Antiretroviral Agent: Darunavir is an antiretroviral drug from the protease inhibitor (PI) class, specifically designed to combat Human Immunodeficiency Virus Type 1 (HIV-1).
Boosting Requirement: The 600 mg tablet must always be taken with a low dose of a pharmacokinetic boosting agent, typically ritonavir (100 mg) or cobicistat (150 mg). The booster increases the concentration of darunavir in the bloodstream to ensure its therapeutic effectiveness.
Twice-Daily Dosing: This specific 600 mg strength is primarily used for a twice-daily dosing regimen, which is the recommended schedule for treatment-experienced adult patients and pregnant individuals.
Component of cART: Darunavir is never used as a monotherapy. It is always prescribed as part of a complete combination antiretroviral therapy (cART) regimen with other active antiretroviral agents.
Advantages
High Barrier to Resistance: Darunavir is known for its high genetic barrier to resistance. Its unique chemical structure allows it to maintain a strong binding affinity to the protease enzyme even when the virus develops mutations that cause resistance to other PIs.
Potent Viral Suppression: When properly boosted, Darunavir provides potent and durable viral suppression, effectively reducing the HIV viral load to undetectable levels and improving the patient’s immune function.
Effective in Treatment-Experienced Patients: It is a preferred choice for patients who have failed previous antiretroviral regimens, as it is highly effective against multidrug-resistant HIV strains.
Well-Established Safety Profile: With years of clinical use, Darunavir has a well-established safety and tolerability profile, making it a reliable component of HIV treatment.
Uses
HIV-1 Infection: Indicated for the treatment of HIV-1 infection in adults and adolescents, and in pediatric patients weighing at least 15 kg, in combination with other antiretroviral agents.
Treatment-Experienced Patients: The 600 mg twice-daily regimen is specifically indicated for patients who have been previously treated and may have darunavir resistance-associated mutations.
Pregnancy: It is a recommended antiretroviral for use in HIV-positive pregnant women to prevent perinatal transmission, with a twice-daily dosing regimen.
Post-Exposure Prophylaxis (PEP): It can be used as a component of PEP regimens to prevent HIV infection following a potential exposure.
Nature
Protease Inhibitor: Darunavir belongs to the protease inhibitor (PI) class.
Mechanism of Action: It works by binding to the active site of the viral enzyme protease. This binding prevents the enzyme from cleaving the large viral polyproteins into functional proteins, resulting in the production of immature, non-infectious HIV particles.
Pharmacokinetic Boosting: Darunavir requires boosting because it is rapidly metabolized by the CYP3A4 enzyme in the liver. A small dose of ritonavir or cobicistat inhibits this enzyme, leading to higher and more sustained plasma concentrations of Darunavir.
Side Effects: Common side effects include rash, diarrhea, and headache. More serious side effects can include severe skin reactions (e.g., Stevens-Johnson syndrome) and hepatotoxicity (liver damage), particularly in patients with pre-existing liver conditions.
Storage
Temperature: Store Darunavir 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: Darunavir must be taken with food to ensure proper absorption and efficacy. The type of food does not significantly affect its absorption.
Patient Compliance: Patients must be educated on the importance of not skipping doses. Skipping doses can lead to a reduction in drug concentration, an increase in viral load, and the development of drug resistance.
