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| __NOTOC__
| | #REDIRECT [[Penbutolol#Warnings]] |
| {{Penbutolol}}
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| {{CMG}}; {{AE}} {{SS}}
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| ==Warnings and Precautions==
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| ===WARNINGS===
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| '''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-blocker]]s 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.
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| '''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 If cardiac failure continues despite adequate intervention with appropriate drugs, levatol® should be withdrawn (gradually, if possible).
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| Exacerbation of Ischemic Heart Disease Following Abrupt Withdrawal: Hypersensitivity to [[catecholamine]]s has been observed in patients who were withdrawn from therapy with ß-blocking agents; exacerbation of [[angina]] and, in some cases, [[myocardial infarction]] have occurred after abrupt discontinuation of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]].
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| Nonallergic Bronchospasm (eg, chronic bronchitis,emphysema): levatol® is contraindicated in [[bronchial asthma]]. In general, patients with bronchospastic diseases should not receive [[ß-blocker]]s. levatol® should be administered with caution because it may block [[bronchodilation]] produced by endogenous [[catecholamine]] stimulation of ß-2 receptors.
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| '''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.
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| 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.
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| '''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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| ===PRECAUTIONS===
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| ====Information for Patients====
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| Patients, especially those with evidence of coronary artery insufficiency, should be warned against interruption or discontinuation of levatol® without the physician’s advice. Although cardiac failure rarely occurs in properly selected patients, those being treated with ß-adrenergic receptor antagonists should be advised of the symptoms of heart failure and to report such symptoms immediately, should they develop.
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| ====Drug Interactions====
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| levatol® has been used in combination with hydrochlorothiazide in at least 100 patients without unexpected adverse reactions.
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| In one study, the combination of penbutolol and alcohol increased the number of errors in the eye-hand psychomotor function test.
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| Penbutolol increases the volume of distribution of lidocaine in normal subjects. This could result in a requirement for higher loading doses of lidocaine. | |
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| Cimetidine has no effect on the clearance of penbutolol. The major metabolite of penbutolol is a glucuronide, and it has been shown that cimetidine does not inhibit glucuronidation.
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| Synergistic hypotensive effects, bradycardia, and arrhythmias have been reported in some patients receiving ß-adrenergic blocking agents when an oral calcium antagonist was added to the treatment regimen.
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| Generally, levatol® should not be used in patients receiving [[catecholamine]]-depleting drugs.
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| ====Digoxin====
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| Both [[digitalis]] glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia.
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| ====Anesthesia====
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| Care should be taken when using anesthetic agents that depress the myocardium, such as ether, cyclopropane, and trichloroethylene, and it is prudent to use the lowest possible dose of levatol®. levatol®, like other [[ß-blocker]]s, is a competitive inhibitor of ß-receptor agonists, and its effect on the heart can be reversed by cautious administration of such agents (eg, dobutamine or isoproterenol — see OVERDOSAGE). Manifestations of excessive vagal tone (eg, profound bradycardia, hypotension) may be corrected with atropine 1 to 3 mg IV in divided doses.
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| ====Risk of Anaphylactic Reaction====
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| While taking [[ß-blocker]]s, patients with a history of severe anaphylactic reaction to a variety of allergens may be more reactive to repeated challenge, either accidental, diagnostic, or therapeutic. Such patients may be unresponsive to the usual doses of [[epinephrine]] used to treat allergic reaction.
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| ====Carcinogenesis, Mutagenesis, and Impairment of Fertility====
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| There was no evidence of carcinogenicity observed in a 21-month study in mice or a 2-year study in rats. Mice were given penbutolol in the diet for 18 months at doses up to 395 mg/kg/day (about 500 times the Maximum Recommended Human Dose (MRHD) of 40 mg in a 50 kg person). Rats were given 141 mg/kg/day for the same length of time. Mice were observed for 3 months and rats for 5.5 to 7 months after termination of treatment before necropsy was performed.
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| No evidence of mutagenic activity of penbutolol was seen in the Salmonella mutagenicity test (Ames test), the point mutation induction test (Saccharomyces), and the micronucleus test.
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| Penbutolol had no adverse effects on fertility or general reproductive performance in mice and rats at oral doses up to 172 mg/kg/day.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = LEVATOL (PENBUTOLOL SULFATE) TABLET [ACTIENT PHARMACEUTICALS, LLC] | url = http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=d241fc80-2c55-4dbb-bdb2-44f731afa137 | publisher = | date = | accessdate = 4 February 2014 }}</ref></div>
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| ==References==
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| {{Reflist|2}}
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| [[Category:Beta blockers]]
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| [[Category:Cardiovascular Drugs]]
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| [[Category:Drugs]]
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