Side-effects

The most commonly observed side-effects of maraviroc are cough, fever, upper respiratory tract infections, rash, musculoskeletal symptoms, abdominal pain, and dizziness.

Caution must be used when prescribing maraviroc to anyone with pre-existing liver dysfunction or who is co-infected with hepatitis B or C. Symptoms such as rash, jaundice, dark urine, vomiting, or abdominal pain should be investigated. In 2% of participants, Grade 3-5 adverse events occurred that included elevated bilirubin, amylase, lipase, AST, and ALT levels.

There have been concerns that CCR5 inhibitors as a class involve a risk of serious liver side-effects and the US FDA's approval for maraviroc states that the product label should include a boxed warning about liver toxicity.

The toxicity warning was issued because in December 2005, one hepatitis C co-infected patient in the MOTIVATE trial developed liver toxicity after five days of treatment with maraviroc. Toxicity was so severe that the patient required a liver transplant. Although the study’s data and safety monitoring board judged the reaction as due to other medications the patient was taking to prevent tuberculosis and Pneumocystis pneumonia (PCP), they could not rule out a contribution of maraviroc.  

The warnings/precautions section of the drug information leaflet also cautions about the possibility of an increased risk of cardiovascular illness such as heart attack or dizziness when standing up quickly, particularly in people with pre-existing renal impairment.

Safety analyses done at 48 weeks continue to show no unexpected adverse events. There was no difference between the placebo group and maraviroc group in rates of discontinuation due to adverse events (around 6%) or in serious adverse events (grade 3-4, around 17%).¹