Evaluation of Roche Abuscreen ONLINE amphetamine immunoassay for screening of new amphetamine analogues.

Some structural analogues of amphetamine are now important drugs of abuse in Thailand. The utility of the Roche Abuscreen ONLINE reagent amphetamine immunoassay test kit to detect these analogues was studied. The test showed high cross-reactivity to 3,4-methylenedioxyamphetamine (MDA), but low cross-reactivity to its parent drugs, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA), as well as to methamphetamine and ethylamphetamine. Also observed in this study was a methamphetamine detection sensitivity enhancement effect of amphetamine, which is the active metabolite of methamphetamine. Correlation between the measured concentration values and the actual amount of these two drugs in the sample was, however, low. Thus, the test can be used to detect methamphetamine only when amphetamine is also present in the sample resulting from either co-administration or metabolism of methamphetamine.

Isomeric separation of methamphetamine by HPLC chiral column.

Methamphetamine and its active metabolite, amphetamine, are optically active compounds which, based upon synthetic routes, can be found in two forms; pure d-form and racemic mixture. Analysis of their isomers can help to identify which precursor is currently spreading widely in a given region. Since there are many drugs that can be metabolized to amphetamine/methamphetamine, isomeric separation can be a useful tool for evaluation of these drugs, as well. Indirect method by using N-trifluoroacetyl-1-prolyl chloride (1-TPC) was found to have limited accuracy due to the contribution effect. In this presentation a direct method using HPLC Chirex chiral column 3022 was studied. Although the method gave no base-line separation of two different isomer peaks, it gave good sensitivity, reliability, and linearity. No contribution effect was found in the method presented. It also gave excellent correlation with the 1-TPC method.

GC-MS analysis of methamphetamine impurities: reactivity of (+)- or (-)-chloroephedrine and cis- or trans-1,2-dimethyl-3-phenylaziridine.

S-(+)-Methamphetamine is frequently found as the only isomer in urine specimens from methamphetamine abuseres. Enantiomerically pure S-(+)-methamphetamine can be synthesized from ephedrine or pseudoephedrine via chloroephedrine intermediates. These intermediates are unstable and capable of cyclizing to form cis- and trans-1,2-dimethyl-3-phenyl aziridine. Studies were done to determine if these intermediates could be detected when using a common gas chromatographic-mass spectrometric analytical method (derivatization with heptafluorobutyric anhydride, HFBA) for toxicological screening of methamphetamine. Analysis of (+)- or (-)-chloroephedrine after extraction into hexane and derivatization with HFBA indicated that both pseudoephedrine and ephedrine were the major compounds detected. Direct derivatization of a hexane solution of cis-1,2-dimethyl-3-phenyl aziridine yielded only the derivatives of ephedrine and pseudoephedrine, indicating that the aziridine intermediate is responsible for the formation of the ephedrine or pseudoephedrine. These studies indicate that the aziridine intermediates would not be detected in methamphetamine samples following HFBA derivatization.