12/19/2012 09:34 am ET Updated Feb 18, 2013

Incivek, Hepatitis C Drug, Can Cause Potentially Fatal Skin Reactions

Dec 19 (Reuters) - Vertex Pharmaceuticals Inc warned on Wednesday its hepatitis C drug Incivek, which is used in conjunction with two other products, can cause serious, potentially fatal skin reactions.

Skin rashes were already a known side effect of Incivek, but an analysis of data since the drug was approved in the United States in 2011 has revealed a number of cases in which the reaction was more severe than those seen in clinical trials of the drug. Some were fatal.

The findings have led Cambridge, Massachusetts-based Vertex to place an enhanced warning, surrounded by a black box, on the drug's prescribing label. Black box warnings are the most serious available.

Incivek is Vertex's flagship product. It is approved to treat hepatitis C, a viral infection that affects the liver, in combination with interferon and ribavirin.

The company said the fatal cases of skin reactions occurred in patients who continued to receive Incivek combination treatment after a serious skin reaction was identified.