maraviroc

Maraviroc targets the CCR5 co-receptor used by HIV to gain entry to human cells. Drugs in this class are called CCR5 antagonists, attachment inhibitors or entry inhibitors. They work by attaching themselves to a protein on the surface of CD4 cells called CCR5, blocking the virusA small infective organism which is incapable of reproducing outside a host cell. from entering the cell. Drugs from this class are particularly useful for treatment-experienced people who have developed resistanceHIV which has mutated and is less susceptible to the effects of one or more anti-HIV drugs is said to be resistant. to other drugs and classes.

CCR5 antagonists can be effective against HIV because they prevent HIV from entering immune system cells (most anti-HIV drugs disrupt the virus' action inside the cells). There is some concern however that the use of CCR5 antagonists could cause HIV to evolve to use another co-receptor, CXCR4, for which no blocking drugs are available. People with lower CD4 cells often have some CXCR4-tropic virus, and this may be associated with more aggressive HIV illness compared with the more common CCR5-tropic virus, so this change could have negative impacts.

To avoid this happening, tests must first be performed to determine the type of virus you have, and people with CXCR4-tropic virus, and those with dual tropism (a combination of both types of virus) are excluded from using this drug.