Naltrexone tablets

Naltrexone (trade name: Naltex) is an oral medication containing naltrexone hydrochloride — a substance from the group of drugs acting on the nervous system, used in treating addictions.

Mechanism of action

Naltrexone blocks opioid receptors in the brain. This way it blocks the effects of opioids — patients do not experience the state of euphoria they experienced after taking opioids.

Two indications

1. Opioid addiction — in combination with other medications or treatment methods, to help patients overcome addiction.
2. Alcohol addiction — as part of a comprehensive treatment programme, to help maintain abstinence.

Naltex is not addictive.

Key difference vs disulfiram (Anticol/Esperal)

Naltrexone does not cause an aversive reaction after consuming alcohol. It does not punish for drinking — it blocks euphoria and reduces the desire to reach for alcohol. This is a fundamental difference compared to Anticol and Esperal, which cause a severe, dangerous reaction after alcohol.

There are three main medications available for pharmacotherapy of alcoholism. Each works differently:

The choice of medication depends on the patient's individual situation — the decision is made by the doctor after assessing contraindications, co-existing conditions and therapeutic goals. More about available options on the alcoholism pharmacotherapy page.

Naltrexone is used in patients in two clinical situations:

1. People addicted to opioids — in combination with other medications or treatment methods, to help overcome addiction.
2. People addicted to alcohol — as part of a comprehensive treatment programme, to help maintain abstinence.

In both cases, naltrexone is used in combination with other treatment methods — the medication alone is not sufficient. Concurrent addiction psychotherapy is essential.

Age restrictions

• Under 18 years: do not administer — insufficient clinical data, safety of use in children has not been established.
• Elderly patients: insufficient data regarding the safety and efficacy of naltrexone use.

Naltrexone should always be used strictly according to the doctor's instructions.

Dosage schedule

• Target dose: 1 tablet (50 mg) per day.
• Starting dose: treatment usually begins with half a tablet (25 mg) per day, which is later increased to a full dose.
• Route of administration: oral, with a small amount of liquid.

Condition for starting treatment

Before starting Naltrexone, no opioids must be used for a period of 7–10 days. The doctor may perform a test to determine whether there are residual opioids in the patient's body.

Practical tips

• Food and drink: have no effect on the therapy — the medication can be taken regardless of meals.
• Treatment duration: may last for three months or longer, depending on the doctor's decision.
• Missed dose: take it as soon as you remember. Do not take a double dose.
• Stopping treatment: must always be consulted with the doctor.

Naltrexone has an extensive list of contraindications, mainly related to opioids and the liver.

Absolute contraindications (must not be used)

• Hypersensitivity to naltrexone hydrochloride or any of the excipients of the medication.
• Severe kidney disorders.
• Severe liver disorders.
• Acute hepatitis.
• Opioid addiction (active) — naltrexone will cause severe withdrawal symptoms.
• Positive urine test for opioids.
• Withdrawal syndrome after naloxone injection.
• Taking medication containing opioids — including some cough medicines, antidiarrheal medicines (such as kaolin and morphine) and painkillers.
• Taking methadone.

Important: Naltrexone has no blocking effect on painkillers that do not contain opioids (e.g. ibuprofen, paracetamol and acetylsalicylic acid). These medicines can be safely used.

Before starting and during treatment with naltrexone, several important issues should be kept in mind:

Do not take opioids!

Although naltrexone usually blocks the effects of opioids, when taking large doses of opioids, breathing difficulties and circulatory problems may occur (opioid poisoning).

Do not attempt to overcome the blockade

The blocking effect of naltrexone should not be overcome by taking large doses of opioids. After the effects of naltrexone wear off, opioids may still be in the body — this risks unintentional overdose with serious consequences.

Reduced tolerance after treatment ends

After completing naltrexone therapy, the patient may have reduced tolerance to opioids. A dose that was tolerated before treatment may lead to life-threatening poisoning (respiratory failure).

Liver monitoring

Naltrexone is eliminated from the body by the liver and kidneys. People addicted to opioids often have liver problems. The doctor will perform liver function tests before and during treatment.

Inform every doctor

Every attending doctor should be informed about taking naltrexone. If anaesthesia is needed in an emergency, non-opioid anaesthetics should be used. If opioids are required, larger doses than usual may be needed — under strict medical supervision.

Before starting treatment, inform the doctor about all medications being taken.

Opioid medications — absolutely do not combine

Some commonly used medications contain opioids that will not work during naltrexone use. This includes:

• Cough medicines (with codeine)
• Antidiarrheal medicines (e.g. kaolin and morphine)
• Opioid painkillers

If the patient needs cough medicine, antidiarrheal or painkillers, they must inform the doctor, as these medicines may contain opioids.

