Consumer medicine information

Tetrabenazine Sun

Tetrabenazine

BRAND INFORMATION

Brand name

Tetrabenazine Sun

Active ingredient

Tetrabenazine

Schedule

SUMMARY CMI

TETRABENAZINE SUN

Consumer Medicine Information (CMI) summary

The full CMI on the next page has more details. If you are worried about using this medicine, speak to your doctor or pharmacist.

1. Why am I using TETRABENAZINE SUN?

TETRABENAZINE SUN contains the active ingredient Tetrabenazine. TETRABENAZINE SUN is used for the treatment of diseases, which cause jerky, irregular, uncontrollable movements such as Huntington's chorea, senile chorea and hemiballismus.

For more information, see Section 1. Why am I using TETRABENAZINE SUN? in the full CMI.

2. What should I know before I use this medicine?

Do not use if you have ever had an allergic reaction to tetrabenazine or any of the ingredients listed at the end of the CMI.

Talk to your doctor if you have any other medical conditions, take any other medicines, or plan to become pregnant.

Do not take TETRABENAZINE SUN if you are pregnant or breastfeeding.

For more information, see Section 2. What should I know before I use this medicine? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with TETRABENAZINE SUN and affect how it works.

A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use this medicine?

The usual starting dose in adults is one tablet twice a day. This may increase to a total of 200 mg (8 tablets) a day. More instructions can be found in Section 4. How do I use this medicine? in the full CMI.

5. What should I know while using this medicine?

Things you should do	Remind any doctor, dentist or pharmacist you visit that you are using this medicine.
Things you should not do	Do not take TETRABENAZINE SUN if you are also taking medicines containing reserpine, levodopa or monoamine oxidase inhibitor. Do not take TETRABENAZINE SUN if you have: Parkinson's disease, Depression, Galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption. TETRABENAZINE SUN tablets contain lactose.
Driving or using machines	This medicine may cause light-headedness, dizziness, faintness, drowsiness in some people when getting out of bed or standing up, get up slowly.
Drinking alcohol	Alcohol can increase some side effects of tetrabenazine such as dizziness, drowsiness and difficulty in concentrating.
Looking after your medicine	Keep TETRABENAZINE SUN in their bottle until it is time to take your dose. Keep TETRABENAZINE SUN in a cool dry place where the temperature stays below 25°C.

For more information, see Section 5. What should I know while using this medicine? in the full CMI.

6. Are there any side effects?

If you experience sleepiness, drowsiness, depression, ucontrollable movements of the hands, arms, legs and head (similar to those in Parkinson's disease), digestive problems, lowering of blood pressure, feeling nervous or anxious, aggravated or trouble sleeping, or skin rash issues, speak to your doctor. For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

FULL CMI

TETRABENAZINE SUN

Active ingredient(s): Tetrabenazine

Consumer Medicine Information (CMI)

This leaflet provides important information about using TETRABENAZINE SUN. You should also speak to your doctor or pharmacist if you would like further information or if you have any concerns or questions about using this medicine.

Where to find information in this leaflet:

1. Why am I using TETRABENAZINE SUN?
2. What should I know before I use this medicine?
3. What if I am taking other medicines?
4. How do I use this medicine?
5. What should I know while using this medicine?
6. Are there any side effects?
7. Product details

1. Why am I using TETRABENAZINE SUN?

TETRABENAZINE SUN contains the active ingredient tetrabenazine.

TETRABENAZINE SUN is used for the treatment of diseases, which cause jerky, irregular, uncontrollable movements such as Huntington's chorea, senile chorea and hemiballismus.

Tetrabenazine affects some chemicals in the brain, and by doing so it helps to control jerky and irregular movements.

Ask your doctor if you have any questions about why TETRABENAZINE SUN have been prescribed for you. Your doctor may have prescribed TETRABENAZINE SUN for another use TETRABENAZINE SUN are not addictive.

2. What should I know before I use this medicine?

Warnings

Do not use this medicine if:

you are allergic to tetrabenazine, or any of the ingredients listed at the end of this leaflet.
Always check the ingredients to make sure you can use this medicine.

Some of the symptoms of an allergic reaction may include:

Shortness of breath
Wheezing or difficulty breathing
Swelling of the face, lips, tongue or other parts of the body
Rash, itching or hives on the skin

Do not take TETRABENAZINE SUN if you are also taking:

Medicine containing reserpine.
Medicine containing levodopa
Medicine known as a monoamine oxidase inhibitor or have taken this medicine in the past 2 weeks.

