maraviroc

Maraviroc is an antiretroviral medication used to treat HIV-1 infection. It acts as a CCR5 receptor antagonist (entry inhibitor), binding to CCR5 on the surface of CD4+ T cells and other cells and thereby preventing CCR5-tropic HIV-1 from entering the cell. Because it does not block CXCR4-utilizing (X4) viruses, tropism testing is required before starting therapy and if virologic failure occurs. It was approved by the U.S. Food and Drug Administration in 2007 for treatment-experienced adults with CCR5-tropic HIV-1. It is marketed under the brand names Selzentry in the United States and Celsentri in other regions. It is not active against CXCR4-tropic or dual-tropism viruses.

Maraviroc is taken orally. The usual half-life is roughly 14–18 hours, and dosing may be adjusted when used with potent CYP3A4 inhibitors or inducers. It is metabolized by CYP3A4; concomitant medications that inhibit CYP3A4 (for example, ketoconazole) increase maraviroc exposure, while inducers (such as rifampin) decrease it. Because of potential drug interactions, therapy requires careful selection of concomitant antiretrovirals and monitoring of viral load and CD4 counts.

Common adverse effects include cough, fever, upper respiratory infections, and rash. Serious hepatotoxicity has been reported, so liver function tests are recommended at baseline and during treatment. Other adverse effects may include musculoskeletal symptoms and dizziness. Safety in pregnancy and in various pediatric populations has been evaluated with careful consideration of benefit-risk.

Resistance may occur if the virus switches to CXCR4 usage or if tropism is not maintained; maraviroc will be ineffective against non-CCR5-tropic HIV-1. Before initiation and after suspected virologic failure, tropism testing is recommended.