acebutolol hydrochloride

acebutolol hydrochloride

Monitan (CA), Rhotral (CA), Sectral

Pharmacologic class: Beta-adrenergic blocker (selective)

Therapeutic class: Antihypertensive, antiarrhythmic (class II)

Pregnancy risk category B

Action

At low doses, selectively inhibits response to adrenergic stimulation by blocking cardiac beta₁-adrenergic receptors (with little effect on beta₂-adrenergic receptors of bronchial and vascular smooth muscle). At high doses, inhibits both beta₁- and beta₂-adrenergic receptors, causing airway resistance.

Availability

Capsules: 200 mg, 400 mg

Tablets: 100 mg, 200 mg, 400 mg

⊘Indications and dosages

➣ Hypertension

Adults: Initially, 400 mg P.O. daily or 200 mg b.i.d.; optimal response usually occurs at 400 to 800 mg daily. For severe hypertension, increase dosage gradually to a maximum of 1,200 mg daily in two divided doses.

➣ Premature ventricular arrhythmias

Adults: Initially, 200 mg P.O. b.i.d. Increase dosage gradually until optimum response occurs, usually at 600 to 1,200 mg daily.

Dosage adjustment

• Renal impairment
• Elderly patients

Off-label uses

• Acute phase of myocardial infarction (MI)
• Stable angina

Contraindications

• Hypersensitivity to drug
• Heart failure or cardiogenic shock
• Second- or third-degree heart block
• Severe bradycardia
• Obstructive airway disease
• Breastfeeding

Precautions

Use cautiously in:
• renal or hepatic impairment, inadequate cardiac function, peripheral or mesenteric vascular disease, hyperthyroidism, diabetes mellitus
• elderly patients
• pregnant patients
• children.

Administration

☞ Withhold drug and notify prescriber if patient's apical pulse is below 60 beats/minute.
• Before surgery, notify anesthesiologist that patient is receiving drug.
• Avoid dosages above 800 mg daily in elderly patients.

Route	Onset	Peak	Duration
P.O. (blood pressure effect)	1-1.5 hr	2-8 hr	12-24 hr
P.O. (antiarrhythmic effect)	1 hr	4-6 hr	Up to 10 hr

Adverse reactions

CNS: fatigue, lethargy, insomnia, dizziness, depression, short-term memory loss, emotional lability, anxiety, confusion, headache, partial sensation loss, hemiparesis

CV: hypotension, chest pain, palpitations, peripheral vascular insufficiency, peripheral vasodilation, worsening arterial insufficiency, claudication, bradycardia, heart failure, intensified atrioventricular nodal block

EENT: dry burning eyes, abnormal or blurred vision, eye irritation and pain, conjunctivitis, tinnitus, pharyngitis

GI: nausea, vomiting, diarrhea, constipation, dyspepsia, abdominal pain, dry mouth, anorexia, mesenteric arterial thrombosis, ischemic colitis

GU: frequent or difficult urination, nocturia, diminished libido, impotence, Peyronie's disease

Hematologic: agranulocytosis, nonthrombocytopenic purpura

Metabolic: type 2 diabetes mellitus, hypoglycemia in nondiabetic patients, increased hypoglycemic response to insulin

Musculoskeletal: joint, back, or muscle pain

Respiratory: dyspnea, wheezing, cough, shortness of breath, bronchospasm, bronchoconstriction

Skin: rash, pruritus, diaphoresis

Other: fever, thirst, edema, pneumonitis, pleurisy, lupus erythematosus-like illness, hypersensitivity reaction, pulmonary granuloma, pleuropulmonary fibrosis

Interactions

Drug-drug. Alpha agonists (such as nasal decongestants and other beta-adrenergic blockers): increased risk of severe hypertension

Aluminum or calcium salts, barbiturates, cholestyramine, colestipol, indomethacin, nonsteroidal anti-inflammatory drugs, penicillin, rifampin, salicylates, sulfinpyrazone: decreased antihypertensive effect

Anticholinergics, hydralazine, methyldopa, prazosin: increased risk of bradycardia and hypotension

Beta₂-agonists (such as theophylline): decreased beta₂-agonist effect, possibly leading to bronchoconstriction

Calcium channel blockers (nondihydropyridine): synergistic effects

Cardiac glycosides: additive negative effect on sinoatrial (SA) or atrioventricular node conduction, slowing or completely suppressing SA node activity

Catecholamine-depleting drugs: marked bradycardia, hypertension, vertigo, syncope, and orthostatic blood pressure changes

Diuretics: increased hypotensive effect

Epinephrine: increased risk of blocked sympathomimetic effects

Ergot alkaloids: increased risk of peripheral ischemia and gangrene

Glyburide in patients with type 2 diabetes: decreased hypoglycemic effect

Lidocaine: increased lidocaine blood level and possible toxicity

Drug-diagnostic tests. Alkaline phosphatase, antinuclear antibody titers, bilirubin, blood urea nitrogen, lactate dehydrogenase, low-density lipoproteins, transaminases: increased levels

Glucose tolerance test: altered tolerance

Drug-herbs. Aloe, buckthorn bark or berry, cascara bark, rhubarb root, senna leaf or fruit: increased acebutolol effect

Ephedra (ma huang): arrhythmias

Patient monitoring

• Carefully monitor blood pressure during initial dosage titration. Notify prescriber of significant or abrupt blood pressure decrease.
• Observe for orthostatic hypotension, especially when giving drug with other antihypertensives.
• Watch closely for marked bradycardia or hypotension if giving drug with reserpine or other catecholamine-depleting agents.
• Be aware that drug may mask signs and symptoms of hypoglycemia in patients with diabetes mellitus or hyperthyroidism.
☞ Taper dosage gradually over 2 weeks when discontinuing. Abrupt withdrawal may exacerbate angina or trigger MI, especially in patients with coronary artery disease.

Patient teaching

• Teach patient how to take his pulse. Tell him to notify prescriber if pulse rate is below 60 beats/minute.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, alertness, and vision.
• Tell patient to watch for and report hypoglycemia signs and symptoms.
• Instruct patient with bronchospastic disease to keep bronchodilator on hand at all times.
• Instruct patient to store drug in tight container at room temperature, protected from light.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.