Tetrabenazine can affect action of these medicines.

Do not take TETRABENAZINE SUN if you have:

Parkinson's disease.
Depression.
Galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption.

TETRABENAZINE SUN contain lactose.

Check with your doctor if you have:

Allergy to any other medicines, foods, preservatives or dyes

Lactose intolerance. TETRABENAZINE SUN contain lactose.
Depression
Suicidal thoughts or behaviour
Parkinson's disease
Abnormal heart rate or rhythm
Kidney disease
Liver disease.

Tell your doctor your CYP2D6 metaboliser status, if known. Your CYP2D6 metaboliser status may affect the dose of tetrabenazine you need and the dose of other medicines you may be taking.

Pregnancy and breastfeeding

Check with your doctor if you are pregnant or intend to become pregnant.

Do not take TETRABENAZINE SUN if you are pregnant or breastfeeding.

Tetrabenazine may harm your unborn baby. Tetrabenazine has been found in breast milk.

3. What if I am taking other medicines?

Tell your doctor or pharmacist if you are taking any other medicines, including any medicines, vitamins or supplements that you buy without a prescription from your pharmacy, supermarket or health food shop.

Some medicines may interfere with Tetrabenazine and affect how it works. These include:

Reserpine and levodopa
Medicines used to treat depression, such as monoamine oxidase inhibitors (MAOIs) and CYP2D6 inhibitors, such as fluoxetine, paroxetine, quinidine, duloxetine, terbinafine, amiodarone, or sertraline
Medicines that affect the brain and nervous system including medication used to treat psychiatric conditions, strong painkillers and medication used to help sleep
Medicines used to treat psychosis, such as haloperidol, chlorpromazine and metoclopramide
Medicines, including beta-blockers used to treat high blood pressure.

Some medicines, when used in combination with Tetrabenazine, may interfere with the rate and rhythm of heart beats. These include medications used to treat psychiatric conditions, antibiotics and medications used to treat problems with heart rhythm conditions.

Check with your doctor or pharmacist if you are not sure about what medicines, vitamins or supplements you are taking and if these affect TETRABENAZINE SUN.

4. How do I use this medicine?

How much to take

Your doctor will decide the best dose for you.

The usual starting dose in adults is one tablet twice a day. This may increase to a total of 200 mg (8 tablets) a day. The doctor will decide the best dose for children and elderly patients.

Do not take more than the dose your doctor has recommended. If you feel unwell during your course of treatment, tell your doctor.

When to take this medicine

Take your medicine at about the same time each day.

Taking it at the same time each day will have the best effect. It will also help you remember when to take it.

How to take this medicine

Swallow the tablet or tablets with water.

If you forget to use this medicine

If you forget to take a dose of TETRABENAZINE SUN, skip that dose completely. Take your next dose at the normal time it is due. Do not take a double dose to make up for the dose that you missed. This may increase your chance of getting an unwanted side effect. If you have trouble remembering when to take TETRABENAZINE SUN, ask your pharmacist for some hints.

If you use too much of this medicine

If you think that you have used too much TETRABENAZINE SUN, you may need urgent medical attention.

You should immediately:

phone the Poisons Information Centre
(by calling 13 11 26), or
contact your doctor, or
go to the Emergency Department at your nearest hospital.

You should do this even if there are no signs of discomfort or poisoning.

5. What should I know while using this medicine?

Things you should do

Make sure that all of your doctors and pharmacists know you are taking TETRABENAZINE SUN. Remind them if any new medicines are about to be started. If you are going to have surgery, tell the surgeon or anaesthetist that you are taking this medicine. It may affect other medicines used during surgery. If you become pregnant while taking this medicine, tell your doctor immediately.

Call your doctor straight away if you:

Difficulty in swallowing
Choking attacks
Stiffness or tightness in the arms or legs
Confusion or having thoughts of irrational ideas not shared by others
Suicidal thoughts or behaviour.

Remind any doctor, dentist or pharmacist you visit that you are using TETRABENAZINE SUN.

Things you should not do

Do not use TETRABENAZINE SUN to treat any complaint other than that directed by your doctor. It may not be safe to use TETRABENAZINE SUN for another complaint.

TETRABENAZINE SUN should only be used by the person for whom it was prescribed. Do not give TETRABENAZINE SUN to anyone else even if they have the same condition as you.

