Short-acting barbiturate overdosage. Correlation of intoxication score with serum barbiturate concentration

Deliberate Self-poisoning with a Lethal Dose of Pentobarbital with Confirmatory Serum Drug Concentrations: Survival After Cardiac Arrest with Supportive Care

INTRODUCTION

Pentobarbital (PB) is a euthanasia drug in doses of 2 to 10 grams, causing death within 15-30 minutes. We report a case of recovery from lethal pentobarbital deliberate self-poisoning with confirmatory serum drug concentrations.

CASE REPORT

A 45-year-old male purchased 20 grams of PB powder over the Internet. He ingested this powder and then alerted his mother 10 minutes later. She found him unresponsive and commenced cardiopulmonary resuscitation (CPR). Within 20 minutes of ingestion, emergency medical services arrived and initiated advanced life support. On arrival to the emergency department, heart rate was 116 bpm, BP 117/62 mmHg, on an epinephrine infusion. He was hypotonic and hypothermic, with absent brainstem reflexes. ECG and CT brain were normal. Activated charcoal was administered and he was admitted to ICU. He remained comatose with absent brainstem reflexes until day 5. Cerebral angiogram on day 3 was normal. Qualitative urine testing detected pentobarbital suggesting ongoing drug effects as the cause of coma. He was extubated on day 10, eventually making a full recovery. At 2.5 hours post-ingestion, PB concentration was 112 mg/L; PB peaked at 116 mg/L at 29 hours; PB was 2 mg/L at 190 hours and undetectable over 200 hours post-ingestion.

DISCUSSION

Average PB concentration in fatalities is reported around 30 mg/L. This patient survived higher serum concentrations with early CPR and prolonged cardiorespiratory support in the ICU. Assessment of brainstem death should be deferred until PB has been adequately eliminated.

Relative toxicity of benzodiazepines in overdose

OBJECTIVE

To assess the sedative effects in overdose of temazepam and oxazepam compared with other benzodiazepines to determine if this explains reported differences in fatal toxicity.

DESIGN

Cohort study of patients admitted with benzodiazepine poisoning.

SETTING

Newcastle, Australia.

SUBJECTS

303 patients who had ingested benzodiazepine alone or in combination with alcohol and presented to a general hospital which served a well defined geographical area.

MAIN OUTCOME MEASURES

Degree of sedation: Glasgow coma score, McCarron Score, and whether patients were stuporose or comatose.

RESULTS

Oxazepam produced less and temazepam more sedation than other benzodiazepines. Unadjusted odds ratios for coma with oxazepam and temazepam compared with other benzodiazepines were 0.0 (95% confidence interval 0.0 to 0.85) and 1.86 (0.68 to 4.77) respectively, chi 2 = 7.08, 2df, P = 0.03. After adjustment for potentially confounding effects of age, dose ingested, and coingestion of alcohol, the odds ratios were 0.22 (0.0 to 1.43) for oxazepam and 1.94 (0.57 to 6.23) for temazepam. Similar results were obtained for other measures of sedation.

CONCLUSIONS

These results were in accordance with fatal toxicity indices derived from coroners' data on mortality and rates of prescription. The relative safety of benzodiazepines in overdose should be a consideration when they are prescribed.