Updated: 1/25/2020

Poisons and Treatments

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Overview
 
Treatment Poison(s) Notes
Deferoxamine  Iron
Used for aluminum poisoning in renal failure
Used in repeat transfusions that can cause iron overload (thalassemia)
Used in iron overdose
Deferasirox
Prussian blue Cesium
Thallium
Used in the case of a radioactive incident
Penicillamine  Copper (Wilson's disease)
Water-soluble form of penicillin
Avoid in patients who have penicillin allergy
Weak association with improve outcomes in scleroderma
EDTA Lead
Can chelate and deplete calcium ions
Only needed in moderate to severe lead poisoning
Dimercaprol (BAL) Arsenic
Lead
Mercury
Used in conjunction with EDTA for lead poisoning
Succimer Arsenic
Lead
Mercury
Chelation therapy more commonly used in children
N-acetylcysteine  Acetaminophen
Best if given with 8-10 hours
Also a mucolytic
Best next step in management if you suspect acetaminophen intoxication yet have no lab results (it is a benign treatment)
Sodium bicarbonate Salicylates 
Tricyclic antidepressants (TCA)
First sign of OD is hyperventilation and respiratory alkalosis
Do not give with physostigmine
First do an EKG, if wide QRS (in TCA overdose) then try sodium bicarbonate
Deprotonation of drugs causes improved urinary excretion
Potassium iodide Radioactive iodine (I-131)
Given to prevent the uptake of I-131
Can also be used in thyroid storm as iodine initially decreases thyroid hormone production
Ammonium chloride (NH4Cl, acidic) Amphetamines (basic)
Eliminates amphetamines by acidifying urine which results in a charged amphetamine molecule which is excreted

Atropine

Anticholinesterases
Organophosphates
Sarin (nerve gas)
Atropine blocks Ach receptors decreasing the effect of these drugs
Pralidoxime, if given in a timely manner, regenerates acetylcholinesterase reversing the initial pathology
Pralidoxime 
Physostigmine Antimuscarinic
Anticholinergic agents
Do not give if patient may have TCA OD as it may lead to heart block or asystole
Tertiary amine that can cross the BBB and reverse CNS symptoms of atropine
Naloxone/naltrexone Opioids
Precipitates withdrawal symptoms in chronic opioid users
Not indicated in neonates who may be withdrawing
Indicated particularly in adult patients who have respiratory depression
Naltrexone decreases alcohol cravings
Flumazenil  Benzodiazepines
May cause seizures in addicted benzodiazepine users
Not routinely used, better to let the patient "sleep off" their benzodiazepine overdose
Ensure patient maintains respiratory effort and airway
Ethanol IV infusion Antifreeze (ethylene glycol)
Methanol
Think antifreeze when ingested substance is said to be sweet and individual appears "drunk without the typical smell of alcohol"
Fomepizole
Glucagon β-blockers  
IM glucagon is best initial therapy
β-blockers (propranolol, esmolol) Theophylline
OD symptoms are due to β2 activation: hypotension, tachycardia, hypokalemia, hyperglycemia

Digitalis antibody, lidocaine, Mg2+

Digitalis
GI disturbance and visual halos classic in overdose
Amyl and sodium nitrite Cyanide 
Cyanide found in rodenticides "gopher goitter", released in burning of plastics and wool, and plants such as cassava
Cyanide binds Fe3+ of cytochrome c in the electron transport chain and blocks cellular respiration
Nitrites generate methemoglobin, which can save the ETC by binding up the cyanide
Sodium thiosulfate
Hydroxycobalamin
Methylene blue Methemoglobin
Iron in the heme molecule is Fe3+ which cannot bind oxygen until it is reduced to Fe2+ by treatment
Vitamin C
100% O2 (consider hyperbaric O2 Carbon monoxide (CO)
CO binds with much greater affinity than O2
Aminocaproic acid  tPA
Streptokinase
-
Vitamin K Warfarin
Bridge with heparin
If patient suddenly has increase in PT/PTT look for other medications that are P450 inhibitors
Plasma infusion
Protamine Heparin 
Protamine is a highly positively charged peptide which strongly binds to the negatively charged heparin
Antivenin Rattlesnake bite
 -

 

