The drugmaker argues the problem is all about inappropriate prescribing. So Cephalon sent letters to docs this week warning that several deaths have been linked to Fentora, a highly addictive narcotic used to treat acute cancer pain. Here’s the catch - Fentora and its predecessor, Actiq, are approved only for use in cancer patients, but are often prescribed off-label for headaches and back pain.

Cephalon has always denied any off-label marketing, but its being investigated by the US attorney in Philadelphia and the Connecticut attorney general (see page 11 of the latest SEC filing), and a congressional probe into off-label treatments. (In the wake of the OxyContin scandal, this shouldn’t come as a surprise).

A Cephalon press release wasn’t specific about the number of deaths, but journalists who asked were told Fentora was linked to four deaths. Three of those were allegedly due to inappropriate prescribing, and the fourth was reportedly a suicide that didn’t involve a scrip from a doc.

In a statement, Connecticut’s attorney general, Richard Blumenthal, said the deaths “tragically confirms concerns raised by our aggressive investigation into Cephalon’s off-label marketing of its drugs.” He added that the results of his investigation should be complete in the “near future.” The Wall Street Journal (subscription required) reported Cephalon is discussing a settlement with the Blumenthal’s office and the US Attorney in Philadelphia.