Pharmacodynamic effects of aripiprazole and ziprasidone with respect to p-glycoprotein substrate properties.

INTRODUCTION: Aripiprazole, an atypical antipsychotic drug with mixed antagonism and agonism on dopamine D2 and serotonin receptors, is a substrate of the efflux transporter P-glycoprotein (P-gp). Here we tested the pharmacodynamic consequences of these properties in a P-gp deficient mouse model by studying the effects of aripiprazole and of ziprasidone on motor coordination. METHODS: The motor behaviour of wild-type (WT) and P-gp deficient [abcb1ab(-/-)] mice was investigated on a RotaRod. Mice received acute injections of either aripirazole or ziprasidone. For comparison, the dopamine receptor antagonist haloperidol and serotonin receptor ligands buspirone and ketanserin were also applied. RESULTS: Pharmacokinetic analyses revealed P-gp activity for aripiprazole and ziprasidone. This was indicated by 3.1- and 1.9-fold higher ratios of brain to plasma concentrations of drugs in knock-out to WT animals. Acute doses of ariprazole or ziprasidone impaired motor behaviour on the RotaRod. Effects were similar after injection of haloperidol, whereas the serotonin receptor ligands buspirone and ketanserin enhanced RotaRod performance. Genotype dependent differences of motor performance were found for aripiprazole but not for ziprasidone. DISCUSSION: Evidence was given that P-gp substrate properties have pharmacodynamic consequences for aripiprazole but not for ziprasidone and thus affect dopamine receptor related motor behaviour.

Evaluation of two immunoassay procedures for drug testing in hair samples.

A preliminary initial enzyme-linked immunosorbent assay (LUCIO-Direct ELISA kit) and a preliminary DRI enzyme immunoassay were evaluated for drug detection in head hair with respect to lowered cutoff values recommended in Germany for the control of abstinence in cases of re-granting of drivers' licences. Following drug classes were included: cannabinoids, opiates, cocaine like substances, amphetamine, methamphetamine (and methylenedioxyamphetamines), methadone, and benzodiazepines. 759 analyses were performed using LUCIO-Direct ELISA kits and 936 analyses using DRI enzyme immunoassay tests. Sample size for each drug group and immunoassay test reached from 74 to 178. The LUCIO-Direct ELISA kit revealed a sensitivity of 91% for amphetamine up to 98% for methadone (methamphetamine 92%, cocaine 94%, opiates 94%, benzodiazepines 96%) and values of specificity of 72% for methadone up to 89% for amphetamine and benzodiazepines. The test was not useful for a preliminary screening for tetrahydrocannabinol (sensitivity of 65%) in consideration of a suggested cutoff of 0.02 ng/mg. The DRI enzyme immunoassay test was only useful for morphine and cocaine testing at low recommended new cutoff values (0.1 ng/mg) revealing sensitivities of 94% and 99%, respectively.

An uncommon case of a suicide with inhalation of hydrogen cyanide.

An uncommon suicide by oral ingestion of potassium cyanide salts and contemporaneous inhalation of hydrogen cyanide is presented. A 48-year-old tradesman was found dead sitting in his car. A penetrating odor of bitter almonds was noticed when opening the doors. A camping stove and a cooking pot containing large amounts of dark blue crystals were found in the footwell of the car. White powder adhered to his fingers and to the area around the mouth. Furthermore bottles containing potassium ferrocyanide and different kinds of acid and leach were found in the car together with internet information about, e.g. potassium ferrocyanide and potassium cyanide. At autopsy hemorrhages and erosions of the mucosa of the respiratory tract, esophagus and stomach were found. Concentrations of cyanide were 0.2mg/l in stomach contents, 0.96mg/kg in brain tissue, 2.79mg/kg in lungs, and 5.3mg/l in blood. The white and toxic powder potassium cyanide was formed by heating of the yellow crystals of potassium ferrocyanide on the camping stove. This powder was probably ingested orally. Addition of acid converted the salt into the highly toxic gas hydrogen cyanide. Oxidation with atmospheric oxygen built the dark blue ferrous compound Prussian blue. This case report of a person who was not familiar with chemicals demonstrates the acquisition of professional information via the internet, enabling a suicide with a complex procedure.