Tetrabenazine 25mg

Tetrabenazine, Nitoman (CDN)/Xenazine (US)
Description: Central Monoamine-Depleting Agent; Vesicular Monoamine Transporter 2 (VMAT2) Inhibitor
 

“ALERT: US Boxed Warning

Depression and suicidality:
Tetrabenazine can increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington disease. Anyone considering the use of tetrabenazine must balance the risks of depression and suicidality with the clinical need for control of chorea. Close observation of patients for the emergence or worsening of depression, suicidality, or unusual changes in behavior should accompany therapy. Patients, their caregivers, and families should be informed of the risk of depression and suicidality and should be instructed to report behaviors of concern promptly to the treating physician.

Particular caution should be exercised in treating patients with a history of depression or prior suicide attempts or ideation, which are increased in frequency in Huntington disease. Tetrabenazine is contraindicated in patients who are actively suicidal, and in patients with untreated or inadequately treated depression.”

CSA NA – FDA Approved – REMS (N) – Can Ship

Tetrabenazine, Nitoman/Xenazine is a reversible inhibitor of the human vesicular monamine transporter type 2 (VMAT-2).   It decreases the uptake of monoamines (dopamine, serotonin, norepinephrine, histamine) into synaptic vesicles and depletes the monoamine stores.

Chorea associated with Huntington disease

Canadian labeling: Additional use (not in US labeling): Treatment of chronic tic disorders, including Tourette syndrome

Before starting Tetrabenazine, Nitoman/Xenazine make sure your physician is aware of any allergies or medications you currently take, if you have a prolactin dependent tumor, CYP2D6 poor metabolizers, if you have hepatic impairment, a depressive disorder, are pregnant, or breastfeeding. Tetrabenazine, Nitoman/Xenazine use has been associated with rare but serious adverse events such as akathisia, CNS depression, depression, suicidal ideation, esophageal dysmotility, aspiration, neuroleptic malignant syndrome, ophthalmic effects, orthostatic hypotension, parkinsonism, QT prolongation, and tardive dyskinesia.

Oral: 12.5 mg once daily in the morning, may increase to 12.5 mg twice daily after 1 week. Dosage may be increased by 12.5 mg daily at weekly intervals; daily doses >37.5 mg should be divided into 3 doses (maximum single dose: 25 mg).

Patients requiring doses >50 mg/day: Genotype for CYP2D6:

Extensive/intermediate metabolizers: Maximum: 100 mg/day; 37.5 mg/dose.

Poor metabolizers: Maximum: 50 mg/day; 25 mg/dose.

How to Take: Follow instructions provided by physician/pharmacy label, take consistently at same times each day unless otherwise directed, store at room temperature.  May administer without regard to meals.  If treatment is interrupted for >5 days, retitration is recommended. If treatment is interrupted for <5 days resume at previous maintenance dose.

You Need to Avoid:  Significant drug interactions exist, requiring dose/frequency adjustment or avoidance so avoid starting any new medications without consulting prescriber.

Drowsiness, sedation, depression, extrapyramidal reaction, fatigue, insomnia, akathisia, anxiety, falling, nausea, upper respiratory tract infection, drug-induced Parkinson’s disease, equilibrium disturbance, irritability, abnormal gait, dizziness, dysarthria, headache, obsessive rumination, dysphagia, vomiting, decreased appetite, dysuria, bruise, bradykinesia, bronchitis, dyspnea

Note this is not a complete list of side effects, only the most common

1. What do I do if my mood worsens on this medication and I feel much worse?
   Contact your physician immediately, it is rare however antidepressant medications can cause suicidal ideation, generally in those under the age of 24.
2. What do I do if side effects are intolerable?
   If the symptoms are causing a lot of distress speak to your physician as soon as possible to discuss how to manage the side effects or to consider therapy modification.
3. What is tardive dyskinesia?
   Tardive dyskinesia is a movement disorder that is sometimes irreversible and involves involuntary movements which can impair daily function.  It generally occurs with long term use of dopamine blocking agents.  This mechanism can be compared to Parkinson’s disease due to both involving reduced dopamine resulting in involuntary movement.
4. What is Neuroleptic Malignant Syndrome?
   NMS is a rare but serious reaction from significant blockade of dopamine which can occur from antipsychotic medications or from being on high dosages of levodopa (dopamine analogue) and stopping suddenly.  Presents initially as muscle cramps, tremors, fever, unstable blood pressure, and sudden changes in mental status.  As it progresses over 8-40 hours it can lead to complications of rhabdomyolysis, hyperkalemia, kidney failure, or seizures.  Seek medical attention immediately if this reaction is suspected.