Verteporfin (Visudyne), a photosensitising drug for the treatment of age-related macular degeneration (AMD), has been launched by Ciba Vision (UK) (see p213). It is the first drug treatment for this disease and is licensed for use as photodynamic therapy. Up to now treatment has been with thermal laser photocoagulation.
AMS is the leading cause of blindness in people over the age of 50, says the company. The condition results in the loss of central vision, leaving patients with only peripheral vision. "Dry" and "wet" AMD are two forms of the condition.
The "wet" (neovascular) form of AMD, for which verteporfin is licensed, is characterised by the growth of abnormal, leaky blood vessels (neovascularisation) across the central part of the retina (macula). These blood vessels leak fluid, eventually resulting in scar tissue and the loss of central vision.
"Wet" AMD is the less common form of the condition. An estimated 10-15 per cent of all patients with AMD have this form, which carries a higher risk of severe sight loss. The company says that of the estimated 16,000 new patients in the UK who develop wet AMD every year, 40-60 per cent will be eligible for treatment with verteporfin.
Photodynamic therapy with verteporfin is a two step process and works by targeting any abnormal blood vessels in the retina. The drug, a dye, is injected intravenously into the patient's arm and a non-thermal laser light is then shone into the eye, activating the drug. Selectivity of photodynamic therapy using verteporfin is based on selective and rapid uptake and retention of the drug by rapidly proliferating cells, including the endothelium of choroidal neovasculature. Blood flow is disrupted which helps to seal damaged blood vessels and prevent further leakage of blood and other fluid.
Ciba Vision (UK) says that a 24-month randomised, placebo-controlled, phase III trial showed that in 243 patients with predominantly classic CNV, vision remained stable or improved in 67 per cent of patients treated with verteporfin. This compared with 39 per cent of patients in the placebo group. The results also showed that fewer treatments were required in the second year, compared with the first year, says the company.