It may not be safe for another person to use TETRABENAZINE SUN.

Do not stop taking your medicine or change the dosage without checking with your doctor.

Driving or using machines

Be careful driving or operating machinery until you know how TETRABENAZINE SUN affects you.

This medicine may cause drowsiness in some people.

If you feel light-headed, dizzy or faint when getting out of bed or standing up, get up slowly.

Standing up slowly, especially when you get up from bed or chairs, will help your body get used to the change in position and blood pressure. If this problem continues or get worse, talk to your doctor. Be careful before you drive or use any machines or tools until you know how this medicine affects you.

Drinking alcohol

Tell your doctor if you drink alcohol.

Avoid or limit the use of alcohol when taking TETRABENAZINE SUN. Alcohol can increase some side effects of tetrabenazine such as dizziness, drowsiness and difficulty in concentrating.

Looking after your medicine

Keep TETRABENAZINE SUN in their bottle until it is time to take your dose.

If you take them out of their container, they may not keep well.

You should not take any left over tablets 28 days (4 weeks) after opening the bottle. Take these tablets to your local pharmacy for safe disposal.

Follow the instructions in the carton on how to take care of your medicine properly.

Store it in a cool dry place away from moisture, where the temperature stays below 25°C; for example, do not store it:

in the bathroom or near a sink, or
in the car or on window sills.

Keep it where young children cannot reach it.

Getting rid of any unwanted medicine

If you no longer need to use this medicine or it is out of date, take it to any pharmacy for safe disposal.

Do not use this medicine after the expiry date.

6. Are there any side effects?

All medicines can have side effects. If you do experience any side effects, most of them are minor and temporary. However, some side effects may need medical attention.

See the information below and, if you need to, ask your doctor or pharmacist if you have any further questions about side effects.

Less serious side effects

Less serious side effects	What to do
Sleepiness and drowsiness Depression Uncontrollable movements of the hands, arms, legs and head (similar to those in Parkinson's disease) Digestive problems Lowering of blood pressure Feeling nervous or anxious Worsening aggression Trouble sleeping Skin rash	Speak to your doctor if you have any of these less serious side effects and they worry you.

Serious side effects

Serious side effects	What to do
Difficulty in swallowing Choking attacks Stiffness or tightness in the arms or legs Confusion or having thoughts of irrational ideas not shared by others Suicidal thoughts or behaviour.	Call your doctor straight away, or go straight to the Emergency Department at your nearest hospital if you notice any of these serious side effects.

Tell your doctor or pharmacist if you notice anything else that may be making you feel unwell.

Other side effects not listed here may occur in some people.

Reporting side effects

After you have received medical advice for any side effects you experience, you can report side effects to the Therapeutic Goods Administration online at www.tga.gov.au/reporting-problems. By reporting side effects, you can help provide more information on the safety of this medicine.

Always make sure you speak to your doctor or pharmacist before you decide to stop taking any of your medicines.

7. Product details

This medicine is only available with a doctor's prescription.

What TETRABENAZINE SUN contains

Active ingredient (main ingredient)	Tetrabenazine
Other ingredients (inactive ingredients)	Maize Starch Lactose Purified Talc Sodium starch Glycollate type A Colloidal anhydrous silica Magnesium stearate Iron oxide yellow.
Potential allergens	Lactose

Do not take this medicine if you are allergic to any of these ingredients.

What this medicine looks like

TETRABENAZINE SUN Tablets 25 mg are yellow, circular, flat faced beveled edge uncoated tablet debossed with “179” on one side and scored on the other side. AUST R 381235

Who distributes this medicine

TETRABENAZINE SUN Tablets are distributed in Australia by:

Sun Pharma ANZ Pty Ltd
Macquarie Park Sydney NSW 2113
[email protected]
Tel: 1800 726 229

This leaflet was prepared in November 2022.

Published by MIMS March 2023

BRAND INFORMATION

Brand name

Tetrabenazine Sun

Active ingredient

Tetrabenazine

Schedule

1 Name of Medicine

Tetrabenazine.

2 Qualitative and Quantitative Composition

Each tablet contains 25 mg tetrabenazine.

Excipients with known effects.

Contains sugars as lactose.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Tablet, uncoated.
Yellow, circular, flat faced beveled edge uncoated tablet debossed with "179" on one side and scored on the other side.

