Tetrabenazine

Dosing and administration times are variable and must be individually adjusted according to the severity of disease and response to treatment; the dose recommendation serves only as a guideline. If no improvement is seen after seven days of taking the maximum dose, the medicine is unlikely to benefit the patient even if the dose is further increased or treatment prolonged, and withdrawal should be considered. Once a stable maintenance dose is achieved, review treatment at regular intervals. Tardive dyskinesia: the recommended initial dose is 12.5 mg per day, then increased depending on the patient's response; discontinue if there is no clear improvement or if adverse reactions cannot be tolerated; the maximum daily dose of 200 mg should not be exceeded. Resumption of treatment after an interruption of more than 5 days (or an interruption due to a change in medical condition or concomitant medicines): retitrate — initiate at 12.5 mg twice a day, wait 7 days, then titrate up by 12.5 mg per day; if akathisia, restlessness, parkinsonism, depression, insomnia, anxiety or intolerable sedation occur, stop titration and reduce the dose. Discontinuation is associated with the return of chorea (without significant worsening compared with baseline). Elderly: no specific studies in patients over 65 years; tetrabenazine 25 mg has been given to elderly patients at the recommended adult dose without discernible adverse effects. Paediatric population: no adequately controlled clinical studies have been performed in children and a dosage recommendation cannot be given — limited clinical experience suggests that treatment be started at approximately half the daily dose for an adult and then slowly and carefully adjusted depending on tolerance and individual reaction. Patients taking CYP2D6 inhibitors: determine the appropriate dose for each patient by titration — the dose required may be influenced by CYP2D6 metaboliser status and by co-administered potent CYP2D6 inhibitors.