toxicology

Question 1

What are the initial non-pharmacologic and pharmacologic priorities in treating a patient with an overdose?

Answer 1

ABC management:
Airway, breathing, circulation
Oxygenation
Vital signs
IV access

Question 2

What is the formula for calculating anion gap?

Answer 2

(Na+ + K+) - (Cl- + HCO3-)

Question 3

What indicates the presence of an anion gap?

Answer 3

Greater than 14

Question 4

Fill in the blank: Activated charcoal can prevent _______ of substances.

Answer 4

absorption

Question 5

What is the dosing for activated charcoal in adults?

Answer 5

1-2 gm/kg ABW or 50-100 gm

Question 6

What is the mechanism of action for sodium bicarbonate as an antidote for salicylate toxicity?

Answer 6

Urine alkalinization

Question 7

What is the indication for administering sodium bicarbonate in salicylate toxicity?

Answer 7

Serum salicylate level > 30 mg/dL, anion gap metabolic acidosis, altered mental status

Question 8

What is the dosing for sodium bicarbonate in salicylate toxicity?

Answer 8

1 to 2 mEq/kg (50 to 100 mEq) IV push over 1 to 2 minutes

Question 9

What are the signs and symptoms of sedative toxicity?

Answer 9

Respiratory depression, altered mental status, bradycardia

Question 10

What is the mechanism of action of flumazenil?

Answer 10

Competes with benzodiazepines at the benzodiazepine binding site of the GABA complex

Question 11

What are the symptoms of serotonin syndrome?

Answer 11

• Altered mental status
• Autonomic instability
• Neuromuscular abnormalities

Question 12

What is the primary treatment for serotonin syndrome?

Answer 12

• D/C offending agent
• Benzodiazepines
• Aggressive cooling
• Cyproheptadine

Question 13

What are the non-cardiac signs of digoxin toxicity?

Answer 13

• Nausea/vomiting
• Abdominal pain
• Anorexia
• Confusion
• Vision changes

Question 14

What is the antidote for digoxin toxicity?

Answer 14

Digoxin Immune Fab (Digibind)

Question 15

What is the indication for administering Digibind?

Answer 15

• Ventricular arrhythmias
• Bradycardia/2nd or 3rd degree heart block not responsive to atropine
• Hyperkalemia with signs/symptoms of toxicity

Question 16

True or False: Hemodialysis is effective for digoxin toxicity.

Answer 16

False

Question 17

What condition is not responsive to atropine?

Answer 17

3rd degree heart block

This is a type of heart block that can be severe and often requires immediate medical intervention.

Question 18

What serum digoxin concentration indicates toxicity?

Answer 18

Serum digoxin concentrations > 10-15 ng/mL drawn at least 6 hours after time of ingestion

This concentration is critical for assessing potential toxicity.

Question 19

What is the ingestion threshold for digoxin in adults that indicates potential toxicity?

Answer 19

> 10 mg

Ingestion of digoxin can lead to serious toxicity, especially at higher doses.

Question 20

What is the ingestion threshold for digoxin in children that indicates potential toxicity?

Answer 20

> 4 mg

Children are particularly vulnerable to digoxin toxicity at lower doses.

Question 21

What is the approximate binding capacity of each vial of Digibind®?

Answer 21

Each vial binds approximately 0.5 mg of digoxin

This is important for calculating the necessary dose based on digoxin ingestion.

Question 22

How is total body load (TBL) of digoxin calculated?

Answer 22

TBL = mg digoxin ingested x 0.8

This formula helps determine the severity of digoxin ingestion.

Question 23

What is the primary management approach for CCB and BB toxicity?

Answer 23

ABC management

This includes airway, breathing, and circulation support.

Question 24

What antidotes may be administered for CCB and BB toxicity?

Answer 24

• Atropine
• Calcium
• Vasopressor Therapy
• Glucagon
• High Dose Insulin Therapy
• Lipid Emulsion Therapy

Each antidote has specific indications and mechanisms of action.

Question 25

What is the mechanism of action of atropine?

Answer 25

Blocks parasympathetic activity to increase heart rate ## Footnote This can be particularly useful in bradycardia.

Question 26

What is the dosing range for atropine in emergency settings?

Answer 26

0.5-1 mg IV push, maximum dose: 3 mg ## Footnote Atropine is readily available but may not be effective in all overdoses.

