A Comparison Of The Efficacy And Side Effects Of Betoptic 0.5% and Betoptic S 0.25%.

Eye care professionals have used betaxolol solution in their armamentarium against glaucoma since its introduction in 1985. However, a new vehicle for betaxolol has recently seen more use. Betoptic S 0. 25% is a betaxolol suspension produced by Alcon Laboratories. It contains half the usual concentration of betaxolol and is a suspension rather than a solution. A solution is a homogeneous mixture of dissolved substances, it does not settle out. A suspension is noncolliodal dispersion of solid particles in a liquid, it will settle out. In the case of Betoptic S 0.25% the drug is bound by polymer resin beads five micrometers in diameter. The beads are in suspension. The benefits of this new suspension include greater bioavailability, hence lower concentration, and improved comfort upon instillation. Betaxolol is a Beta blocker. Beta receptors are part of the sympathetic nervous system. They are located in the lungs, heart, liver, arterioles, veins, and ciliary body as well as other parts of the body. There are two forms of Beta receptors, B1 and B2. Betaxolol reduces aqueous production and IOP by blocking B1 receptors on the ciliary body. Betaxolol is cardioselective because it blocks B1 receptors on the heart but does not block B2 receptors in the lungs. Cardioselectivity is beneficial because betaxolol can be more safely used than other Beta blockers in patients with pulmonary disease. Mild bradycardia is a reported side effect of Betoptic solution. Topical ophthalmic betaxolol can also lower both systolic and diastolic blood pressure. The intent of our research was to determine whether there was any difference in ability to lower intraocular pressure (IOP), affect blood pressure and heart rate, or cause ocular discomfort. The single most noted adverse effect of ocular betaxolol 0. 5% solution is transient discomfort, reported to occur in 25 to 40% of patients. "A Double-Masked Three-Month Comparison Between 0. 25% Betaxolol Suspension and 0. 5% Betaxolol Ophthalmic Solution", published in the August 15, 1990 issue of the American Journal of Ophthalmology reported no significant difference in IOP reduction, or effect on mean arterial pressure, or effect on pulse rate. However, ocular discomfort was significantly greater with the 0.5% solution. Greater comfort with the suspension can be attributed to the lower drug concentration and slower delivery from the vehicle.