Xenazine

Xenazine Uses, Dosage, Side Effects, Food Interaction and all others data.

Prolongation of the QTc interval has been observed at doses of 50 mg. In rats, it has been observed that tetrabenazine or its metabolites bind to melanin-containing tissues such as the eyes and skin. After a single oral dose of radiolabeled tetrabenazine, radioactivity was still detected in eye and fur at 21 days post dosing.Xenazine is a reversible human vesicular monoamine transporter type 2 inhibitor (Ki = 100 nM). It acts within the basal ganglia and promotes depletion of monoamine neurotransmitters serotonin, norepinephrine, and dopamine from stores. It also decreases uptake into synaptic vesicles. Dopamine is required for fine motor movement, so the inhibition of its transmission is efficacious for hyperkinetic movement. Xenazine exhibits weak in vitro binding affinity at the dopamine D2 receptor (Ki = 2100 nM).

Prolongation of the QTc interval has been observed at doses of 50 mg. In rats, it has been observed that tetrabenazine or its metabolites bind to melanin-containing tissues such as the eyes and skin. After a single oral dose of radiolabeled tetrabenazine, radioactivity was still detected in eye and fur at 21 days post dosing.

Trade Name Xenazine
Availability Prescription only
Generic Tetrabenazine
Tetrabenazine Other Names Tetrabenazina, Tetrabenazine, Tetrabenazinum
Related Drugs Austedo, deutetrabenazine, Xenazine
Weight 12.5mg, 25mg,
Type Oral tablet
Formula C19H27NO3
Weight Average: 317.4226
Monoisotopic: 317.199093735
Protein binding

Tetrabenazine = 82 - 88%; α-HTBZ = 60 - 68%; β-HTBZ = 59 - 63%.

Groups Approved, Investigational
Therapeutic Class Atypical neuroleptic drugs
Manufacturer
Available Country United States, Netherlands, Switzerland,
Last Updated: September 19, 2023 at 7:00 am
Xenazine
Xenazine

Uses

Xenazine is used for the treatment of chorea associated with Huntington's disease.

Xenazine is also used to associated treatment for these conditions: Gilles de la Tourette's Syndrome, Hemiballismus, Huntington's Disease (HD), Tardive Dyskinesia (TD), Senile chorea

How Xenazine works

Xenazine is a reversible human vesicular monoamine transporter type 2 inhibitor (Ki = 100 nM). It acts within the basal ganglia and promotes depletion of monoamine neurotransmitters serotonin, norepinephrine, and dopamine from stores. It also decreases uptake into synaptic vesicles. Dopamine is required for fine motor movement, so the inhibition of its transmission is efficacious for hyperkinetic movement. Xenazine exhibits weak in vitro binding affinity at the dopamine D2 receptor (Ki = 2100 nM).

Dosage

Xenazine dosage

General Dosing Considerations:

The chronic daily dose of Xenazine used to treat chorea associated with Huntington's disease (HD) is determined individually for each patient. When first prescribed, Xenazine therapy should be titrated slowly over several weeks to identify a dose of XENAXINE that reduces chorea and is tolerated. Xenazine can be administered without regard to food.

Individualization Of Dose:

Dosing Recommendations Up to 50 mg per day: The starting dose should be 12.5 mg per day given once in the morning. After one week, the dose should be increased to 25 mg per day given as 12.5 mg twice a day. Xenazine should be titrated up slowly at weekly intervals by 12.5 mg daily, to allow the identification of a tolerated dose that reduces chorea. If a dose of 37.5 to 50 mg per day is needed, it should be given in a three times a day regimen. The maximum recommended single dose is 25 mg. If adverse reactions such asakathisia, restlessness,parkinsonism, depression, insomnia, anxiety or sedation occur, titration should be stopped and the dose should be reduced. If the adverse reaction does not resolve, consideration should be given to withdrawing Xenazine treatment or initiating other specific treatment (e.g.,antidepressants).

Dosing Recommendations Above 50 mg per day: Patients who require doses of Xenazine greater than 50 mg per day should be first tested and genotyped to determine if they are poor metabolizers (PMs) or extensive metabolizers (EMs) by their ability to express the drug metabolizing enzyme, CYP2D6. The dose of Xenazine should then be individualized accordingly to their status as PMs or EMs

Extensive and Intermediate CYP2D6 Metabolizers:

Genotyped patients who are identified as extensive (EMs) or intermediate metabolizers (IMs) of CYP2D6, who need doses of Xenazine above 50 mg per day, should be titrated up slowly at weekly intervals by 12.5 mg daily, to allow the identification of a tolerated dose that reduces chorea. Doses above 50 mg per day should be given in a three times a day regimen. The maximum recommended daily dose is 100 mg and the maximum recommended single dose is 37.5 mg. If adverse reactions such as akathisia, parkinsonism, depression, insomnia, anxiety or sedation occur, titration should be stopped and the dose should be reduced. If the adverse reaction does not resolve, consideration should be given to withdrawing Xenazine treatment or initiating other specific treatment (e.g., antidepressants)

Side Effects

The following serious adverse reactions are Depression, Suicidality Akathisia, restlessness, and agitation, Parkinsonism, Dysphagia, Sedation and somnolence

Toxicity

Dose-limiting adverse effects are sedation, parkinsonism, akathsia, and depression. LD50 oral, mouse: 550 mg/kg

Precaution

May exacerbate symptoms of parkinsonism. Caution to be exercised when driving or performing skilled tasks. Pregnancy.

Interaction

Xenazine should not be given with or within 14 days of discontinuation of MAOI therapy. Blocks action of reserpine. Decreases effects of levodopa and worsen parkinsonism. Increased risk of extrapyramidal side effects when given with amantadine, metoclopramide, antipsychotics.