Question 27

What does calcium do in the context of CCB toxicity?

Answer 27

Opens calcium channels and promotes release of calcium from sarcoplasmic reticulum resulting in myocardial contractility ## Footnote Calcium is crucial in reversing the effects of CCB toxicity.

Question 28

What is the dosing for calcium chloride in emergencies?

Answer 28

Calcium chloride 1-2 g IV q 10-20 mins ## Footnote Calcium chloride is more effective in acute settings.

Question 29

What is the mechanism of action of glucagon in overdose management?

Answer 29

Stimulates contractility by bypassing beta receptors and binding to Gs receptors ## Footnote This mechanism is vital in cases of beta-blocker overdose.

Question 30

What is the dosing for glucagon in adults?

Answer 30

3-10 mg IV bolus ## Footnote Dosing may need adjustment based on the patient's response.

Question 31

What is the primary concern with iron toxicity?

Answer 31

Absorption of iron into tissue ## Footnote This can lead to serious complications, including organ damage.

Question 32

What is the antidote for iron toxicity?

Answer 32

Deferoxamine (Desferal®) ## Footnote This medication chelates iron and enhances renal elimination.

Question 33

What is the dosing for deferoxamine in cases of severe iron poisoning?

Answer 33

Start at 15 mg/kg/hour, may increase to 45 mg/kg/hour ## Footnote Dosing adjustments may be necessary based on patient response.

Question 34

What is the common dose for whole bowel irrigation in children aged 9 months to 6 years?

Answer 34

500 mL/hr ## Footnote This method helps in the management of iron overdose.

Question 35

What are the common pediatric exposures leading to toxicity?

Answer 35

* Household cleaning substances (10.1%) * Analgesics (9.13%) * Cosmetics/personal care products (9.1%) * Foreign bodies/toys (8.03%) * Dietary supplements/herbals/homeopathic (6.88%) ## Footnote Awareness of these exposures can aid in prevention and education.

Question 36

signs and symptoms of salicylate toxicity

Answer 36

- mixed acid/base disorder - increased anion gap and hyperventilation - electrolyte disturbances (hypokalemia and hypo/hypernatremia)

Question 37

toxic concentrations of salicylates

Answer 37

Analgesic properties: 10-15 mg/dL Anti-inflammatory properties: 15-20 mg/dL Mild toxicity: >30 mg/dL Tinnitus, dizziness Severe toxicity: >80 mg/dL AMS, breathing difficulty

Question 38

s/sx of salicylate toxicity

Answer 38

N/V Tinnitus and diaphoresis Decreased GI motility AMS Seizures Hyperventilation

Question 39

s/sx of sedative toxicity

Answer 39

CNS depression Respiratory depression Bradycardia Hypotension

Question 40

s/sx of TCA toxicity

Answer 40

AMS Hypotension Tachycardia Prolonged QRS >100 msec → increased risk of seizure activity >150 msec → increased risk of cardiac arrhythmias Seizures Anticholinergic Metabolic acidosis → promotes unbinding of drug from proteins

Question 41

s/sx of antipsychotic toxicity

Answer 41

Hypotension Tachycardia QT/QRS prolongation EPS Neuroleptic malignant syndrome (NMS) Sedation Serotonin Syndrome

Question 42

s/sx of NMS

Answer 42

Hyperpyrexia up to 108 F with AMS (delirium or coma) and led pipe muscular rigidity 3-9 days after therapy initiation or addition of a second agent

Question 43

s/sx of serotonin syndrome

Answer 43

AMS, autonomic instability, neuromuscular abnormalities Low fever, myoclonus hyperreflexia lasting less than 24 hours

Question 44

s/sx of digoxin toxicity

Answer 44

Non-Cardiac signs/sx N/V Abdominal pain Anorexia Confusion Vision changes Cardiac Bradycardia 2nd or 3rd degree heart block Hyperkalemia

Question 45

S/sx of BB toxicity

Answer 45

Hypoglycemia Bronchospasms Hypotension/bradycardia Arrhythmias/cardiogenic shock CNS depression

Question 46

s/sx of CCB toxicity

Answer 46

Hyperglycemia Metabolic acidosis Pulmonary edema Ileus Hypotension/bradycardia Arrhythmias/cardiogenic shock CNS depression

