Intoxication by benzodiazepines: studies with diazepam used as a model compound suggest an interaction with red blood cells calmodulin dependent (Ca2+, Mg2+) ATPase

20 patients under therapy or intoxicated by benzodiazepines were studied. A partial inhibition of (Ca2+, Mg2+)ATPase on 'B' membranes (CaM rich membranes) was evident in 2 cases. A total inhibition of (Ca2+, Mg2+) ATPase on both 'B' and 'A' (CaM depleted) membranes was noted in 1 case: the patient who was severely intoxicated had pronounced hemolysis. As an attempt to elucidate the mechanism of this action, the effect of diazepam chosen as model compound was studied on 'B' and 'A' membranes prepared from normal human RBC previously incubated with diazepam. A high concentration of diazepam, corresponding to a 20-fold therapeutic level results in a 50% inhibition of the maximal activity of the enzyme on 'B' membranes. It may be speculated from these experiments that the effect of high concentration of benzodiazepines on CaM dependent (Ca2+, Mg2+) ATPase leads to accelerated RBC destruction.

Physostigmine treatment in various drug-induced intoxications

Eighty three patients who were comatose or confused due to intoxication with various drugs were treated repeatedly with 2 mg doses of physostigmine until maximal neurological improvement or side effects appeared. During therapy special attention was paid to the level of consciousness (Glasgow coma score) and to the general cardiorespiratory state. According to the main drug ingested the patients were divided into the following groups: anticholinergic (35 patients), benzodiazepine (12 patients), non-anticholinergic (22 patients) and unclassified (14 patients). The best antidotal effect of physostigmine was in the anticholinergic group (91%) and in the benzodiazepine group (67%), whereas in the non-anticholinergic and in the unclassified group only 32% and 50% of the patients, respectively, showed any improvement in mental condition during the physostigmine application. After the antidotal therapy, relapses occurred in 21/32 patients in the anticholinergic group, whereas the figures for the benzodiazepine and the non-anticholinergic groups were only 2/8 and 0/7. Major side effects of physostigmine were noted in two patients, one had ventricular extrasystoles and the other an acute grand mal attack. In this series the diagnostic value of physostigmine was considerable, but the therapeutic benefit was limited.

Application of radioreceptor assay of benzodiazepines for toxicology

A radioreceptor assay (RRA) for determining benzodiazepines (BZ) has been developed and applied to toxicological analysis of serum from 21 patients with acute BZ overdosage. The method was sensitive (e.g., lorazepam 17 nM, diazepam 41 nM), and specific for pharmacologically active BZ derivatives. The reproducibility of the results was good (intra-assay variation less than 8%, inter-assay variation less than 10%). Concentrations measured by the RRA showed a good correlation with those obtained by gas-liquid chromatographic analysis of the same samples. The quantitative results represent the sum of one or several parent substances and all biologically active metabolites, in proportion to their receptor binding affinities.

Effect of ethanol ingestion on outcome of drug overdose

It was traditionally assumed that ethanol, as part of an intentional drug overdose, will increase morbidity and mortality. The authors prospectively studied the effect of ethanol on the outcome of intentional drug overdose in 468 adults, 196 of whom required hospital admission. Ethanol was detected in significantly fewer patients who required admission. Ethanol ingestion was not related to coma, impaired vital signs or mortality. Indeed, the duration of coma was significantly shorter in patients in whom ethanol was detected, but this group had a lesser incidence of multiple drug and nonbarbiturate hypnotic ingestion and a greater incidence of chronic ethanol use. Thus, it seems that ethanol is not associated with a worse clinical course if the drug overdose patient reaches medical care before an irreversible event.

