Macular degeneration agents

Macular degeneration is an age-related condition that affects the retina, leading to a progressive decline in central visual acuity. The disease is largely linked to neovascularization in the subretinal space, with vascular endothelial growth factor (VEGF) playing a significant role. In response, various agents have been formulated to target VEGF, effectively slowing the progression of the neovascular or "wet" form of macular degeneration.

Mechanism of Action

The vascularization in macular degeneration is believed to be driven, at least in part, by the action of VEGF. Therefore, drugs that specifically inhibit VEGF have been shown to be effective in treating the wet form of the condition.

List of Macular Degeneration Agents

Several therapeutic agents are used in the treatment of macular degeneration. They can be classified as follows:

• Monoclonal antibodies to VEGF: bevacizumab, ranibizumab
• Aptamers: pegaptanib
• Fusion VEGF receptor proteins: aflibercept

All these agents are administered through intravitreal injections, typically every 4 to 8 weeks. Most of their side effects are ocular, often linked to the injection process. Systemic exposure is minimal, making ex-ocular adverse events rare. Notably, these agents have been linked to cardiovascular or cerebrovascular thromboembolic events, albeit rarely. None of these agents, when administered via intravitreal injection, have been implicated in hepatotoxicity.

Bevacizumab

• Brand Name: Avastin
• Description: Bevacizumab is a humanized monoclonal antibody that targets VEGF. While it is approved for intravenous use in various cancers, it has been employed off-label to treat macular degeneration. In clinical trials, its efficacy was found to be comparable to that of ranibizumab.
• Dosage: Off-label use for macular degeneration involves administering 1.25 mg (0.05 mL) once monthly via intravitreal injection.

Ranibizumab

• Brand Name: Lucentis
• Description: Ranibizumab is a recombinant humanized monoclonal antibody fragment (Fab) that targets VEGF. It has been approved for the treatment of neovascular (wet) age-related macular degeneration and other ocular conditions.
• Dosage: The advised dosage is 0.5 mg once monthly by intravitreal injection.

Pegaptanib

• Brand Name: Macugen
• Description: Pegaptanib is a pegylated aptamer, which binds with and neutralizes extracellular VEGF. It has received approval for treating neovascular (wet) age-related macular degeneration.
• Dosage: The recommended dosage is 0.3 mg administered via intravitreal injection once every six weeks.

Aflibercept

• Brand Name: Eylea
• Description: Aflibercept is a unique fusion protein that acts as a decoy receptor, competing for VEGF binding. It has been approved for a range of ocular conditions, including neovascular age-related macular degeneration.
• Dosage: Initially, 2 mg once monthly by intravitreal injection is recommended.

Note: Aflibercept is also available as ziv-aflibercept (Zaltrap) for parenteral use in metastatic colon cancer combined with other antineoplastic agents. The addition of ziv-aflibercept to this combination has not shown an increased risk of liver injury.

Conclusion

Macular degeneration agents have revolutionized the treatment of the wet form of the disease. By specifically targeting VEGF, they slow down the progression and offer improved quality of life to those affected. As with any medication, monitoring for side effects and understanding potential risks are essential.

Macular Degeneration Agents, Monoclonal Antibodies

• Dailymed label info on Macular degeneration agents
• FDA Macular degeneration agents