A Patient taking overdose of sleeping pills By Dr WL Yip, AED, QMH

Case report F / 28, good past health Taken 30tabs of ‘sleeping pills’ suicidal attempt Drowsy, and brought to private hospital by friends within 1 hour

Clinical findings GCS E4 V1 M5 10/15 Pupil E&R 2mm ECG sinus tachycardia 142/min PR 145, QRS 81, QTc 339

ECG

Management Gastric lavage Activated charcoal 50gm Witnessed generalized seizure (last ~30sec) 1 hour after ingestion, resolved spontaneously Transferred to AED after stablized (within 2 hours after ingestion)

Progress in AED BP 130/65, P 130 Temp 36.5 H’stix 6.6 GCS E4 V1 M5 10/15 ECG sinus tachycardia 123/min PR 144, QRS 82, QTc 389 Admit medical

Progress in ward Stable all along Blood test unremarkable Toxicology: BDZs, diphenhydramine Fully conscious next day Seen by psychiatrist: adjustment disorder Discharged home

Unisom SleepGel Contain diphenhydramine 50mg in each tablet

Diphenhydramine overdose First-generation antihistamines H1-blockers Ethanolamine Dose-dependent toxicity Ingestion >1gm at risk developing severe symptoms

Anticholinergic syndromes Peripheral (dry mucous membrane, hot, dry and flushed skin, peripheral vasodilation, dilated pupil, blurred vision, urinary retention, intestinal ileus, sinus tachycardia) Central (disorientation, agitation)

Seizures Not common Generally short-lived May be prolonged / repeated if large dose taken

Other CNS effects Sedation Catatonic stupor (highly specific) Acute extrapyramidal movement disorders Anxiety Toxic psychosis

Cardiac toxicity Sinus tachycardia Quinidine-like conduction abnormalities Slow sodium channels conduction result in decreased conduction and contractility Associated prolonged QT

Other rare features Rhabdomyolysis Hyperthermia Ventricular tachycardia

Management ABC Activated charcoal Gastric lavage –Consider even after 1 hour since diphenhydramine decreases your gut motility

Treatment of agitation Due to anti-cholinergic effects Benzodiazepines Physostigmine (if no conduction disturbance)

Cardiovascular toxicity No treatment for sinus tachycardia Intravenous sodium bicarbonate for conduction abnormalities

Prognosis Most recovered with supportive treatment and observation

Learning Points We should consider the potential risk of aspiration if we perform GL in patient with impaired conscious level and at risk of developing convulsion Airway protection should be ensured Precautions and potential advantages in using physostigmine for the treatment of anti- cholinergic poisoning (Burns et al, Ann Emerg Med. April 2000;35: )

Thank you