Acebutolol Hydrochloride

INDICATIONS AND USAGE Hypertension Acebutolol hydrochloride capsules are indicated for the management of hypertension in adults. It may be used alone or in combination with other antihypertensive agents, especially thiazide-type diuretics. Ventricular Arrhythmias Acebutolol hydrochloride capsules are indicated in the management of ventricular premature beats; it reduces the total number of premature beats, as well as the number of paired and multiform ventricular ectopic beats, and R-on-T beats.

DOSAGE AND ADMINISTRATION Hypertension The initial dosage of acebutolol in uncomplicated mild-to-moderate hypertension is 400 mg. This can be given as a single daily dose, but in occasional patients twice daily dosing may be required for adequate 24-hour blood-pressure control. An optimal response is usually achieved with dosages of 400 mg to 800 mg per day, although some patients have been maintained on as little as 200 mg per day. Patients with more severe hypertension or who have demonstrated inadequate control may respond to a total of 1200 mg daily (administered b.i.d.), or to the addition of a second antihypertensive agent. Beta-1 selectivity diminishes as dosage is increased. Ventricular Arrhythmia The usual initial dose of acebutolol is 400 mg daily given as 200 mg b.i.d. Dosage should be increased gradually until an optimal clinical response is obtained, generally at 600 to 1200 mg per day. If treatment is to be discontinued, the dosage should be reduced gradually over a period of about two weeks. Use in Older Patients Older patients have an approximately 2-fold increase in bioavailability and may require lower maintenance doses. Doses above 800 mg/day should be avoided in the elderly.

CONTRAINDICATIONS Acebutolol hydrochloride is contraindicated in: 1) persistently severe bradycardia; 2) second- and third-degree heart block; 3) overt cardiac failure; and 4) cardiogenic shock (see WARNINGS ).

WARNINGS Cardiac Failure Sympathetic stimulation may be essential for support of the circulation in individuals with diminished myocardial contractility, and its inhibition by β-adrenergic receptor blockade may precipitate more severe failure. Although β-blockers should be avoided in overt cardiac failure, acebutolol can be used with caution in patients with a history of heart failure who are controlled with digitalis and/or diuretics. Both digitalis and acebutolol impair AV conduction. If cardiac failure persists, therapy with acebutolol should be withdrawn. In Patients Without a History of Cardiac Failure In patients with aortic or mitral valve disease or compromised left ventricular function, continued depression of the myocardium with β-blocking agents over a period of time may lead to cardiac failure. At the first signs of failure, patients should be digitalized and/or be given a diuretic and the response observed closely. If cardiac failure continues despite adequate digitalization and/or diuretic, acebutolol therapy should be withdrawn. Exacerbation of Ischemic Heart Disease Following Abrupt Withdrawal Following abrupt cessation of therapy with certain β-blocking agents in patients with coronary artery disease, exacerbation of angina pectoris and, in some cases, myocardial infarction and death have been reported. Therefore, such patients should be cautioned against interruption of therapy without a physician’s advice. Even in the absence of overt ischemic heart disease, when discontinuation of acebutolol is planned, the patient should be carefully observed, and should be advised to limit physical activity to a minimum while acebutolol is gradually withdrawn over a period of about two weeks. (If therapy with an alternative β-blocker is desired, the patient may be transferred directly to comparable doses of another agent without interruption of β-blocking therapy.) If an exacerbation of angina pectoris occurs, antianginal therapy should be restarted immediately in full doses and the patient hospitalized until his condition stabilizes. Peripheral Vascular Disease Treatment with β-antagonists reduces cardiac output and can precipitate or aggravate the symptoms of arterial insufficiency in patients with peripheral or mesenteric vascular disease. Caution should be exercised with such patients, and they should be observed closely for evidence of progression of arterial obstruction. Bronchospastic Disease PATIENTS WITH BRONCHOSPASTIC DISEASE SHOULD, IN GENERAL, NOT RECEIVE A β-BLOCKER. Because of its relative β 1 -selectivity, however, low doses of acebutolol may be used with caution in patients with bronchospastic disease who do not respond to, or who cannot tolerate, alternative treatment. Since β 1 -selectivity is not absolute and is dose-dependent, the lowest possible dose of acebutolol should be used initially, preferably in divided doses to avoid the higher plasma levels associated with the longer dose-interval. A bronchodilator, such as theophylline or a β 2 -stimulant, should be made available in advance with instructions concerning its use. WARNINGS, Major Surgery Chronically administered beta-blocking therapy should not be routinely withdrawn prior to major surgery; however, the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures. Diabetes and Hypoglycemia β-blockers may potentiate insulin-induced hypoglycemia and mask some of its manifestations such as tachycardia; however, dizziness and sweating are usually not significantly affected. Diabetic patients should be warned of the possibility of masked hypoglycemia. Thyrotoxicosis β-adrenergic blockade may mask certain clinical signs (tachycardia) of hyperthyroidism. Abrupt withdrawal of β-blockade may precipitate a thyroid storm; therefore, patients suspected of developing thyrotoxicosis from whom acebutolol therapy is to be withdrawn should be monitored closely.

