The pharmacological effects of amphetamine, methamphetamine, MDA, MDMA, and MDEA depend on their mirror-image molecular forms (enantiomers), which differ in how they act in the body. Analysis of plasma from clinical toxicology cases and from drivers suspected of drug impairment showed that concentrations of most enantiomers were lower in routine screening samples than in intoxication or driving-under-the-influence cases. Drivers under the influence had higher levels of both amphetamine enantiomers than intoxicated patients. Differences in the ratio of R to S enantiomers for several drugs between groups suggest these ratios can help distinguish recent from past use. In one MDMA poisoning, the R form cleared more slowly (half-life 6.0 hours) than the S form (4.1 hours), and the ratio of R to S rose over time.
An assay was developed to measure the enantiomers of the designer drugs MDA, MDMA, and MDEA in small plasma volumes (0.2 mL or less). After extraction and derivatization, the enantiomers were separated by gas chromatography and detected by mass spectrometry within 17 minutes. The method was linear for MDA at 1–50 μg/L and for MDMA and MDEA at 5–250 μg/L per enantiomer, with extraction yields of 82.1%–95.3%. Applied to samples from a controlled study after a single 75 mg dose of racemic MDMA, the assay showed that R-(−)-MDMA concentrations significantly exceeded those of S-(+)-MDMA, with ratios always above 1.0 and increasing over time. S-(+)-MDA concentrations exceeded those of R-(−)-MDA, with ratios also increasing but remaining below 1.0.
A method for simultaneously measuring multiple hallucinogens, chlorpheniramine, ketamine, ritalinic acid, and several metabolites in human urine was developed and validated. The procedure uses solid-phase extraction followed by liquid chromatography-tandem mass spectrometry, with all drugs eluting within 14 minutes. Using 500 microliters of urine, limits of quantification ranged from 0.05 ng/mL for LSD to 10 ng/mL for other hallucinogens, with linear or quadratic regression from each compound's limit up to 500 ng/mL. Precision and accuracy were acceptable, and processed samples remained stable in the autosampler for at least 24 hours. The method was successfully applied to authentic urine samples containing chlorpheniramine, ketamine, LSD, and psilocin.