ARATAC

What it is

Aratac is amiodarone hydrochloride, a Class III antiarrhythmic agent. Aratac is available in 100 mg and 200 mg tablet strengths.

Approved indications —

Severe cases of tachyarrhythmias including Wolff-Parkinson-White syndrome, supraventricular tachycardias, nodal and ventricular tachycardias, atrial flutter and fibrillation, and ventricular fibrillation not responding to other therapy.

Dosing overview

Due to poor absorption and wide inter-patient variability, dosing schedules must be individually titrated, and it is particularly important that the minimum effective dose be used. For adults, initial stabilisation involves starting with 200 mg three times daily for one week, then reducing to 200 mg twice daily for a further week. After this initial period, the dosage is reduced to 200 mg daily, or less if appropriate. The scored 100 mg tablet should be used to titrate the minimum dosage required to maintain control of the arrhythmia. In elderly patients, the minimum effective dose is important; whilst dosage requirements are not necessarily different, they may be more susceptible to bradycardia and conduction defects if too high a dose is used.

Key safety warnings

Treatment should be initiated in hospital. Patients should be regularly monitored for possible toxicity including thyroid function, chest X-ray, ophthalmological examination and liver function during the entire course of therapy and for several months after discontinuation. Amiodarone may induce thyroid disorders, particularly in patients with personal or family history of thyroid disorders, and clinical and biological monitoring with ultrasensitive TSH assay is recommended before starting treatment, during treatment and for several months following treatment discontinuation. Severe cases with clinical presentation of thyrotoxicosis, sometimes fatal, require emergency therapeutic management. Clinical and radiological evidence of pulmonary fibrosis and/or pneumonitis has been reported, sometimes presenting as unexplained or disproportionate dyspnoea, and regular chest X-ray should be performed routinely in patients undergoing long-term therapy. Interstitial pneumonitis is generally reversible following early withdrawal of amiodarone, with clinical signs usually resolving within three to four weeks, followed by slower radiological and lung pulmonary function improvement within several months. Corneal deposits develop in almost all patients and regular ophthalmological monitoring is recommended. Appearance of optic neuropathy and/or optic neuritis requires amiodarone withdrawal due to the potential progression to blindness. Photosensitivity is quite common, and patients should be instructed to avoid exposure to the sun or use protective measures during therapy. Some patients have developed skin pigmentation of exposed areas, which can be avoided if doses are kept as low as possible, and if cosmetically unsightly, amiodarone should be discontinued if alternative therapy is possible. Regular monitoring of liver function tests is recommended as soon as amiodarone is started and regularly during treatment, and hepatotoxicity has occasionally been reported. Acute liver disorders including severe hepatocellular insufficiency or hepatic failure, sometimes fatal, and chronic liver disorders may occur; amiodarone dose should be reduced or treatment discontinued if transaminases increase exceeds three times the normal range.

Contraindications

Aratac is contraindicated in patients with known hypersensitivity to iodine or amiodarone or to any of the excipients. It is contraindicated in pregnancy and lactation. Aratac is contraindicated in patients with sinus bradycardia and sino-atrial heart block. Aratac is contraindicated in patients with evidence or a history of thyroid dysfunction. Combined therapy with drugs which may induce Torsades de Pointes is contraindicated, as is use in patients with hypotension, severe respiratory failure, cardiomyopathy, heart failure, circulatory collapse, severe arterial hypotension and bi- or tri-fascicular conduction disorders.

PBS listing

The 100 mg tablet is listed on the PBS with one item, restriction type of restricted, and an ex-manufacturer price of A$4.00.

Regulatory history

Aratac 200 mg tablets were first registered on the ARTG on 30 October 1991, and Aratac 100 mg tablets were first registered on the same date.