Oral heroin in opioid-dependent patients: pharmacokinetic comparison of immediate and extended release tablets.

In diacetylmorphine prescription programs for heavily dependent addicts, diacetylmorphine is usually administered intravenously, but this may not be possible due to venosclerosis or when heroin abuse had occurred via non-intravenous routes. Since up to 25% of patients administer diacetylmorphine orally, we characterised morphine absorption after single oral doses of immediate and extended release diacetylmorphine in 8 opioid addicts. Plasma concentrations were determined by liquid chromatography-mass spectrometry. Non-compartmental methods and deconvolution were applied for data analysis. Mean (+/-S.D.) immediate and extended release doses were 719+/-297 and 956+/-404 mg, with high absolute morphine bioavailabilities of 56-61%, respectively. Immediate release diacetylmorphine caused rapid morphine absorption, peaking at 10-15 min. Morphine absorption was considerably slower and more sustained for extended release diacetylmorphine, with only approximately 30% of maximal immediate release absorption being reached after 10 min and maintained for 3-4h, with no relevant food interaction. The relative extended to immediate release bioavailability was calculated to be 86% by non-compartmental analysis and 93% by deconvolution analysis. Thus, immediate and extended release diacetylmorphine produce the intended morphine exposures. Both are suitable for substitution treatments. Similar doses can be applied if used in combination or sequentially.