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

The supply of substitute opioid medication as a treatment for heroin depend ence is now common practice. There is growing international interest in the prescription of injectable diamorphine for subgroups of patients who are u nable to stop injecting opiate drugs; in the United Kingdom it is estimated that there are currently 300 patients prescribed diamorphine for this purp ose. The detection of illicit heroin misuse (through urinary diamorphine me tabolites) is confounded in subjects prescribed diamorphine. We investigate d the potential to distinguish between the use of street heroin and pharmac eutical diamorphine through the detection in urine of various opiate alkalo ids originating in the opium poppy, Papaver somniferum. Over a 7-week perio d, 532 clients of an urban substance misuse ser vice provided a total of 11 22 urine samples for clinical purposes. Using a novel mixed-mode solid-phas e extraction and gas chromatography/mass spectrometry technique, we screene d samples for morphine, 6-monoacetylmorphine, codeine, meconine, papaverine , noscapine, thebaine and their metabolites. All urine samples from diamorp hine-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, 6 1% (95% CI: 55-67%), from the "other treatments" group were positive for at least one of codeine, meconine and putative noscapine or papaverine metabo lites. This was reduced to 56% (95% CI: 50-62%) when excluding codeine. Onl y one sample (0.1%) was positive for any one of these putative markers in t he absence of morphine, when excluding codeine. These findings show that th e detection of urinary noscapine and papaverine metabolites is useful in di stinguishing between use of pharmaceutical diamorphine and street heroin. T his may be of benefit to promote safer and more effective prescribing of di amorphine in opiate dependency, and as an outcome measure in trials of diam orphine prescribing.