Tetrabenazine

Marketed under its US brand name of Xenanine, Tetrabenazine is administered orally as a tablet.

Overview

Tetrabenazide is a prescription medication that is used to treat the symptoms of muscle disorders, such as hyperkinetic muscle movement. It is particularly common as a treatment for the involuntary muscle movements (chorea) that are caused by Huntington’s disease. It is also available under the brand name Xenanine in the United States.

The medication works by lowering the amount of monoamines such as serotonin, dopamine, and norepinephrine in the brain. These substances are involved in the functioning of muscles and become overactive when a patient experiences uncontrollable movements. Reduction of these substances leads to increased relaxation in the muscles and therefore less unpleasant movements.

Tetrabenazine is part of the monomine depletors family of drugs. It supplied in a tablet, to be administered orally, usually once or twice per day depending on the individual patient. This may be increased as the course progresses and if the patient does not show any harmful side effects. The medication can be taken with or without food, but should be taken at regular intervals throughout any 24 hour period. The maximum dosage prescribed is 200 mg per day.

There have been studies to show that Tetrabenazide may alter the mood of those taking it, resulting in low mood or depression in some cases. This is particularly apparent for people that suffer from Huntington’s disease. This should be closely monitored throughout each course and, if symptoms persist or grow in severity, medication should be stopped. [ref 1]

Conditions treated

  • Huntington’s disease – chorea
  • Involuntary muscle movements
  • Hyperkinetic muscle disorder

Type of medicine

  • Oral

Side effects

There are various possible side effects that people taking a course of Tetrabenazine may experience. Many of these side effects are considered normal, and are usually only experienced on a mild level at the start of a course. If symptoms persist, or if patients are worried about any of the feelings experienced as a result of taking Tetrabenazine, they should contact their doctor for advice.

Those suffering from Huntington’s disease should consult their doctor if they experience depression or any other forms of mood alteration, particularly if these feelings are severe.

Side effects are usually minimal as long as the dosage of Tetrabenazine is increased very gradually, and in accordance with the patient’s medical condition, reaction to treatment and any other conditions he or she suffers from.

Common side effects are, but not limited to, the following:

  • Difficulty balancing, or dizziness
  • Congestion in the ears
  • Irritability
  • Loss of interest in activities that one would usually enjoy
  • Unusual allergic reactions
  • Rash on the skin, itchiness, hives, blistering, peeling skin
  • Wheezing, coughing, tightness in the chest, sore throat
  • Difficulty breathing or shortness of breath after undertaking even simple tasks
  • Swelling in the face, mouth, tongue, lips, throat
  • Shaking, trembling
  • Stiffness of the body
  • Restlessness
  • Extreme tiredness or lethargy
  • Confusion or forgetfulness
  • Increased or irregular heartbeat
  • Fainting
  • Lack of periods for women
  • Poorer vision than usual
  • Discharge from the nipple or swollen breasts
  • Decreased libido
  • Nausea and vomiting
  • Insomnia or irregular sleeping patterns
  • Anxiety and depression
  • Symptoms of the common cold, such as running nose, sore throat, watery eyes

Taking Tetrabenazide can result in serious side effects in rare instances. If you experience the symptoms of neuroleptic malignant syndrome (NMS), you should contact a doctor as soon as possible. Symptoms of this condition – which can be triggered by taking Tetrabenazine – include muscle cramps, fever, migraine, confusion, faster heartbeat, dizziness, stiffness of the body and excess sweating.

If you are worried about any side effects that you think might be linked to your prescription of Tetrabenazine, you can contact the FDA on 1-800-FDA-1088, or visit the website for advice at www.fda.gov/medwatch.

Dosage

The dosage prescribed of Tetrabenazide depends largely on the individual concerned and will vary according to a number of factors, such as seriousness of the condition, history of reactions to similar drugs and age, among others. However, the following guidelines usually apply.

For standard oral tablets that are 12.5 mg and 25 mg in strength: The initial dosage is typically 12.5 mg taken orally once per day in the mornings. After one week, this is usually increased to 12.5 mg taken orally twice per day, resulting in a daily dose of 25 mg.

If a patient responds well to Tetrabenazine, or if involuntary muscle movement is more persistent, the doctor may increase the dosage to up to three times per day. This is usually advised over a course of several weeks. Dosages are usually increased slowly to give the body time to adjust and adapt to the medication, and to keep side effects to a minimum.

The maximum dosage of Tetrabenazine is 200 mg per day. If there is no improvement at that dose in the condition of the patient within a seven day period, there is no known benefit of continuing the treatment, and an alternative drug may be considered. Prolonged administration of the drug at maximum dosage may result in harm to the patient.

