Acebutolol

Absorption

Well absorbed from the Gl tract with an absolute bioavailability of approximately 40% for the parent compound. In

Toxicity

Symptoms of overdose include extreme bradycardia, advanced atrioventricular block, intraventricular conduction defects, hypotension, severe congestive heart failure, seizures, and in susceptible patients, bronchospasm, and hypoglycemia.

Chemical properties

Crystalline Solid

Originator

Sectral ,May and Baker ,UK ,1975

The Uses of Acebutolol

Cardioselective ?adrenergic blocker. Antihypertensive; antianginal; antiarrhythmic (class II)

The Uses of Acebutolol

Cardioselective β-adrenergic blocker. Antihypertensive; antianginal; antiarrhythmic (class II).

The Uses of Acebutolol

Acebutol is 3′-acetyl-4′-[2-hydroxy-3-(iso-propylamino)propoxy] butyranilide (12.1.6) [9,10].Acebutol is a selective β1-adrenoblocker. It possesses antianginal, antihypotensive, and antiarrhythmic action. It is used for arterial hypertension, preventing attacks of angina, and cardiac rhythm disturbances.

Background

A cardioselective beta-adrenergic antagonist with little effect on the bronchial receptors. The drug has stabilizing and quinidine-like effects on cardiac rhythm as well as weak inherent sympathomimetic action.

Indications

For the management of hypertension and ventricular premature beats in adults.

Definition

ChEBI: An ether that is the 2-acetyl-4-(butanoylamino)phenyl ether of the primary hydroxy group of 3-(propan-2-ylamino)propane-1,2-diol.

Manufacturing Process

Crude 5'-butyramido-2'-(2,3-epoxypropoxy)acetophenone (16 g), isopropylamine (20 g) and ethanol (100 ml) were heated together under reflux for 4 hours. The reaction mixture was concentrated under reduced pressure and the residual oil was dissolved in N hydrochloric acid. The acid solution was extracted with ethyl acetate, the ethyl acetate layers being discarded. The acidic solution was brought to pH 11 with 2 N aqueous sodium hydroxide solution and then extracted with chloroform. The dried chloroform extracts were concentrated under reduced pressure to give an oil which was crystallized from a mixture of ethanol and diethyl ether to give 5'-butyramido- 2'-(2-hydroxy-3-isopropylaminopropoxy)acetophenone (3 g), MP 119-123°C.
Crude 5'-butyramido-2'-(2,3-epoxypropoxy)acetophenone used as starting material was prepared as follows: p-butyramidophenol (58 g; prepared according to Fierz-David and Kuster, Helv. Chim. Acta 1939,2282), acetyl chloride (25.4 g) and benzene (500 ml) were heated together under reflux until a solution formed (12 hours). This solution was cooled and treated with water. The benzene layer was separated and the aqueous layer was again extracted with benzene.
The combined benzene extracts were dried and evaporated to dryness under reduced pressure to give p-butyramidophenyl acetate (38 g) as an off-white solid, MP 102-103°C. A mixture of p-butyramidophenyl acetate (38 g), aluminum chloride (80 g) and 1,1,2,2-tetrachloroethane (250 ml) was heated at 140°C for 3 hours. The reaction mixture was cooled and treated with iced water. The tetrachloroethane layer was separated and the aqueous layer was extracted with chloroform. The combined organic layers were extracted with 2 N aqueous sodium hydroxide and the alkaline solution was acidified to pH 5 with concentrated hydrochloric acid. The acidified solution was extracted with chloroform and the chloroform extract was dried and concentrated under reduced pressure to give 5'-butyramido-2'-hydroxyacetophenone (15.6 g), MP 114-117°C. A solution of 5'-butyramido-2'-hydroxyacetophenone (15.6 g) in ethanol (100 ml) was added to an ethanolic solution of sodium ethoxide which was prepared from sodium (1.62 g) and ethanol (100 ml). The resulting solution was evaporated to dryness under reduced pressure and dimethylformamide (100 ml) was added to the solid residue. Approximately 10 ml of dimethylformamide was removed by distillation under reduced pressure. Epichlorohydrin (25 ml) was added and the solution was heated at 100°C for 4 hours. The solution was concentrated under reduced pressure to give a residual oil which was treated with water to give a solid. The solid was dissolved in ethanol and the resulting solution was treated with charcoal, filtered and concentrated under reduced pressure to give crude 5'-butyramido- 2'-(2,3-epoxypropoxy)acetophenone (16 g), MP 110-116°C.
The crude compound may be purified by recrystallization from ethyl acetate, after treatment with decolorizing charcoal, to give pure 5'-butyramido-2'-(2,3- epoxypropoxy)acetophenone, MP 136-138°C.

brand name

Sectral (Dr. Reddy’s).