Non-opioid medications — safe

Naltrexone has no blocking effect on painkillers that do not contain opioids:

• Ibuprofen
• Paracetamol
• Acetylsalicylic acid (aspirin)

In emergencies

Despite contraindications for simultaneous opioid use, in emergencies a painkiller may need to be administered at a higher dose than usual. Strict medical supervision is absolutely necessary, as respiratory depression and other symptoms may be stronger and last longer.

Food and drink

Eating and drinking have no effect on naltrexone therapy.

Like all medicines, naltrexone can cause side effects, although not everybody gets them.

Very common (may affect more than 1 in 10 patients)

• Difficulty falling asleep
• Anxiety or nervousness
• Abdominal cramps and pain
• Nausea and/or vomiting
• Weakness
• Joint and/or muscle pain
• Headache
• Fast or irregular heartbeat
• Restlessness

Common (may affect less than 1 in 10 patients)

• Irritability, mood changes, increased energy, feeling low
• Dizziness, chills, increased sweating
• Increased heart rate, palpitations, ECG changes, chest pain
• Diarrhoea, constipation
• Rash
• Urinary retention, delayed ejaculation, erectile dysfunction
• Loss of appetite, thirst

Uncommon (< 1 in 100)

• Some infections (cold sores, athlete's foot)
• Hallucinations, confusion, depression, paranoia, disorientation
• Tremor, drowsiness, blurred vision
• Liver function disorders (including hepatitis), increased liver enzyme activity
• Itching, acne, hair loss
• Weight loss or gain, fever

Rare (< 1 in 1,000)

• Suicidal thoughts, suicide attempts
• Blood clotting disorders
• Speech disorders

Very rare (< 1 in 10,000)

• Euphoria
• Skin rash/lesions
• Skeletal muscle damage

Naltrexone may affect liver function. The doctor may perform a blood test before starting treatment and during treatment to monitor liver function.

Symptoms of liver failure — STOP the medication and see a doctor immediately

If any of the following symptoms occur, stop taking the medication and see a doctor immediately:

• Abdominal pain lasting more than a few days
• White stools
• Dark urine
• Yellowing of the whites of the eyes

Symptoms of allergic reaction — see a doctor immediately

Seek immediate medical attention if you experience:

• Swelling of face, lips or tongue
• Skin rash
• Difficulty breathing

These may be symptoms of an allergic reaction requiring immediate medical attention.

Pregnancy

The safety of naltrexone use during pregnancy has not been established. If the patient is pregnant, suspects she may be pregnant or is planning to have a baby, she should consult her doctor before using this medication.

Breastfeeding

It is not known whether naltrexone passes into breast milk. Since the safety of naltrexone use in children and infants has not been established, breastfeeding should be avoided during medication use.

Driving and operating machinery

Naltrexone may affect the mental and/or physical ability to perform potentially dangerous activities such as driving or operating machinery. Caution should be exercised.

Lactose

Naltex contains lactose monohydrate. If the patient has been told they have an intolerance to some sugars, they should contact their doctor before taking the medication.

Active substance

Naltrexone hydrochloride (Naltrexoni hydrochloridum), 50 mg per tablet.

Excipients

• Tablet core: lactose monohydrate, microcrystalline cellulose, crospovidone, colloidal anhydrous silica, magnesium stearate.
• Coating: hypromellose (E464), macrogol 400, polysorbate 80 (E433), yellow iron oxide (E172), red iron oxide (E172), titanium dioxide (E171).

Appearance

Yellow, round, biconvex, film-coated tablets with a score line on one side. The tablet can be divided into two equal doses (25 mg each).

Pack sizes

Blisters containing 7, 14, 28, 30, 50 and 56 tablets. Not all pack sizes may be marketed.

Manufacturer: Accord Healthcare Polska Sp. z o.o., Warszawa.

Naltrexone treatment requires a prescription — the medication is not available over the counter. Here is how the treatment process works:

1. Medical consultation — in person or online. The doctor conducts a medical interview, verifies contraindications and orders liver function tests.
2. Issuing an e-prescription — if there are no contraindications, the doctor issues an electronic prescription.
3. For opioid addiction: minimum 7–10 days without opioids before the first tablet. The doctor may perform a test for the presence of opioids in the body.
4. Starting treatment — first dose: 25 mg (half tablet), then increased to 50 mg.
5. Regular check-up visits — monitoring liver function and medication tolerance.

Naltrexone is most effective when used as part of comprehensive therapy — combined with addiction psychotherapy and regular contact with a therapist.