Burns after photodynamic therapy: manufacturer's response to second authors' reply

Editor—Scotia Holdings notes the publication of a response on bmj.com by two of the authors of a drug point headed “Burns after photodynamic therapy,”¹ originally published in the BMJ of 6 May.² [This response was also published as a letter in last week's journal.³] These authors suggest that a contributing factor to the skin burns seen in six out of 14 men treated with Foscan (temoporfin) may have resulted from the drug being given in a new solvent formulation.

Foscan was originally formulated as a powder that had to be reconstituted with water before its administration, and the addition of a solvent has enabled the drug to be administered as a ready-mixed fluid to patients, resulting in greater convenience for the administering doctor.

In clinical studies around the world, other than in the study conducted by the Charterhouse Clinical Research Unit and reported by Hettiaratchy et al,² 100 patients have received the new formulation and no patients have suffered injuries as described in the Hettiaratchy et al study.

The directors of Scotia believe that it is reasonable to conclude that, with an incidence of 0% in 100 patients so far (excluding the Charterhouse study), the new formulation is unlikely to be associated with a true incidence of adverse events that is different from the overall incidence of 2.3% (serious adverse drug reactions attributable to photosensitivity, including burns) recorded to date in 957 volunteers and patients.⁴