Diamorphine treatment for opiate dependence: putative markers of concomitant heroin misuse.

The supply of substitute opioid medication as a treatment for heroin dependence is now common practice. There is growing international interest in the prescription of injectable diamorphine for subgroups of patients who are unable to stop injecting opiate drugs; in the United Kingdom it is estimated that there are currently 300 patients prescribed diamorphine for this purpose. The detection of illicit heroin misuse (through urinary diamorphine metabolites) is confounded in subjects prescribed diamorphine. We investigated the potential to distinguish between the use of street heroin and pharmaceutical diamorphine through the detection in urine of various opiate alkaloids originating in the opium poppy, Papaver somniferum. Over a 7-week period, 532 clients of an urban substance misuse service provided a total of 1122 urine samples for clinical purposes. Using a novel mixed-mode solid-phase extraction and gas chromatography/mass spectrometry technique, we screened samples for morphine, 6-monoacetylmorphine, codeine, meconine, papaverine, noscapine, thebaine and their metabolites. All urine samples from diamorphine-treated patients were positive for morphine. Of samples from patients receiving other treatments, 30% (95%CI: 27-33%) were positive for morphine, indicating probable street heroin misuse. Of morphine-positive samples, 61% (95%CI: 55-67%), from the "other treatments" group were positive for at least one of codeine, meconine and putative noscapine or papaverine metabolites. This was reduced to 56% (95%CI: 50-62%) when excluding codeine. Only one sample (0.1%) was positive for any one of these putative markers in the absence of morphine, when excluding codeine. These findings show that the detection of urinary noscapine and papaverine metabolites is useful in distinguishing between use of pharmaceutical diamorphine and street heroin. This may be of benefit to promote safer and more effective prescribing of diamorphine in opiate dependency, and as an outcome measure in trials of diamorphine prescribing.