Darunavir is a prescription-only antiretroviral drug belonging to the protease inhibitor class. It is formulated as a solid oral pill and is available in strengths of 600 mg and 800 mg. In Hong Kong, Darunavir is regulated by the Department of Health and is prescribed for adults living with Human Immunodeficiency Virus (HIV) infection. The medication is commonly administered together with a pharmacokinetic booster such as ritonavir or cobicistat to achieve optimal blood levels.
Darunavir inhibits the HIV-1 protease enzyme, a key viral protein that cleaves newly synthesized poly-proteins into functional viral components. By blocking this enzymatic step, the drug prevents the maturation of infectious virions, leading to a reduction in the amount of circulating virus (viral load). The antiviral effect begins within a few days of the first dose, peaks after several weeks of consistent therapy, and is maintained as long as the medication is taken as prescribed. Because Darunavir is metabolized primarily by the liver enzyme CYP3A4, co-administration with a CYP3A4 inhibitor (e.g., ritonavir) markedly increases its plasma concentration, allowing once-daily dosing in many treatment regimens.
In Hong Kong, the Drug Office lists Darunavir as part of the standard antiretroviral therapy (ART) guidelines for managing HIV infection.
Key administration points
Overdose management
Discontinuation
This article provides educational information about darunavir and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
Darunavir’s plasma levels are suboptimal when administered alone; therefore, approved regimens in Hong Kong require co-administration with a pharmacokinetic booster (ritonavir or cobicistat) to achieve therapeutic concentrations.
Mild rashes are common and may resolve without intervention, but any spreading, blistering, or systemic symptoms warrant immediate medical evaluation to rule out a severe hypersensitivity reaction.
Darunavir is eliminated primarily by the liver, so mild to moderate renal impairment does not usually require dose adjustment. However, patients with severe kidney disease should have their regimen reviewed by a specialist.
Taking darunavir with a meal, especially one containing some fat, can enhance absorption and reduce gastrointestinal upset. Consistency in taking the medication with food is recommended.
Weight changes are not a primary side effect of darunavir. Any significant weight fluctuation should be discussed with a healthcare provider to assess underlying causes.
Herbal supplements such as St. John’s wort and over-the-counter anticonvulsants can induce CYP3A4 and lower darunavir levels. Always disclose all non-prescription products to your clinician.
Both strengths contain the same active ingredient. The 800 mg tablet is typically used in once-daily boosted regimens, while the 600 mg tablet is used twice daily when higher exposure is needed or when resistance patterns dictate.
Darunavir-based regimens are considered safe in pregnancy when benefits outweigh potential risks. The decision is individualized and should involve an obstetric specialist familiar with HIV care.
Most patients achieve viral suppression within 8-12 weeks of initiating a fully suppressive regimen, provided adherence is high and the virus is susceptible to the drugs used.
Standard workplace or sports drug screens do not test for antiretroviral medications like darunavir. However, specific therapeutic drug monitoring may be requested in specialized clinical settings.