Major drug interactions

If you are taking any other medication for any other conditions, you should always tell your doctor before a course of Tetrabenazine is prescribed. Some drugs may interact with the effects of Tetrabenazine and therefore impact the effectiveness of the drug – or, worse, contribute to the unwanted side effects that you may experience. You should always keep a record of any other medication you are taking, and share it with a pharmacist and doctor.

The level of interaction between drugs varies. There may be some drugs that interact with Tetrabenazine, but you may still be able to take both together. This may just alter the dosage of Tetrabenazine that you are prescribed.

It’s the drugs that cause major interactions that you should avoid taking with Tetrabenazine at all times. One drug that has a major interaction with Tetrabenazine is Reserpine. You should not take Tetrabenazine while you are using Reserpine and should wait at least 20 days before taking it after your course of Reserpine has stopped.

Do not take MAO inhibitors with Tetrabenazine. MAO inhibitors (such as procarbazine, selegiline, rasagiline, isocarboxazid, linezolid, moclobemide, safinamide, methylene blue, tranylcypromine and phenelzine) can cause a serious and even fatal reaction in patients if mixed with Tetrabenazine. You should also leave at least two weeks between taking these medications. You should always ask your doctor for advice on when to take these medications if you are in doubt.

There are 943 drugs (a total of 5,513 generic and brand names) that have been known to interact with Tetrabenazine. 113 of these are major interactions, 824 of these are moderate interactions and six are minor interactions. [ref 2]

Other major drug interactions are, in alphabetical order:

  • amiodarone
  • amitriptyline, perphenazine
  • amoxapine
  • anagrelide
  • aripiprazole
  • arsenic trioxide
  • artemether, lumefantrine
  • asenapine
  • bedaquiline
  • benzoic acid, hyoscyamine, methenamine, methylene blue, phenyl salicylate
  • bepridil
  • brexpiprazole
  • bupropion
  • bupropion, naltrexone
  • ceritinib
  • chlorothiazide, reserpine
  • chlorpromazine
  • chlorthalidone, reserpine
  • cinacalcet
  • cisapride
  • citalopram
  • clozapine
  • codeine, phenylephrine, promethazine
  • codeine, promethazine
  • crizotinib
  • deutetrabenazine
  • dextromethorphan, promethazine
  • dextromethorphan, quinidine
  • disopyramide
  • dofetilide
  • dolasetron
  • dronedarone
  • droperidol
  • droperidol, fentanyl
  • efavirenz
  • efavirenz, emtricitabine, tenofovir
  • escitalopram
  • fingolimod
  • fluoxetine
  • fluoxetine, olanzapine
  • fluphenazine
  • furazolidone
  • gatifloxacin
  • grepafloxacin
  • halofantrine
  • haloperidol
  • hydralazine, hydrochlorothiazide, reserpine
  • hydrochlorothiazide, reserpine
  • hydroflumethiazide, reserpine
  • hyoscyamine, methenamine, methylene blue, phenyl salicylate
  • hyoscyamine, methenamine, methylene blue, phenyl salicylate, sodium biphosphate
  • hyoscyamine, methenamine, methylene blue, sodium biphosphate
  • ibutilide
  • iloperidone
  • isocarboxazid
  • ivabradine
  • levomethadyl acetate
  • linezolid
  • loxapine
  • lurasidone
  • meperidine, promethazine
  • mesoridazine
  • methadone
  • methdilazine
  • methotrimeprazine
  • methyclothiazide, reserpine
  • methylene blue
  • metoclopramide
  • mifepristone
  • molindone
  • moxifloxacin
  • nilotinib
  • olanzapine
  • osimertinib
  • paliperidone
  • panobinostat
  • papaverine
  • paroxetine
  • pasireotide
  • perphenazine
  • phenelzine
  • phenylephrine, promethazine
  • pimozide
  • polythiazide, reserpine
  • procainamide
  • procarbazine
  • prochlorperazine
  • promazine
  • promethazine
  • propiomazine
  • quetiapine
  • quinidine
  • rasagiline
  • reserpine
  • reserpine, trichlormethiazide
  • risperidone
  • safinamide
  • saquinavir
  • selegiline
  • sodium oxybate
  • sotalol
  • sparfloxacin
  • thiethylperazine
  • thioridazine
  • thiothixene
  • toremifene
  • tranylcypromine
  • trifluoperazine
  • triflupromazine
  • trimeprazine
  • vandetanib
  • vemurafenib
  • ziprasidone

Warnings

Food and alcohol interactions

Alcohol is the only food or drink that is found to have a moderate interaction with Tetrabenazine. Therefore, it is not recommended to consume alcohol during treatment. You should at least limit your intake of alcohol during your treatment; you should avoid more than one drink per day and stick to the recommended dose of Tetrabenazine at all times. The Tetrabenazine in your system can heighten the effects of alcohol. You may be more vulnerable to side effects such as nausea, dizziness, slurred speech and lack of coordination or judgement. Likewise, consuming too much alcohol may also impair the drug’s effectiveness on your condition, and leave you more open to side effects.

