psychiatric drug poisoning

Question 1

anticholinergic syndrome

Answer 1

A term used to refer to signs and symptoms resulting from the toxic effects of anticholinergic agents (e.g., atropine, scopolamine), including hyperthermia, tachycardia, delirium, mydriasis, hot and dry skin, ileus, and urinary retention.

Question 2

serotonin syndrome

Answer 2

A potentially life-threatening condition caused by serotonergic overactivity. Clinical features include the classic triad of neuromuscular excitability, which can lead to hyperthermia; autonomic dysfunction; and altered mental status. Severe serotonin syndrome can cause rhabdomyolysis, seizures, and death.

Question 3

morbidity for antidepressant overdose is greatest for which drug classes

Answer 3

TCAs and MAOIs

Question 4

activated charcoal

Answer 4

ecommended for the majority of recent ingestions in patients who are alert and/or have a protected airway.

Question 5

you should consider sodium bicarbonate for

Answer 5

TCA, SNRI, and bupropion overdose with QRS prolongation or ventricular arrhythmias.

Question 6

clinical features of TCA overdose

Answer 6

Anticholinergic syndrome (e.g., hyperthermia, delirium, ileus, urinary retention)
Cardiotoxicity: hypotension, tachycardia, arrhythmias
Neurotoxicity
Altered mental status (e.g., lethargy, coma)
Seizures
Respiratory depression
Myoclonus
Extrapyramidal syndrome

Question 7

likely ECG findings for TCA poisoning

Answer 7

Sinus tachycardia
Prolonged QRS interval: QRS interval >100ms is associated with severe symptoms eg. seizures, ventricular dysrhythmias
Prolonged QTc interval
Terminal R wave in aVR
Ventricular and supraventricular arrhythmias

Question 8

toxicological and lab studies for TCA poisoning

Answer 8

serum TCA levels
- correlate poorly with poisoning severity
urine drug screens
electrolytes
VBG for acidemia

Question 9

initial management of TCA poisoning

Answer 9

A-E
manage agitation and seizures with benzodiazepines
provide supportive care eg. fluid resuscitation, treat hypoglycaemia, electrolyte repletion
initiate continuous cardiac monitoring
consider GI decontamination with activated charcoal or gastric lavage

Question 10

how to manage TCA poisoning cases with QRS interval > 100ms

Answer 10

administer hypertonic sodium bicarbonate
dosing is based on expert opinion
repeat until cardiac abnormality resolves
obtain ECGs to monitor response to treatment

Question 11

how to manage TCA overdose with toxic seizures

Answer 11

treat with benzos
phenytoin is contraindicated as it can worsen cardiac toxicity

Question 12

are SSRI doses usually fatal

Answer 12

Selective serotonin reuptake inhibitors (SSRIs) have a high therapeutic index and thus overdoses are well-tolerated and rarely fatal.

Question 13

clinical presentation of SSRI overdose

Answer 13

Common: drowsiness, tremor, nausea, vomiting
Rare: seizures, symptoms of serotonin syndrome

Question 14

ECG findings of SSRI overdose

Answer 14

Sinus tachycardia
Prolonged QTc interval
Wide QRS complex

Question 15

can you do toxicological studies for SSRIs

Answer 15

Serum SSRI levels are not available at most hospitals.
Urine drug screens usually do not assess for SSRIs.

Question 16

clinical features of SNRI overdose

Answer 16

Hyperadrenergic symptoms (e.g., tachycardia, hypertension)
Seizures
Symptoms of rhabdomyolysis (e.g., myalgia, generalized weakness)
Symptoms of serotonin syndrome
Hypotension due to acute heart failure (in massive overdose)

Question 17

toxicological and lab studies for SNRI overdose

Answer 17

Serum SNRI levels are not available at most hospitals.
Urine drug screens usually do not assess for SNRIs.
Laboratory studies: CPK level to evaluate for rhabdomyolysis

Question 18

clinical features of MAOI overdose

Answer 18

Hyperadrenergic symptoms (early)
Hypotension (late) [4]
Hyperthermia
Seizures
Symptoms of rhabdomyolysis (e.g., myalgia, generalized weakness)

Question 19

what causes hyperadrenergic crisis in people who take MAOIs

Answer 19

Consumption of tyramine-containing foods
Tyramine is found in red wine, aged cheese, liver, smoked meat, and yeast extract.
Exposure to other sympathomimetics (e.g., cocaine)

Question 20

symptoms of hyperadrenergic crisis

Answer 20

tachycardia, hypertension, flushing, diaphoresis

Question 21

patients taking selegiline will test positive on drug screening for

Answer 21

Patients taking selegiline will test positive for methamphetamine on drug screening, as methamphetamine is a metabolite of selegiline.

Question 22

lab studies for MAOI poisoning

Answer 22

CPK level: to evaluate for rhabdomyolysis
Troponin level: to evaluate for cardiac ischemia

Question 23

management for MAOI instability

Answer 23

A-E assessment
manage autonomic instability: hyper or hypotension
manage hyperthermia: initiate cooling measures such as cooling blankets or ice packs, cold IV fluids, ice baths
manage agitation ad toxic seizures using benzodiazepines
manage serotonin syndrome

Question 24

classic triad of serotonin syndrome

Answer 24

To differentiate between serotonin syndrome and other drug-induced hyperthermia conditions, remember that only SErotonin Shakes your Extremities (myoclonus and hyperreflexia, mostly of the lower limbs).

Question 25

symptom specific management for agitation and excessive muscle activity in serotonin syndrome

Answer 25

treat with benzodiazepines

Question 26

treatment for refractory cases of serotonin syndrome

Answer 26

Consider treatment with 5-HT2A receptor antagonists: cyproheptadine if Temperature > 41.1°C: Sedate, paralyze, and intubate patients. Use nondepolarizing NMJ blocker as paralytic agent for intubation, e.g., rocuronium. Avoid depolarizing NMJ blockers (e.g., succinylcholine), as, in severe cases of serotonin syndrome, they can cause hyperkalemia, adding to the risk of hyperkalemia and cardiac arrhythmia from rhabdomyolysis.

Question 27

the treatment of lithium toxicity in patients with an altered mental status, seizures, and/or life-threatening arrhythmias

Answer 27

haemodialysis