Evaluation of the EMIT Tox enzyme immunoassay for toxicological analysis of benzodiazepines in serum

Immunoenzymatic test, EMIT Tox, proposed for qualitative and semi quantitative determination of toxicological levels of benzodiazepines in serum is compared with gas chromatography. When used for qualitative purposes in 102 sera, the EMIT Tox test gave 5% error. In semi quantitative determinations, the EMIT Tox test was applied to 139 sera with one or more of the three benzodiazepines (oxazepam, desmethyldiazepam, diazepam), showing a significant correlation with levels measured by gas chromatography; but the EMIT Tox test frequently yields values too low for elevated oxazepam and desmethyldiazepam concentrations.

Self-poisoning with drugs: a 3 1/2-year study in Newcastle, NSW

This is a review of 963 cases of self-poisoning with drugs (8.5% of all medical emergencies) treated in the three major Newcastle hospitals over a 3 1/2-year period. The number of patients admitted rose from 243 (July 1976 to June 1977) to 326 (January to December, 1979)-an overall increase of 34%. The most common drugs used were benzodiazepines (34.9% of cases); barbiturates (11.2%); tricyclic depressants (9.2%); paracetamol (8.1%) and phenothiazines (6.2%). In four of 134 cases involving barbiturates, phenobarbitone had been used as part of an anticonvulsant regimen. Six patients died in hospital and 31 who committed suicide with drugs were not admitted to the hospital, but were investigated by the Regional Forensic Pathologist.

Dialysability of benzodiazepines by haemodialysis and controlled sequential ultrafiltration (CSU) in vitro

The efficacy of haemodialysis and controlled sequential ultrafiltration (CSU) for the elimination of three hypnotic and 6 benzodiazepine drugs was compared in vitro. In comparison to haemodialysis the efficacy of ultrafiltration by CSU was poor, as the mean per cent of CSU/haemodialysis (mg/hr) for 5 benzodiazepines was only 0.6-4.0% and for three hypnotics, phenobarbital 3.4%, pyrithyldione 8.2% and glutethimide 2.5% of the haemodialysis values. In haemodialysis in vitro phenobarbital, pyrithyldione, glutethimide and chlordiazepoxide were significantly and markedly more dialysable than 5 other benzodiazepines. The mean clearance of six benzodiazepine derivatives was about 2 to 3 times higher at blood flow rates of 200 ml/min. than 100 ml/min. In CSU experiments in vitro it was possible to remove approximately (as the mean percent of the initial dose) only the amount of five benzodiazepines corresponding to the per cent of the protein unbound fraction in the plasma (correlation r = 0.975, P less than 0.01). Only low amounts of three hypnotics, especially glutethimide, were removed by CSU in vitro.

Effects of physostigmine on benzodiazepine toxicity

The interactions between physostigmine and chlordiazepoxide, diazepam, flurazepam were experimentally evaluated in rats and mice by the following test: loss of righting reflex (LRR), acute toxicity, cardiovascular toxicity and EEG pattern. Physostigmine did not modify the duration of LRR produced by chlordiazepoxide. Conversely, the recovery after diazepam was significantly longer. The LD50 of diazepam and chlordiazepoxide were not modified by physostigmine administration, but that of flurazepam was significantly decreased. Heart rate and blood pressure did not change significantly with physostigmine pre-treatment. However, the total lethal dose was lowered for chlordiazepoxide and flurazepam. Only the reversal by physostigmine of the EEG pattern due to benzodiazepines, offers experimental support to the claimed usefulness of physostigmine in benzodiazepine intoxication in humans. Furthermore, the potentiation of flurazepam toxicity must be taken into account in the debate concerning the clinical advantages of physostigmine.

Thin-layer chromatography, with fluorescence detection, of benzodiazepines and tricyclic antidepressants in serum from emergency-room patients

We describe a rapid, sensitive procedure for detecting benzodiazepines and tricyclic antidepressants in serum. After the compounds are adsorbed on charcoal and eluted with an organic solvent mixture, the drugs are thin-layer chromatographed and detected by their fluorescence. Because it is so fast and easy (turn-around time of about 1 h), the method can be used for emergency toxicology screening. An analysis requires 1.0 mL of serum, and the limit of detection for each of the drugs is about 0.75 mg/L. The procedure is sensitive enough to allow the use of serum instead of urine for the detection of these drugs, because serum has certain advantages over urine as the sample and better reflects the state of the patient's toxicity.

