AMITRIPTYLINE-WGR

What it is

Amitriptyline-WGR is a tricyclic antidepressant with sedative properties. The medicine contains amitriptyline hydrochloride in strengths of 10 mg, 25 mg or 50 mg. Amitriptyline inhibits the membrane pump mechanism responsible for uptake of noradrenaline and serotonin in adrenergic and serotonergic neurons, and this interference with the uptake of noradrenaline and/or serotonin is believed to underlie the antidepressant activity of amitriptyline.

Approved indications

— Treatment of major depression. — Nocturnal enuresis where organic pathology has been excluded.

Dosing overview

Dosage should be initiated at a low level and increased gradually, noting carefully the clinical response and any evidence of intolerance.

Key safety warnings

The risk of suicide attempt is inherent in depression and may persist until significant remission occurs. Patients with depression may experience worsening of their depressive symptoms and/or the emergence of suicidal ideation and behaviour, whether or not they are taking antidepressant medications. As improvement may not occur during the first few weeks or more of treatment, patients should be closely monitored for clinical worsening and suicidality, especially at the beginning of a course of treatment, or at the time of dose changes. Pooled analyses of antidepressant trials in children and adolescents revealed a greater risk of adverse events representing suicidal behaviour or thinking during the first few months of treatment, with an average risk of 4% in patients treated with an antidepressant compared with 2% given placebo. Severe cutaneous adverse reactions (SCARs) including drug reaction with eosinophilia and systemic symptoms (DRESS), which can be life-threatening or fatal, have been reported in association with amitriptyline treatment, with most occurring within 2 to 6 weeks. At the time of prescription patients should be advised of the signs and symptoms and monitored closely for cutaneous reactions; if signs and symptoms suggestive of these reactions appear, Amitriptyline-WGR should be withdrawn immediately and an alternative treatment should be considered. Patients with cardiovascular disorders should be watched closely, as tricyclic antidepressant medicines, particularly when given in high doses, have been reported to produce arrhythmias, sinus tachycardia, and prolongation of the conduction time, and myocardial infarction and stroke have been reported with medicines of this class. Amitriptyline-WGR should be used with caution in patients with a history of seizures. Due to its atropine-like action, Amitriptyline-WGR should be used with caution in patients with narrow angle glaucoma or increased intraocular pressure; in patients with narrow angle glaucoma, even average doses precipitate an attack.

Contraindications

Amitriptyline-WGR is contraindicated in patients who have shown prior hypersensitivity to it. Amitriptyline-WGR should not be given concurrently with monoamine oxidase inhibitors, including selegiline, as the combination has caused severe convulsions, hyperpyretic crises and death. Amitriptyline-WGR is contraindicated in patients taking cisapride due to the possibility of adverse cardiac interactions including prolongation of the QT interval, cardiac arrhythmias and conduction system disturbances. Amitriptyline-WGR is not recommended for use during the acute recovery phase following myocardial infarction.

Regulatory history

Amitriptyline-WGR was first registered on the Australian Register of Therapeutic Goods on 18 May 2020, with three strengths listed: 10 mg, 25 mg, and 50 mg tablet blister packs (licence category RE).