ADVERSE REACTIONS Acebutolol is well tolerated in properly selected patients. Most adverse reactions have been mild, not required discontinuation of therapy, and tended to decrease as duration of treatment increases. The following table shows the frequency of treatment-related side effects derived from controlled clinical trials in patients with hypertension, angina pectoris, and arrhythmia. These patients received acebutolol, propranolol, or hydrochlorothiazide as monotherapy, or placebo. TOTAL VOLUNTEERED AND ELICITED (U.S. STUDIES) Body System/ Adverse Reaction Acebutolol (N=1002) % Propranolol (N=424) % Hydrochlorthiazide (n=178) % Placebo (N=314) % Cardiovascular Chest Pain 2 4 4 1 Edema 2 2 4 1 Central Nervous System Depression 2 1 3 1 Dizziness 6 7 12 2 Fatigue 11 17 10 4 Headache 6 9 13 4 Insomnia 3 6 5 1 Abnormal dreams 2 3 0 1 Dermatologic Rash 2 2 4 1 Gastrointestinal Constipation 4 2 7 0 Diarrhea 4 5 5 1 Dyspepsia 4 6 3 1 Flatulence 3 4 7 1 Nausea 4 6 3 0 Genitourinary Micturition (frequency) 3 1 9 < 1 Musculoskeletal Arthralgia 2 1 3 2 Myalgia 2 1 4 0 Respiratory Cough 1 1 2 0 Dyspnea 4 6 4 2 Rhinitis 2 1 4 < 1 Special Senses Abnormal Vision 2 2 3 0 The following selected (potentially important) side effects were seen in up to 2% of acebutolol patients: Cardiovascular: hypotension, bradycardia, heart failure. Central Nervous System: anxiety, hyper/hypoesthesia, impotence. Dermatological: pruritus. Gastrointestinal: vomiting, abdominal pain. Genitourinary: dysuria, nocturia. Liver and Biliary System: A small number of cases of liver abnormalities (increased SGOT, SGPT, LDH) have been reported in association with acebutolol therapy. In some cases increased bilirubin or alkaline phosphatase, fever, malaise, dark urine, anorexia, nausea, headache, and/or other symptoms have been reported. In some of the reported cases, the symptoms and signs were confirmed by rechallenge with acebutolol. The abnormalities were reversible upon cessation of acebutolol therapy. Musculoskeletal: back pain, joint pain. Respiratory: pharyngitis, wheezing. Special Senses: conjunctivitis, dry eye, eye pain. Autoimmune: In extremely rare instances, systemic lupus erythematosus has been reported. The incidence of drug-related adverse effects (volunteered and solicited) according to acebutolol dose is shown below. (Data from 266 hypertensive patients treated for 3 months on a constant dose.) Body System 400 mg/day (N=132) 800 mg/day (N=63) 1200 mg/day (N=71) Cardiovascular 5% 2% 1% Gastrointestinal 3% 3% 1% Musculoskeletal 2% 3% 4% Central Nervous system 9% 13% 17% Respiratory 1% 5% 6% Skin 1% 2% 1% Special Senses 2% 2% 6% Genitourinary 2% 3% 1% Potential Adverse Events In addition, certain adverse effects not listed above have been reported with other β-blocking agents and should also be considered as potential adverse effects of acebutolol. Central Nervous System: Reversible mental depression progressing to catatonia (an acute syndrome characterized by disorientation for time and place), short-term memory loss, emotional lability, slightly clouded sensorium, and decreased performance (neuropsychometrics). Cardiovascular: Intensification of AV block (see CONTRAINDICATIONS ). Allergic: Erythematous rash, fever combined with aching and sore throat, laryngospasm, and respiratory distress. Hematologic: Agranulocytosis, nonthrombocytopenic, and thrombocytopenic purpura. Gastrointestinal: Mesenteric arterial thrombosis and ischemic colitis. Miscellaneous: Reversible alopecia and Peyronie’s disease. The oculomucocutaneous syndrome associated with the β-blocker practolol has not been reported with acebutolol during investigational use and extensive foreign clinical experience.