Food Interaction

  • Avoid alcohol. Ingesting alcohol may increase the drowsiness caused by tetrabenazine.
  • Take with or without food.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Volume of Distribution

Steady State, IV, in HD or tardive dyskinesia patients: 385L. Xenazine is rapidly distributed to the brain following IV injection. The site with the highest binding is the striatum, while the lowest binding was observed in the cortex.

Elimination Route

Following oral administration of tetrabenazine, the extent of absorption is at least 75%. After single oral doses ranging from 12.5 to 50 mg, plasma concentrations of tetrabenazine are generally below the limit of detection because of the rapid and extensive hepatic metabolism of tetrabenazine. Food does not affect the absorption of tetrabenazine. Cmax, oral = 4.8 ng/mL in HD or tardive dyskinesia patients;
Tmax, oral = 69 min in HD or tardive dyskinesia patients

Half Life

α-HTBZ = 7 hours; β-HTBZ = 5 hours; 9-desmethyl-β-DHTBZ = 12 hours.

Clearance

IV, 1.67 L/min in HD or tardive dyskinesia patients

Elimination Route

After oral administration, tetrabenazine is extensively hepatically metabolized, and the metabolites are primarily renally eliminated (75%). Xenazine is also cleared fecally (7% to 16%). Unchanged tetrabenazine has not been found in human urine. Urinary excretion of α-HTBZ or β-HTBZ (the major metabolites) accounted for less than 10% of the administered dose.

Pregnancy & Breastfeeding use

Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. Xenazine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers: It is not known whether Xenazine or its metabolites are excreted in human milk. Since many drugs are excreted into human milk and because of the potential for serious adverse reactions in nursing infants from Xenazine, a decision should be made whether to discontinue nursing or to discontinue Xenazine, taking into account the importance of the drug to the mother.

Contraindication

Xenazine is contraindicated in patients:

  • Who are actively suicidal, or in patients with untreated or inadequately treated depression
  • With hepatic impairment
  • Taking monoamine oxidase inhibitors (MAOIs). XENAZINE should not be used in combination with an MAOI, or within a minimum of 14 days of discontinuing therapy with an MAOI

Special Warning

Pediatric Use: The safety and efficacy of Xenazine in pediatric patients have not been established.

Geriatric Use: The pharmacokinetics of Xenazine and its primary metabolites have not been formally studied in geriatric subjects.

Hepatic Impairment: Because the safety and efficacy of the increased exposure to Xenazine and other circulating metabolites are unknown, it is not possible to adjust the dosage of Xenazine in hepatic impairment to ensure safe use. The use of Xenazine in patients with hepatic impairment is contraindicated

Acute Overdose

Three episodes of overdose occurred in the open-label trials performed in support of registration. Eight cases of overdose with Xenazine have been reported in the literature. The dose of Xenazine in these patients ranged from 100 mg to 1g. Adverse reactions associated with Xenazine overdose include acute dystonia, oculogyric crisis, nausea and vomiting, sweating, sedation, hypotension, confusion, diarrhea, hallucinations, rubor, and tremor.

Treatment should consist of those general measures employed in the management of overdosage with any CNS-active drug. General supportive and symptomatic measures are recommended. Cardiac rhythm and vital signs should be monitored. In managing overdosage, the possibility of multiple drug involvement should always be considered. The physician should consider contacting a poison control center on the treatment of any overdose.

Innovators Monograph

You find simplified version here Xenazine

Xenazine contains Tetrabenazine see full prescribing information from innovator Xenazine Monograph, Xenazine MSDS, Xenazine FDA label

FAQ

What is Xenazine used for?

Xenazine is used to treat chorea sudden movements that you cannot control caused by Huntington's disease an inherited disease that causes the progressive breakdown of nerve cells in the brain.

How to use Xenazine?

Take this medication by mouth with or without food, usually once a day in the morning when you first start treatment or as directed by your doctor.

What's the common side effects of Xenazine?

Xenazine may cause common side effects are include:

  • nausea.
  • diarrhea.
  • vomiting.
  • decreased appetite.
  • headache.
  • pain or burning upon urination.
  • bruising.
  • difficulty speaking or being understood.

Is Xenazine safe during pregnancy?

Xenazine should not be used during pregnancy unless no other treatment is available.

Is Xenazine safe during breastfeeding?

It is not known whether tetrabenazine passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

Can I drink alcohol with Xenazine?

Drinking alcohol while you are taking Xenazine may cause you to feel abnormally sleepy.It is not recommended to use this medicine with certain types of antidepressants, alcohol,opioids, beta blockers, antihypertensive drugs , hypnotics and neuroleptics (medicine to treat psychotic disorders).


Can I drive after taking Xenazine?

Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.

What does Xenazine do to the brain?

It works by changing the activity of certain natural substances in the brain that affect nerves and muscles.

How long does it take Xenazine to work?

Improvements may be seen in as little as 1 to 2 weeks. However, it can sometimes take up to 6 weeks to see the full benefits of the medication.

Can I just stop taking Xenazine?

You should not stop using Xenazine suddenly or your symptoms may return. Talk to your doctor before you stop taking this medicine.

Does Xenazine cause weight gain?

Weight increase was 0.8 lb/mo in the Xenazine group compared with 1.7 lb/mo in the neuroleptic group. Most patients who switched from a neuroleptic drug to Xenazine subsequently lost weight.

Can Xenazine be crushed?

Administer with food and swallow tablets whole,do not crush, break or chew.

What does Xenazine do to the brain?

Xenazine works by changing the activity of certain natural substances in the brain that affect nerves and muscles.

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*** Taking medicines without doctor's advice can cause long-term problems.
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