Driving and other activities that require mental alertness and judgement

When taking a course of Tetrabenazine, you should also avoid strenuous or potentially dangerous activity, such as operating hazardous machinery. Tetrabenazine can lead to a lack of judgement, which can impair your ability to carry out these tasks in a safe and responsible manner. You should also avoid driving in the early stages of taking the medication, until you are aware of how it affects your body. You should always consult your doctor if you are in doubt.

Other diseases

There are seven diseases that are known to have an interaction and you should not take Tetrabenazine if you suffer from any of the following:

  • Cardiac Arrhythmias
  • Depression
  • Dysphagia
  • Hepatic Impairment
  • Huntington's Disease
  • Hyperprolactinemia
  • Hypotension

Contact your doctor if you think you might be suffering from any of the above disorders; he or she may decide to prescribe you with a different medication.

Children

There are limited studies into the impact of this medication on children. Therefore, administering the drug to infants and children should be approached with extra caution and only on the advice of a professional.

Pregnancy and breast-feeding

It is not recommended to take Tetrabenazine during pregnancy, with the exception being that no other suitable treatment is available, or the risk to the mother outweighs that to the unborn child. There have been various studies on animals that have revealed that the drug leads to increased likelihood of still births, mortality, delayed and under-development, and hypothermia. There is also an increased risk in animals of the fetus becoming damaged.

There is no data available of how this drug impacts human pregnancy, as there are only a limited number of women of child-bearing age that have taken this medication.

Missing a dose

This medication is most effective when it is taken at the times prescribed. If you find you’ve missed a dose, skip the dose entirely if it’s close to the time for your next dose. If not much time has passed since your missed dose, you can take the missed pill.

Storage

You should always store your medication out of the sight and reach of children. It should be stored in the container it was originally supplied with. The drugs may be supplied with a tamper-proof lid. If this is the case, always use the container provided, as this lockable lid will prevent children gaining access to the tablets.

The drug does not require any particular storage conditions with regards to temperature and climate. As a general rule, store it at room temperature, in the packet or container provided, and keep it away from extreme heat, light or cold temperatures.

Disposal

If you have left-over medication that you no longer need, you should dispose of it. There are safe ways to dispose of medication, the safest being through a FDA take-back scheme. These schemes are designed to prevent medication getting into the wrong hands, or being consumed by children or animals. You should not attempt to flush, grind or dissolve your medication. Nor should you throw the medication away with the regular garbage. If no take-back schemes are available in your area, you can take various steps recommended by the FDA to dispose of your unwanted medicine safely. First, mix the whole tablets with another, inconsumable substance. Those commonly recommended include cat litter, soil or used coffee beans. Then, put the medication mixture into a sealable plastic bag and make sure it is tightly shut. Then, put the bag into the regular trash.

You can read more about safe disposal methods and take-back schemes in your area by visiting the FDA website. [ref 3]

Summary

Tetrabenazine is an effective treatment for involuntary muscle movements caused by a variety of health conditions. It has been used relatively safely by patients of a range of age groups. The main cause for concern when using this drug is that it may trigger depression in those patients that suffer from Huntington’s disease, as a large clinical study has recently found.

Therefore, patients with a higher risk of developing depression – and those with Huntington’s disease – should be very closely monitored throughout their course. Healthcare professionals may also choose to prescribe the patient a different medication if these issues are a factor.

Caution should also be taken during the first stages of taking the medication. As there are a wide range of side effects that can be experienced, patients should be closely monitored throughout their treatment, particularly if that treatment or dosage is increased. Limited studies into the impacts of the medicine on children or pregnant women means that these groups should be approached with caution.

Patients should be mindful of the importance of being upfront about medical conditions and other medications taken when about to undergo a prescription of Tetrabenazine. There are various other drugs that have a major interaction with Tetrabenazine, so it is extremely essential to let your doctor know what you are taking, and for which other conditions. Patients should also be mindful of the effects of alcohol while taking the drug, and should be cautious when undertaking tasks that require acute mental awareness.

The drug is not meant as a long-term treatment for chronic conditions. It is meant to offer a short- to mid-term treatment option during times of involuntary muscle activity. If this medication is taken in a safe and correct manner, it can successfully and effectively eradicate involuntary muscle movements – or at least reduce them – so that the patient can enjoy a normal life without interference. As a result, this is a popular medication for those suffering from Huntington’s disease and other muscle-related conditions.

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Last Reviewed:
December 23, 2017
Last Updated:
December 22, 2017
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