标题：Smoking Abuse of Methamphetamine Mixed with Tobacco. Thermal Properties of N-Cyanomethylmethamphetamine and Its Degradation in Plasma and Aqueous Media
摘要：The thermal properties of a characteristic pyrolyzed product from the smoking of methamphetamine (MA) with tobacco, N-cyanomethylmethamphetamine (CMMA), in a free form and a hydrochloric salt (HCl salt) were investigated by thermogravimetry (TG)-differential thermal analysis and TG-mass spectrometry in comparison with those of MA and its hydrochloride (MA·HCl). The stability of CMMA·HCl in water, physiological saline and plasma was investigated by gas chromatography (GC), GC-mass spectrometry and nuclear magnetic resonance spectrometry. CMMA was stable when heated in a base form, but not in a HCl salt form, whereas MA was stable when heated in either form. CMMA began to vaporize without any decomposition at a temperature (80°C) higher than MA did (30°C). CMMA·HCl, in contrast, decomposed with a weight loss at over 100°C, although MA·HCl began to decrease appreciably at a higher temperature than its fusion point (174°C). CMMA and CMMA·HCl stored as a pure form or in organic solvents in a refrigerator did not decompose over a 12 month period. However, CMMA·HCl was primarily unstable in any aqueous medium of water, physiological saline or plasma. The lower concentration of CMMA·HCl in the aqueous medium and the higher temperature of the medium appreciably accelerated its decomposition rate. Even if stored at 4°C, CMMA·HCl in plasma at 0.01 mg/ml decreased to 65% of initial value after 2 h, and when stored at 37°C, it had completely decomposed after 2 h. Our results, however, indicated that treatment of CMMA as a free base form at a temperature lower than 4°C and within 30 min after defrosting minimized its decomposition in an aqueous medium. It was demonstrated that CMMA·HCl in aqueous media decomposed largely to MA, CH2O and HCN.
