CLINICAL PHARMACOLOGY
Betaxolol hydrochloride, a cardioselective (beta1) adrenoceptor antagonist, does not have significant membrane-stabilizing (local anesthetic) activity and is devoid of intrinsic sympathomimetic action. Orally administered beta-adrenergic blocking agents reduce cardiac output in healthy subjects and subjects with heart disease. In patients with severe impairment of myocardial function, beta-adrenergic receptor antagonists may inhibit the sympathetic stimulatory effect necessary to maintain adequate cardiac function.
Pilocarpine is a direct acting cholinergic parasympathomimetic agent which acts through direct stimulation of muscarinic neuroreceptors and smooth muscle such as the iris and secretory glands. Each of these compounds lowers elevated intraocular pressure (IOP) by different mechanisms of action. Betaxolol lowers IOP predominately by decreasing aqueous humor production. Pilocarpine lowers IOP predominantly by increasing the outflow of aqueous humor from the eye.
The efficacy and safety of Betoptic®Pilo Ophthalmic Suspension dosed TID was evaluated in two prospective, multicenter, controlled clinical trials. In both controlled studies, Betoptic®Pilo Ophthalmic Suspension dosed TID provide up to an additional 1-3 mmHg IOP lowering from the BETOPTIC®-S BID baseline. Betoptic®Pilo has not been shown to be superior to any other beta-blocker aside from Betoptic®-S.
The potential for systemic absorption was evaluated following topical use of Betoptic®Pilo Ophthalmic Suspension TID. After five and eight days of dosing with Betoptic®Pilo Ophthalmic Suspension TID, plasma levels of betaxolol were below the level of quantification (2.0 ng/mL) indicating that TID dosing results in a low systemic exposure to the drug. Plasma concentrations of pilocarpine were higher following topical ocular administration of Pilocarpine HCl Solution 4% QID than after dosing with Betoptic®Pilo Ophthalmic Suspension TID.
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