Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Visudyne (CIBA Vision)
vials containing 15 mg as powder for reconstitution
Approved indication: macular degeneration
Australian Medicines Handbook Section 11.4
As people grow older they can develop macular degeneration. This is caused by a failure to clear the products of retinal metabolism. In some patients this prompts vessels to grow from the choroid into the retina. If these abnormal vessels leak or bleed, the resulting scar reduces the patient's central vision. The only treatment is laser photocoagulation, but this has several limitations.1
Verteporfin is a drug treatment which aims to destroy new blood vessels affecting the retina. As verteporfin is not very soluble it has to be formulated in aliposomal delivery system. This is diluted and given as an infusion over 10minutes. Verteporfin is transported around the body by lipoproteins.
To activate the drug a non-thermal laser light is shone into the affected eye15 minutes after the infusion begins. An exposure of 83 seconds generates reactiveo xygen radicals which may cause damage to vascular endothelium. This can lead to the occlusion of the abnormal vessels.
In double-blind trials involving 609 patients, 402 eyes were given photodynamic therapy with verteporfin and 207 eyes were treated with a placebo. The treatments were repeated every three months if fluoroscein angiography revealed leaking vessels. After one year the visual acuity and angiographic assessments were significantly better in the eyes exposed to verteporfin. The loss of visual acuity was particularly reduced in a sub-group of patients with classic choroidal revascularisation. Only 33% of this group had a substantial loss of vision compared with 61% of the placebo group.2 Verteporfin has only been approved for use in patients with predominantly classic subfovealchoroidalneovascularisation.
There were few serious adverse reactions to verteporfin. Compared to placebo, there were more complaints about visual disturbance, injection site reactions and nausea.2 Although verteporfin has a half-life of 5-6hours, patients are advised to remain indoors for five days after treatment. This is because they become photosensitive after treatment. Although verteporfin may tend to accumulate in abnormal vessels it can also enter the retina. This could result in retinal damage when the drug is activated.
The long-term effects of verteporfin are currently unknown. Although it can help some patients with macular degeneration, future research is needed to prevent this common cause of blindness.1
