Pegaptanib is a medication used in ophthalmology, specifically designed to address certain eye conditions. This article will provide an overview of pegaptanib, its function within the eye, the specific conditions it treats, and what patients can expect during treatment.
Understanding Pegaptanib and Its Mechanism
Pegaptanib, known by its brand name Macugen, is classified as a vascular endothelial growth factor (VEGF) antagonist. It belongs to a class of therapeutic agents called aptamers, which are single strands of nucleic acids engineered to bind to a particular target molecule. Pegaptanib is a pegylated RNA aptamer, meaning it has polyethylene glycol (PEG) attached, which increases its stability and duration of action in the body.
The specific mechanism of action for pegaptanib involves its binding to vascular endothelial growth factor (VEGF), a protein that plays a role in the formation of new blood vessels (angiogenesis) and in increasing the permeability of existing blood vessels, leading to leakage. Pegaptanib specifically targets and binds to the VEGF165 isoform. This selective binding inhibits the activity of VEGF165, preventing the growth of abnormal blood vessels and controlling leakage and swelling within the eye.
Treating Eye Conditions with Pegaptanib
Pegaptanib is approved to treat neovascular, or “wet,” age-related macular degeneration (AMD). This advanced form of AMD, a common eye condition affecting central vision, occurs when abnormal blood vessels grow underneath the macula, the central part of the retina responsible for sharp, detailed vision.
These newly formed, abnormal blood vessels are often fragile and can leak fluid or blood, leading to damage and scarring of the macula. This leakage can cause blurred vision, distorted vision, or blind spots in the central visual field, and if left untreated, can lead to rapid and severe vision loss. By inhibiting VEGF165, pegaptanib reduces the growth of these unwanted blood vessels and minimizes fluid leakage, helping to stabilize vision and reduce the risk of further decline. While pegaptanib primarily treats wet AMD, other less common or off-label uses may exist.
Receiving Pegaptanib Treatment and Potential Effects
Pegaptanib is administered through an intravitreal injection, directly into the vitreous humor, the jelly-like substance that fills the eye. An ophthalmologist performs this procedure in a sterile environment, often in a doctor’s office. Before the injection, the eye is cleaned to prevent infection, and a local anesthetic is applied to numb the eye, minimizing discomfort.
Patients may feel some pressure in the eye during the injection. The standard dose is 0.3 mg, administered once every six weeks. After the injection, the doctor will examine the eye for any immediate effects. Patients should report any unusual symptoms to their doctor immediately.
Common side effects include eye irritation, eye pain, blurred vision, and floaters. Some patients may also experience increased intraocular pressure, which requires monitoring. Less common but more serious risks include endophthalmitis (an infection inside the eye), retinal detachment, or bleeding within the eye. Symptoms such as severe eye pain, redness, reduced vision, or sensitivity to light should be reported to a doctor immediately.