Medical Therapy for Glaucoma
Neil T. Choplin, Carlo E. Traverso in Atlas of Glaucoma, 2014
Betaxolol (Figure 14.8) is the only commercially available topical β1 selective intraocular pressure-lowering medication. It is available as a 0.25% suspension (Betoptic-S) and a 0.5% solution. The suspension is more comfortable than the solution for most patients, but the two are equally efficacious. Both formulations lower intraocular pressure between 20% and 25% from baseline. This agent can be considered in patients with mild to moderate pulmonary disease without other contraindications to this class of compounds. All β-adrenoreceptor antagonists must be used with caution in any patient with a history of reactive airway disease. It is advisable to consult with a patient’s internist or pulmonologist prior to prescribing these agents in patients with pulmonary disease. Betaxolol has intrinsic calcium channel blocking activity, which may increase ocular blood flow. Additional investigations of this property and the potential clinical benefit need to be conducted.
Cardiovascular Drugs during Pregnancy
“Bert” Bertis Britt Little in Drugs and Pregnancy, 2022
No human teratology or reproduction studies with betaxolol, carteolol, nadolol, penbutolol, or timolol have been published. No increase in congenital malformations was noted in the offspring of pregnant mice who received up to 150 mg/kg/day of carteolol (Tanaka et al., 1979). Only six infants were exposed to betaxolol during the first trimester in the Swedish Birth Defects Registry (Kallen, 2019). Also, no increase in the frequency of malformations was found among the offspring of rats, rabbits, and hamsters that had received nadolol in doses several times higher than the usual human dose (Sibley et al., 1978; Stevens et al., 1984). No increased frequency of adverse fetal effects was found in the offspring of mice treated with penbutolol (Sugisaki et al., 1981).
Adrenoceptor Antagonists
Kenneth J. Broadley in Autonomic Pharmacology, 2017
Several β-adrenoceptor antagonists including timolol, carteolol, levobunolol and betaxolol (Buckley et al. 1990) are used topically for the treatment of open-angle glaucoma (Table 5.3). In open-angle glaucoma, drainage of aqueous humour is not impaired by narrowing of the drainage angle but is related to the diffusion through the trabecular network to the canal of Schlemm (Figure 1.7). In Chapter 4, it was noted that adrenaline is also effective in the treatment of open-angle glaucoma, part of this activity being due to β-adrenoceptor-mediated vasodilatation of the veins draining the canal of Schlemm. It is therefore anomalous that β-blockers should also be useful. Their mechanism of action is probably due to impaired production of aqueous humour by the ciliary body. The precise site of action is still uncertain, but β-adrenoceptor blockade rather than ISA or membrane stabilizing properties is involved; these properties being absent in the most active agent, timolol. There may be blockade of β2-adrenoceptors in the epithelial cells of the ciliary body that control active transport and secretion of aqueous humour (Lotti et al. 1984). β1-Selective antagonists in general are not effective, although betaxolol is an exception. Additionally, there may be a reduction in blood flow to the ciliary body and therefore a decreased formation of ultrafiltrate (Lesar 1987). The advantages of β-blockers in the treatment of glaucoma is that they produce minimal local adverse effects. Care must nevertheless be exercised in their use in patients with bronchial asthma or heart disease.
Adrenergic agonists and antagonists as antiglaucoma agents: a literature and patent review (2013–2019)
Published in Expert Opinion on Therapeutic Patents, 2019
Alessio Nocentini, Claudiu T. Supuran
Betaxolol is a β1-selective adrenoceptor antagonist. It exerts the effect on IOP by inhibiting aqueous humor flow [28]. As the ciliary body hardly contains β1-adrenoceptors, it is likely that betaxolol lower IOP by its weak β2-blocking properties. As a result, the effect betaxolol 0.5% (Betoptic®) on IOP is smaller than timolol (18 to 26%) [29]. Nonetheless, betaxolol better preserves the visual field than timolol over the long term. Burning and stinging are frequently observed after topical administration. Clinical evidence showed that betaxolol has less effect on cardiac and pulmonary function than nonselective β-blockers. Unexpectedly, cardiovascular adverse effects such as bradycardia, arrhythmias, and congestive heart failure occur less frequently with betaxolol than with nonselective β-blockers probably because it strongly binds to plasma proteins reducing free plasma concentration [30].
Emerging drugs for the treatment of glaucoma: a review of phase II & III trials
Published in Expert Opinion on Emerging Drugs, 2022
Tyler M. Kaplan, Arthur J. Sit
Beta blockers reduce aqueous humor production by 20–50% through the reduction of intracellular cAMP in the ciliary epithelium [53,54]. Members of this class of medication include timolol, carteolol, levobunolol, and betaxolol, which reduce IOP by 20–25% except betaxolol which reduces IOP by 15–20% [11,55,56]. While beta blockers can cause conjunctival injection and blepharitis [3], they are generally very well tolerated in terms of local side effects. However, beta blockers are less effective at night [57], likely because aqueous production is reduced by approximately 50% at night [58,59]. They may also reduce outflow facility [60] and decrease ocular perfusion pressure [61] which can potentially worsen disease status. Further, they can cause systemic side effects including decreased cardiac output, decompensated heart failure, heart block, and bradycardia. Patients with asthma or chronic obstructive pulmonary disease (COPD) can develop respiratory side effects [3,6]. These systemic side effects are most frequently seen in nonselective beta blocker due to inhibition of beta-1 and beta-2 receptors, while betaxolol has a lower risk of pulmonary complications since it is more beta-1 selective [62].
Age-dependent sympathetic neural responses to ß1 selective beta-blockade in untreated hypertension-related tachycardia
Published in Blood Pressure, 2018
Dagmara Hering, Wiesława Kucharska, Marzena Chrostowska, Krzysztof Narkiewicz
This study is the first to demonstrate the effects of highly β1 cardioselective beta-adrenergic receptor antagonist betaxolol on sympathetic CV profile in males with untreated hypertension and ambulatory tachycardia. The major novel findings are that (1) the autonomic neural responses to betaxolol are age-dependent in untreated hypertension-related tachycardia; (2) chronic treatment with betaxolol reduces sympathetic drive to the heart but not to the peripheral vessels in younger adults; and (3) the paradoxical reduction in MSNA achieved with betaxolol occurs despite lowering of HR and BP in older males. Our study also revealed three other new findings to indicate (1) age-related difference in hemodynamic and sympathetic profile in hypertension-related tachycardia; (2) lowering HR with betaxolol bore no association with an inhibition of MSNA; and (3) betaxolol improves the dynamics of HRV in younger, but not in older subjects with untreated hypertension and tachycardia. Betaxolol was well tolerated and no drug-related side effects were noted in the study cohort.
Related Knowledge Centers
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