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Home ›› Consumers ›› Treatment ›› Heroin ›› Natrexone
Naltrexone is a drug prescribed to assist people in maintaining
abstinence after they have detoxified or withdrawn from opioids (eg
heroin) or alcohol.
Mode of action
Naltrexone is classed as an opioid
agonist. It works by blocking the opioid receptors in the brain so
that opiates have no effect on the brain.
The person who is taking naltrexone will not
experience any euphoric effects from it and none from heroin.
Although a person on naltrexone will
not be able to achieve a high from using they may still experience
some cravings.
You cannot become
physically dependent on naltrexone and it does not produce any
euphoric effects.
The mechanism of
action of naltrexone with alcohol is not fully understood. However,
opioid agonists have been shown to reduce alcohol consumption.
Naltrexone is not aversive therapy and does not
cause negative response to alcohol consumption.
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Effectiveness of
Naltrexone
The effectiveness of naltrexone as a treatment will depend
on:
- The context in which it is
prescribed, including the level of commitment of the patient, and
- The treatment program in which it is prescribed.
Some clients actively stop taking naltrexone so that they can
begin to use heroin again. These clients have not altered enough of
their thinking/lifestyle and still feel the need to use.
Some clients think/feel that they continue to
need heroin as they can have difficulty allowing themselves to be
helped by a treatment program.
Naltrexone is one of a range of
pharmacotherapeutic treatment options available.
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Guidelines
for Treatment
A patient must be free of opioids for 7 to 10 days and free from
methadone for 10 days in order to be treated with naltrexone. If
this is not the case, the patient could go into acute, instant,
withdrawal from the opioid.
Existing
conditions such as acute hepatitis or pregnancy would also need to
be considered in using naltrexone as a treatment.
People who have support from family/friends and
are highly motivated to be opioid free are more likely to benefit
from naltrexone as a treatment.
Other
factors which need to be considered in a treatment using
naltrexone:
- Support: the support of family, friends,
doctor and/or counsellor is very important to assist a person
through withdrawal
- To be away from drugs: to be out of the
environment in which drugs are readily available. This may include
giving up friends and moving to a new area
- To understand his/her drug use: need to understand why this
person uses this particular drug. What might be the triggers for
use, what other emotional practical issues might they be facing?
Naltrexone treatment involves taking a prescribed amount of the
drug for as long as it is perceived to be required; based entirely
on an individual basis.
Naltrexone tablets are taken orally
once a day, or every second or third day, depending on the
dose.
Daily doses are often recommended to help establish a
routine and keep a stable level of naltrexone in by blood.
A
supportive family member/friend, carer, doctor or pharmacist will
often supervise the administration of the dose.
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Side Effects of Naltrexone
The side effects of naltrexone are more likely to occur in the
first week of treatment and they most likely relate to the person
withdrawing from opioids whilst they are taking naltrexone.
The most frequently reported side effects
are:
- anxiety;
- disturbed sleep;
- headache;
- joint and muscle pain;
- low-energy;
- nausea and/or vomiting;
- nervousness; and
- low-energy.
Side effects that are reported less frequently are:
- chills;
- constipation;
- decreased potency;
- delayed ejaculation;
- diarrhoea;
- dizziness;
- feeling depressed;
- increased energy;
- increased thirst;
- irritability;
- loss of appetite; and
- skin rash.
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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 assess the degree of physical dependence that a patient has on
opioids.
If symptoms only indicate a mild
withdrawal, the first dose of naltrexone can be provided.
Risks
The greatest risk associated with naltrexone is when heroin is
used either after a naltrexone does is missed or if a person has
stopped taking naltrexone altogether.
Tolerance
If naltrexone is ceased abruptly and heroin
use recommenced, the risk of overdose is increased.
People
planning to use heroin after naltrexone should consider themselves
‘new’ users.
It is important to remember
that the blocking effect of naltrexone wears off gradually. If a
dose is skipped and heroin is used in the interim a ‘high’ may not
be achieved immediately.
As the naltrexone slowly wears off, the
‘full’ effects of the heroin can be experienced, increasing the
chances of overdose.
Pain
Control
Patients taking naltrexone will have no response to opioids
prescribed for analgesia. This is due to the blocking effects on the
receptors. It is preferable therefore to take non-opioid analgesics
and non-steroidal anti-inflammatory drugs or paracetamol or
aspirin.
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(Southcity Clinic
acknowledges the assistance of the Australian Drug Foundation
in compiling this information)
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