The US Food and Drug Administration (FDA) has decided to change the label on Merck's new hepatitis C treatment Victrelis.
According to the FDA, HIV patients need to be made aware that the drug is not suitable when combined with some antiretroviral treatments.
Announcing the desire to change Victrelis labels, the FDA stated that co-administration of the drug with HIV treatments is not recommended because the efficacy of both could be reduced - leading to a rise in HIV and HCV levels in the blood.
The drug was approved in May of last year, but concerns were raised when a new study looking at drug interactions was published in February.
As a result of the small-scale research, Merck announced that it would be mounting its own clinical trial investigation into various drug interactions with Victrelis.
Earlier this month, Merck published clinical research that showed Victrelis treatment in anaemia sufferers requires careful monitoring of combination drug levels.