Heroin withdrawal precipitated by Naltrexone
This information should be read in conjunction with the product information literature from the distributor, Orphan Australia (phone (03) 9769 5744). These notes have been modified from a longer document written by Dr Malcolm Young as part of the National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD) project.
Naltrexone precipitated withdrawals in opioid dependent patients usually occur within 20-60 minutes of ingesting Naltrexone, and lasts about 4 hours. Patients suffering this condition are probably best observed in an emergency department unless the condition is mild.
The most important part of treatment is to reassure the patient that although the symptoms are severe, they only last a short time. The distress of the withdrawal means that this reassurance needs to be given repeatedly.
Domains in the management of heroin withdrawal precipitated by Naltrexone
Altered mental states
Patients withdrawing become agitated and distressed, and may become delirious and confused. This is usually short-lived. Patients can usually be re-oriented. If they require sedation, rapidly acting benzodiazepines (e.g. diazepam 5 mg qid or midazolam 5-10 mg IM) are the drugs of choice.
Significant fluid loss from vomiting and diarrhoea
Treat by careful assessment of the state of hydration and give either oral or IV rehydration with fluids and electrolytes.
Vomiting with the risk of aspiration
There is an increased risk of vomiting due to withdrawal. Aspiration can occur especially if patients are confused and sedated. If conventional anti-emetics (maxolon 10 mg, ondansitron 4 - 8 mg IM) have not been effective and Octreotide (Sandostatin) 100 mcg sc may be effective. Prescribers need to be aware of the PBS guidelines for the more potent anti-emetics.
Sympathetic over-activity of a withdrawal
This is best treated with clonidine 100-150 mcg qid orally or 100 mcg IM, but beware of clonidine’s effect on blood pressure especially in a patient with hypovolaemia. This treatment should only be needed for a short period of time.
Risk of death
This occurs either from aspiration, or from respiratory depression either due to over-sedation or opioid overdose once Naltrexone effect has worn off. Appropriate close nursing supervision to prevent aspiration is important.
Once the effects have worn off
Ensure that the patient understands the danger of using Naltrexone and heroin in combination. Naltrexone blocks the heroin receptors rendering patients resistant to the effects of heroin. However when Naltrexone is stopped the body over the next 48 hours becomes exquisitely sensitive to heroin and a previous dose which did nothing may this time be fatal.
This information is a general guide for the management of heroin withdrawal precipitated by Naltrexone. Consultation with a specialist service (e.g. DACAS) is recommended for patients using multiple drugs or with serious medical or psychiatric conditions. The drug doses given are a guide only and should be adjusted to suit individuals.