Naltrexone

• Naltrexone is a drug prescribed to help people maintain abstinence after they have withdrawn (detoxified) from heroin or other opioids.
• Naltrexone is also used in an experimental treatment to bring about rapid withdrawal from opioids.
• Naltrexone has also been used as a treatment to support abstinence for people who are dependent on alcohol.

Effects

Naltrexone is classed as an opioid antagonist. It works by blocking the opioid receptors in the brain and therefore blocking the effects of heroin and other opioids. It can assist in maintaining abstinence from heroin because the person is aware that they cannot achieve a 'high' from using heroin. Therefore, any money spent on heroin will be wasted. It does not directly stop a person wanting to use heroin, although it may reduce or prevent cravings in some people. You cannot become physically dependent on naltrexone and it does not produce any euphoric effects.

How effective is naltrexone?

The effectiveness of naltrexone treatment is dependent on:

• the person's particular situation, including their level of commitment to staying off heroin and the level of support available to them; and
• it being one part of a comprehensive treatment program, which includes regular counselling.

It is important to recognise that naltrexone treatment may be effective for some people, but will not suit everyone.

Is naltrexone maintenance treatment right for you?

Naltrexone is one of a number of treatments for heroin dependence. Other treatments include:

• Methadone maintenance.
• Withdrawal/detoxification (residential or home-based/medical or non-medical).
• Counselling (outpatient or as part of residential rehabilitation).

It is strongly recommended that a person wanting to remain abstinent from heroin engages in a treatment program that addresses both the physical and psychological aspects of drug dependency. This usually includes combining various treatments, such as methadone maintenance with counselling, or progressing from withdrawal to counselling/rehabilitation.

A doctor or drug counsellor that spends time assessing the person’s situation and explaining the different treatment options will more likely recommend a program that is appropriate for that person.

If applying for the naltrexone program, see a doctor who is experienced in this treatment (your statewide drug phone service can provide an appropriate referral).

Other considerations

Having the right support and environment is crucial in helping the person give up and, perhaps more importantly, stay off heroin.

What are the side effects?

Most of the side effects occur very early in treatment. It is important to note that some of these effects may be due to the combined experience of withdrawal from opioids and taking naltrexone.

Most commonly reported:

• Difficulty in sleeping, anxiety, nervousness, abdominal pain/cramps, nausea and/or vomiting, low energy, joint and muscle pain and headache.
• Less commonly reported:
• Loss of appetite, diarrhoea, constipation, increased thirst, increased energy, feeling depressed, irritability, dizziness, skin rash, delayed ejaculation, decreased potency, and chills.

What does the treatment involve?

Treatment involves taking a prescribed amount of naltrexone for as long as it is perceived to be required; the length of the program depends on the individual’s situation. The tablets are taken orally, once a day, the usual dose being 50mg, or every couple of days at a higher dose (e.g. 100mg on alternate days or 150mg every three days). Daily doses are often recommended in order for the person to develop a routine, and to keep a stable level of naltrexone in the blood. Often a carer, family member, doctor or pharmacist supervises the administration of the dose.

The Naloxone (Narcan) Challenge Test (NCT)

Following abstinence from opioids for a period of 7–10 days, and after a negative urine test has been achieved for opioids, a naloxone (Narcan) challenge test is usually administered by a doctor to determine the remaining degree of physical dependence on opioids.

Naloxone is injected into the individual and they are then monitored for approximately 20 minutes to assess any signs of withdrawal. If moderate to severe withdrawal symptoms are identified, the test can be undertaken again 24 hours later. If the symptoms indicate only mild withdrawal, the first dose of naltrexone can be provided.

Agitation and temporary numbness/pins and needles have been infrequently reported with the use of naloxone.

Risks

The greatest risk associated with naltrexone is when heroin is used either after a naltrexone dose has been skipped or if a person stops taking naltrexone altogether. While the person is on naltrexone, tolerance to heroin decreases. Therefore, if heroin is used (and the effects of naltrexone are either diminished or worn off completely), the risk of overdosing from heroin is greatly increased. People who are planning to use heroin after being on naltrexone should consider themselves 'new’ users. Overdose may occur if the person uses the same or even a smaller amount of heroin compared to what they did before being on naltrexone.

If a naltrexone dose is skipped, it is important to remember that the blocking effect wears off gradually (e.g. the usual daily dose of 50mg will wear off in 24-72 hours). Therefore, if heroin is used in the meantime, a ‘high’ may not be achieved immediately and there may be a temptation to use again and/or increase the dosage. As the naltrexone slowly wears off, the ‘full’ effects of all of the heroin can be experienced, increasing the chances of overdose.

Emergency cards

Given that naltrexone blocks the effects of opioids, if painkillers are required which are opioid based, they will not be effective. It is important that doctors/medical staff are aware if an individual is taking naltrexone so that opioid-free drugs can be administered.

 An Emergency Card is a useful method of alerting medical staff that an individual is taking naltrexone.

How can I support someone who is on the naltrexone program?

Supporting your family member/friend on the naltrexone program may include:

• Being committed to supervising the naltrexone dose for the duration of the treatment.
• Knowing what to do in the event of an overdose.
• Encouraging your friend/family member to develop their friendships and support networks, to get involved in positive, healthy activities (such as taking a class, joining a support group, being active).
• Going with your friend/family member to appointments (doctors, counsellors).
• Attending couple or family counselling if appropriate.

How can I find out more?

If a person is interested in entering a naltrexone treatment program, they should contact their local Aboriginal Health Service, their doctor or a drug and alcohol service.

• Direct Line. Phone; 1800 888 236
• Family Drug Help; Phone: 1300 660 068
• Youth Substance Abuse Service (YSAS); Phone: 1800 014 446; Website: www.ysas.org.au
  Drug and alcohol services for people aged between 12 and 21 who are experiencing significant problems related to their drug use.
• Alcoholism and Drug Treatment Centre Moreland Hall; Phone: 9386 2876.

This fact sheet has been adapted from more detailed information provided by the DrugInfo Clearinghouse.