Medical Health Encyclopedia

Interactions with Other Medications. The effects of the eye medication may be additive to other oral medications, such as oral beta-blockers, calcium-channel blockers, or the antiarrhythmic drug quinidine. Diabetics on insulin or hypoglycemic medications should realize that timolol side effects may resemble and mask the symptoms of hypoglycemia.

Prostaglandins

Prostaglandins are hormone-like substances that help open blood vessels. Drugs that resemble prostaglandins increase outflow through the uveoscleral pathway (not the trabecular meshwork). Some experts believe that the uveoscleral pathway may be responsible for up to 50% of outflow in healthy eyes, which could explain the very large benefit produced by drugs acting on this channel.

Brands. Latanoprost (Xalatan) and unoprostone (Rescula) are the standard brands.Latanoprost is the first prostaglandin to be approved as first-line treatment for elevated eye pressure. Two newer prostaglandins, travoprost (Travatan) and bimatoprost (Lumigan), are showing great promise and may effective in some patients who do not respond to latanoprost. These drugs may also benefit patients with normal-tension glaucoma. Latanoprost, travoprost, and bimatoprost need to be taken only once daily. Unoprostone needs to be taken twice a day and is not as effective as others, but it still can reduce IOP significantly and is the least expensive of these drugs.

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Latanoprost has been shown to reduce pressure by between 45 - 70%. Some, but not all studies, have suggested that newer prostaglandins travoprost (Travatan) and bimatoprost (Lumigan) are more effective than latanoprost, but the older drug appears to be better tolerated. All of these drugs may be more effective than timolol in lowering IOP. The newer prostaglandins may be especially superior to timolol in treating African American patients. In comparison studies, latanoprost achieved better IOP pressure reduction than brimonidine. Studies have suggested that bimatoprost is more effective in lowering eye pressure than a combination of timolol and dorzolamide (Cosopt). Studies have been mixed on whether latanoprost is superior to the combination.