4 Clinical Particulars

4.1 Therapeutic Indications

May be useful for the control of chorea, hemiballismus, tardive and buccolingual dyskinesias and certain dystonic syndromes.

4.2 Dose and Method of Administration

Dosage.

Dosage given below is a guide only. For each patient, the dose of tetrabenazine should be titrated to determine the most appropriate dose. Treatment should be reassessed periodically in the context of the patient's underlying condition and concomitant medications.

Method of administration.

Adults.

An initial dosage in adults of 25 mg twice a day is recommended. This can be increased by 25 mg a day every 3 or 4 days until the desired therapeutic effect is achieved, or until 200 mg/day is given, or unwanted side effects intervene.

Children.

In children, 12.5 mg twice a day has been used as an initial dose with increments of 12.5 mg every 3 to 4 days until the desired therapeutic effect is obtained, or an upper limit of 3 mg/kg/day is reached, or unwanted side effects intervene.

Note.

Only very limited information on use in children is available.

Dosage adjustment.

Dosage may need to be reduced in patients with impaired renal or hepatic function or in elderly patients. It is reported that if no improvement is found after 7 to 10 days at the maximum dose then it is unlikely that a higher dose or a longer duration of therapy will benefit the patient.

4.3 Contraindications

Tetrabenazine should not be given closer than one day before or in combination with levodopa or reserpine as it blocks the action of these drugs, particularly the central action.
Tetrabenazine should not be administered to persons with a known sensitivity to tetrabenazine or to any of the excipients.
Tetrabenazine should not be given to patients with Parkinsonism or depression, as it may worsen these conditions. It should not be administered within two weeks of treatment with a monoamine oxidase inhibitor (MAOI).
Tetrabenazine is contraindicated during breast-feeding.

4.4 Special Warnings and Precautions for Use

Identified precautions.

As for other CNS active drugs, the effect of combination of tetrabenazine and other central depressants including alcohol should be considered. Tetrabenazine may potentiate the action of antihypertensive drugs.

Depression.

Tetrabenazine may cause depression or worsen pre-existing depression. Cases of suicidal ideation and behaviour have been reported in patients taking the product. Particular caution should be exercised in treating patients with a history of depression or prior suicide attempts or ideation.
If depression or suicidal ideation occurs it should be controlled by reducing the dose 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.
MAOI antidepressants should not be used until at least two weeks have elapsed since the last tetrabenazine dose, to avoid restlessness, disorientation and confusion, as well as a potentially serious drug interaction resulting in hypertensive crisis.

Parkinsonism.

Tetrabenazine can induce Parkinsonism and exacerbate pre-existing symptoms of Parkinson's disease. The tetrabenazine dose should be adjusted as clinically indicated to minimise this side effect.

Neuroleptic malignant syndrome.

Neuroleptic malignant syndrome is a rare complication of tetrabenazine therapy. Neuroleptic malignant syndrome most often occurs early in treatment or in response to changes in dose. 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.

Tetrabenazine causes a small increase (about 8 msec) in the corrected QT interval. In slow metabolisers this increase may be greater (30 msec). Tetrabenazine should be used with caution 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 Interactions with Other Medicines and Other Forms of Interactions).

Dysphagia and choking.

Dysphagia and choking attacks with a possibly consequent bronchopneumonia appear to be the only acutely dangerous adverse effects of tetrabenazine reported so far. If these occur, therapy should be discontinued.

Lactose.

Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption, should not take tetrabenazine tablets as they contain lactose.

Orthostatic hypotension.

Tetrabenazine may induce postural hypotension at therapeutic doses and symptoms may include postural dizziness and fainting. These should be considered in patients who may be vulnerable to hypotension or its effects. Monitoring of vital signs on standing should be considered in patients who are vulnerable to hypotension.

Use in renal impairment.

The use of tetrabenazine in patients with renal insufficiency has not been studied.

Use in the elderly.

No specific studies have been performed in the elderly.

Paediatric use.

No adequately controlled clinical studies have been performed in children.

Effects on laboratory tests.

There are no special requirements to monitor effects on laboratory tests.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Interaction may occur when the following medications are administered with tetrabenazine (see Section 4.3 Contraindications; Section 4.4 Special Warnings and Precautions for Use):

Reserpine and levodopa.

Inhibit the action of these drugs and thereby attenuate their effects.

MAOIs.

