Volatilisation of diacetylmorphine: in vitro simulation of 'chasing the dragon'.

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.