Iron Poisoning
  • Most deaths due to iron poisoning (ingestion of iron tablets) occur in children between 12 - 24 months of age
  • Symptoms occur within 30 min to several hours
    • abdominal pain, diarrhea, vomiting
    • cyanosis, drowsiness, hyperventilation resulting from acidosis
  • Death can result in six hours, but an apparent recovery may happen from 6 - 12 hours with death ensuing in the next 12 hours
  • If not treated early, damage to the stomach can lead to pyloric stenosis or gastric scarring
  • Early treatment with deferoxamine can reduce mortality significantly from 45% to 1%
  • Mechanism of action of iron related damage
    • iron overdose results in the peroxidation of membrane lipids leading to cell death
    • the Fenton reaction produces dangerous free radicals
Methanol and Ethylene Glycol Toxicity
  • Each are competitive substrates for alcohol dehydrogenase (ADH) 
  • Methanol 
    • metabolized by ADH to formaldehyde followed by aldehyde dehydrogenase to form formic acid which is toxic to the optic nerve
      • early toxicity of formic acid is metabolic acidosis by formic acid itself
      • formic acid also binds to cytochrome oxidase blocking oxidative phosphorylation
      • resulting in lactic acidosis which is the latter and leading cause of the metabolic acidosis
    • signs and symptoms appear within 12 - 24 hours after ingestion
      • CNS depression
        • methanol acts similarly as ethanol as a CNS depressant
      • metabolic acidosis
      • visual changes
        • blindness occurs with as little as 30 mL and death at 100 mL ingestion
  • Ethylene glycol
    • colorless, odorless, sweet-tasting liquid
    • toxicity derives from the hepatic oxidation of ethylene glycol to oxalic acid
      • degraded by same pathway as methanol
        • the glycolic acid produced by aldehyde dehydrogenase is converted in oxalic acid
      • oxalic acid binds calcium and forms calcium oxalate crystals that damage the heart, brain, lungs, kidneys
    • signs and symptoms develop in stages after ingestion
      • first stage: 0.5 - 12 hours
        • stronger inebriant than methanol and ethanol causing mild depression of CNS resulting in seizures and coma
        • patients appear "drunk without smelling like alcohol"
        • within 4 - 12 hours, calcium oxalate crystals deposit in the brain causing CNS toxicity, cerebral edema, meningismus (nuchal rigidity, photophobia, headache without infection or inflammation)
        • hypocalcemia occurs due to binding of calcium by oxalic acid and can cause prolonged QT, arrhythmias, myocardial depression
      • second stage: 12 - 24 hours
        • tachypnea occurs to offset the metabolic acidosis due to the toxic metabolites produced
        • multiorgan failure (CHF, lung injury, myositis) due to widespread crystal deposition
        • NOTE: most deaths occur in the second stage
      • third stage: 24 - 72 hours
        • acute anuric renal failure from crystal deposition but full recovery occurs within weeks to months
  • Treatment
    • IV ethanol: competitive substrate for ADH and has greater affinity for ADH than methanol and ethylene glycol
    • fomepizole: inhibits ADH preventing production of toxic metabolites
Ingested seafood toxins
  • Tetrodotoxin
    • Highly potent toxin that binds to fast voltage-gated Na+ channels, preventing depolarization
    • Presents with nausea, diarrhea, paresthesias, weakness, dizziness, and loss of reflexes
 
 

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(M1.PH.15.75) A steel welder presents to his family physician with a one-week history of intense abdominal cramping with nausea, vomiting, constipation, headaches, myalgias, and arthralgias. He claims that the symptoms started about two months after he began work on replacing the pipes in an early 20th century house. Blood was taken and he was found to have a microcytic, hypochromic anemia with basophilic stippling. Which of the following is the best treatment for his symptoms? Tested Concept

QID: 106842
1

Deferoxamine

15%

(14/96)

2

EDTA

71%

(68/96)

3

Deferasirox

2%

(2/96)

4

Prussian blue

4%

(4/96)

5

N-acetylcysteine

5%

(5/96)

M 3 D

Select Answer to see Preferred Response

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(M1.PH.15.1) A 5-year-old boy is brought to the emergency room lapsing in and out of consciousness. The mother reports that 30 minutes ago, the young boy was found exiting the garage severely confused. A container of freshly spilled antifreeze was found on the garage floor. The next appropriate step would be to administer: Tested Concept

QID: 107080
1

Dimercaprol

12%

(21/170)

2

N-acetylcysteine

8%

(13/170)

3

Ammonium chloride

4%

(6/170)

4

Flumazenil

6%

(10/170)

5

Fomepizole

68%

(115/170)

M 3 D

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(M1.PH.15.75) At 10 a.m. this morning, a semi-truck carrying radioactive waste toppled over due to a blown tire. One container was damaged, and a small amount of its contents leaked into the nearby river. You are a physician on the government's hazardous waste committee and must work to alleviate the town's worries and minimize the health hazards due to the radioactive leak. You decide to prescribe a prophylactic agent to minimize any retention of radioactive substances in the body. Which of the following do you prescribe? Tested Concept

QID: 106841
1

Methylene blue

18%

(11/60)

2

Vitamin C

12%

(7/60)

3

Potassium iodide

40%

(24/60)

4

EDTA

12%

(7/60)

5

Succimer

18%

(11/60)

M 3 D

Select Answer to see Preferred Response

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