Commencing methadone from heroin use
Size of the first dose
Stabilisation
Transfer from other pharmacotherapies

Commencing methadone from heroin use

Objectives during induction to methadone are to retain individuals in treatment by reducing the signs and symptoms of withdrawal and to ensure their safety. This can be achieved by careful explanation regarding intoxicating effects and withdrawal during the induction and maintenance phases of methadone treatment, establishment of a therapeutic relationship, safe dosing and repeated observation of patients.

It is particularly important to clearly explain that it takes time to complete induction onto methadone and that patients will experience increasing effects from methadone over the first few days of treatment even if the dose is not increased.

There is a need to achieve a balance between adequate relief of withdrawal symptoms and the avoidance of toxicity and death during the induction phase of MMT. The aim is to minimise the symptoms and signs of withdrawal while simultaneously minimising the risks of sedation and toxicity. While doses of methadone which are too high can result in toxicity and death, inadequate commencement doses may cause patients experiencing withdrawal symptoms to "top up" the prescribed dose of methadone with heroin, benzodiazepines or illicit methadone. This can also have potentially lethal consequences.

For most patients withdrawal symptoms will be alleviated but not entirely eliminated by doses less than 30mg.

Deaths during the induction phase of methadone treatment have been related to:
  • Concomitant use of other drugs (particularly sedatives such as alcohol and benzodiazepines);
  • Inadequate assessment of tolerance;
  • Commencement on doses that are too high for the level of tolerance;
  • Lack of understanding of the cumulative effect of methadone;
  • Inadequate observation and supervision of dosing;
  • Individual variation in metabolism of methadone.
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Size of the first dose

The first dose of methadone should be determined for each patient based on the severity of dependence and level of tolerance to opioids.
  • The history of quantity, frequency and route of administration of opioids, findings on examination, corroborative history and urine testing together provide an indication of the level of tolerance a patient has to opioids, but do not predict it with certainty.

  • A defined period of observation for signs and symptoms of opioid toxicity and withdrawal is a more accurate method of assessing opioid tolerance than history alone. In circumstances where there is doubt about the degree of tolerance, a review of the patient at a time when withdrawal symptoms are being experienced may help to resolve uncertainty about a safe starting dose.

  • Prescribers should make every effort to communicate with other practitioners who may have seen the patient previously in order to corroborate significant elements of the patient's history and to assist in decision making about commencing treatment.

  • New patients should be dosed with caution. Deaths in the first two weeks have been associated with doses in the range 25-100 mg/day, with most occurring at doses of 40-60 mg/day.

  • If at all possible, patients should be observed 3-4 hours after the first dose (ie. at the time of peak effect) for signs of toxicity or withdrawal (see Appendix 2 & Appendix 3).

    • If the patient is experiencing persistent withdrawal symptoms at 4 hours, a supplementary dose of 5mg can be considered.

  • When deciding on the commencing dose, also consider:

    • Where dosing is to occur.

      • Are staff and facilities available for observation and assessment of the patient before and after dosing?
      • Who will assess withdrawal/intoxication prior to dosing? (see Section 4.3)

    • Time since last opioid use.

    • Concomitant use of benzodiazepines or alcohol (see also Section 4.2 & Section 4.9).

      • The risk of overdose increases most markedly when other central nervous system depressants are also used.
      • If the patient shows signs of intoxication with benzodiazepines or alcohol, the dose should be withheld or reduced.

  • Induct morphine, codeine and oxycodone users as if they were heroin users
Note:
  • A dose of less than or equal to 20 mg for a 70kg patient can be presumed to be safe, even in opioid-na´ve users as this is the lowest dose at which toxicity has been observed.

  • Caution should be exercised for starting doses of 30mg or more.

  • Exercise extreme caution if an initial dose of methadone exceeding 40mg is considered necessary. Specialist consultation may be advisable.
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Stabilisation

During the first two weeks of MMT the aim is to stabilise the patient so that they are not oscillating between intoxication and withdrawal. This does not necessarily mean that the patient will reach an optimum maintenance dose in that time and further dose adjustments may be required after the patient has been initially stabilised.

Monitoring during the first two weeks

  • Patients should be observed daily prior to dosing and an assessment made of intoxication. If any concern they should be seen by a doctor before the dose is administered.

  • Because of the pharmacology of methadone, to ensure safety, it is desirable that patients are reviewed at least once, and preferably twice by an experienced clinician (doctor or nurse) in the first week with a view to assessing intoxication from methadone.

  • Dose increases should only be considered subject to assessment by the prescriber. Assessment should include withdrawal severity (see Appendix 3), intoxication (see Appendix 2), other drug use (see Section 4.9) side effects and patient perception of dose adequacy, and adherence to dosing regime.

Dose titration

  • Stabilisation is about titrating the dose against needs of the individual patient.

    • Do not increase the methadone dose for at least the first 3 days of treatment unless there are clear signs of withdrawal at the time of peak effect (i.e 3-4 hours after dose) as the patient will experience increasing effects from the methadone each day.

    • Consider dose increments of 5-10mg every 3 days subject to assessment.

    • Total weekly increase should not exceed 20mg.

    • The maximum dose at the end of the first week should typically be no more than 40mg.

    • Patients should be warned not to drive or operate machinery during periods of dose adjustments.

Transfer from other pharmacotherapies

Prescribers may need to seek specialist advice when prescribing for patients who are transferring from other pharmacotherapies with which they are unfamiliar.

Buprenorphine

(See also "National guidelines and procedures for the use of buprenorphine in the treatment of heroin dependence")
  • Consideration should be given to transferring a patient from buprenorphine to methadone under the following circumstances:

    • Patient experiencing intolerable side effects to buprenorphine;

    • Inadequate response with buprenorphine treatment;

    • Transferring to a program where buprenorphine is not available.

  • Patients should be stabilised on daily doses of buprenorphine and their buprenorphine dose reduced to 16mg or less for several days prior to transfer. Top of page

  • Methadone can be commenced 24 hours after the last dose of buprenorphine.

  • The initial methadone dose should not exceed 40mg.

  • Patients transferring from lower doses of buprenorphine (4 mg or less) should be commenced on lower doses of methadone.

  • Care should be taken not to increase the dose of methadone too quickly.

Naltrexone

  • Transfer will generally be considered because of relapse to opioid use following cessation of naltrexone.

  • After a short period, possibly only a few days, on naltrexone the patient loses tolerance to opioids. Consequently, patients transferring from naltrexone should be treated as if they were na´ve to opioids and non tolerant to their effects unless the clinical circumstances clearly indicate a return to regular, heavy heroin use.

  • Do not administer methadone until at least 72 hours after the last dose of naltrexone.

  • Extreme caution should be exercised with commencing doses of methadone which should be no greater than 20mg.