Possible serious interactions resulting in hypertensive crisis. At least 14 days should elapse between the discontinuation of a MAOI and initiation of treatment with tetrabenazine.

Tricyclic antidepressants.

Have been reported to antagonise the locomotor activity induced by tetrabenazine in animals.

CNS stimulants and depressants.

Possible additive sedative effects should be considered when used in conjunction with CNS depressants (including alcohol, neuroleptics, hypnotics and opioids).

Neuroleptic agents.

Potential for significant dopamine depletion when administering with neuroleptic agents e.g. haloperidol, chlorpromazine and metoclopramide. Patients should be monitored clinically for the development of Parkinsonism. Neuroleptic malignant syndrome has been observed in isolated cases.

Antihypertensives.

May increase risk of orthostatic hypotension.

Beta-blockers.

May increase risk of orthostatic hypotension.

CYP2D6 inhibitors.

In vitro and in vivo studies indicate that tetrabenazine and its metabolites, α- and β-dihydotetrabenazine and are substrates for CYP2D6. β-HTBZ was also an inhibitor of CYP2D6 at clinically relevant concentrations. Caution should be used when adding a CYP2D6 inhibitor (such as fluoxetine, paroxetine, quinidine, duloxetine, terbinafine, amiodarone, or sertraline) to a patient already receiving a stable dose of tetrabenazine, or if the dose is influenced by the patient's CYP2D6 metaboliser status. A reduction in the dose of tetrabenazine should be considered.

Antipsychotics, antibiotics and class IA and III antiarrhythmic medications.

Tetrabenazine causes a small increase (about 8 msec) in the corrected QT interval.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

There are no data available on the potential of tetrabenazine to affect fertility.
(Category B3)
There is inadequate evidence of safety of the drug in human pregnancy, and the potential risk to humans is unknown. Tetrabenazine crosses the placenta and, because of the lack of data, tetrabenazine should not be used during pregnancy. In the developmental toxicity tests there was no evidence of in utero mortality, growth retardation or teratogenicity in either rats or rabbits at oral doses up to 5 and 27 times the clinical dose based on body surface area. When tetrabenazine was administered orally to female rats from the beginning of organogenesis to weaning, an increase in stillbirths and postnatal mortality was observed from 15 mg/kg/day, while delayed development was seen at 30 mg/kg/day. The no-effect dose for neonatal effects (5 mg/kg/day) was approximately equivalent to the clinical dose based on body surface area. The relative contributions of in utero and neonatal exposure and postnatal maternal neglect to these effects are unclear.
Tetrabenazine is excreted in milk. Oral administration to rats from early gestation to weaning was associated with increased stillbirths, hypothermia and neonatal mortality in pups (15 mg/kg/day, twice the clinical dose based on body surface area), and delayed pup development (30 mg/kg/day, 5 fold the clinical dose). The relative contributions of in utero and neonatal exposure and postnatal maternal neglect to these effects are unclear. Tetrabenazine is contraindicated during breast-feeding.

4.7 Effects on Ability to Drive and Use Machines

As drowsiness may occur in up to 20% of patients, caution should be used when driving or operating machines until competence to do so under treatment has been established. It might be possible to reduce the drowsiness by careful dosage adjustment, especially initially.

4.8 Adverse Effects (Undesirable Effects)

Side effects include drowsiness, depression (which has on occasion been reported to be associated with suicidal ideation and behaviour) and Parkinsonism. The most commonly reported side effects are as follows (see Table 1):
Neuroleptic malignant syndrome (NMS) associated with the use of tetrabenazine has been reported rarely. This may occur soon after initiation of therapy, following an increase in dosage or after prolonged treatment. The main symptoms are mental changes, rigidity, hyperthermia, autonomic dysfunction and elevated creatinine phosphokinase levels. If NMS is suspected tetrabenazine should be withdrawn and appropriate supportive therapy instituted; treatment with dantrolene and bromocriptine may be effective.

Reporting of suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at www.tga.gov.au/reporting-problems.

