WBR0392

Author	[[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::A 35-year-old male, previously diagnosed with HIV, presents to the infectious disease clinic for a standard follow-up. His last CD4 count, 3 months ago, was 670 cells/mm3 and his viral load was low to undetectable. Twice in the past month, the patient was admitted to the hospital for a community acquired pneumonia and gastroenteritis. His recent tests demonstrate a CD4 count of 231 cells/mm3 and a viral load of 325000 copies/ml. Based on the recent findings, you decide to initiate highly active antiretroviral therapy (HAART) in the patient. Which of the following drug regimens is most suitable for this patient?]]
Answer A	AnswerA::Tenofovir + emtricitabine + abacavir
Answer A Explanation	AnswerAExp::This combination has 3 NRTIs, a combination that is usually not recommended.
Answer B	AnswerB::Darunavir + raltegravir + lamivudine
Answer B Explanation	AnswerBExp::This combination has only 1 NRTI a combination that is usually not recommended. Darunavir is a protease inhibitor, while raltegravir is an integrase inhibitor.
Answer C	AnswerC::Efavirenz + tenofovir + nevirapine
Answer C Explanation	AnswerCExp::This combination has only 1 NRTI, a combination that is usually not recommended. Efavirenz and nevirapine are both NNTRIs.
Answer D	AnswerD::Ritonavir + tenofovir + lopinavir
Answer D Explanation	AnswerDExp::This combination has only 1 NRTI. Ritonavir and lopinavir are both protease inhibitors.
Answer E	AnswerE::Raltegravir + tenofovir + emtricitabine
Answer E Explanation	AnswerEExp::This combination is most suitable because it includes 2 NRTIs (tenofovir + emtricitabine) and 1 integrase inhibitor.
Right Answer	RightAnswer::E
Explanation	[[Explanation::Prior to the introduction of highly active antiretroviral therapy (HAART) in 1995, early regimens, which consisted of only two drugs against HIV, failed to sustain a therapeutic benefit. HAART consists of three or more agents and has been associated with a remarkable improvement in clinical outcomes. The CD4 count and viral load are the two lab markers used to determine the optimal time for initiation of HAART. A CD4 count below 350 cells/mm3 in conjunction with any AIDS-defining illness often indicates a need for therapy. Viral loads >100000 copies/ml are not an absolute indication for treatment, and some physicians opt to wait based on the patient's CD4 count. The recommended regimens frequently include a combination of 2 nucleoside reverse transcriptase inhibitors (NRTIs) with either a non-nucleoside reverse transcriptase inhibitor (NNRTI), a protease inhibitor, or an integrase inhibitor. The most commonly used combinations include: Efavirenz + tenofovir + emtricitabine Ritonavir-boosted atazanavir + tenofovir + emtricitabine Ritonavir-boosted darunavir + tenofovir + emtricitabine Raltegravir + tenofovir + emtricitabine Educational Objective: HAART consists of three or more agents, frequently including a combination of 2 nucleoside reverse transcriptase inhibitors (NRTIs), with either a non-nucleoside reverse transcriptase inhibitor (NNRTI), a protease inhibitor, or an integrase inhibitor. References: Piacenti FJ. An update and review of antiretroviral therapy. Pharmacotherapy. 2006;26(8):1111-33. U.S. Department of Health and Human Services (2009). Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Available online: http://www.aidsinfo.nih.gov/contentfiles/AdultandAdolescentGL.pdf.]]
Approved	Approved::Yes
Keyword	WBRKeyword::HAART therapy, WBRKeyword::HIV, WBRKeyword::AIDS, WBRKeyword::CD4 count, WBRKeyword::HIV drug combinations
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