Ranibizumab is a drug in the monoclonal antibody drug class that is used to treat macular degeneration.
What is ranibizumab?
Ranibizumab is a drug in the monoclonal antibody drug class that is used to treat macular degeneration. The drug ranibizumab is a monoclonal antibody fragment (Fab). Monoclonal antibodies are antibodies that are produced by a specific cell clone and are derived from only one B-lymphocyte. Especially in diagnostics, therapy and research, monoclonal immunologically active proteins play an important role because they are able to bind a specific number of molecules. A physiological immune response, on the other hand, always consists of polyclonal antibodies. The company Genentech developed and markets the drug substance ranibizumab. Genentech is a subsidiary of the Swiss pharmaceutical companies Novartis and Hoffman-La Roche. The drug was first approved in the USA and Switzerland in 2006. In 2007, the EU Commission approved ranibizumab for all EU countries. With the exception of North America, Novartis still has sole marketing rights. Ranibizumab is manufactured using recombinant DNA obtained from the bacterium E. coli (Escherichia coli) by genetic modification. Ranibizumab is a fragment of the monoclonal antibody bevacizumab and prevents new blood vessel formation in the eye. Similar agents are increasingly used in cancer therapy.
Pharmacologic action
The monoclonal antibody fragment ranibizumab has high affinity for and thus binds to vascular endothelial growth factor A (VEGF-A) isoforms. VEGF-A appears to be the key molecule in the development of exudative age-related macular degeneration. Due to the binding by ranibizumab, the receptors VEGFR-1 and VEGFR-2 on the surface of the endothelial cells are not activated. Since ranibizumab has a very small molecule size, it passes through all retinal layers to reach the so-called choroidal neovascularization (CNV). In macular degeneration, these changes tend to cause bleeding. Ranibizumab prevents the corresponding receptors from being activated and thus inhibits the growth of choroidal neovascularization. As an antibody fragment, ranibizumab also reduces the risk of inflammation in the retinal area.
Medical Application and Uses
Ranibizumab is used to treat wet age-related macular degeneration (AMD). The drug is also used for visual acuity deterioration associated with diabetic macular edema. In AMD, so-called choroidal neovascularizations form below the retina and bleed rapidly. In the final stage, parts of the retina undergo scarring, often resulting in under-bleeding scars. AMD quickly leads to reading blindness. The ability to read decreases, and contrast perception and color vision are also impaired. The adaptation to changing light conditions is difficult, at the same time the sensitivity to glare increases. In more severe cases, central visual field loss may also develop. Diabetic macular edema develops in the context of the metabolic disease diabetes mellitus. If left untreated, this edema can lead to severe visual impairment or even complete vision loss. In both diseases, ranibizumab is injected into the vitreous body of the eye under local anesthesia. The dose is usually 0.05 milliliters. In the first three months of treatment, one injection is given monthly. In the following phase, the drug is administered only if vision loss recurs. In diabetic macular edema, on the other hand, monthly injections are given until maximum visual acuity is achieved. Because use should be under aseptic conditions only, only a qualified ophthalmologist should administer the drug.
Risks and side effects
Eye problems with mouches volantes, foreign body sensation, pain, and bleeding are among the most common side effects. An increase in intraocular pressure with headache or arterial hypertension may also occur during treatment with ranibizumab. Rarely, infections of the interior of the eye or damage to the retina occur. To prevent infection, antibiotic eye drops may be administered to the patient after treatment.In rare cases, a cataract may develop after therapy with ranibizumab. Despite the rather low rate of side effects, therapy with ranibizumab is more frequently criticized. Studies have compared the two agents ranibizumab and bevacizumab. They showed that bevacizumab is just as effective as the significantly more expensive active substance ranibizumab. Moreover, the use of bevacizumab is not associated with any higher risk or more side effects, so that use of the more expensive ranibizumab is not actually justified.
