The Food and Drug Administration (FDA) has approved label updates for Invirase (saquinavir mesylate; Genentech) with drugs that are contraindicated or interact with Invirase/ritonavir. In addition, a warning against the concomitant use of cobicistat with Invirase was added to the label. 

Under the Dosage and Administration section, the following statement has been added: “Cobicistat is not interchangeable with ritonavir to increase systemic exposure of saquinavir. For patients already taking ritonavir 100mg twice daily as part of their antiretroviral regimen, no additional ritonavir is needed.”

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Under the Contraindications section, the list of agents that are contraindicated with Invirase/ritonavir have been updated to include: anti-infectives (eg, clarithromycin, erythromycin, halofantrine, pentamidine), atazanavir, tacrolimus, neuroleptics (eg, pimozide, chlorpromazine, sertindole, clozapine, haloperidol, mesoridazine, phenothiazines, thioridazine, ziprasidone); and other CYP3A substrates (eg, dapsone, disopyramide, quinine). 

Under the Warnings and Precautions section, the following statement has been added: “Invirase is not recommended for use in combination with cobicistat. Dosing recommendations for this combination have not been established. Cobicistat is also not recommended in combination with regimens containing ritonavir due to similar effects of cobicistat and ritonavir on CYP3A.”

The Drug Interactions section and clinical comments were also updated accordingly to reflect when coadministration is not recommended or when additional monitoring is needed. Further information regarding interactions with fosamprenavir were also included. 

Invirase is an HIV protease inhibitor currently approved for HIV infection in combination with ritonavir. It is available as 500mg strength tablets and 200mg strength hard gel capsules

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