Given the task definition and input, reply with output. Generate an explanation for the given claim using the provided supporting material from the paragraph. Please consider the following points while generating an output. 1) The claim will always have supporting proof in the paragraph, and the paragraph will have a clear point of view supporting the claim. 2) There can be instances where direct correlation to the claim is not available. Make use of the sentences in the paragraph to provide a corresponding output supporting the claim. 3) The explanation should be at least one and at most twelve sentences long.

Paragraph: The letter, sent by J&J's Tibotec Therapeutics unit to doctors this month, cited cases of drug-induced hepatitis as well as liver injury and death. "We are issuing a new warning on our labeling," Tibotec Therapeutics spokeswoman Pam Van Houten told Reuters. The company said in its letter that the problems have not been linked directly to Prezista, a once-daily protease inhibitor that was given in combination with the drug ritonavir. Ritonavir is sold by Abbott Laboratories under the name Norvir. Fifteen cases of liver problems were reported during clinical trials, Van Houten said. She added the company did not provide information on post-marketing cases reported after the drug's U.S. approval in 2006. Most of the cases occurred in patients with advanced HIV, who were taking multiple medications, as well as those who were also infected with hepatitis B or C, the letter said. The letter and Van Houten did not say how many liver-related deaths occurred. The FDA warning was released on its Web site here Claim: J&J, FDA warn of liver risk with HIV drug patients.
Johnson & Johnson and the U.S. Food and Drug Administration warned of reported liver damage and death in patients taking the company's HIV drug Prezista, according to a letter released on Wednesday.