COMMUNITY PRESCRIBING FOR OPIATE DEPENDENCY

The medium to long-term plan, following induction onto a stabilisation dose will depend on an assessment of the client's motivation to engage in the various options for further management, and how realistic their expectations of treatment are. It is vital to avoid imposing a plan for reduction or detoxification on a patient who is not ready for this.

Following the initial induction period (weeks to 2 months), some patients will wish to detoxify immediately. The client should be prepared for this and a realistic after-care plan formulated. A protracted opiate withdrawal syndrome characterised by agitation, malaise, craving and insomnia may persist for many months following detoxification; if no thought is given to the difficulties which will be faced following detoxification, relapse to heroin misuse is highly likely to occur.

For clients who are not immediately motivated to undergo detoxification, or in those that are unrealistic in their plan for abstinence, an objective of on-going stabilisation should be set. A period of maintenance on methadone will allow an opportunity to develop the psychological and social tools which may maintain abstinence in the future. Additionally, there is a wealth of evidence that the benefits of methadone stabilisation outweigh the risks in terms of reduced illicit drug use, reduced injecting drug use, reduced crime and reduced spread of viral illnesses such as HIV (Newman & Whitehill 1979, Gunne & Gronbladh, 1981). The rationale for such prescribing is one of 'harm-minimisation' and is widely held to be responsible for the very low rates of HIV infection in the UK as compared to other European countries.

In contrast to the early induction period of prescribing where the immediate aim was to control withdrawal symptoms, the dosage should now be directed towards reducing and stopping illicit opiate misuse. The compulsion to use heroin is not directed merely by a need to prevent withdrawal (negative reinforcement) but also by a need to experience the positive effects such as euphoria (positive reinforcement). The desire to experience positive effects in the dependent user should not be understood in terms of a willful and consciously motivated act; rather it is directed by primitive components of the central nervous system such as the nucleus accumbens, which operate at the unconscious level. This desire may be reduced, if not eliminated, by the prescription of larger doses of methadone than those required to eliminate physical withdrawal (Effectiveness Review, 1996). There is a substantial body of evidence demonstrating a direct correlation between methadone dosage and reduced heroin misuse (Ball & Ross, 1991, Caplehorn & Bell, 1991, Ling et al, 1996).

During this phase of treatment, the patient should be seen ideally fortnightly and at least monthly. Dosage should be maintained at a level which 'holds' the patient, and prevents heroin misuse. Thus the response to a patient who is complying with appointment attendance but who is continuing to report regular heroin misuse, will often be to increase the methadone dosage. The usual maintenance dose will often be between 60 and 120mg daily (Drug Misuse and Dependence - Guidelines on Clinical Management, 1999), although some will require smaller doses. Doses over 100mg daily should usually only be prescribed following specific advice from specialist services.

PREscriptIONS

It will usually be appropriate to continue on a daily dispensing regime for the first year of such prescribing. Where a trusting relationship has developed between the patient and prescriber, and there is evidence that successful stabilisation has been achieved, this rule may be relaxed in increments. It is inadvisable to dispense more than one week's worth of methadone at any one time, whatever the eventuality. Other exceptions to this rule may occur in order to support a client in remaining in employment, where a daily collection may interfere with working responsibilities, and the benefits are judged to outweigh the risks.

URINALYSIS

Urine 'drugs of abuse' screens should be performed on an occasional 'random' basis throughout this period. Detection of substances other than those reported should be discussed with the client, but should not automatically lead to discontinuation of treatment. Many clients will be mistrustful of their doctor's response in the case of their continued illicit drug use, and fear losing their prescription if they admit to this.

One major aim of urinalysis is to confront mis-reporting in a positive and non-punitive way, thus demonstrating to the client that they will not automatically lose their prescription by engaging in an honest and trusting relationship with their doctor.As discussed above, the appropriate response to an opiate positive urine screen may be to increase rather than to decrease the methadone dosage.

POOR COMPLIANCE

This is discussed in detail below (Section E10, page 104).

CONCLUSIONS

1. Before commencing a methadone prescription always:
   • confirm opiate misuse with a urine drugs of abuse screen.
   • record a history of physical withdrawal symptoms and regular (usually daily) opiate use.
2. The formulation prescribed should be methadone mixture 1mg/ml.
3. The starting dose should never be more than 30mg daily. For the initial period of prescribing, dispensing should be on a supervised and daily basis.
4. As a routine, the dosage may then be increased at a rate of 10mg weekly, although this process may be more rapid if the patient can be seen more frequently than once weekly.
5. A rough guide to the final stabilisation dose can be calculated by multiplying the daily heroin use in grams by 0.07; thus a 1g/day heroin habit equates to approximately 70mg methadone.

However:

6. There is significant inter and intra-individual variation in metabolism of methadone, with half-lives varying between 10 and 150 hours in different individuals. It is thus vital that dosage is tailored to the individual. When the aim is stabilisation of illicit opiate misuse, then the dosage should be increased so as to ameliorate the positive (euphoric) effects of heroin use, rather than merely to prevent withdrawal. This should be judged mainly from the patient's self-report of how well the prescription is 'holding' them, but also from the detection (or non-detection) of morphine (heroin metabolite) in the urine. If the client is presenting as drowsy then the dosage is probably too high. It should also be noted that significant intra-individual changes in metabolism occur over the first several months of treatment, and the dose may need to altered in response to this. Physiological changes in the third trimester of pregnancy also often lead to reduced plasma methadone concentration and increased dosage requirements.
7. Whatever the calculation in (5) reveals, the majority of addicts will require at least 60mg of methadone daily to prevent the continued misuse of heroin on-top of their prescribed methadone.
8. It will be unusual to increase the daily dose above 100mg methadone, and the dosage should never be increased above 120mg daily without specialist advice.
9. If there is concern regarding the possible diversion of prescribed methadone to the grey market, then place the client on a supervised consumption regime or seek specialist advice.
10. There is usually little point in commencing a detoxification or reduction regime following stabilisation, if the patient is not motivated to comply with this. Physician-imposed reduction or detoxification regime is likely to result only in relapse to heroin misuse and a loss of the advantages of methadone stabilisation leading to increased crime, spread of HIV and hepatitis, and failure to retain the patient in treatment.

Next page .. SLOW METHADONE REDUCTION REGIMES

Alcohol Guidelines index

The above information is copyright of Dr Bruce Trathen MBBS MRCPsych (2006). ISBN 0-9545164-0-0. The author grants permission for these guidelines to be downloaded, copied and distributed freely, but does not grant permission for their sale.