SPECIALIST PHARMACOLOGICAL & BIOCHEMICAL INTERVENTIONS

PRESCRIBING INJECTABLE FORMULATIONS

The use of injectable formulations in the management of addiction should only ever be considered for the treatment of opiate dependency. Only doctors with a special Home Office licence can prescribe diamorphine for the treatment of addiction. Currently, any registered doctor can prescribe injectable methadone, although this position may change in the near future with the introduction of new legislation.

The provision of injectable formulations of methadone and diamorphine for the treatment of opiate dependency is a contentious area. The rationale for such prescribing is that of harm-minimisation; injecting drug users (IDUs) may benefit from the provision of sterile drugs of known purity as compared to contaminated street drugs of uncertain purity. Equally, the potential to attract users into treatment by such prescribing may result in further health improvements achieved indirectly through the provision of other services such as HIV screening (for example) which would not otherwise have been accessed. Several studies examining the effectiveness of such interventions have failed to demonstrate any clear advantage for the group over treatment with non-parenteral formulations, neither in terms of health gains nor in improved engagement with services. Such studies are, however, prone to methodological difficulties and it may well be the case that certain subgroups have the potential to benefit from injectable prescribing.

Such treatments should only be prescribed after a full assessment by specialist services, and when the prescriber is in receipt of documented advice from specialist services which is supportive of the intervention. In general, consideration for the prescription of injectable methadone or diamorphine should be restricted to opiate-dependent patients who meet all the following criteria:

• At least a ten-year history of opiate dependency.
• Currently injects opiates on a daily basis, and has done so for at least the last five years.
• Has tried and failed to cease illicit drug use through the use of non-injectable treatments in the past.
• The patient and prescriber are clear that the patient will continue to inject street drugs on a regular basis in the absence of a prescription for injectable methadone or diamorphine.
• The patient and prescriber are clear that the patient will cease or significantly reduce the injection of street drugs if such a prescription is provided.

The importance of instituting all the usual controls around prescribing is of especial concern in view of the greater street value and potential to cause accidental overdose of injectable opiates over oral and sublingual preparations. Prescribers should generally try to provide as few ampoules as possible for a given dose, to limit the potential for diversion of medication to the black market. The drug of choice will usually be methadone, although diamorphine may be preferred in patients who will only comply with a diamorphine prescription.

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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.