Indications
Naltrexone is used as part of a full treatment programme, including counselling and support, to help people stay off opioids (such as heroin) after they have fully detoxified, and to reduce craving and heavy drinking in alcohol dependence.
How It Works
Naltrexone blocks opioid receptors in the brain. While it is in the body, opioids cannot produce their usual “high”, and the rewarding feeling from alcohol is reduced. This helps lower cravings and the urge to relapse. It does not cause dependence itself.
Dosage and Administration
Take as prescribed. A common adult dose is 50 mg once a day by mouth, but the doctor may use a different schedule. Treatment for opioid dependence must only start after the person has been free of all opioids for at least 7 to 10 days, otherwise sudden withdrawal can occur. It can be taken with food to reduce stomach upset.
Interactions
- Opioid medicines, including painkillers like Morphine and Tramadol, cough medicines with Codeine and anti-diarrhoea medicines like Loperamide in high doses, will not work properly.
- Trying to overcome the block with large amounts of opioids can cause fatal overdose.
- Medicines that may harm the liver, such as high-dose Paracetamol, need care.
Contraindications
- Current use of opioids or opioid dependence without completed detoxification.
- Acute opioid withdrawal.
- Acute hepatitis or severe liver or kidney failure.
- Allergy to naltrexone.
Side Effects
Common effects include nausea, stomach pain, headache, trouble sleeping, anxiety, tiredness, low energy, joint and muscle pain, and dizziness. In some people liver enzymes rise.
Get urgent medical help for yellow skin or eyes, dark urine, severe stomach pain, signs of opioid withdrawal or overdose, thoughts of self-harm, or a severe allergic reaction such as swelling of the face or difficulty breathing.
Pregnancy and Lactation
There is limited information in pregnancy, so it is used only if the doctor thinks it is clearly needed. It passes into breast milk in small amounts; discuss with the doctor before breastfeeding.
Precautions and Warnings
- After stopping naltrexone, or near the end of a dose, the body is more sensitive to opioids: even a previously used amount can cause fatal overdose.
- Carry a card saying you take naltrexone, so emergency staff know opioid painkillers may not work.
- Liver function is usually checked before and during treatment.
- Watch for low mood or suicidal thoughts and report them.
Overdose
Experience of overdose is limited. Take the person to a doctor; treatment is supportive and liver tests may be done.
Therapeutic Class
Opioid antagonist (used in dependence treatment).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.