Therapeutic Function

beta-Adrenergic blocker

General Description

Acebutolol is one of the very few β-blockers whosemetabolite plays a significant role in its pharmacological actions.This drug is absorbed well from the gastrointestinaltract, but it undergoes extensive first-pass metabolic conversionto diacetolol by hydrolytic conversion of the amidegroup to the amine, followed by acetylation of the amine. After oral administration, plasma levels of diacetololare higher than those of acebutolol. Diacetolol is also aselective β1-blocker with partial agonistic activity; it has littlemembrane-stabilizing activity. It has a longer half-life (8–12hours) than the parent drug and is excreted by the kidneys.

Pharmacokinetics

Acebutolol is a cardioselective, beta-adrenoreceptor blocking agent, which possesses mild intrinsic sympathomimetic activity (ISA) in its therapeutically effective dose range. In general, beta-blockers reduce the work the heart has to do and allow it to beat more regularly. Acebutolol has less antagonistic effects on peripheral vascular ?2-receptors at rest and after epinephrine stimulation than nonselective beta-antagonists. Low doses of acebutolol produce less evidence of bronchoconstriction than nonselective agents like propranolol but more than atenolol.

Clinical Use

Acebutolol (Sectral) is a cardioselective 1-adrenoceptor blocking agent that also has some minor membrane stabilizing effects on the action potential. Acebutolol is effective in the management of the patient with essential hypertension, angina pectoris, and ventricular arrhythmias. Antiarrhythmic effects are observed with the patient both at rest and taking exercise.

Side Effects

Adverse effects include bradycardia, gastrointestinal upset, dizziness, and headache.

Safety Profile

Moderately toxic by intravenousroute. Human systemic effects by ingestion: developmentalabnormalities of the cardiovascular and respiratory systems;effects on newborn in biochemical and metabolicabnormalities and reduced growth statistics. A humanter

Drug interactions

Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect.
Analgesics: NSAIDs antagonise hypotensive effect.
Anti-arrhythmics: increased risk of myocardial depression and bradycardia; increased risk of bradycardia, myocardial depression and AV block with amiodarone; increased risk of myocardial depression and bradycardia with flecainide.
Antidepressants: enhanced hypotensive effect with MAOIs.
Antihypertensives: enhanced hypotensive effect; increased risk of withdrawal hypertension with clonidine; increased risk of first dose hypotensive effect with post-synaptic alpha-blockers such as prazosin.
Antimalarials: increased risk of bradycardia with mefloquine.
Antipsychotics enhanced hypotensive effect with phenothiazines.
Calcium-channel blockers: increased risk of bradycardia and AV block with diltiazem; hypotension and heart failure possible with nifedipine and nisoldipine; asystole, severe hypotension and heart failure with verapamil.
Cytotoxics: possible increased risk of bradycardia with crizotinib.
Diuretics: enhanced hypotensive effect.
Fingolimod: possibly increased risk of bradycardia.
Moxisylyte: possible severe postural hypotension.
Sympathomimetics: severe hypertension with adrenaline and noradrenaline and possibly with dobutamine.

Metabolism

Subject to extensive first-pass hepatic biotransformation (primarily to diacetolol).

Metabolism

About half of an orally administered dose of acebutolol (Sectral) is absorbed. Approximately 25% of the drug is bound to plasma proteins, and its plasma halflife is about 4 hours.Metabolism of acebutolol produces a metabolite with -blocking activity whose half-life is 10 hours.

Precautions

Acebutolol should not be administered in cardiogenic shock, uncontrolled heart failure, or severe bradycardia or to patients with known hypersensitivity to the drug.