β1-adrenergic receptor ( Ki = 0.76 nM ); β2-adrenergic receptor ( Ki = 32.6 nM )

Levobetaxolol has a greater affinity with Ki values of 0.76 and 32.6 nM for cloned human β1 and β2 receptors, respectively [1]. With Kb values of 6 and 39 nM, respectively, levobetaxolol suppresses the functional activity of cells expressing human recombinant β1 and β2 receptors [1].

The pharmacological characteristics of levobetaxolol, a single active isomer of betaxolol, were determined and compared with activities of other beta-adrenoceptor antagonists. Levobetaxolol (43-fold beta1-selective) exhibited a higher affinity at cloned human beta1 (Ki = 0.76 nM) than at beta2 (Ki = 32.6 nM) receptors, while dextrobetaxolol was much weaker at both receptors. Levobetaxolol potently antagonized functional activities at cloned human beta1 and beta2 receptors, and also at guinea pig atrial beta1, tracheal beta2 and rat colonic beta3 receptors (IC50s = 33.2 nM, 2970 nM and 709 nM, respectively). Thus, levobetaxolol was 89-times beta1-selective (vs beta2). Levobetaxolol (Ki = 16.4 nM) was more potent than dextrobetaxolol (Ki = 2.97 microM) at inhibiting isoproterenol-induced cAMP production in human non-pigmented ciliary epithelial cells. Levobunolol and (l)-timolol had high affinities at beta1 and beta2 receptors but were considerably less beta1-selective than levobetaxolol. Levo-, dextro- and racemic-betaxolol exhibited little or no affinity, except at sigma sites and Ca2+-channels (IC50s > 1 microM), at 89 other receptor/ligand binding sites. Levobetaxolol exhibited a micromolar affinity for L-type Ca2+-channels. In conscious ocular hypertensive cynomolgus monkeys, levobetaxolol was more potent than dextrobetaxolol, reducing intraocular pressure by 25.9+/-3.2% at a dose of 150 microg/eye (n = 15-30). Quantitative [3H]-levobetaxolol autoradiography revealed high levels of binding to human ciliary processes, iris, choroid/retina, and ciliary muscles. In conclusion, levobetaxolol is a potent, high affinity and beta1-selective IOP-lowering beta-adrenoceptor antagonist.[1]

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Levobetaxolol (150 mg/eye) is more potent than dextrobetaxolol, reducing intraocular pressure by 25.9% in conscious ocular hypertensive cynomolgus monkeys. [1] In a rat model of photic-induced retinopathy, Levobetaxolol (20 mg/kg) significantly protects retinal function and causes the RPE and outer nuclear layer to thicken. Levobetaxolol (20 mg/kg) increases the levels of bFGF and CNTF mRNA by a factor of ten and two, respectively. These trophic factors have been demonstrated to prevent retinal degeneration in several species. [3]

Rats were dosed (IP) with vehicle or levobetaxolol (10 and 20 mg kg(-1)) 48, 24 and 0 hr prior to exposure for 6 hr to fluorescent blue light. The electroretinogram (ERG) and retinal morphology were assessed after a 3 week recovery period. Evaluation of the ERG demonstrated significant protection of retinal function in levobetaxolol (20 mg kg(-1))-dosed rats compared to vehicle-dosed rats. Similarly, the RPE and outer nuclear layer were significantly thicker in levobetaxolol (20 mg kg(-1))-dosed rats compared to vehicle-dosed rats. To elucidate potential mechanism(s) of the neuroprotective activity of levobetaxolol, bFGF and CNTF mRNA levels in normal rat retinas were evaluated 12 hr after a single i.p. injection. Northern blot analysis of levobetaxolol treated retinas demonstrated a 10-fold up-regulation of bFGF and a two-fold up-regulation of CNTF mRNA levels, trophic factors that have been shown to inhibit retinal degeneration in a number of species. These studies suggest that levobetaxolol can be used as a novel neuroprotective agent to ameliorate retinopathy.[3]

Absorption, Distribution and Excretion
Levobetaxolol is applied topically to the eye but some does reach systemic circulaton with a Tmax of 3 h.

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Biological Half-Life
The mean half life of levobetaxolol is 20 h.

[1]. Sharif NA, et al. Levobetaxolol (Betaxon) and other beta-adrenergic antagonists: preclinical pharmacology, IOP-lowering activity and sites of action in human eyes. J Ocul Pharmacol Ther. 2001 Aug;17(4):305-17.
[2]. Osborne NN, et al. Effectiveness of levobetaxolol and timolol at blunting retinal ischaemia is related to their calcium and sodium blocking activities: relevance to glaucoma. Brain Res Bull. 2004 Feb 15;62(6):525-8.

(S)-betaxolol is the (S)-enantiomer of betaxolol. It is an enantiomer of a (R)-betaxolol.
Levobetaxolol is a beta-blocker used to lower the pressure in the eye to treat conditions such as glaucoma. It was marketed as a 0.5% ophthalmic solution of levobetaxolol hydrochloride under the trade name Betaxon but has been discontinued.
Levobetaxolol is the S-isomer of betaxolol, a selective beta-1 adrenergic receptor antagonist with anti-glaucoma activity and devoid of intrinsic sympathomimetic activity. When applied topically in the eye, levobetaxolol reduces aqueous humor secretion and lowers the intraocular pressure (IOP).

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Drug Indication
Used in the treatment of open-angle glaucoma and ocular hypertension.
FDA Label

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Mechanism of Action
The exact mechanism by which levobetaxolol lowers intraocular pressure is not known. It it thought that antagonism of β-adrenergic receptors may reduce the production of aqueous humour stimulated via the cyclic adenosine monophosphate-protein kinase A pathway. It is also thought that the vasoconstriction produced by antagonism of β adrenergic receptors reduces blood flow to the eye and therefore the ultrafiltration responsible for aqueous humour production. β1 selective antagonists are less effective than non-selective β adrenergic receptor antagonists because β2 receptors make up the bulk of the population in the eye. They do, however, come with the benefit of reduced respiratory complications.

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Pharmacodynamics
Levobetaxolol is a selective β1 adrenergic receptor antagonist. It acts to lower intraocular pressure. Levobataxolol is condsidered to be the more active component of the betaxolol racemate.

C18H29NO3

307.43

307.215

93221-48-8

116209-55-3 (HCl); 93221-48-8; Betaxolol hydrochloride; 63659-19-8; Levobetaxolol hydrochloride; 116209-55-3; Betaxolol-d5; 1189957-99-0; 63659-18-7; 93221-48-8 (S-isomer free base); 116209-55-3 (S-isomer HCl)

60657

Typically exists as solid at room temperature

1.067g/cm3

448ºC at 760 mmHg

71-72ºC

224.7ºC

1.529

2.784

2

4

11

22

286

1

CC(C)NC[C@@H](COC1=CC=C(C=C1)CCOCC2CC2)O

NWIUTZDMDHAVTP-KRWDZBQOSA-N

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/t17-/m0/s1

(2S)-1-[4-[2-(cyclopropylmethoxy)ethyl]phenoxy]-3-(propan-2-ylamino)propan-2-ol

Levobetaxolol; (S)-Betaxolol; Levobetaxolol; (S)-Betaxolol; 93221-48-8; (-)-Betaxolol; (S)-(-)-Betaxolol; Levobetaxolol [INN]; Betaxolol, (s)-; (2S)-1-[4-[2-(cyclopropylmethoxy)ethyl]phenoxy]-3-(propan-2-ylamino)propan-2-ol; (S)-(-)-Betaxolol

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)