Kleckham, Julia; (1999) An investigation into the effects of methadone on cognitive and psychomotor function, mood, concentration and craving. Doctoral thesis (D.Clin.Psy.), University College London.

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Abstract

Methadone is a synthetic opioid that produces cross-tolerance with opiate drugs and can therefore be used to suppress withdrawal symptoms in opiate dependent patients. Methadone is the main treatment offered by the NHS in the UK for opiate dependence. Methadone can be used for both detoxification (if the primary treatment aim is abstinence from opiates), or as a maintenance dose (if the primary treatment aim is harm reduction until the patient is ready to detoxify). In the UK the number of deaths from methadone exceeds the number of deaths from heroin and numbers have increased over the last ten years.(ONS England and Wales: 1993-1997, 220 to 368 deaths from methadone, 55 to 169 deaths from heroin. Curran et.al. (1999) found no sedative, cognitive or psychomotor effects but an increase in craving for opiates in methadone maintenance outpatients, with a 33% increase in their prescribed maintenance dose of methadone. Previous studies have methodological limitations (Zacny, 1995, Weinreib et al, 1993) and inconclusive results. The aim of this study is to investigate the cognitive, psychomotor and mood effects of a 100% increase in methadone dose for opiate dependent in-patients, using a double blind, placebo controlled design, with urinalysis to address some limitations of previous research. A range of measures was used to assess the effects of this increase on cognitive and psychomotor functioning, mood and craving. On admission, participants were stabilised on methadone for 5 days, before the dose is reduced for detoxification in the usual way. Participants were assessed on day 3 and day 5. All participants received their complete dose each day, half the participants received methadone as one whole dose. The others received methadone in a divided dose (50% in the morning, 50% in the evening). The design was balanced for treatment order. Methadone vehicle (linctus) was used as a placebo to maintain double-blind conditions, resulting in the same quantity of linctus administered on each occasion. Both placebo and methadone were flavoured with peppermint so appeared, tasted and smelled the same. Participants were unable to distinguish methadone from placebo. There was no evidence of illicit drug use detected by urinalysis. Results suggest that Methadone has no effect on craving for heroin or mood, but significantly affects delayed recall. The implications of these findings for the treatment of opiate dependency are discussed.

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