Drug points: Burns after photodynamic therapy

Abstract

Photodynamic therapy comprises a photosensitising agent, which accumulates in malignant tissue, and a light source, which activates the photosensitiser, causing it to generate highly reactive oxygen species that destroy malignant cells. Temoporfin is a second generation photosensitiser that has a shorter half life than its predecessors and is thought to be more selective towards tumours. These two factors should decrease the incidence of photosensitivity, one of the main side effects of photodynamic therapy. We report on a group of patients who received a single dose of temoporfin (Foscan, Scotia Pharmaceuticals) and developed partial thickness burns after minimal exposure to light.Fourteen healthy men aged between 20 and 26 were given a single dose (0.100-0.129 mg/kg) of temoporfin as part of a pharmacokinetic study. The dosage was a standard therapeutic one.1 After two weeks they were exposed to a test dose of sunlight. Twelve men showed no photosensitivity and were told to avoid prolonged exposure to bright sunlight for three months. Within 48 hours of discharge six of the 12 men had developed partial thickness burns on the left forearm (figure) and more superficial burns on other body areas (about 1% of total body surface area) after transient exposure to daylight. They were referred to the regional burns centre where they were treated conventionally with paraffin dressings and reviewed at five day intervals. Healing was much slower than with conventional thermal injury (28 versus 14 days), with prominent scarring in several men. As the men had signed disclaimers before the trial, they were not automatically entitled to compensation.Photodynamic therapy is used in the treatment of various malignancies, 2 3 and photosensitivity is a recognised complication. There is only one report of a skin burn, 4

Reforms to the health sector must retain vertical programmes like those for tuberculosis

“…1 The term immigrant is not used accurately. An immigrant to the United States is a person who is admitted as a lawful permanent resident or who becomes a permanent resident while living there.…”

“…1 Many of the points discussed are highly relevant to assays measuring drug resistance in patients with HIV infection.…”

“…1 Testing for resistance of HIV may be appropriately evaluated by this type of study, although, as in other areas, convincing the medical community of the merits of this approach and securing funding may be problematic. 5 A randomised trial would collect the information required for analyses to elucidate the clinical significance of viral mutations.…”

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

“…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.…”

“…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…”