Antaxone (Capsules) Instructions for Use

ATC Code

N07BB04 (Naltrexone)

Active Substance

Naltrexone (Rec.INN)

Clinical-Pharmacological Group

Competitive opioid receptor antagonist

Pharmacotherapeutic Group

Opioid receptor antagonist

Pharmacological Action

Specific antagonist of opioid receptors.

It competitively binds to all types of opioid receptors and prevents or eliminates the effects of both endogenous opioids and exogenous opioid drugs – opioid analgesics and their surrogates. The action of this antagonist can be weakened or eliminated by administering opioids in increased doses.

Antaxone does not possess significant intrinsic pharmacological properties, except for some pupillary constriction.

Antaxone does not cause addiction or drug dependence.

When administered at a dose of 50 mg, Antaxone blocks the pharmacological effects caused by intravenous administration of 25 mg of heroin for 24 hours. Doubling the dose of Antaxone prolongs the blocking effect to 48 hours, and tripling it to 72 hours.

Pharmacokinetics

Absorption and Distribution

After oral administration, Naltrexone is well absorbed from the gastrointestinal tract. C_max of naltrexone and its active metabolite 6-beta-naltrexol is reached within 1 hour.

The drug penetrates well through tissue barriers, V_d is 1350 L.

Metabolism

95% of the naltrexone dose is biotransformed in the liver to form pharmacologically active metabolites, the main one being 6-beta-naltrexol, which is also an opioid antagonist. The second metabolite is 2-hydroxy-3-methoxy-6-beta-naltrexol. Naltrexone and its metabolites undergo enterohepatic recirculation.

Elimination

Naltrexone and its metabolites are primarily excreted by the kidneys. Less than 1% of the naltrexone dose is excreted unchanged in the urine; the remainder is excreted as metabolites (including 38% as free and conjugated 6-beta-naltrexol). The mean T_1/2 of naltrexone is 4 hours, and that of 6-beta-naltrexol is 13 hours, which explains its ability to accumulate.

Indications

• As part of complex therapy for opioid drug addiction (dependence) to maintain a state in the patient where opioids cannot exert their characteristic effect; the drug is prescribed only after the withdrawal syndrome has been relieved. The use of Antaxone begins in specialized drug addiction treatment departments 7-10 days after the last intake of an opioid drug. Subsequently, the patient must be under strict medical supervision; the patient must have a positive attitude towards addiction treatment;
• As part of complex therapy for chronic alcoholism (including maintenance therapy) in the same doses as for heroin addiction, against the background of psychotherapy.

ICD codes

Dosage Regimen

Capsules

Treatment of heroin addiction

Initiation phase of Antaxone therapy

Treatment with Antaxone can be started no earlier than 7-10 days after the last intake of narcotic substances and provided there are no signs of withdrawal syndrome. Abstinence from the use of narcotic substances is determined by the results of a urine test for opioid content.

Treatment with Antaxone is not started until the provocative test with intravenous administration of 500 mcg of naloxone becomes negative. The naloxone test is not performed on patients with signs of withdrawal syndrome or if opioids are detected in the urine. The naloxone test can be repeated after 24 hours.

The recommended initial single dose of Antaxone is 20 mg orally (as a solution). If no signs of withdrawal syndrome appear within 1 hour, the patient can be given the remaining part of the daily dose (30 mg). The physician must control the patient’s swallowing of the drug.

Maintenance therapy with Antaxone

After the initiation phase is completed, Antaxone is prescribed at a dose of 50 mg every 24 hours (this dose will be sufficient to block the effect of 25 mg of heroin administered intravenously).

Other treatment regimens can be used.

1. 50 mg of Antaxone is prescribed daily for the first 5 days of the week and 100 mg on the 6th day.
2. 100 mg of Antaxone is prescribed every 2 days or 150 mg every 3 days.
3. 100 mg of Antaxone is prescribed on day 1 (e.g., Monday), 100 mg on day 2 (Tuesday), and 150 mg on day 5 (Friday). This regimen is convenient for patients committed to long-term opioid deprivation.

The minimum course of treatment is 3 months; the recommended course is from 6 months.

Treatment of chronic alcoholism

The drug is prescribed daily at a dose of 50 mg once/day. The minimum course of treatment is 3 months.

Treatment is not started until a naloxone test has been performed to rule out the presence of opioids in the body.

Adverse Reactions

When Antaxone is used according to indications in therapeutic doses in patients whose bodies do not contain opioids, the development of serious side effects is usually not observed.

With a frequency of more than 10% (both before the start of treatment with Antaxone and during its use), patients experienced: sleep disorders, anxiety, increased irritability, weakness, headaches, abdominal pain, nausea, vomiting, muscle and joint pain.

With a frequency of less than 10% decreased appetite, constipation, diarrhea, psychomotor agitation, dizziness, skin rash, chills, decreased sexual potency, delayed ejaculation.

In isolated cases increased fatigue, confusion, depression, hallucinations, nightmares, photophobia, cough were noted.

Laboratory tests may show increased transaminase activity, lymphocytosis.

All noted symptoms occurred both before the start of treatment and during the administration of Antaxone, and they apparently cannot be unambiguously considered a manifestation of the drug’s side effect.

One case of idiopathic thrombocytopenic purpura was described in a patient who may have been sensitized to Antaxone during previous treatment (recovery occurred after drug withdrawal and a course of corticosteroid therapy).

Contraindications

• Use of narcotic analgesics;
• Positive result of urine test for opioids or opiates;
• Lack of data on the provocative test with naloxone;
• Opioid withdrawal syndrome;
• Acute hepatitis;
• Hepatic insufficiency;
• Hypersensitivity to naltrexone.

The safety of using Antaxone in patients under 18 years of age, during pregnancy and lactation (breastfeeding) has not been established.

With caution the drug should be prescribed for impaired liver and/or kidney function.

Use in Pregnancy and Lactation

The safety of using Antaxone during pregnancy and lactation (breastfeeding) has not been established.

Use in Hepatic Impairment

Contraindicated in severe hepatic insufficiency. With caution the drug should be prescribed for impaired liver function.

Use in Renal Impairment

With caution the drug should be prescribed for impaired kidney function.

Pediatric Use

The safety of using Antaxone in patients under 18 years of age has not been established.

Special Precautions

Antaxone must be discontinued at least 48 hours before surgery requiring the prescription of opioid analgesics.

The patient should carry an Antaxone prescription card to inform other healthcare professionals in case emergency care is needed.

If it is necessary to overcome the blockade of opioid receptors (induction anesthesia, pain relief in emergency situations), short-acting opioid analgesics in high doses should be used, which reduces the risk of respiratory depression and vascular collapse.

Use in pediatrics

The safety of using Antaxone in children and adolescents under 18 years of age has not been established.

Effect on ability to drive vehicles and operate machinery

When used in recommended doses, the drug does not affect the ability to engage in potentially hazardous activities requiring increased attention.

Overdose

There is currently insufficient clinical data on the possibility of overdose.

Treatment if intoxication is suspected, symptomatic therapy should be performed.

Drug Interactions

With simultaneous use with Antaxone, the effectiveness of drugs containing opioids (antitussives, opioid analgesics, antidiarrheal agents) is reduced.

When used together, hepatotoxic agents increase the risk of liver damage.

Cases of incompatibility with other drugs have not been described.

Storage Conditions

The drug should be stored at a temperature not exceeding 25°C (77°F). Special storage precautions are not required.

Shelf Life

The shelf life is 3 years.

Dispensing Status

The drug is dispensed by prescription.

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.