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WARNINGS 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 If cardiac failure continues despite adequate intervention with appropriate drugs, levatol® should be withdrawn (gradually, if possible).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Heart Disease Following Abrupt Withdrawal: Hypersensitivity to catecholamines has been observed in patients who were withdrawn from therapy with ß-blocking agents; exacerbation of angina and, in some cases, myocardial infarction have occurred after abrupt discontinuation of such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.
ADVERSE REACTIONS levatol® is usually well tolerated in properly selected patients. Most adverse effects observed during clinical trials have been mild and reversible. Table 1 lists the adverse reactions reported from 4 controlled studies conducted in the United States involving once-a-day administration of levatol® (at doses ranging from 10 to 120 mg) as monotherapy or in combination with hydrochlorothiazide. levatol® doses above 40 mg/day are not, however, recommended. The table includes only those events where the prevalence rate in the levatol® group was at least 1.5%, or where the reaction is of particular interest. Over a dose range from 10 to 40 mg, once a day, fatigue, nausea, and sexual impotence occurred at a greater frequency as the dose was increased. Table 1 ADVERSE REACTIONS DURING CONTROLLED US STUDIES Body System Experience Penbutolol (N=628) Placebo (N=212) Propranolol (N=266) Body as a Whole % % % Asthenia 1.6 0.9 4.9 Pain, chest 2.4 2.8 2.3 Pain, limb 2.4 1.4 1.5 Digestive System Diarrhea 3.3 1.9 2.6 Nausea 4.3 0.9 2.3 Dyspepsia 2.7 1.4 5.3 Nervous System Dizziness 4.9 2.4 4.2 Fatigue 4.4 1.9 2.6 Headache 7.8 6.1 7.5 Insomnia 1.9 0.9 2.6 Respiratory System Cough 2.1 0.5 1.1 Dyspnea 2.1 1.4 3.4 Upper respiratory infection 2.5 3.3 4.9 Skin and Appendages Sweating, excessive 1.6 0.5 2.3 Urogenital System Impotence, sexual 0.5 0.0 0.8 In a double-blind clinical trial comparing levatol® (40 mg and greater once a day) and propranolol (40 mg or more twice a day), heart rates of less than 60 beats/min. were recorded at least once in 25% of the patients in the group receiving levatol® and in 37% of the patients in the propranolol group. Corresponding figures for heart rates of less than 50 beats/min. were 1.2% and 6% respectively. No symptoms associated with bradycardia were reported. Discontinuations of levatol® because of adverse reactions have ranged between 2.4% and 6.9% of patients in double-blind, parallel, controlled clinical trials, as compared to 1.8% to 4.1% in the corresponding control groups that were given placebo. The frequency and severity of adverse reactions have not increased during long-term administration of levatol®. The prevalence of adverse reactions reported from 4 controlled clinical trials (referred to in Table 1) as reasons for discontinuation of therapy by > 0.5% of the levatol® group is listed in Table 2. Table 2 DISCONTINUATIONS DURING CONTROLLED US STUDIES Body System Experience Penbutolol (N=628) Placebo (N=212) Propranolol (N=266) Body as a Whole % % % Asthenia 0.6 0.0 0.4 Pain, chest 0.6 1.4 0.4 Digestive System Nausea 0.8 0.0 0.8 Nervous System Depression 0.6 0.5 0.8 Dizziness 0.6 0.0 0.4 Fatigue 0.5 0.5 0.0 Headache 0.6 0.5 0.4 Potential Adverse Effects: In addition, certain adverse effects not listed above have been reported with other ß-blocking agents and should also be considered as potential adverse effects of levatol®. 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 ß-blocker practolol has not been reported with levatol® during investigational use and extensive foreign clinical experience.