Rapid and sensitive gas chromatographic determination of diacetylmorphine and its metabolite monoacetylmorphine in blood using a nitrogen detector

Kinetic characterization of cholinesterases and a therapeutically valuable cocaine hydrolase for their catalytic activities against heroin and its metabolite 6-monoacetylmorphine

As the most popularly abused one of opioids, heroin is actually a prodrug. In the body, heroin is hydrolyzed/activated to 6-monoacetylmorphine (6-MAM) first and then to morphine to produce its toxic and physiological effects. It has been known that heroin hydrolysis to 6-MAM and morphine is accelerated by cholinesterases, including acetylcholinesterase (AChE) and/or butyrylcholinesterase (BChE). However, there has been controversy over the specific catalytic activities and functional significance of the cholinesterases, which requires for the more careful kinetic characterization under the same experimental conditions. Here we report the kinetic characterization of AChE, BChE, and a therapeutically promising cocaine hydrolase (CocH1) for heroin and 6-MAM hydrolyses under the same experimental conditions. It has been demonstrated that AChE and BChE have similar k_cat values (2100 and 1840 min^-1, respectively) against heroin, but with a large difference in K_M (2170 and 120 μM, respectively). Both AChE and BChE can catalyze 6-MAM hydrolysis to morphine, with relatively lower catalytic efficiency compared to the heroin hydrolysis. CocH1 can also catalyze hydrolysis of heroin (k_cat = 2150 min^-1 and K_M = 245 μM) and 6-MAM (k_cat = 0.223 min^-1 and K_M = 292 μM), with relatively larger K_M values and lower catalytic efficiency compared to BChE. Notably, the K_M values of CocH1 against both heroin and 6-MAM are all much larger than previously reported maximum serum heroin and 6-MAM concentrations observed in heroin users, implying that the heroin use along with cocaine will not drastically affect the catalytic activity of CocH1 against cocaine in the CocH1-based enzyme therapy for cocaine abuse.

Gas chromatographic data for 187 nitrogen- or phosphorus-containing drugs and metabolites of toxicological interest analysed on methyl silicone capillary columns

Retention data, retention indices and retention times relative to diazepam, associated with 187 nitrogen- or phosphorus-containing drugs and metabolites likely to be found in toxicological analysis, are presented. The work was carried out with cross-linked methyl silicone, siloxane-deactivated fused-silica capillary columns in different gas chromatographs equipped with nitrogen-phosphorus flame ionization detectors and a gas chromatograph-mass spectrometer. Results show the high reproducibility offered by the capillary system, which permits the reduction of identification problems and analysis time.

Simple high-performance liquid chromatographic method for the separation of 3,6-diacetylmorphine hydrochloride (heroin) and hydrolysis products

The application of reversed-phase high-performance liquid chromatography to the measurement of 3,6-diacetylmorphine (DAM) hydrochloride and its degradation products is described. This method has been applied to study the kinetics of the DAM hydrolysis at 26 +/- 0.1 degrees and 48 +/- 0.1 degrees. The hydrolysis of DAM involved a two-step first-order sequential mechanism between pH 3 and 8.6. The first-order rate constants of each step at all pH levels have been determined. The pH rate profile was constructed from kinetic measurements and demonstrated that stability of DAM hydrochloride solutions was optimal at pH 4.3. This information is being applied to the development of parenteral dosage forms of DAM hydrochloride.