There are two new exhibits to be entered into evidence that drug safety is complicated. First, the back-from-exile MS drug Tysabri may have unexpected effects on patients with a family history of melanoma. A letter published in the New England Journal of Medicine details the experience of two women who, soon after starting Tysabri therapy, developed fast-spreading melanoma. Already at least one Wall Street analyst has picked up on the letter, writing to investors that Biogen Idec, which makes Tysabri, may have forecast unrealistic growth for the drug. The company says its data shows no significant link between Tysabri and melanoma.
Second, there's Trasylol, which was suspended from the market last fall after research linked it to renal failure. A new study suggests that the link may not be so direct, or so clear. Patients given Trasylol during so-called "on-pump" heart surgery--when a machine takes over circulating a patient's blood--showed no significant kidney problems afterward. Patients given the drug along with an ACE inhibitor during "off-pump" surgery showed a twofold increase in the risk of kidney dysfunction. But it wasn't just the addition of the ACE inhibitor; "on-pump" patients given the combo showed no significant increase in renal problems.
Will this new research help usher Trasylol back onto the market? Maybe, maybe not--the drug has also been linked to other serious side effects, such as heart failure. But this new study also shows that--as in the tragic case of actor Heath Ledger--it's not just the drug, but a complex interaction of one drug with another, plus other possibly unknown factors. Of course, when people's lives are at stake, erring on the side of caution seems warranted. Red flags, such as the two melanoma cases in Tysabri patients, should be raised. Deciding what to do with that information, however, requires a lot more thought.