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Questions & Answers
Side Effects & Adverse Reactions
Cardiac Failure: Sympathetic stimulation may be essential for supporting circulatory function in patients with heart failure, and its inhibition by ß-adrenergic receptor blockade may precipitate more severe failure. Although ß-blockers should be avoided in overt congestive heart failure, levatol® can, if necessary, be used with caution in patients with a history of cardiac failure who are well compensated, on treatment with vasodilators, digitalis and/or diuretics. Both digitalis and penbutolol slow AV conduction. Beta-adrenergic receptor antagonists do not inhibit the inotropic action of digitalis on heart muscle. If cardiac failure persists, treatment with levatol® should be discontinued.
Patients Without History of Cardiac Failure: Continued depression of the myocardium with ß-blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first evidence of heart failure, patients receiving levatol® should be given appropriate treatment, and the response should be closely observed. If cardiac failure continues despite adequate intervention with appropriate drugs, levatol® should be withdrawn (gradually, if possible).
Exacerbation of Ischemic Heart Disease Following Abrupt Withdrawal: Hypersensitivity to catecholamines has been observed in patients who were withdrawn from therapy with ß-blocking agents; exacerbation of angina and, in some cases, myocardial infarction have occurred after abrupt discontinuation of such therapy. When discontinuing levatol®, particularly in patients with ischemic heart disease, the dosage should be reduced gradually over a period of 1 to 2 weeks and the patient should be monitored carefully. If angina becomes more pronounced or acute coronary insufficiency develops, administration of levatol® should be reinstated promptly, at least on a temporary basis, and appropriate measures should be taken for the management of unstable angina. Patients should be warned against interruption or discontinuation of therapy without the physician’s advice. Because coronary artery disease is common and may not be recognized, it may not be prudent to discontinue levatol® abruptly, even in patients who are being treated only for hypertension.
Nonallergic Bronchospasm (eg, chronic bronchitis,emphysema): levatol® is contraindicated in bronchial asthma. In general, patients with bronchospastic diseases should not receive ß-blockers. levatol® should be administered with caution because it may block bronchodilation produced by endogenous catecholamine stimulation of ß-2 receptors.
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 Mellitus and Hypoglycemia: Beta-adrenergic receptor blockade may prevent the appearance of signs and symptoms of acute hypoglycemia, such as tachycardia and blood pressure changes. This is especially important in patients with labile diabetes. Beta-blockade also reduces the release of insulin in response to hyperglycemia; therefore, it may be necessary to adjust the dose of hypoglycemic drugs. Beta-adrenergic blockade may also impair the homeostatic response to hypoglycemia; in that event, the spontaneous recovery from hypoglycemia may be delayed during treatment with ß-adrenergic receptor antagonists.
Thyrotoxicosis: Beta-adrenergic blockade may mask certain clinical signs (eg, tachycardia) of hyperthyroidism. Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of ß-adrenergic receptor blockers that might precipitate a thyroid storm.
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FDA Safety Alerts
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FDA Labeling Changes
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levatol® is indicated in the treatment of mild to moderate arterial hypertension. It may be used alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.
There is currently no drug history available for this drug.
levatol® (penbutolol sulfate) is a synthetic ß-receptor antagonist for oral administration. The chemical name of penbutolol sulfate is (S)-1-tert-butylamino-3-(o-cyclopentylphenoxy)-2-propanol sulfate. It is provided as the levorotatory isomer. The empirical formula for penbutolol sulfate is C36H60N2O8S. Its molecular weight is 680.94. A dose of 20 mg is equivalent to 29.4 µmol. The structural formula is as follows:
Penbutolol is a white, odorless, crystalline powder. levatol® is available as tablets for oral administration. Each tablet contains 20 mg of penbutolol sulfate. It also contains corn starch, D&C Yellow No. 10, lactose, magnesium stearate, povidone, silicon dioxide, talc, titanium dioxide, synthetic black iron oxide, hypromellose, simethicone and other inactive ingredients.