Molecular Formula: C18H30ClNO3
Molecular weight: 307.4 g/mol
CAS No: 63659-18-7
ATC Code: C07AB05
Drug Class: Beta Blockers
General Properties:
Betaxolol Hydrochloride is the hydrochloride salt form of betaxolol, a beta-1-selective adrenergic receptor antagonist without intrinsic sympathomimetic activity. Betaxolol hydrochloride acts on the heart and circulatory system and decreases cardiac contractility and rate, thereby reducing cardiac output. When applied topically in the eye, it lowers intraocular pressure by reducing aqueous humor secretion.
A cardioselective beta-1-adrenergic antagonist with no partial agonist activity.
Indication:
Betaxolol is a lipophilic beta-adrenergic blocker that is selective to the beta-1 adrenergic receptor, with a limited beta-2 blocking effect. This factor is an important distinction compared to topical nonselective beta-blockers. Administration of the drug can be either via topical or systemic routes. The FDA primarily indicates topical betaxolol for use in patients with ocular hypertension and chronic open-angle glaucoma. In the systemic form, the FDA approves its use to treat essential hypertension, post-myocardial infarction, and chronic stable angina. Similar to the other beta-1 selective beta-blockers, betaxolol is associated with a decreased risk of stroke, congestive heart failure, and coronary artery disease. It also demonstrates decreased mortality and morbidity post-myocardial infarction. The non-FDA uses for betaxolol include tremor reduction, migraine prophylaxis, certain cardiac arrhythmias, and anxiety disorders. Recently, one study showed the use of topical betaxolol in the treatment of relapsing paronychia, also known as a skin infection around a fingernail.
Glaucoma is an optic neuropathy defined by the death of retinal ganglion cells and characteristic changes to the optic nerve head. Intraocular pressure, as well as other factors, are factors for the loss of ganglion cells. While the exact mechanism of glaucoma is not completely known, there are two main independent pathways, the trabecular meshwork and uveoscleral, that contribute to the intraocular pressure. In primary open-angle glaucoma, there is increased resistance to the outflow of aqueous humor, a clear fluid produced by the ciliary bodies, through the trabecular meshwork of the eye. This action increases intraocular pressure, leading to the degeneration of retinal ganglion cells and the optic nerve over time, causing progressive vision loss that typically starts at the periphery and can expand to involve the whole field of vision for that eye. It is also known that patients with normal intraocular pressure can also develop glaucoma.
Beta-blockers like betaxolol were once first-line treatment for open-angle glaucoma, but now topical prostaglandin analogs, like latanoprost, are often the first drugs of choice. This change in prescribing is because even in the topical form, beta-blockers have more systemic side effects compared to prostaglandin analogs. Betaxolol and other beta-blockers like timolol are often the drugs of choice when patients cannot tolerate prostaglandins.
Additional pressure reduction is needed, or there is a rare contraindication to them. Betaxolol’s niche comes when a patient also has mild respiratory comorbidity like asthma or COPD. Betaxolol’s selective beta-1 adrenergic blockade decreases the likelihood of systemic, respiratory side effects compared to nonselective beta-blockers like timolol.