Acute and chronic drug abuse emergencies in Metropolitan Toronto

From 3,548 drug overdose or abuse cases presenting at 21 Metropolitan Toronto hospitals' Emergency departments, data concerning demographic and medical characteristics, investigative and management procedures, drug analysis services, and disposition of patients were collected. Of the 3,548 cases, 2,723 (77%) were acute overdose and 816 (23%) were drug abuse. Drug overdose was more common than drug abuse for both sexes, but was more characteristic of females. The drugs most frequently alleged ingested were benzodiazepines (34%), ethanol (32%), salicylates (16%), and barbiturates (14%). The frequency with which particular classes of drugs are alleged in overdose corresponds closely to the frequency of prescribing these drugs in Ontario.

Benzodiazepine overdosage: plasma concentrations and clinical outcome

Plasma concentrations and their relation to clinical outcome were evaluated in 21 patients who reached emergency treatment facilities following acute overdosage with benzodiazepine derivatives. Diazepam was implicated in 18 of the 21 cases, with plasma diazepam levels ranging from 585-8,635 ng/ml. In four cases of overdosage with diazepam alone, patients were minimally sedated and were discharged within 24 h, despite diazepam doses as high as 750 mg and plasma levels as high as 4,792 ng/ml. However, concurrent ingestion of diazepam together with other central depressant drugs (such as ethanol, barbiturates, analgesics, or tricyclic antidepressants) produced serious intoxication in 5 of the remaining 14 patients, regardless of the diazepam dosage or plasma concentration. Thus the severity of poisoning following benzodiazepine overdosage is determined largely by co-ingestion of other central depressants rather than the amount of benzodiazepine ingested or its concentration in plasma.

Changing pattern of drugs used for self-poisoning

In 1967-76 the annual number of admissions to a poisoning treatment centre rose from 964 to 2134. The proportion of admissions caused by taking barbiturate hypnotics and methaqualone fell considerably while that caused by taking benzodiazepines and tricyclic antidepressants increased. As a result the proportion of patients admitted unconscious fell from 23% to 15%. The declining contributions of barbiturates and methaqualone and increased importance of tricyclic antidepressants were significant in all grades of coma. The change in drugs taken, however, has not yet reduced the percentage of unconscious patients needing endotracheal intubation or assisted ventilation, and hypothermia remains as common. Only hypotension has become less frequent as antidepressants replace barbiturates as the main cause of drug-induced coma. The use of salicylates for self-poisoning is declining slowly, and paracetamol poisoning is now as common.

Child-resistant packaging and accidental child poisoning

From Jan. 1, 1976, all children's aspirin and paracetamol preparations were required to be presented either in child-resistant containers or in dark-tinted unit packaging. In two areas hospital admissions of children under 5 years for accidental ingestion of aspirin were monitored from 1974 to 1976 to assess the effectiveness of this measure. There was a highly significant fall in admissions for accidental salicylate poisoning (129 in 1975 to 48 in 1976, P less than 0-001). Admissions fell throughout 1976 as old stocks were used up. Further analysis of cases in one area suggests that the fall in admissions from accidental salicylate poisoning was due to the packaging of one preparation of junior aspirin in child-resistant containers.

The extraction and analysis of benzodiazepines in tissues by enzymic digestion and high-performance liquid chromatography

A simple, rapid and sensitive method is described for the analysis of unchanged benzodiazepine drugs and their metabolites, in human and animal tissues, using the proteolytic enzyme subtilisin Carlsberg followed by reverse-phase liquid chromatography. The enzymic digestion yields far higher recoveries than conventional extraction methods, while the liquid chromatogrpahic analysis allows the rapid separation and detection of nanogram quantities of these drugs without the need for elaborate "clean-up" procedures.