Psychopharmacology
October 30, 2010
Johannes G. Ramaekers, Eef L. Theunissen, Marjolein de Brouwer et al.
168 citations
Heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive tasks, but they do not develop cross-tolerance to the impairing effects of alcohol. In a double-blind study, 21 heavy cannabis users received alcohol at three levels (targeting blood alcohol concentrations of 0, 0.5, and 0.7 mg/ml) and smoked a THC cigarette (400 μg/kg) 3 hours after drinking began. Alcohol alone impaired performance on tests of perceptual motor control, divided attention, and motor inhibition, while THC alone generally did not affect performance. However, combining THC and alcohol produced greater impairments in divided attention than alcohol alone, indicating that alcohol can potentiate THC effects in tolerant users.
Therapeutic Drug Monitoring
April 1, 2002
Manfred R. Moeller, Thomas Kræmer
98 citations
Driving under the influence of drugs is a growing concern in industrialized countries, contributing to road accidents. In forensic toxicology, the increasing number of blood samples for drug testing results from zero-tolerance laws and better-trained police officers. This review describes procedures for detecting amphetamine, methamphetamine, MDMA, MDEA, MDA, cannabinoids (THC and its metabolites), cocaine and its metabolites, opiates (heroin, 6-monoacetylmorphine, morphine, codeine), methadone, GHB, LSD, PCP, and psilocybin/psilocin in whole blood, plasma, and serum. Sensitive immunologic screening methods are available for many analytes. Gas chromatography-mass spectrometry remains the gold standard for confirmatory analysis, with liquid chromatography-mass spectrometry also included. Two tables summarize basic data on biosample, internal standard, workup, column, mobile phase, detection mode, and validation.
Psychopharmacology
October 5, 2011
Eef L. Theunissen, Gerold F. Kauert, Stefan W. Toennes et al.
82 citations
Heavy cannabis users develop tolerance to some impairing effects of cannabis, observable both in behavior and in brain electrical activity. In a double-blind, placebo-controlled crossover study, 12 occasional and 12 heavy cannabis users smoked a joint containing either 0 or 500 μg/kg body weight THC. During a divided attention task, THC reduced P100 amplitude in occasional users but not in heavy users, indicating tolerance at the neural level. P300 amplitude decreased in both groups. Performance on the stop signal task was impaired in both groups after THC, while divided attention task performance was impaired only in occasional users. Tolerance was evident in event-related potentials, suggesting it is not solely due to behavioral compensation.