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Betoptic Pilo (Betaxolol Hydrochloride / Pilocarpine Hydrochloride) - Description and Clinical Pharmacology

 
 



Betoptic®Pilo Ophthalmic
Suspension
(betaxolol 0.25% / pilocarpine
hydrochloride 1.75% ophthalmic
suspension)

DESCRIPTION

Betoptic®Pilo Ophthalmic Suspension contains betaxolol hydrochloride, a cardiovascular (beta1) adrenoceptor antagonist and pilocarpine hydrochloride, a cholinergic parasympathomimetic agent.

Betaxolol hydrochloride is a white, crystalline powder. Its chemical name is (±)-1[p-(cyclopropylmethoxy)ethyl]phenoxy]-3-(isopropylamino)-2-propanol hydrochloride with an empirical formula of C18H29NO3HCl and a molecular weight of 343.89. The chemical structure of betaxolol hydrochloride is as follows:

Pilocarpine hydrochloride is a white powder. Its chemical name is 2(3H)-furanone, 3-ethyldihydro-4-[(1-methyl-1H-imidazol-5-yl)-methyl]-, monohydrochloride, (3S-cis)- with an empirical formula of C11H16N2O2HCl and a molecular weight of 244.72. The chemical structure of pilocarpine hydrochloride is as follows:

Each mL of Betoptic®Pilo Ophthalmic Suspension contains the following:

Active: Betaxolol hydrochloride 2.8 mg equivalent to 2.5 mg betaxolol base and pilocarpine hydrochloride 17.5 mg;

Preservative: Benzalkonium chloride 0.01%.

Inactive: Mannitol, poly(styrene-divinyl benzene) sulfonic acid, carbomer 934P, boric acid, edetate disodium, sodium hydroxide and/or hydrochloric acid to adjust to a pH 6.0-8.0 and purified water.

Betoptic®Pilo Ophthalmic Suspension is provided as a two-part unit for combination by the Pharmacist. It consists of the following components: Part I – a glass syringe containing pilocarpine hydrochloride 8.75%, sodium hydroxide and/or hydrochloric acid (pH 5.0 ± 0.2) and purified water to 1.6 mL; and Part II – a DROP-TAINER® containing betaxolol 0.313%, poly(styrene-divinyl benzene) sulfonic acid, carbomer 934P, boric acid, mannitol, edetate disodium, benzalkonium chloride, sodium hydroxide (pH 8.0 ± 0.2) and purified water to 6.4 mL.

Betoptic®Pilo Ophthalmic Suspension is prepared by affixing a one-inch, blunt, 27 gauge cannula (supplied) to the syringe containing the pilocarpine hydrochloride solution and adding the entire contents of the syringe through the opening in the dropper tip to the DROP-TAINER® containing the betaxolol suspension and mixing well. The final pH of the combination suspension is 6.0 to 8.0


Remove Cap from DropTainer

Add Contents of Syringe through Orifice in DropTainer

Cap and Mix Well. Label with a 2-Week Expiry Period

ADD CONTENTS OF PART I TO PART II AND MIX WELL IMMEDIATELY PRIOR TO DISPENSING AND LABEL WITH A TWO (2) WEEK EXPIRATION DATE

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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