Potentiation of ethanol in spatial memory deficits induced by some benzodiazepines.

Triazolam caused no significant increase in the total error at 0.05 and 0.1 mg/kg. However, at 0.2 mg/kg, it caused a significant increase in total error. Almost the same findings were observed with brotizolam and rilmazafone. That is, at 0.2 and 0.5 mg/kg of brotizolam, 0.5 and 1.0 mg/kg of rilmazafone caused no significant increase in the total error. However, brotizolam at 1.0 mg/kg and rilmazafone at 2.0 mg/kg caused a significant increase in total error. Triazolam (0.05 mg/kg) and ethanol (1.0 g/kg) showed no significant effect on the numbers of errors when used alone separately, but the simultaneous use of triazolam and ethanol caused a significant increase in total error. Almost the same findings were observed with the coadministration of brotizolam (0.2 mg/kg) or rilmazafone (0.5 mg/kg) with ethanol. These results clearly indicate that all the short-acting benzodiazepines used in the study showed potentiation by ethanol in spatial memory deficits in mice.

An in vitro approach to detect metabolite toxicity due to CYP3A4-dependent bioactivation of xenobiotics.

Many adverse drug reactions are caused by the cytochrome P450 (CYP) dependent activation of drugs into reactive metabolites. In order to reduce attrition due to metabolism-mediated toxicity and to improve safety of drug candidates, we developed two in vitro cell-based assays by combining an activating system (human CYP3A4) with target cells (HepG2 cells): in the first method we incubated microsomes containing cDNA-expressed CYP3A4 together with HepG2 cells; in the second approach HepG2 cells were transiently transfected with CYP3A4. In both assay systems, CYP3A4 catalyzed metabolism was found to be comparable to the high levels reported in hepatocytes. Both assay systems were used to study ten CYP3A4 substrates known for their potential to form metabolites that exhibit higher toxicity than the parent compounds. Several endpoints of toxicity were evaluated, and the measurement of MTT reduction and intracellular ATP levels were selected to assess cell viability. Results demonstrated that both assay systems are capable to metabolize the test compounds leading to increased toxicity, compared to their respective control systems. The co-incubation with the CYP3A4 inhibitor ketoconazole confirmed that the formation of reactive metabolites was CYP3A4 dependent. To further validate the functionality of the two assay systems, they were also used as a "detoxification system" using selected compounds that can be metabolized by CYP3A4 to metabolites less toxic than their parent compounds. These results show that both assay systems can be used to screen for metabolic activation, or de-activation, which may be useful as a rapid and relatively inexpensive in vitro assay for the prediction of CYP3A4 metabolism-mediated toxicity.

Sexual assault under benzodiazepine submission in a Paris suburb.

Sexual assaults under benzodiazepine submission have been described, since use of benzodiazepine enables non consensual sexual activity but rarely fully reported. An accurate evaluation of the phenomenon has seemed interesting. Files of 23 adult males and females examined at the Emergency Forensic Unit of an University Teaching Hospital near Paris were reviewed. All the victims had complained from sexual assault under drug submission, in the years 1996 and 1997. A complete examination for sexual assault was realised linked to clinical examination of drug intoxication. Every victim of rape under drug submission was sampled for urine screening (mean delay of 17.5 h after sexual assault) and blood alcohol level quantification. Urine was screened for benzodiazepines, cocaine, opiates and cannabinoids with qualitative immunochromatographic test. Traumatic lesions of sexual penetration were retrieved in 10 victims and sperm in 5. Clinical signs of benzodiazepine intoxication were retrieved in 12 out of 23 victims. Urine benzodiazepine screening was positive, over the cut-off values (300 ng/mL)when sampled less than 20 h after the facts. In 6 out of 23 victims, drugs of abuse and alcohol were associated to benzodiazepines. A reinforced attention can be brought to the rape under drug submission including the need of a proper examination and samplings shortly after the alleged facts to ascertain the diagnosis and to help the victim facing the Justice inquiry.

