Clinical Chemistry
July 1, 1999
John K. Fallon, Andrew T. Kicman, J. A. Henry et al.
137 citations
After a 40 mg oral dose of racemic MDMA (ecstasy) to eight men, the R-enantiomer reached higher and longer-lasting plasma levels than the S-enantiomer. The R-enantiomer's half-life was 5.8 hours versus 3.6 hours for S-MDMA, and its area under the curve was 2.4 times greater. More R-MDMA was excreted in urine (21.4% of dose) than S-MDMA (9.3%). The demethylated metabolite MDA appeared in smaller amounts, with S-MDA slightly exceeding R-MDA. Mathematical modeling of plasma enantiomer ratios over time suggests that analyzing stereochemical composition could help estimate time since drug intake for forensic purposes.
Clinical Chemistry
October 1, 2001
Mèonica Navarro, Simona Pichini, Magí Farré et al.
135 citations
After a single 100-mg dose of MDMA, concentrations in saliva ranged from 1728.9 to 6510.6 μg/L, peaking at 1.5 hours, then declining to a mean of 126.2 μg/L at 24 hours. The saliva-to-plasma ratio varied from 32.3 to 1.2, with a peak of 18.1 at 1.5 hours. Salivary pH decreased by 0.6 units after drug administration, from a predose mean of 7.4 to 6.9 at 1.5 hours and 6.8 at 4 hours. Measuring MDMA in saliva offers a noninvasive alternative to plasma testing for clinical and toxicologic studies.
Clinical Chemistry
December 1, 2000
Karine M. Clauwaert, Jan F. van Bocxlaer, Els A. de Letter et al.
68 citations
A method using high-performance liquid chromatography with fluorescence detection, confirmed by liquid chromatography-tandem mass spectrometry, accurately measures the designer drugs MDMA, MDEA, and their metabolite MDA in whole blood, serum, vitreous humor, and urine. The method is linear from 2 to 1000 μg/L for blood, serum, and vitreous humor, and from 0.1 to 5 mg/L for urine, with detection limits as low as 0.8 μg/L. Extraction recoveries exceed 70%, and imprecision ranges from 2.5% to 19%. In a rabbit thanatochemical distribution study, serum MDMA concentrations ranged from 5.3 to 685 μg/L, and whole blood MDMA from 19.7 to 710 μg/L. For routine toxicology urine samples, MDMA concentrations reached up to 157 mg/L.
Clinical Chemistry
August 11, 2005
Frank T. Peters, Nele Samyn, C. T. J. Lamers et al.
49 citations
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.
Clinical Chemistry
January 23, 2009
Allan J. Barnes, Bruno Spinosa de Martinis, David A. Gorelick et al.
38 citations
In a controlled study, 15 healthy volunteers with prior MDMA use received placebo, low (1.0 mg/kg), and high (1.6 mg/kg) oral doses of MDMA in random order while wearing sweat patches for up to 7 days. MDMA was the main substance found in 59.7% of patches, with concentrations up to 3007 ng/patch; its metabolite MDA appeared in 29.4% of patches at lower levels, while other metabolites were undetected. At the 25-ng/patch threshold, 35% of patches were positive for MDMA. Sweat testing reliably detects MDMA use, but high variability in excretion means results should be interpreted qualitatively, not quantitatively.
Clinical Chemistry
February 1, 1977
W A Ratcliffe, S.m. Fletcher, A.c. Moffat et al.
38 citations
High-titre antisera were raised to two LSD-bovine serum albumin conjugates, each specific for different parts of the LSD molecule. These antisera enabled a double-antibody radioimmunoassay with a detection limit of about 0.4 micrograms of LSD per liter of unextracted urine or serum, with no nonspecific interference from urine, serum, or common drugs. Immunoassay values from the two antisera correlated well (r = 0.91), though the antiserum linked via the indole nitrogen gave consistently higher results for samples from people who had taken LSD due to greater cross-reactivity with LSD metabolites. Using two such antisera provides a more specific screening procedure for LSD abuse and allows measurement of metabolites for which no satisfactory method previously existed.
Clinical Chemistry
September 1, 2002
Gisela Skopp, Lucia Pötsch, Rainer Mattern et al.
37 citations
Lysergic acid diethylamide (LSD) is a potent hallucinogen that is rapidly metabolized and unstable in biological fluids, making its detection in urine challenging. After a typical street dose of 40–120 μg, LSD concentration in urine falls below 1 μg/L within hours. Metabolites N-desmethyl-LSD (nor-LSD) and 2-oxo-3-hydroxy-LSD (O-H-LSD) have been identified, with O-H-LSD measured at concentrations severalfold higher (0.02–21.4 μg/L). Liquid chromatography–tandem mass spectrometry (LC-MS/MS) improves detection. LSD decomposes in urine exposed to heat, sunlight, or ultraviolet light, but stability data on its major metabolites were lacking. This study assessed the stability of LSD, O-H-LSD, and nor-LSD in urine under different storage conditions using LC-MS/MS, aiming to inform sample transport and storage practices.
Clinical Chemistry
December 19, 2007
Erin A Kolbrich, Ross H. Lowe, Marilyn A. Huestis
36 citations
A two-dimensional gas chromatography–mass spectrometry method with cryofocusing simultaneously quantifies MDMA, its metabolites MDA, HMMA, and HMA, and MDEA in human plasma. Limits of quantification were 1.0 μg/L for MDA and 2.5 μg/L for the other four compounds. Calibration curves were linear up to 100 μg/L for MDA and HMA and up to 400 μg/L for MDEA, MDMA, and HMMA, with correlation coefficients above 0.997. Extraction efficiencies from plasma were at least 85%, recoveries ranged from 85.6% to 107.2% of target, and intra- and interassay imprecision was below 8.5% at three concentrations. None of 66 tested exogenous compounds interfered. The assay achieves low quantification limits suitable for pharmacokinetic studies and may apply to other analytes and complex matrices.
