Norvir (ritonavir) can be coadministered with Prezista (darunavir) [1]. However, increasing the dosages while using the drugs in combination is not recommended.
Ritonavir as a part of anti-HIV therapy inhibits viral replication, increases the number of CD4 cells in the blood and reduces the viral load, prolongs remission, improves hematological parameters. The drug works as a pharmacokinetic booster, due to ritonavir inhibiting the metabolism that is mediated by the cytochrome CYP3A4 isoenzyme [2]. The degree of the boosting action depends on the metabolic path of the coadministered HIV protease inhibitor and its effect on ritonavir metabolism. The maximum inhibition of metabolism with the combined use of an HIV protease inhibitor, as a rule, is achieved with a dose of ritonavir from 100 mg once daily to 200 mg twice daily and depends on the jointly-used antiretroviral medicine.
Prezista, or darunavir, is a prescription medicine used for treating HIV infection in adults and children older than 3 years. It is approved by the FDA and is used in combination with ritonavir or another booster to enhance its levels. Darunavir is classified as a protease inhibitor. It blocks the activity of the HIV protease enzyme used to form new viral particles. Replication of HIV is delayed, therefore slowing the rate at which the immune system is damaged [3]. This ARV medication does not cure HIV infection but helps manage it and reduces the risk of transmission. Prezista should not be used by children younger than 3 years of age because of the elevated risk of darunavir-related side effects.
Prezista must be coadministered with Norvir in order to boost its therapeutic effect. The combination though must be prescribed by a doctor in order to determine the correct dosages of both substances. In case one fails to correctly mix these two drugs, plasma levels of darunavir will be inadequate to achieve the required antiviral effect and may alter drug interactions [1].
Though it is safe to coadminister the meds without any risks of harm to the patient, increasing the dosage of ritonavir is not recommended since it will affect the concentration of darunavir, though not significantly.
Consulting a healthcare professional for a prescription is necessary.