Cyclopyrrolones, unlike some benzodiazepines, do not induce physical dependence in mice.

In a model of physical dependence in mice, treatment with cyclopyrrolones such as zopiclone and suriclone (from 4 to 400 mg/kg/day), did not modify the sensitivity of the gamma-aminobutyric acid (GABA) receptor complex to the partial inverse agonist FG 7142 following their withdrawal, whereas sensitivity changes were observed after treatment and withdrawal from some benzodiazepines (e.g. lorazepam, diazepam, flunitrazepam and triazolam). These data suggest that, in contrast to some benzodiazepines, zopiclone and suriclone may not produce physical dependence.

Preclinical evaluation of behavioral deficits following hypnotic drug treatment.

Most hypnotic medications result in performance decrements, or "hangover effects," the morning after bedtime ingestion. However, the severity of hangover effects with new compounds is difficult to predict prior to clinical trials. This paper describes a preclinical procedure that is predictive of human hangover effects following bedtime ingestion of hypnotic medication. Four cebus monkeys were shaped to discriminate between two levers such that rapid responses following the cue light maximized the probability of reinforcement. Subsequently, performance was evaluated one hr (immediate condition) and 8 3/4 hr (delayed condition) after the administration of flurazepam, triazolam, pentobarbital and placebo. All drugs caused dose-dependent performance decrements in both conditions. Significantly higher doses of triazolam were required to impair performance during the delayed condition as compared to the immediate condition, but no such differences occurred with either flurazepam or pentobarbital. These findings parallel human data which indicate that sleep-inducing doses of flurazepam and many barbiturates, but not triazolam, cause performance decrements the morning after bedtime ingestion.

Morning amnestic effects of triazolam.

The effects of triazolam on immediate and delayed recall were evaluated in a double-blind placebo controlled study in 22 normal volunteers. Subjects were randomized to receive triazolam or a placebo as a single dose administered at bedtime. Immediate and delayed recall are tested using a modified version of the "Williams Word Memory Task" before and at .5, 8, and 14 hours after drug administration. Delayed recall was evaluated at the 14 hour time point for words recalled at the pre drug and 1/2 and 8 hour time points. No significant difference was noted between the triazolam and placebo group with regard to their immediate recall ability at any of the time points. The placebo group demonstrated no decrease in their delayed recall ability during any of the various post drug time points. However, when evaluating delayed recall in the triazolam group, a statistically significant (p less than .05) decrease compared to baseline in their recall ability of words remembered at the .5 and 8 hour time points was noted. This study suggests that triazolam's amnestic effect may extend beyond the duration of its generally accepted hypnotic efficacy. This is consistent with the hypothesis that amnestic potency among the benzodiazepines is related to benzodiazepine receptor binding affinity and lipophilicity.

Relative abuse liability of triazolam: experimental assessment in animals and humans.

The abuse liability of a drug is a positive, interactive function of the reinforcing and adverse effects of the drug. The relative abuse liability of the hypnotic benzodiazepine, triazolam, has been controversial. This paper reviews animal and human studies bearing on its relative abuse liability, including data on pharmacological profile, reinforcing effects, liking, speed of onset, discriminative stimulus effects, subjective effects, physiological dependence, rebound and early morning insomnia, drug produced anxiety, lethality in overdose, psychomotor impairment, interactions with ethanol, anterograde amnesia, impaired awareness of drug effect, and other psychiatric and behavioral disturbances. It is concluded that the abuse liability of triazolam is less than that of the intermediate duration barbiturates such as pentobarbital. Although there are considerable data indicating similarities of triazolam to other benzodiazepines, there is also substantial speculation among clinical investigators and some limited data suggesting that the abuse liability of triazolam is greater than that of a variety of other benzodiazepines, and virtually no credible data or speculation that it is less. Further research will be necessary to clarify definitively the abuse liability of triazolam relative to other benzodiazepines.