John D Ramsey | PubMed Health

PubMed2005

Analysis for identification in amnesty bin samples from dance venues.

The analysis of unknown substances discarded in amnesty bins, first described by Ramsey et al, from a large central London club and 7 smaller clubs in Manchester, UK are described. The contents of the bins were collected between July 2003 and March 2004. Solid dosage formulations were identified using the TICTAC database, chemical tests, and GC-MS screening. Drugs that could not be readily identified were subjected to other analytical techniques. The goal was to document the current range of drugs available on the dance scene and compare the findings between the London club, which had been the subject of a previous survey, and Manchester clubs. More than 1000 tablets, capsules, and powder doses were discarded in the amnesty bins. Tablets containing only MDMA (ecstasy) were found to be >94% and >84% of the total in London and Manchester, respectively. Although the quantities of tablets and powders recovered were different between London and Manchester, the proportions of the drugs were remarkably similar. The most common drugs found in powders in London and Manchester respectively were cocaine (29%, 40%), amphetamine (25%, 26%), ketamine (19%, 20%), and MDMA (19%, 11%).

Adolescent↗

PubMed2002

Primary standardization of assays for anticonvulsant drugs: comparison of accuracy and precision.

BACKGROUND: The accuracy and precision of methods for the measurement of the anticonvulsants phenytoin, phenobarbital, primidone, carbamazepine, ethosuximide, and valproate in human serum were assessed in 297 laboratories that were participants in the United Kingdom National External Quality Assessment Scheme (UKNEQAS). METHODS: We distributed lyophilized, serum-based materials containing low, medium, and high weighed-in concentrations of the drugs. The 297 participating laboratories received the materials on two occasions, 7 months apart. Expected concentrations were determined by gas chromatography or HPLC methods in five laboratories using serum-based NIST reference materials as calibrators. RESULTS: In general, bias was consistent across concentrations for a method but often differed in magnitude for different drugs. Bias ranged from -1.9% to 8.6% for phenytoin, -2.7% to 3.1% for phenobarbital, -2.7% to 0.5% for primidone, -8.6% to 0.3% for carbamazepine, -5.6% to 2.0% for ethosuximide, and -7.2% to 0.1% for valproate. Intralaboratory sources of imprecision significantly exceeded interlaboratory sources for many drug/method combinations. The mean CVs for intra- and interlaboratory errors for the different drugs were 6.3-7.8% and 3.3-4.2%, respectively. CONCLUSIONS: For these long-established and relatively high-concentration analytes, the closed analytical platforms generally performed no better than open systems or chromatography, where use of calibrators prepared in house predominated. To improve the accuracy of measurements, work is required principally by the manufacturers of immunoassays to ensure minimal calibration error and to eliminate batch-to-batch variability of reagents. Individual laboratories should concentrate on minimizing dispensing errors.

Anticonvulsants↗