Protease Inhibitor & Booster: Ritonavir is a protease inhibitor (PI) with potent antiviral activity, but at the 100 mg dose, its primary function is as a pharmacokinetic boosting agent.
Key Component of cART: It is a foundational component of modern combination antiretroviral therapy (cART), used to enhance the efficacy of other antiretroviral drugs.
Standard Dosing: The 100 mg tablet is the standard dose used for boosting other protease inhibitors like atazanavir or darunavir. It is typically taken once or twice daily depending on the co-administered medication.
Film-Coated Tablet: The tablet is film-coated and should be swallowed whole. It should not be crushed, broken, or chewed.
Advantages
Powerful Pharmacokinetic Boosting: Ritonavir is a potent inhibitor of the CYP3A4 enzyme, which is responsible for the metabolism of many drugs. This boosting effect leads to higher and more sustained plasma concentrations of co-administered antiretrovirals.
Simplified Dosing Regimens: By boosting the primary antiretroviral drug, Ritonavir can often allow for a less frequent dosing schedule (e.g., once daily), which simplifies the treatment regimen and improves patient adherence.
Enhanced Antiviral Effect: The increased concentration of the primary drug in the bloodstream provides a more potent and durable antiviral effect, leading to better viral suppression.
High Barrier to Resistance: The boosting effect helps maintain drug concentrations above the minimum required to suppress the virus, which contributes to a higher genetic barrier to resistance.
Uses
HIV-1 Infection: Indicated as a pharmacokinetic booster for other protease inhibitors and certain other antiretrovirals in adults and pediatric patients.
Combination Therapy: It is always used in combination with other antiretroviral agents, such as atazanavir or darunavir, and is a key component of regimens used to treat both treatment-naïve and treatment-experienced patients.
Post-Exposure Prophylaxis (PEP): It is a component of PEP regimens to prevent HIV infection following a potential exposure.
Neonatal Prophylaxis: It has been used in pediatric formulations for the treatment of infants to prevent mother-to-child transmission.
Nature
Drug Class: Ritonavir belongs to the protease inhibitor (PI) class of antiretrovirals.
Mechanism of Action: At the 100 mg dose, its primary mechanism is to inhibit the liver enzyme cytochrome P450 3A4 (CYP3A4). By blocking this enzyme, it prevents the rapid metabolism of co-administered drugs, leading to increased plasma levels.
Antiviral Activity: While its main use is as a booster, Ritonavir does have direct antiviral activity as a protease inhibitor, but this is only significant at much higher doses than 100 mg.
Drug Interactions: A key characteristic of Ritonavir is its high potential for drug-drug interactions due to its potent CYP3A4 inhibition. This requires careful consideration and dose adjustments when co-prescribing other medications.
Storage
Temperature: Store Ritonavir tablets at a controlled room temperature, typically between 20∘C to 25∘C (68∘F to 77∘F).
Protection: Keep the tablets in their original, tightly closed container, protected from light and moisture.
Administration: The tablets must be taken with food to enhance their absorption and efficacy.
Patient Warning: Patients must be educated on the importance of taking every dose as prescribed and on time to prevent the development of viral resistance