Clinical Chemistry
March 2, 2007
Frank T. Peters, Nele Samyn, Thomas Kræmer et al.
36 citations
A gas chromatography–mass spectrometry method using negative-ion chemical ionization was developed to separately measure the left- and right-handed forms (enantiomers) of amphetamine, methamphetamine, MDA, MDMA, and MDEA in oral fluid. After adding a buffer and a derivatizing agent, the enantiomers were extracted and analyzed. The method was linear from 5–250 μg/L per enantiomer for MDA and from 25–1250 μg/L per enantiomer for the other drugs. Recoveries and precision were acceptable except for MDEA. When applied to samples from a controlled MDMA study and real driving-under-the-influence cases, the oral fluid concentrations and enantiomer ratios did not reliably predict plasma levels.
Clinical Chemistry
October 7, 2011
Andrea E. Schwaninger, Markus R. Meyer, Allan J. Barnes et al.
33 citations
After oral MDMA (ecstasy) intake, human urine contains mostly sulfate and glucuronide conjugates of MDMA metabolites, with sulfates present at higher concentrations than glucuronides. More than 90% of the metabolites DHMA and HMMA were excreted as conjugates. HMMA sulfate had the longest detection window in urine. The ratio of HMMA sulfate to glucuronide was 2.0, and the ratio of DHMA 3-sulfate to 4-sulfate was 5.3 during the first 24 hours, matching predictions from earlier lab experiments. These findings can improve direct urine analysis for MDMA and its metabolites in clinical and forensic toxicology.
Clinical Chemistry
July 20, 2006
Stéphane Pirnay, T. T. Abraham, Marilyn A. Huestis
29 citations
A sensitive gas chromatography-mass spectrometry method was developed and validated to simultaneously measure MDEA, MDMA, and its metabolites (HMA, MDA, HMMA) in human urine. The method involves acid hydrolysis of 1 mL urine, solid-phase extraction, and derivatization before analysis. Limits of quantification were 25 μg/L for all analytes, with linear calibration up to 5000 μg/L. Extraction efficiencies exceeded 85.5%, and imprecision (coefficient of variation) was below 15% at tested concentrations. The assay meets federal workplace drug testing guidelines for these substances.
Clinical Chemistry
April 1, 1997
Detlef Ritter, Cherise M Cortese, Linda C Edwards et al.
24 citations
A high rate of false-positive LSD results (4.2%) occurred in urine samples from psychiatric patients when using the Emit assay. These positive results could not be confirmed by two different radioimmunoassays or by gas chromatography–mass spectrometry. Adding therapeutic medications commonly prescribed to these patients to normal urine samples produced positive LSD results with the Emit assay, indicating that those drugs interfere specifically with the Emit test for LSD.
Clinical Chemistry
May 1, 1988
José Manuel Ramos, R.l. Fitzgerald, Alphonse Poklis
10 citations
The Abbott TDx amphetamine/methamphetamine reagents show cross-reactivity with MDMA and MDA, meaning these drugs can produce false-positive results when testing for amphetamines. This finding has implications for forensic toxicology and clinical drug testing, as it may lead to misidentification of substances.
Clinical Chemistry
May 1, 1998
Sarah Kerrigan, Donald E Brooks
6 citations
A new antibody targeting LSD enabled the development of an indirect ELISA that measures LSD in urine with better performance than a commercial assay. The test uses 50 μL of urine and detects concentrations from ng/L to μg/L. The limit of detection is 8 ng/L, compared to 85 ng/L for the commercial assay, and analytical recoveries range from 98–106%. At 0.1 μg/L, the intraassay coefficient of variation (CV) was 2.4% (n=8), versus 6.0% at 0.5 μg/L for the commercial assay (n=20). The upper and lower quantification limits are 7 μg/L and 50 ng/L. Cross-reactivity with 24 related substances was evaluated. The new assay offers improved sensitivity and precision, enabling more certain quantitative estimation of LSD in urine at lower concentrations.
Clinical Chemistry
October 1, 2025
Se Yeon Oh, Kim Pham, Rajendra Singh et al.
A new immunoassay, the ARK Ketamine II Assay, accurately detects ketamine in human urine at two cutoff concentrations (50 and 100 ng/mL) with high precision and specificity. In tests on 223 negative urine samples, the assay correctly identified all as negative, including 22 that had produced a response above the detection limit in the earlier version. For positive samples confirmed by LC-MS/MS, the assay showed 100% sensitivity and 100% specificity at both cutoffs. The assay also cross-reacts with the major metabolite nor-ketamine at about 45–47%, while cross-reactivity to methoxetamine is less than 0.3%. The method is suitable for routine clinical chemistry analyzers.
Clinical Chemistry
October 1, 2025
Stephanie Marco
In 2024, among 328 suspected driving-under-the-influence cases, the most common psychedelic or dissociative drug detected was phencyclidine (PCP, 220 cases), followed by MDMA (81 cases) and ketamine (22 cases). LSD and psilocin were found in only 2 and 5 cases, respectively. Drug concentrations varied widely, with ketamine ranging from 25 to 880 ng/mL, LSD from 3 to 9.8 ng/mL, PCP from 6 to 270 ng/mL, and MDMA from 5.5 to 850 ng/mL. Most drivers also had other central nervous system depressants in their blood. The findings highlight safety concerns for driving as psychedelic therapies become more available.