Tablet: Data of the SEARCH study verify an increased risk of myopathy or rhabdomyolysis in combined use of amiodarone and simvastatin, which varies with the daily dose of simvastatin. The pharmacological mechanism on which this interaction is based is not known.
Indication for concurrent therapy of amiodarone with a statin should therefore be made with special caution. As no risk of myopathy or rhabdomyolysis is assumed only in case of a combined daily dose of amiodarone with simvastatin at low daily dose ≤20 mg, this simvastatin dose should not be exceeded.
Other statins, not simvastatin, should be used at low dosage in concurrent therapy with amiodarone.
Eyes: During treatment with amiodarone HCl, regular ophthalmic examinations are indicated-including fundoscopy and examinations by means of a slit-lamp (see Adverse Reactions).
Skin: Exposure to sunlight should be avoided during therapy with amiodarone HCl; 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 HCl, a light protector is necessary for some more time.
Thyroid Gland: Due to the risk of developing a thyroid dysfunction (hyperthyroidism or hypothyroidism) on treatment with amiodarone HCl, thyroid function should be examined prior to the onset of treatment. During therapy and up to 1 year after withdrawing from therapy, these examinations should be repeated at regular intervals and the patients examined for clinical symptoms of hyperthyroidism or hypothyroidism.
Amiodarone HCl 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 finding constellation alone should not result in discontinuing therapy.
The clinical diagnosis of hypothyroidism is confirmed by proof of evidently increased ultrasensitive thyroid-stimulating hormone (TSH) value as well as decreased T4 value. By proof of hypothyroidism, the amiodarone HCl dosage should be reduced, if possible, and/or substitution with L-thyroxine started. In isolated cases, discontinuation of amiodarone HCl may be required.
The clinical diagnosis of hyperthyroidism is confirmed by proof of evidently decreased ultrasensitive TSH as well as increased T3 and T4 values. By proof of hyperthyroidism, the dosage should be reduced, if possible, or amiodarone HCl discontinued; in severe cases, treatment with thyroid depressants, β-adrenergic blocking agents and/or corticosteroids should be initiated.
On account of its iodine content, amiodarone HCl falsifies classic thyroid tests (iodine binding test).
Lung: There is the risk of developing severe inflammatory pneumopathy (hypersensitivity pneumonitis, alveolar or interstitial pneumonitis) during therapy with amiodarone HCl. Thoracic roentgenography and pulmonary function test should therefore be performed prior to the onset of treatment. These examinations should be repeated at intervals of approximately 3-6 months in the further therapeutic course. These examinations should also be carried out if dyspnea (symptom of a possible pulmotoxic effect) occurs.
In patients with severe hepatopathies, pulmonary function is possibly more frequently to be monitored, as these patients have a worse prognosis if pulmotoxic effects occur. By proof of hypersensitivity pneumonitis, amiodarone HCl is to be withdrawn immediately and therapy with corticosteroids initiated. By proof of alveolar/interstitial pneumonia, treatment should be carried out with corticosteroids and the dose reduced or, if possible, amiodarone HCl should be discontinued.
Liver: Liver values should be monitored at regular intervals, particularly at higher dosage. In cases of persistent clinically relevantly increased liver enzymes, cholestatic icterus or hepatomegaly, discontinuation of amiodarone HCl should be taken into consideration.
Cardiovascular System: Electrocardiogram alterations, imposing as QT prolongation (in dependence of prolonged repolarisation) possibly in connection with the development of U-wave as well as prolongation and deformation of the T-wave, demonstrate the pharmacological activity of amiodarone HCl. There is an increased risk of torsades de pointes in case of an excessive QT prolongation.
Others: The possibility of a syndrome of inappropriate (increased) secretion of antidiuretic hormone (SIADH) should be considered in patients experiencing asthenia during treatment with amiodarone: Sodium levels and osmolality in serum, as well as osmolality and sodium concentration in urine should be measured.
Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take amiodarone 200 mg.
Injection: Hypotension occurring with IV amiodarone therapy should be treated initially by slowing the infusion; additional standard therapy may be needed, including the following: vasopressor drugs, positive inotropic agents, and volume expansion.
The pharmacological action of amiodarone includes ECG changes: QT prolongation (related to prolonged repolarization) with the possible development of U-waves; these changes do not reflect toxicity.
In the elderly, heart rate may decrease markedly.
Treatment should be discontinued in case of onset of 2nd and 3rd degree A-V block, sinoatrial block, or bifascicular block.
Amiodarone contains iodine and thus may interfere with radioiodine uptake. However, thyroid function tests T3, T4, ultrasensitive TSH (usTSH) remain interpretable.
Dyspnea or non-productive cough may be related to pulmonary toxicity.
Before treatment initiation, perform an ECG, usTSH assay and serum potassium measurement.
Undesirable effects are usually dose-related; therefore, careful attention should be paid to determine the minimum effective maintenance dose in order to avoid or minimize undesirable effects.
Patients should be instructed to avoid exposure to sun or to use protective measures during therapy since amiodarone may induce photosensitization.
Amiodarone may induce thyroid disorders particularly in patients with personal or family history of thyroid disorders. Therefore, clinical and biological monitoring is recommended before starting treatment, during treatment and for several months after treatment discontinuation. Serum usTSH level should be measured when regular dysfunction is suspected.
Effects on the Ability to Drive or Operate Machinery: Tablet: 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 dosage and changing the preparation as well as in combination with alcohol.
Use in Pregnancy & Lactation: Tablet: There is no sufficient experience regarding safe administration during pregnancy.
Amiodarone HCl and N-demethyl amiodarone pass the placenta and reach concentrations in the child of 10-25% of the maternal plasma concentration. Growth disturbances, premature births and thyroid dysfunctions in the neonate are the most frequent complications. Hypothyroidism, bradycardia and prolonged QT intervals have been ascertained in approximately 10% of neonates. In isolated cases, thyroid enlargement or cardiac murmur have been found. The malformation rate does not seem to be increased; however, the possibility of cardiac defects should be taken into consideration.
Due to the long t½ of amiodarone HCl, women who want to become pregnant should plan the beginning of a pregnancy 6 months after ending therapy at the earliest in order to avoid any exposure of the child in early pregnancy.
Transition into mother's milk is proven for the active substance and the active metabolite. Measurable plasma levels are reached in breast-fed children. If treatment is necessary in the lactation period or if amiodarone HCl has been taken during pregnancy, breastfeeding should be refrained from.
Use in Children: Injection: The safety and effectiveness of amiodarone in children have not been established.
Use in Elderly: Injection: In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy