Invirase (saquinavir mesylate) is a protease inhibitor antiretroviral drug indicated for the treatment of HIV, and should be used in combination with other antiretroviral medications.
Dosage and administration
Dosage depends on whether or not the patient is treatment-naïve or switching from other antiretroviral drugs, and is also based on weight in children 16 and under; it can be used in adults and children age two and up. Invirase should be taken within two hours of a meal. Tablets should not be crushed, but the capsule may be given in a suspension. Instructions and dosage regimes are given in the product monograph.
Invirase does not require dosage adjustments for patients with mild to moderate hepatic impairment, and is contraindicated (especially when boosted with ritinovir) in severe hepatic impairment. Invirase may worsen liver disease in patients with alcoholism, comorbid hepatitis B (HBV) or hepatitis C (HCV) infection, liver cirrhosis, and other liver diseases. Invirase does not require dosage adjustment in renal impairment, but should be used with caution in patients with severe kidney impairment.
The use of Invirase in combination with ritinovir (“boosting”) may cause significant QT prolongation, as well as first, second, and third degree heart blocks. Torsades de Pointes has also been reported. This combination is contraindicated in patients with long QT syndrome, or hyperkalemia or hypomagnesemia.
Patients using this medication may experience side effects, which include, but are not limited to:
- nausea, vomiting
- stomach pain
- changes in distribution of body fat
Patients should contact a medical professional if they are experiencing any of the following serious side effects:
- stabbing chest pain
- rapid heart rate
- problems breathing or swallowing
All patients who test positive for HIV infection should be screened for comorbid HBV infection. Co-infected patients should start on an antiretroviral regimen targeting both viruses, regardless of CD4 counts or HBV viral loads, and treatment should be continued indefinitely to achieve HIV suppression and prevention of HBV activation. Co-infected patients will require vaccination against hepatitis A and HBV, and should avoid alcohol.
Current HIV treatment guidelines recommend testing HIV-positive patients for hepatitis C virus (HCV), and regular ongoing testing for those deemed to be high risk. If HIV/HCV co-infection is identified, consideration should be given to treating both infections concurrently.
Pregnancy and lactation
Highly active retroviral combination treatment should be used in all pregnant women, regardless of viral load and CD4 count. There is insufficient data to determine whether Invirase causes birth defects. Clinicians should report exposure to Invirase before or during pregnancy to the Antiretroviral Pregnancy Registry to assist in data collection. Current guidelines should be consulted when treating women in pregnancy. Excretion of Invirase in the breast milk is unknown. The CDC recommends that all HIV-positive women, treated or untreated, avoid breastfeeding to prevent vertical transmission of the virus.
Drug interactions are detailed in the product monograph and should be reviewed by medical professionals prescribing this medication.
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