Question 1

Question

A 42-year-old man with HIV on antiretroviral therapy (ritonavir-boosted darunavir) develops depression and is prescribed St. John's Wort by a naturopath. His HIV viral load, previously undetectable, rises to 50,000 copies/mL after 3 weeks. He reports perfect medication adherence. Drug levels show subtherapeutic protease inhibitor concentrations despite ritonavir boosting. Evaluate the pharmacokinetic mechanisms and implications of this interaction.

Accepted Answer

St. John's Wort induced CYP3A4, overwhelming ritonavir's inhibitory effect

Answer

St. John's Wort induced glucuronidation pathways, creating alternative elimination route

Answer

St. John's Wort competitively inhibited ritonavir, preventing darunavir boosting

Answer

St. John's Wort induced P-glycoprotein, increasing intestinal efflux of darunavir

Answer

St. John's Wort decreased intestinal absorption through altered pH

Pharmacokinetics (ADME principles) — MCQs

Pharmacokinetics (ADME principles) — MCQs

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