jam, consumed after the mixture has been stirred for 30 seconds. The drug should be taken within two hours of a meal in order to maximize its absorption by the digestive system. Patients should avoid consuming grapefruit or grapefruit juice while taking this medication, as these can alter its levels in the blood. Saquinavir is intended to be taken with other antiretroviral medications, especially Ritonavir (trade named Norvir). The combination used may vary depending on the prescription. Expired tablets and capsules should not be ingested.

Saquinavir Side Effects

Various side effects associated with other HIV medications have been observed in patients taking Saquinavir. To reduce the risk of side effects, prospective patients should consult with their health care provider regarding any other medications being taken, as these may interact with Saquinavir and increase the likelihood and severity of side effects.

The following are common and often manageable side effects of taking Saquinavir:

  • nausea
  • diarrhea
  • vomiting
  • constipation
  • fatigue

The following are less common, but more severe side effects that may require immediate medical attention:

  • rash
  • skin peeling
  • weakness
  • excessive sweating
  • fever
  • discoloring of urine or stool
  • wheezing, coughing, or shortness of breath
  • allergic reaction symptoms, such as swelling of the face, skin pain or hives

It should be noted that the safety of taking Saquinavir while pregnant has not yet been evaluated. As such, pregnant women should avoid the medication unless the risks of treatment have been assessed by their health care provider. 

Fortovase Dosage

The standard dosage of Fortovase (Saquinavir) is 1000 mg, twice daily, taken as either five 200 mg capsules or two 500 mg tablets. As Invirase, this is typically recommended to be taken alongside 100 mg of Ritonavir, taken at the same times, twice per day. Patients who are treatment naïve and beginning treatment with Saquinavir are normally advised to take 500 mg per day for two weeks, after which the above dosage applies. Saquinavir is intended for use in patients who are between the ages of 16 and 65; outside this age range, the effects of the drug have not been fully evaluated.

Disclaimer: Please note that the contents of this article are for informational purposes only and should not be considered medical advice. This article, and other AIDS and HIV Information articles on AIDS Drugs Online, are not written by AIDS Drugs Online or reviewed by its staff for medical validity. All views and opinions expressed by the third-party authors are not endorsed by AIDS Drugs Online or its staff. Always consult a medical professional for medical advice.


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