Pfizer has sent out a letter to physicians warning that anaphylactoid reactions have been reported with its recently-launched blindness drug Macugen, and patients’ medical histories should be checked for hypersensitivity reactions before the drug is administered.

The drugmaker said it is not possible to say if Macugen (pegaptanib sodium) is responsible for the reactions, which occurred in some patients after the drug was administered by injection into the eye.

“Rare reports of anaphylaxis/anaphylactoid reactions, including angioedema following the administration of Macugen along with various medications administered as part of the injection preparation, were described,” according to a report on the FDA’s MedWatch service.

Macugen, originally developed by OSI Pharmaceuticals, is used to treat a leading cause of blindness known as neovascular or ‘wet’ age-related macular degeneration. It was approved for marketing in the European Union in February, and got the go-ahead in the USA at the end of 2004.

At present, the market for AMD therapies is estimated at more than $650 million, with Novartis/QLT's photodynamic therapy Visudyne (verteporfin) dominating the sector with sales of around $450 million last year.

Macugen made good progress in 2005, racking up $185 million in the USA last year, but is facing competition from a drug which work in a similar fashion, Novartis and Genentech's Lucentis (ranibuzumab), which was filed for approval in the USA in December 2005.