at both reduces chorea and is well tolerated. If the adverse effect does not resolve or decrease, consideration should be given to discontinuing tetrabenazine.
Once a stable dose has been achieved, treatment should be reassessed periodically in the context of the patient's underlying condition and their concomitant medications (see section 4.5).
Parkinsonism
Tetrabenazine can induce parkinsonism and exacerbate pre-existing symptoms of Parkinson's disease. In such a case, the dose should be reduced and discontinuation of tetrabenazine be considered if event does not resolve.
Sedation and Somnolence
Sedation is the most common dose-limiting adverse effect of tetrabenazine. Patients should be cautioned about performing activities requiring mental alertness, such as operating a motor vehicle or operating hazardous machinery, until they are on a maintenance dose of tetrabenazine and know how the drug affects them.
Neuroleptic Malignant Syndrome
A neuroleptic malignant syndrome has been described under the use of tetrabenazine and after abrupt withdrawal.
Neuroleptic malignant syndrome is a rare complication of tetrabenazine therapy. Neuroleptic Malignant Syndrome most often occurs early in treatment, in response to changes in dose or after prolonged treatment. The main symptoms of this condition are mental changes, rigidity, hyperthermia, autonomic dysfunction (sweating and fluctuations in blood pressure) and elevated creatinine phosphokinase levels. If Neuroleptic Malignant syndrome is suspected Tetrabenazine should be withdrawn immediately and appropriate treatment initiated.
QTc Prolongation
Tetrabenazine causes a small increase (up to 8 msec) in the corrected QT interval. Tetrabenazine should be used with caution in combination with other drugs known to prolong QTc and in patients with congenital long QT syndromes and a history of cardiac arrhythmias (see section 4.5).
Depression/Suicidality
Tetrabenazine may cause depression or worsen pre-existing depression. Cases of suicidal ideation and behaviour have been reported in patients taking this product. Particular caution should be exercised in treating patients with a history of depression or prior suicide attempts or ideation (See also section 4.3). Patients should be closely monitored for the emergence of such adverse events and patients and their caregivers should be informed of the risks and instructed to report any concerns to their doctor immediately.
If depression or suicidal ideation occurs it may be controlled by reducing the dose of tetrabenazine and/or initiating antidepressant therapy. If depression or suicidal ideation is profound, or persists, discontinuation of tetrabenazine and initiation of antidepressant therapy should be considered.
There is a potential risk of anger and aggressive behaviour occurring or worsening in patients taking tetrabenazine with a history of depression or other psychiatric illnesses.
MAO-inhibitors
When using tetrabenazine MAO-inhibitors are contraindicated (see section 4.3) and should be stopped 14 days before the treatment with tetrabenazine starts.
Akathisia, Restlessness and Agitation
Patients taking tetrabenazine should be monitored for the presence of extrapyramidal symptoms and akathisia and also for signs and symptoms of restlessness and agitation, as these may be indicators of developing akathisia. If a patient develops akathisia, the tetrabenazine dose should be reduced. Some |
