Acute Poisonings

Question 1

Vomit

Answer 1

• alkaloid: syrup of ipecac, stimulates CTZ
• don’t give if tox: hydrocarbon, corrosive, acidic, causative, patient not alert
• not recommended!

Question 2

Activated charcoal

Answer 2

Carbon powder, large surface area to absorb substances

Question 3

When activated charcoal is not given?

Answer 3

If Poison is polar compound with low mol weight (methanol, ethylene glycol), metals (iron, lead), highly ionized salts (lithium, cyanide); p cannot drink, if poison is inhaled

Question 4

Gastric lavage

Answer 4

Orogastric or nasogastric tube inserted through mouth or nose, saline/water added, solution of poison is aspirated back until returning fluid is clear

Question 5

When gastric lavage doesn’t work?

Answer 5

Late tablets or concentrations may not pass up the tube

Question 6

Whole bowel irrigation (WBI) useful in

Answer 6

Large ingestion, ingestion of sustained release or enteric coated preparations, and metal poisoning

Question 7

WBI procedure

Answer 7

Flushes gi lumen with polyethylene glycol electrolyte to speed elimination (1-2L/h for several hrs until rectal effluent is clear)

Question 8

When do you target metabolism of toxins?

Answer 8

When drug is absorbed and gets bioactivated to toxic species - inhibit metabolism to limit toxicity
(Eg: ethylene glycol, methanol)

Question 9

Drug used in Methanol poisoning

Answer 9

Alcohol or fomepizole

Question 10

Alcohol/fomepizole mechanism

Answer 10

Inhibit alcohol dehydrogenase. Inhibit conversion of methanol to formaldehyde (for mic acid - blindness) or inhibit production of oxalis acid from ethylene glycol that can cause metabolic acidosis

Question 11

Methanol or ethylene glycol poisoning symptoms

Answer 11

• first few hours: inebriation, metabolic acidosis
• post 6-8 hrs: severe met acidosis, retinal toxicity (methanol), renal toxicity (ethylene glycol), seizures, coma , death
• look for metabolic acidosis (low pH, low bicarbonate and osmol gap)

Question 12

Osmol gap

Answer 12

• anion gap: Na-Cl-HCO3= (8-12 mEq/L)

- osmol gap = measured Osm - calculated Osm = measured Osm - (2Na + glucose + urea)= usually less than 10 mOsm/L

Question 13

Elevated anion gap acronym

Answer 13

Methanol
Uraemia
Diabetic ketoacidosis

Paraldehyde
Iron, isoniazid
Lactic acidosis 
Ethylene glycol 
Salicylates

Question 14

Elevated osmolar gap

Answer 14

Methanol
Ethylene glycol

Diuretics (mannitol)
Isopropyl alcohol
Ethanol

Question 15

Acetaminophen overdose

Answer 15

Facilitate glutathione detoxification by giving thiol donor. (n acetylcysteine)
- don’t try to inhibit CYP activation step

Question 16

Acetaminophen metabolism

Answer 16

Phenolsulfotransferase, UDP- glucuronyltransferase

NAPQI- toxic binds to renal and hepatic protons, detoxified by GSH (glutathione)

Question 17

Facilitate elimination of weak acids

Answer 17

With sodium bicarbonate, use HHequation, ion trapping: pKa - pH = log [HA]- [A]
- hemodialysis to remove chemical and to correct fluid and electrolyte imbalances

Question 18

Some antidotes and chelators

Answer 18

Fomepizole (methanol, EG)
N-acetylcysteine (acetaminophen)
Fab fragments (digibind)
Desferoxamine (iron)
Atropine (cholinergic excess)
Naloxone (opioid)
Hydrocobalamine (for cyanide)
Flumazenil - bzd

Question 19

Competitive antagonism

Answer 19

Naloxone for morphine opioid R
Oxygen for carbon monoxide at hemoglobin
Flumazenil for BZD at GABAR

Question 20

Non competitive antagonism

Answer 20

Atropine for cholinesterase inhibitors

Diazepam for strychnine (ant of glycine)

Question 21

Sympathetic toxidrome

Answer 21

• pupil dilation
• low salivary production
• low mucus production
• high heart rate and force
• bronchial m relaxed
• low peristalsis In stomach
• low motility in intestines
• liver: high conversion of glycogen to glucose
• kidney: low urine secretion
• adrenal medulla: NEpi and Epi secreted
• bladder: wall relaxed and sphincter closed

Question 22

Parasympathetic toxidrome

Answer 22

• pupil constriction
• high salivary production
• high mucous production
• low heart rate and force
• bronchial m contracted
• high gastric juice and motility in stomach
• high digestion in small i
• high secretion and motility in large I
• no change in liver
• high urine secretion In kidneys
• no change I adrenal medulla
• bladder wall contracted and sphincter relaxed

Question 23

Cholinergic stimulation

Answer 23

Direct on Receptors: muscarinic, nicotinic

Indirect: inhibit acetylcholinesterase

Question 24

Muscarinic receptor stimulation

Answer 24

Salivation
Lacrimation (tearing)
Urination
Diarrhea 
Gi upset
Emesis

Or

Diarrhea
Urination
Mitosis,muscle weakness
Bronchospasm
Bradycardia
Emesis
Lacrimal ion
Salivation, sweating, seizures

Question 25

Nicotinic receptor stimulation

Answer 25

``` Stimulation of skeletal muscle and ganglia: Muscle fasciculations (twitching) Cramping Hypertension Tachycardia Pupil dilation Pallor Or ``` ``` Monday - mydriasis Tuesday - tachycardia Wednesday - weakness THursday - hypertension Friday - fasciculations/cramping ```

Question 26

Anti cholinergic mnemonic

Answer 26

``` Mad as a hatter (delusional) Dry as a bone Red as a beet (flushed) Hot as a hare (temp) Blind as a bat (visual disturbances) ```

Question 27

Decontamination ways

Answer 27

- remove source, wash - activated charcoal - gastric lavage - whole bowel irrigation

Question 28

Ecstasy mechanism

Answer 28

Elevated serotonin, norepinephrine, dopamine | Metabolized by CYP2D6

Question 29

Ecstasy symptoms

Answer 29

``` Hypertension Tachycardia Jaw clenching, bruxism Hyponatremia Liver toxicity Neurotoxicity ```