Abstract
In preparation for a trial on co-prescription of heroin to chronic treatment-resistant addicts, a pharmaceutical dosage form for smokable heroin was developed. During development of this product (a mixture of diacetylmorphine and caffeine), in vitro experiments were performed simulating ‚chasing the dragon‘: the technique used by addicts for inhalation of heroin after volatilisation. Samples were heated on aluminium foil using a heating device and the vapours were collected and analysed using a HPLC-UV method. The recovery of diacetylmorphine and caffeine in vapours was studied after volatilisation of different powder mixtures at temperatures between 200 and 350 degrees C. Furthermore, the volatilisation set-up was combined with an Andersen sampler to determine the sizes of aerosol particles. Only small differences in recovery of diacetylmorphine and caffeine were found between temperatures and between powder mixtures: 46-62% of diacetylmorphine from the sample was recovered in vapour and 65-83% of caffeine. The only degradation product detected in vapour was 6-acetylmorphine (4.1-7.1%). In the temperature range studied, temperature mainly influenced the volatilisation rate. Mass median aerodynamic diameters of aerosols from diacetylmorphine-containing samples ranged from 1.8-4.1 microm; 45-60% of each sample was recovered as aerosol particles <5 microm. Volatilising pharmaceutical smokable heroin resulted in sufficient amounts of diacetylmorphine in vapour and in particles suitable for effective deposition in the lungs.
Pharmaceutical heroin for inhalation was developed for a clinical trial on co-prescription of heroin and methadone to chronic treatment-resistant heroin addicts. Diacetylmorphine base was selected as the active pharmaceutical ingredient for this product with caffeine anhydrate added as an excipient. Differential scanning calorimetry and thermogravimetric analysis showed that addition of caffeine resulted in a lower melting temperature and a higher volatilisation rate for the mixture than for diacetylmorphine base alone. Recovery experiments showed that 40.8+/-5.3% of diacetylmorphine base could be found in smoke condensate after volatilisation of diacetylmorphine-caffeine tablets. All of the caffeine from each tablet was recovered unchanged in the fumes, while 85.6% of the diacetylmorphine from each tablet was recovered, either unchanged in the fumes or as non-volatilised residue. Recovery was found to be reproducible and only small differences were found between the tablet types. The experimental set-up was found to efficiently collect the vapours resulting from heating the powder. Under the tested experimental conditions, no evidence was found that degradation products of diacetylmorphine or caffeine, other than 6-acetylmorphine (5.9%) had volatilised, even though a decomposed residue was present after heating diacetylmorphine-caffeine samples. Diacetylmorphine-caffeine was found to be a suitable basis for pharmaceutical heroin to be used by ‚chasing the dragon‘.
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