d 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 (see section 4.3). 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/m² by mouth twice daily and should not exceed 600 mg twice daily. Norvir should be started at 250 mg/m² and increased at 2 to 3 day intervals by 50 mg/m² twice daily. When possible, dose should be administered using a calibrated dosing syringe.
Paediatric Dosage Guidelines
Body Surface area* (m²)
Twice daily dose 250 mg/m²
Twice daily dose 300 mg/m²
Twice daily dose 350 mg/m²
0.25
0.8 ml (62.5 mg)
0.9 ml (75 mg)
1.1 ml (87.5 mg)
0.50
1.6 ml (125 mg)
1.9 ml (150 mg)
2.2 ml (175 mg)
1.00
3.1 ml (250 mg)
3.8 ml (300 mg)
4.4 ml (350 mg)
1.25
3.9 ml (312.5 mg)
4.7 ml (375 mg)
5.5 ml (437.5 mg)
1.50
4.7 ml (375 mg)
5.6 ml (450 mg)
6.6 ml (525 mg)
* Body surface area can be calculated with the following equation
BSA (m²) = √(Height (cm) X Weight (kg) / 3600)
Doses for intermediate body surface areas not included in the above table can be calculated using the following equations:
To calculate the volume to be administered (in ml) the body surface area should be multiplied by a factor of: 3.1 for a dose of 250 mg/m²; 3.8 for one of 300 mg/m²; and by 4.4 for 350 mg/m².
Renal impairment: Currently, there are no data specific to this patient population and therefore specific dosage recommendations cannot be made. The renal clearance of ritonavir is negligible; therefore, a decrease in the total body clearance is not expected in patients with renal impairment. Because ritonavir is highly pro |
