Estimates suggest that in Europe 2.3% of people older than 65 years have neovascular age-related macular degeneration, which can lead to loss of central vision.1 The condition is the leading cause of blindness in the western world, and the third commonest worldwide.2 It is characterised by growth of new blood vessels beneath the retina (choroidal neovascularisation), a process stimulated by the secretion of vascular endothelial growth factor (VEGF).3 Two new drugs, ▼pegaptanib sodium (Macugen – Pfizer) and ▼ranibizumab (Lucentis – Novartis), that block the effects of VEGF are now licensed in the UK for patients with neovascular age-related macular degeneration.4^,5 A third drug that inhibits VEGF activity, ▼bevacizumab (Avastin – Roche), is also used for this condition but is licensed only for metastatic colorectal or breast cancer.6 Here we consider the role of pegaptanib, ranibizumab and bevacizumab in patients with neovascular age-related macular degeneration.

What is VEGF?

VEGF is an endogenous protein involved in the biological pathways that are responsible for initiating and sustaining physiological and pathological development of new blood vessels, vascular permeability and inflammation.7 In animal models, over-expression of VEGF in the retinal pigment epithelium is sufficient to cause choroidal neovascularisation8 that, in turn, can be prevented by inhibitors of VEGF expression.9^,10 There are four major isoforms of VEGF, containing 121, 165, 189, and 206 amino acids, respectively.7 Of these, VEGF₁₆₅ is the commonest form and is believed to be most involved with pathological ocular neovascularisation seen in animal studies.7

Pegaptanib sodium

Pegaptanib (pronounced pe-gap-ta-nib) sodium is a short nucleotide chain (oligonucleotide) that has been modified by addition of polyethylene glycol chains (pegylation). It selectively binds to the VEGF₁₆₅ isoform and inhibits its activity.3 Its licensed dose is 0.3mg by …