For preliminary examinations and monitoring of the patients see also Warnings and Adverse Reactions.
Cases have been described, especially with the chronic use of antiarrhythmic substances, in which the threshold for ventricular defibrillation and/or pacing of pacemakers or implantable cardioverter-defibrillators were increased. Thus, the function of the devices could potentially be affected. Therefore, it is recommended to repeatedly check the functionality of the devices before and during amiodarone therapy.
Before starting treatment it is recommended to check the cardiac function (ECG), the serum potassium value, liver values, the thyroid and lung function and to perform a chest X-ray.
Cardiologic check-ups should be performed during treatment at regular intervals (e.g. standard ECG at intervals of one month or long-term ECG at intervals of three months and if appropriate stress ECG). The therapy should be reevaluated, if a deterioration of individual parameters, such as extension of the QRS or QT interval by more than 25% or of the PQ time by more than 50% and QT prolongation to more than 500 ms or an increase in the number and severity of arrhythmia occurs.
For prognosis and progression of the lung see Warnings and Adverse Reactions.
Endocrine disorders (see Warnings and Adverse Reactions): Due to the risk of developing a thyroid dysfunction (hyperthyroidism or hypothyroidism) on treatment with amiodarone, thyroid function should be examined prior to the onset of treatment.
During therapy and up to one year after its withdrawing, these examinations should be repeated at regular intervals and the patients examined for clinical symptoms of hyperthyroidism or hypothyroidism.
Amiodarone inhibits the transformation of thyroxine (T4) into triiodothyronine (T3) and may lead to increased T4 values as well as to decreased T3 values in clinically inconspicuous (euthyroid) patients. This findings constellation alone should not result in discontinuing therapy.
The following symptoms can be signs of hypothyroidism: Weight gain, cold intolerance, fatigue, extreme bradycardia that exceeds the effect expected with amiodarone.
The clinical diagnosis of hypothyroidism is confirmed by proof of evidently increased ultrasensitive TSH as well as decreased T4 values. After discontinuation of treatment, normalisation of the thyroid function occurs usually within 1-3 months.
The amiodarone dose should - if possible - be reduced and/or substitution with levothyroxine be started if hypothyroidism is detected. In individual cases, a discontinuation of amiodarone may be required.
On account of its iodine content, amiodarone falsifies classic thyroid tests (iodine binding test).
Skin: Exposure to sunlight should be avoided during therapy with amiodarone; this also applies to UV light applications and solaria. If this is not possible, uncovered skin areas, particularly the face, should be protected by application of an ointment with a high protection factor. Even after withdrawal of amiodarone, a light protector is necessary for some more time.
Anaesthesia (see Interactions and Adverse Reactions): Prior to surgery, the anaesthesiologist should be informed about the amiodarone therapy.
Effects on ability to drive and use machines: Treatment with this medicinal product requires regular medical monitoring. Even when this medicinal product is used according to the instructions, reactivity may be changed in such a way that the ability to drive, to operate machinery or to work in an unsafe posture is impaired.
This applies to a higher extent at the onset of therapy, when increasing the dose and changing the preparation as well as in combination with alcohol.
Use in Children (see Dosage & Administration, Pharmacology: Pharmacodynamics and Pharmacokinetics under Actions): The safety and efficacy of amiodarone in children has not been established. Therefore, administration in children is not recommended.