4.9 Overdose

Signs and symptoms of overdosage may include nausea, vomiting, diarrhoea, confusion, hallucinations, sedation, drowsiness, sweating, hypotension and hypothermia.
Management should be supportive. There is no information available on the effect of pharmacological antagonists or of dialysis.
For information on the management of overdose, contact the Poisons Information Centre on 131126 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Tetrabenazine is a synthetic derivative of benzylquinolizine that causes depletion of dopamine and other monoamines in the central nervous system.
Studies conducted in vitro have shown that tetrabenazine is an inhibitor of monoamine transportation into pre-synaptic neuronal vesicles, by inhibition of VMAT2 (vesicular monoamine transporter 2), which is principally located in the central nervous system. Dihydrotetrabenazine, the principal metabolite of tetrabenazine, has a similar affinity and more significant selectivity for VMAT2, and both compounds are believed to contribute to the pharmacological effect.
At a synaptic level tetrabenazine creates a reversible depletion of monoamines in the presynaptic vesicles. Animal studies have shown that tetrabenazine causes preferential depletion of dopamine from nerve terminals in the CNS but neurotransmitter depletion by a single dose of tetrabenazine is reversible and lasts only a few hours. This pharmacological effect explains the therapeutic benefit of tetrabenazine in patients' suffering from hyperkinetic movement disorders.

Clinical trials.

No data available.

5.2 Pharmacokinetic Properties

Absorption.

Based on metabolite levels, tetrabenazine is quickly and mostly absorbed after oral administration. Its absorption is not affected by the taking of food. After administration of single doses from 12.5 to 50 mg of tetrabenazine, for the metabolites alpha and beta dihydrotetrabenazine, the maximum plasma concentration and the area under the curve increased approximately in proportion to the dose, indicating a linear kinetic. Clinical testing has shown that a single oral dose of tetrabenazine undergoes extensive (> 75%) absorption from the gastro-intestinal tract.

Metabolism.

The metabolism of tetrabenazine is complex, initially proceeding via the formation of alpha and beta dihydrotetrabenazine. The majority of the observed metabolites appear to be formed from these dihydrotetrabenazines as a result of O-dealkylation, hydroxylation and conjugation. No significant build-up has been observed after daily administration. The elimination half-life of dihydrotetrabenazine is approximately 5 to 6 hours.

Excretion.

Tetrabenazine is mostly eliminated in metabolised form in urine.

5.3 Preclinical Safety Data

Genotoxicity.

Tetrabenazine and its major metabolites, α- and β-dihydrotetrabenazine, were negative in the in vitro bacterial reverse mutation assay. Tetrabenazine was clastogenic in the in vitro chromosome aberration assay in Chinese hamster ovary cells in the presence of metabolic activation, while α- and β-dihydrotetrabenazine were clastogenic in Chinese hamster lung cells in the presence and absence of metabolic activation. In vivo micronucleus tests in rats and mice with tetrabenazine were negative. The genotoxic potential of tetrabenazine is considered to be low.

Carcinogenicity.

A 6 month study in transgenic p53 (+/-) heterozygous mice and a long term study in male rats at oral doses up to 30 mg/kg/day and 6 mg/kg twice daily, respectively, did not provide any evidence of carcinogenic potential. These doses correspond to exposures approximately 3 to 4 times the clinical exposure, based on plasma AUC or dose based on body surface area. Mammary gland hyperplasia was observed in female rats that received twice daily oral doses of 7.5 mg/kg or greater for 6 months associated with exposures (plasma AUC) similar to the clinical exposure. As the effect of tetrabenazine on prolactin levels is not known, the relevance of this finding is uncertain.

6 Pharmaceutical Particulars

6.1 List of Excipients

Lactose, maize starch, sodium starch glycollate type A, purified talc, magnesium stearate, iron oxide yellow, and colloidal anhydrous silica.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Storage conditions.

Store below 25°C. Store in original container. Discard 4 weeks after opening.

6.5 Nature and Contents of Container

Container type.

White round high-density polyethylene (HDPE) tablet container with a child-resistant, tamper-evident polypropylene (PP) screw cap with mounted desiccant containing 112 tablets.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.

6.7 Physicochemical Properties

Tetrabenazine is white to slightly yellow crystalline powder. Tetrabenazine is soluble in hot water, but practically insoluble in acetone. UV max (alcohol): 230, 284 nanometre (ε 7780, 3820).

CAS number.

58-46-8.

Chemical name.

1,3,4,6,7,11b-Hexahydro-9,10-dimethoxy-3-(2-methylpropyl)- 2H-benzo-[a]quinolizin-2-one.

Chemical structure.

7 Medicine Schedule (Poisons Standard)

Prescription only medicine - Schedule 4 (S4).

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Tetrabenazine Sun

Tetrabenazine

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BRAND INFORMATION

Tetrabenazine Sun 25 mg Tablets