| Warnings
Exacerbation of Ischaemic Heart Disease Following Abrupt Withdrawal
Hypersensitivity to catecholamines has been observed in patients withdrawn from beta-blocker therapy; exacerbation of angina, hypertension, and, in some cases, myocardial infarction have occurred after abrupt discontinuation of such therapy. When discontinuing chronically administered nadolol, particularly in patients with ischaemic heart disease, the dosage should be gradually reduced over a period of one to two weeks, and the patient should be carefully monitored. If angina markedly worsens or acute coronary insufficiency develops, nadolol administration should be re-instituted promptly (at least temporarily), and other measures appropriate for the management of unstable angina should be taken. Patients should be warned against interruption or discontinuation of therapy without the physician's advice. Because coronary artery disease is common and may be unrecognised, it may be prudent not to discontinue nadolol therapy abruptly, even in patients under treatment for hypertension alone.Patients with a History of Cardiac Failure - Sympathetic stimulation may be a vital component supporting circulatory function in patients with congestive heart failure, and beta-blockade may worsen failure.Although beta-blockers including nadolol should be avoided in overt congestive heart failure, they can be cautiously used, if necessary, in patients with a history of heart failure who are well compensated (usually with digitalis and diuretics). Beta-adrenergic blocking agents do not abolish the inotropic action of digitalis on heart muscle.Patients Without a History of Heart Failure - Continued depression of the myocardium with beta blockade over a period of time can, in some cases, lead to cardiac failure. At the first sign or symptom of impending heart failure, the patient should be fully digitalised and/or treated with diuretics, and the response observed closely.If cardiac failure continues despite adequate digitalisation and diuresis, Corgard should be withdrawn (gradually, if possible).Major Surgery - Beta-blockade impairs the ability of the heart to respond to reflex stimuli and may increase the risks of general anaesthesia and surgical procedures, resulting in protracted hypotension or low cardiac output. It has generally been suggested that beta blocker therapy should be withdrawn several days prior to surgery. Recognition of the increased sensitivity to catecholamines of patients recently withdrawn from beta-blocker therapy, however, has made this recommendation controversial. If possible, beta-blockers including nadolol should be withdrawn well before surgery takes place. In no circumstances should beta-blockers be discontinued prior to surgery in patients with phaeochromocytoma or thyrotoxicosis.In the event of emergency surgery, the anaesthesiologist should be informed that the patient is on beta-blocker therapy. The effects of nadolol can be reversed by administration of beta-receptor agonists such as isoprenaline or dobutamine. However, such patients may be subject to protracted severe hypotension. Difficulty in restarting and maintaining the heart beat has also been reported with beta-adrenergic receptor blocking agents.(An exception to the above paragraph is thyroid surgerysee under 'Thyrotoxicosis' in section 4.1 Indications and section 4.2 Posology and method of administration).Nonallergic Bronchospasm (e.g. chronic bronchitis, emphysema) - Patients with bronchospastic diseases should not, in general, receive beta-blockers since they may block bronchodilation produced by endogenous or exogenous catecholamine stimulation of beta receptors.(NOTE: Corgard is contra-indicated in asthmatic patients.)Diabetes and Hypoglycaemia - Beta-adrenergic blockade may prevent the appearance of warning signs and symptoms (e.g. tachycardia and blood pressure changes) of acute hypoglycaemia. This is especially important with labile diabetics. Beta-blockade also reduces the release of insulin in response to hyperglycaemia; therefore, it may be necessary to adjust the dose of anti-diabetic drugs.Occasionally causes hypoglycaemia, even in non-diabetic patients, e.g., neonates, infants, children, elderly patients, patients on haemodialysis or patients suffering from chronic liver disease and patients suffering from overdose. Severe hypoglycaemia associated with nadolol has rarely presented with seizures and/or coma in isolated patients.Skin Rashes - There have been reports of skin rashes (including a psoriasiform type) and/or ocular changes (conjunctivitis and `dry eye') associated with the use of beta-adrenergic blocking drugs. The reported incidence is small and in most cases the symptoms have cleared when the treatment was withdrawn. Discontinuation of the drug should be considered if any such reaction is not otherwise explicable. Cessation of the therapy with a beta-adrenergic blocker should be gradual.Treatment for Anaphylactic Reaction - While taking beta-blockers, patients with a history of severe anaphylactic reaction 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.(NOTE: Epinephrine combined with non cardio-selective beta blockers such as nadolol can cause a hypertensive episode followed by bradycardia.)Thyrotoxicosis - Beta-adrenergic blockade may mask certain clinical signs of hyperthyroidism (e.g. tachycardia). Abrupt withdrawal of nadolol in thyroid patients can precipitate thyroid storm.Precautions Occasionally, beta-blockade with drugs such as nadolol may produce hypotension and/or marked bradycardia, resulting in vertigo, syncope or orthostatic hypotension.Impaired Renal or Hepatic Function - Nadolol should be used with caution in patients with impaired renal or hepatic function (see section 4.2 Posology and method of administration). Carcinogenesis, Mutagenesis, Impairment of Fertility - In chronic oral toxicologic studies lasting one to two years, nadolol did not produce any significant toxic effects in mice, rats, or dogs. In two-year oral carcinogenic studies in rats and mice, nadolol did not produce any neoplastic, pre-neoplastic, or non-neoplastic pathologic lesions. In fertility and general reproductive performance studies in rats, nadolol caused no adverse effects.
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