Intravenous administration of calcium antagonists of the verapamil-type should not be given to patients treated with β-blockers.
Generally, when treating patients with asthma, concomitant therapy with a β2-agonist (tablet and/or inhalation) should be administered. The dosage of β2-agonists may require adjustment (increase) when treatment with Betaloc ZOK is started. The risk of Betaloc ZOK interfering with β2-receptors is however less than with conventional tablet formulations of β1-selective blockers.
During treatment with Betaloc ZOK, the risk of interfering with carbohydrate metabolism or masking hypoglycemia is likely to be less than during treatment with conventional tablet formulations of β1-selective blockers and much less than with nonselective β-blockers.
Patients suffering from heart failure should have their decompensation treated both before and during treatment with Betaloc ZOK.
Very rarely, a preexisting AV conduction disorder of moderate degree may become aggravated (possibly leading to AV block).
If the patients develop increasing bradycardia, Betaloc ZOK should be given in lower doses or gradually withdrawn.
Betaloc ZOK may aggravate the symptoms of peripheral arterial circulatory disorders, mainly due to its blood pressure-lowering effect.
Where Betaloc ZOK is prescribed for a patient known to be suffering from a phaeochromocytoma, an α-blocker should be given concomitantly.
Prior to surgery, the anaesthetist should be informed that the patient is receiving Betaloc ZOK. It is not recommended to stop β-blocker treatment in patients undergoing surgery. Acute initiation of high-dose metoprolol to patients undergoing noncardiac surgery should be avoided, since it has been associated with bradycardia, hypotension and stroke including fatal outcome in patients with cardiovascular risk factors.
Efficacy/safety data from controlled clinical studies in severe stable symptomatic heart failure (NYHA class IV) are limited. Treatment of heart failure in these patients should therefore only be initiated by physicians with special experience and training in this area (see Dosage & Administration).
Patients with symptomatic heart failure in association with acute MI and unstable angina pectoris were excluded from the study on which the indication of heart failure is found. Efficacy/safety conditions have therefore not been documented. Use in unstable decompensated heart failure is contraindicated (see Contraindications).
Abrupt interruption of the medication is to be avoided. Sudden withdrawal of β-blockade is hazardous, especially in high-risk patients, and may aggravate chronic heart failure as well as increase the risk of MI and sudden death. Any withdrawal of Betaloc ZOK should therefore, if possible, be made gradually over at least 2 weeks when the dose is reduced by half in each step, down to the final dose when a 25-mg tablet is reduced to half tablet. The final dose should be given for at least 4 days before discontinuation. If symptoms occur, a slower withdrawal rate is recommended.
In patients taking β-blockers, anaphylactic shock assumes a more severe form.
Effects on Ability to Drive and Use Machines: Patients should know how they react to Betaloc ZOK before they drive or use machines because occasionally, dizziness or fatigue may occur.