Question 47

salicylate antidote(s)

Answer 47

Antidote: Sodium Bicarbonate MOA: urine alkalinization Indications: Serum salicylate level >30 mg/dL AMS Anion gap metabolic acidosis Dose: 1-2 mEq/kg (50 to 100 mEq) IVP over 1-2 minutes Monitoring: Serum pH 7.5-8, electrolytes

Question 48

Sedative antidote

Answer 48

Flumazenil MOA: competes with benzos at benzo binding site on GABA receptor Dosing: 0.2 mg IVP Contraindicated in patients with seizure history Can induce withdrawal symptoms N/V, agitation Activated charcoal May be used within 1-2 hours of ingestion

Question 49

TCA antidote

Answer 49

Sodium Bicarb MOA: increased sodium gradient of poisoned sodium channels Indications: QRS interval > 100 msec TCA induced arrhythmias or hypotension Metabolic acidosis Dose: 1-2 mEq/kg (50 to 100 mEq) IVP over 1-2 minutes Monitoring: Serum pH 7.45 - 7.55 Discontinue when QRS interval <100 msec Resolution of ECG Hemodynamically stable

Question 50

TCA seizure management

Answer 50

Usually with phenobarbital or benzodiazepines

Question 51

atypical antipsychotic EPS management

Answer 51

Benztropine 2 mg IM Diphenhydramine 1-2 mg/kg IV or IM (up to 50 mg) Must continue with oral therapy for 3-4 days 50 mg PO TID

Question 52

atypical antipsychotic serotonin syndrome management

Answer 52

D/C offending agent Benzos Aggressive cooling Cyproheptadine (Periactin) Histamine receptor blocking agent 4 mg PO q1h Max dose = 16 mg

Question 53

typical antipsychotic NMS management

Answer 53

D/C offending agent Rapid external cooling Benzoss Dantrolene - antidote Initial: 2.5 mg/kg up to 10 mg/kg Maintenance: 2.5 mg/kg Q6H until resolved Also used: Bromocriptine

Question 54

Digoxin toxicity management

Answer 54

D/C digoxin ABC management Monitoring: Serum digoxin concentration and BMP Vital signs and ECG Treatment Activated charcoal if within 2 hours of ingestion Digibind Indications Arrhythmias, bradycardia, heart block Hyperkalemia Serum dig concentrations >10-15 ng/mL (6 hours after ingestion) Ingestion >10 mg in adults NO hemodialysis

Question 55

BB/CCB toxicity management

Answer 55

otes: Activated charcoal Atropine → not typically used Increases HR 1mg q3-5 mins up to 3mg Calcium → more effective for CCB overdose Calcium chloride 1-2 g IV q 10-20 mins More prone to extravasation Calcium gluconate 3-6 g IV q10-20 mins Vasopressors → high doses to overcome b receptor blockade Stimulates calcium release & improve contractility Vasodilatory shock → NE Cardiogenic shock → epinephrine Glucagon Acts as a vasopressor Stimulates conversion of ATP to cAMP Dose: 3-10 mg IV bolus May cause N/V → add ondansetron Insulin (high dose) Acts as a vasopressor Dose: 0.5 to 1 unit/kg/hr Administer with dextrose Monitoring: Titrate to SBP >90-100 mmHg Goal glucose: 100-250 mg/dL Serum electrolytes every 1–2 hours Lipid emulsion MOA: limits bioavailability & creates a lipid sink 1.5 mL/kg bolus, 0.025 mL/kg/min May need multiple pumps to administer Max dose: 10 mL/kg

Question 56

iron tox management

Answer 56

ABC, vitals, hydration, serum iron concentration 4 hours post ingestion, KUB scan Can NOT use activated charcoal Whole bowel irrigation PEG 500 mL-hr in children 9 months to 6 years 1000 mL/hr in children 6-12 years 1000-2000 mL/hr in adults Deferoxamine – chelates iron and enhances renal elimination Indications: metabolic acidosis or shock, clinical deterioration, presence of iron tabs on KUB, serum concentration >500 mcg/mL Dosing: 15 mg/kg/hr up to 45 mg/kg/her

Question 57

uses of hemodialysis

Answer 57

Uses: alcohols, lithium, salicylates, theophylline