Sulphatoxymelatonin excretion during opiate withdrawal: a preliminary study.

The excretion of sulphatoxymelatonin (aMT6S), a major metabolite of melatonin in urine, is dependent on noradrenergic (NA) neuronal activity within the pineal gland and thus represents a neuroendocrine marker of NA neuronal function. Many of the clinical features of opiate withdrawal result from increased firing of central NA neurones. In this study, we test the hypothesis that aMT6S excretion is increased during opiate withdrawal in opiate-dependent patients. The 24-h urinary aMT6S excretion was measured at three time points during in-patient methadone detoxification treatment in 11 opiate-dependent patients, during methadone stabilisation and on Days 6 and 12 of withdrawal treatment. There was a significant increase in aMT6S excretion on Day 6 but not on Day 12, compared to stabilisation. A significant correlation between individual withdrawal symptom score severity and aMT6S excretion was demonstrated during stabilisation (r=.68, P<.05) and on Day 6 of treatment (r=.62, P<.05). Our preliminary findings suggest that melatonin secretion may represent a neuroendocrine marker of NA neuronal hyperactivity during opiate withdrawal in opiate-dependent patients. Areas of future research are discussed.