Pfizer's Penis-Straightening Drug May Cause "Swelling, Redness and Bruising"

Xiaflex, the penis-straightening drug being developed by Auxilium for Pfizer, causes "a lot of different reactions such as swelling and redness and bruising" in some patients, according to Auxilium chief medical officer Anthony DelConte.

DelConte made the remark in a conference call with analysts May 6. The news adds a new wrinkle to the unlikeliest drug in Pfizer's pipeline. Auxilium has secured a priority review with the FDA for Xiaflex for Dupuytren's contracture, a condition that deforms the hands into claws. The company is still working on the penis curvature indication, Peyronie's disease. Previously the major worry for Peyronie's sufferers was that this drug has to be injected at the site of the problem. But in the conference call, analysts asked company execs about the drug's side effects. Here's what they said:

John Newman - Oppenheimer & Co.: I know that you have said during the phase III studies you haven't seen any evidence of systemic hypersensitivity which is encouraging. Have you seen any evidence for something like Uticaria or local reactions and if so was that something that is common or is that something that is uncommon?

CEO Armando Anido: Local reactions are things that happen with a lot of patients and that is stuff that we have talked about previously. We believe that it is due predominantly to the action of the drug and the breakdown of the collagen core.

Tony DelConte: Yes, we do see local reactions, but we see those independent of which injection they get, so we actually see patients who have these local reactions even on the first injection. That is one of the attributes that makes us believe that it is not due to a hypersensitivity, but can be due to other causes as well.

We also know that if you inject small collagen fragments in animals you will see similar types of reactions. We also know if you inject inactivated collagen you don't see a reaction. So we believe that part of it is at least explained in part by a pharmacologic effect or just the effect of the drug. But, we do see a lot of different reactions such as swelling and redness and bruising.

• See previous coverage of Xiaflex:
• FDA Gives Pfizer's Penis-Straightening Drug Priority Review
• Pfizer to Sell Penis-Straightening Drug