Cosopt is the brand name of a combination ophthalmic drop manufactured by Merck. Cosopt contains two different active ingredients, timolol and dorzolamide. Cosopt is used to treat glaucoma, or high intraocular (eye) pressure which damages the optic nerve and can cause vision loss. As with any medication, Cosopt can cause side effects and should not be used by some people. For many glaucoma sufferers, Cosopt eye drops are an effective medication.
Purpose
The purpose of Cosopt drops is to prevent damage to the optic nerve, which transmits messages to the brain where they are translated into visual images. High intraocular pressure damages the nerve by compressing the sheath through which the optic nerve travels. Cosopt prevents damage by reducing intraocular pressure.
Mechanism
The two active ingredients in Cosopt, timolol and dorzolamide, reduce intraocular pressure in different ways. Timolol is a beta blocker that decreases the production of aqueous humor fluid, the fluid that controls eye pressure, and also increases fluid drainage from the eye, according to the Indiana University Optometry Clinic. Dorzolamide is a carbon anhydrase inhibitor also decreases aqueous humor, though in a different way. The two drugs together decrease pressure more than giving either drug alone, Merck reports.
Considerations
Certain people should not use Cosopt. This includes people taking an oral beta blocker and people with heart conditions such as a slow heart rate, coronary artery disease or congestive heart failure. Beta blockers block certain autonomic nervous system reactions and cause the heart to be more slowly and less forceful than normal. Cosopt should be used cautiously in people with asthma, diabetes, hyperthyroid disease, kidney or liver disease, or those with a sulfa allergy. Cosopt should not be used by pregnant or breastfeeding women, or children.
Side Effects
Cosopt has many side effects. Among the most common are itching, stinging, blurred vision and a strange taste in the mouth. Less common side effects are dizziness, nausea, a rise in blood pressure, dry eye, swollen eyelids and erosion of the cornea. Conjunctivitis, inflammation of the tissues lining the eyelid, and headache may also occur.
Warnings
Cosopt is absorbed systemically, even though it's put into the eye. Severe allergic reactions can occur in people allergic to sulfanomides or any sulfa drugs. Severe allergic symptoms include swelling of the face, shortness of breath, wheezing, collapse and even death. Because Cosopt contains beta blockers, it can cause bronchospasm in people with asthma. People with heart conditions that cause a slow heart rate or heart block should not take beta blockers while on this medication as it can worsen this effect.
