Betaxolol

Betaxolol is a beta blocker used in the treatment of hypertension and angina.^[1]

Betaxolol

Clinical data
Trade names	Kerlone
AHFS/Drugs.com	Monograph
MedlinePlus	a609023
Pregnancy category	AU: C
Routes of administration	By mouth, ocular
Drug class	Beta blocker; β-Adrenergic receptor antagonist; Selective β1-adrenergic receptor antagonist
ATC code	C07AB05 (WHO) S01ED02 (WHO)
Legal status
Legal status	In general: ℞ (Prescription only)
Pharmacokinetic data
Bioavailability	89%
Metabolism	Liver
Elimination half-life	14–22 hours
Excretion	Kidney (20%)
Identifiers
IUPAC name (RS)-1-{4-[2-(cyclopropylmethoxy)ethyl]- phenoxy}-3-(isopropylamino)propan-2-ol
CAS Number	63659-18-7 Y
PubChem CID	2369
IUPHAR/BPS	549
DrugBank	DB00195 Y
ChemSpider	2279 Y
UNII	O0ZR1R6RZ2
KEGG	D07526 Y
ChEBI	CHEBI:3082 Y
ChEMBL	ChEMBL423 Y
CompTox Dashboard (EPA)	DTXSID2022674
ECHA InfoCard	100.113.058
Chemical and physical data
Formula	C18H29NO3
Molar mass	307.434 g·mol−1
3D model (JSmol)	Interactive image
Chirality	Racemic mixture
SMILES O(CCc1ccc(OCC(O)CNC(C)C)cc1)CC2CC2
InChI InChI=1S/C18H29NO3/c1-14(2)19-11-17(20)13-22-18-7-5-15(6-8-18)9-10-21-12-16-3-4-16/h5-8,14,16-17,19-20H,3-4,9-13H2,1-2H3 Y Key:NWIUTZDMDHAVTP-UHFFFAOYSA-N Y
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It acts as a selective β₁-adrenergic receptor antagonist.

The drug was patented in 1975 and approved for medical use in 1983.^[2]

Medical uses

Hypertension

Betaxolol is most commonly ingested orally alone or with other medications for the management of essential hypertension.^[3] It is a cardioselective beta blocker, targeting beta-1 adrenergic receptors found in the cardiac muscle. Blood pressure is decreased by the mechanism of blood vessels relaxing and improving the flow of blood.^[4][5]

Glaucoma

Ophthalmic betaxolol is an available treatment for primary open angle glaucoma (POAG) and optical hypertension. Betaxolol effectively prevents the increase of intracellular calcium, which leads to increased production of the aqueous humor. In the context of open angle glaucoma, increased aqueous humor produced by ciliary bodies increases intraocular pressure, causing degeneration of retinal ganglion cells and the optic nerve.^[6]

Furthermore, betaxolol is additionally able to protect retinal neurones following topical application from excitotoxicity or ischemia-reperfusion, providing a neuroprotective effect. This is thought to be attributed to its capacity to attenuate neuronal calcium and sodium influx.^[7] Betaxolol is also an effective treatment for Intraocular pressure^[8]

Other uses

Betaxolol has been used to treat anxiety as well.^[9][10]

One study showed that topical betaxolol can be used in treating relapsed paronychia.^[11]

Contraindications

• Hypersensitivity to the drug
• Patients with sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure

Side effects

The adverse side effects of betaxolol can be categorized into local and systemic effects.^[6] The local effects include:

• transient irritation (20-40% of patients)
• burning
• pruritus, or general itching
• punctate keratitis
• blurry vision^[12]

Systemically, patients taking betaxolol might experience:

• bradycardia
• hypotension
• fatigue
• sexual impotence
• hair loss
• confusion
• headache
• dizziness
• bronchospasm at higher doses
• cardiac problems such as arrhythmia, bundle branch block, myocardial infarction, sinus arrest, and congestive heart failure
• mental effects such as depression, disorientation, vertigo, sleepwalking, rhinitis
• dysuria
• metabolic side effects such as an increase in LDL cholesterol levels
• can mask the symptoms of hypoglycemia diabetic patients

See also: Beta blocker

Pharmacology

Pharmacodynamics

Betaxolol is a beta blocker and acts specifically as a selective β₁-adrenergic receptor antagonist. It has no partial agonist action (i.e., intrinsic sympathomimetic activity) and shows minimal membrane-stabilizing activity (i.e., sodium channel blockade or local anesthetic activity).^[13] Being selective for beta₁ receptors, it typically has fewer systemic side effects than non-selective beta-blockers, for example, not causing bronchospasm (mediated by beta₂ receptors) as timolol may. Betaxolol also shows greater affinity for beta₁ receptors than metoprolol. In addition to its effect on the heart, betaxolol reduces the pressure within the eye (intraocular pressure). This effect is thought to be caused by reducing the production of the liquid (which is called the aqueous humor) within the eye. The precise mechanism of this effect is not known. The reduction in intraocular pressure reduces the risk of damage to the optic nerve and loss of vision in patients with elevated intraocular pressure due to glaucoma.

Chemistry

The experimental log P of betaxolol is 2.4 to 2.81.^[14][15]

History

Betaxolol was approved by the U.S. Food and Drug Administration (FDA) for ocular use as a 0.5% solution (Betoptic) in 1985 and as a 0.25% solution (Betoptic S) in 1989.

Society and culture

Brand names

Brand names include Betoptic, Betoptic S, Lokren, Kerlone.

See also

• Levobetaxolol
• Cicloprolol