Drug Class Description

Generic Name

Drug Description

Presentation

Indications

Adult Dosage

Ritonavir should be administered by physicians who are experienced in the treatment of HIV infection.

Norvir solution is administered orally and should preferably be ingested with food.

Ritonavir dosed as a pharmacokinetic enhancer

The following HIV-1 protease inhibitors have been approved for use with ritonavir as a pharmacokinetic enhancer at the noted doses.

Adult use:

Amprenavir 600 mg twice daily with ritonavir 100 mg twice daily

Atazanavir 300 mg daily with ritonavir 100 mg daily

Fosamprenavir 700 mg twice daily with ritonavir 100 mg twice daily

Lopinavir 400 mg co-formulated with ritonavir 100 mg twice daily

Saquinavir 1000 mg twice daily with ritonavir 100 mg twice daily

Tipranvir 500 mg twice daily with ritonavir 200 mg twice daily

Darunavir 600 mg twice daily with ritonavir 100 mg twice daily

Paediatric use: Lopinavir co-formulated with ritonavir is recommended for children 2 years of age and older. For further dosage recommendations, refer to the product information of other Protease Inhibitors approved for co-administered with ritonavir.

Renal impairment: As ritonavir is primarily metabolised by the liver, ritonavir may be appropriate for use with caution as a pharmacokinetic enhancer in patients with renal insufficiency depending on the specific protease inhibitor with which it is co-administered. However, since the renal clearance of ritonavir is negligible, the decrease in the total body clearance is not expected in patients with renal impairment. For specific dosing information in patients with renal impairment, refer to the Summary of Product Characteristics (SPC) of the co-administered protease inhibitor.

Hepatic impairment: Ritonavir should not be given as a pharmacokinetic enhancer to patients with decompensated liver disease. In the absence of pharmacokinetic studies in patients with stable severe hepatic impairment (Child Pugh Grade C) without decompensation, caution should be exercised when ritonavir is used as a pharmacokinetic enhancer as increased levels of the co-administered PI may occur. Specific recommendations for use of ritonavir as a pharmacokinetic enhancer in patients with hepatic impairment are dependent on the protease inhibitor with which it is co-administered. The SPC of the co-administered PI should be reviewed for specific dosing information in this patient population.

Ritonavir dosed as an antiretroviral agent

Adult use: The recommended dosage of Norvir solution is 600 mg (7.5 ml) twice daily by mouth.

Gradually increasing the dose of ritonavir when initiating therapy may help to improve tolerance. Treatment should be initiated at 300 mg (3.75 ml) twice daily for a period of three days and increased by 100 mg (1.25 ml) twice daily increments up to 600 mg twice daily over a period of no longer than 14 days. Patients should not remain on 300 mg twice daily for more than 3 days.

Paediatric use (2 years of age and above): the recommended dosage of Norvir solution in children is 350 mg/m^² by mouth twice daily and should not exceed 600 mg twice daily. Norvir should be started at 250 mg/m^² and increased at 2 to 3 day intervals by 50 mg/m^² twice daily. When possible, dose should be administered using a calibrated dosing syringe.

Paediatric Dosage Guidelines