Side-effects

Although generally well tolerated in clinical trials, since the approval of etravirine, two types of severe reaction to the drug have been reported: toxic epidermal necrolysis (TEN) and drug rash with eosinophilia and systemic symptoms (DRESS).

Reported cases of these reactions developed between three and six weeks after treatment with the drug was started. In most cases, they disappeared when treatment with etravirine was stopped and therapy with corticosteroids was provided. Symptoms include rash, fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjunctivitis, hepatitis, and high concentrations of a type of blood cell calls eosinophils.

In August 2009, the US Food and Drug Administration inserted a new warning to the package insert for etravirine (Intelence). It stated that severe cases of rash occurred in around 1.3% of people in phase 3 studies of the drug and 2% of people had to stop taking the drug due to serious rash, usually occurring in the first six weeks of treatment. In the most serious cases, people taking etravirine developed Stevens-Johnson syndrome or other severe skin reactions in which regions of the skin blister and peel away. It is expected that a similar warning will be added to European package inserts by the European Medicines Agency.

People who develop a severe rash while taking etravirine were advised to seek immediate medical advice. If a hypersensitivity reaction to the drug is diagnosed, treatment with it should be stopped immediately. People who have stopped treatment due to hypersensitivity reactions should not restart therapy.