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FM 4 > Toxicology > Flashcards

Toxicology Flashcards

1
Q

Give examples of the four most common classes of drugs that are frequently monitored and state the rationale for monitoring.

A

Antibiotics
o Ex: amikacin, gentamicin, tobramycin, vancomycin
o Toxic effects: nephrotoxic, ototoxic

Anti-seizure agents
o	Ex: carbamazepine, lamotrigine, phenytoin, phenobarbital, primidone, valproic acid
o	Narrow therapeutic windows
•	Too low: risk of seizures
•	Too high: depress CNS → coma

Immunosuppressants
o Ex: azathioprine, cyclosporine, methotrexate, mycophenolate mofetil, sirolimus, tacrolimus
o Ensure adequate immune suppression to prevent transplant rejection
o Some reports of hepatoxicity and nephrotoxicity

Cardiac medications
o Ex: amiodaroen, digoxin, flecainide, lidocaine, procainamide, quinidine
o Cardiac glycosides (digoxin) = narrow therapeutic windows
o Overdose: vomiting, diarrhea, confusion, visual disturbances, cardiac arrhythmias

Some psychiatric drugs

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2
Q

Describe the unique issues regarding cannabis, cocaine and opioid testing.

A

Cannabis:
o THC persists in urine for many days
o Lipophilic = can reside in fat stores for longer
o Pantoprazole (PPI drug for acid reflux), ibuprofen = can cause false positives

Cocaine 
o	Primary metabolite = benzoylecgonine
•	Long ½ life compared to parent drug
o	Result = better marker for abuse
•	Can be detected in urine 3-5 days later (vs. cocaine only 1 day later)

Opioids
o Many drugs of opioid class can cross-react in screening tests
o Many opioids metabolize to other opioids
o Note: may need to test for opioid use/patient adherence (ensure patient is taking medication before writing new prescription)
Note: only metabolite of heroin = 6-acetyl morphine

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3
Q

Drugs affecting nutrients: steroids

A

Vit D and Ca2+

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4
Q

Drugs affecting nutrients: Phenytoin

A

Antiepileptic

Vit D, Ca2+, Folate

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5
Q

Drugs affecting nutrients: sulfasalazine

A

IBD tx

folate

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6
Q

Drugs affecting nutrients: TMP/sulfa

A

(if long term use)

folate

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7
Q

Drugs affecting nutrients: INH

A

(TB prophylaxis)

Vit B6

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8
Q

Drugs affecting nutrients: methotrexate

A

folate, vit B12

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9
Q

Drugs affecting nutrients: PPI

A

Vit B12, magnesium, Ca2+, iron

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10
Q

Cholinergic toxidrome

A

Cholinergic: organophosphates, carbamates

DUMBELS:
o	Diarrhea, Diaphoresis
o	Urination
o	Miosis (Constricted)
o	Bradycardia, Bronchosecretions
o	Emesis
o	Lacrimation
o	Salivation

Antidote: atropine, pralidoxine

What is the most life threatening effect of cholinergic poisoning?
• Pulmonary edema

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11
Q

Anticholinergic toxidrome

A

Anticholinergic: antihistamines, TCA’s

Think:
•	Hot as a hare, red as a beet; dry as a bone; blind as a bat, mad as a hatter
o	Hyperthermia
o	Dry Skin
o	Mydriasis (Dilated)
o	Delerium, Hallucinations
o	Tachycardia
o	Urinary Retention
o	Seizure

Antidote: physostigmine

How do you differentiate anticholinergic toxicity from sympathomimetic toxicity?
• Anticholinergic = dry skin, urinary retention
• Sympathomimetic = diaphoresis (sweating)

What is the most life threatening effect of anticholinergic toxicity?
• Hyperthermia, seizures

In addition to an antidote, what other medication may be useful?
• Adjunct: benzodiazepine

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12
Q

Sympathomimetic toxidrome

A

Sympathomimetic: cocaine, amphetamines

o	Hyperthermia
o	Diaphoresis
o	Mydriasis (Dilated)
o	Tachycardia
o	Hypertension
o	Seizure

Antidote: none

What are the most life threatening effects of sympathomimetic toxicity?
• Seizure, cardiac arrest

What are the key principles underlying management of these patients?
Supportive care:
o	Maintain airway
o	Active cooling for hyperthermia
o	Seizure control
o	Na+HCO3- bolus for dysarrhythmia
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13
Q

Opioid Toxidrome

A

Opioid: heroin, methadone, oxycodone, hydrocodone

o	Miosis (Constricted)
o	Hypoventilation
o	Coma
o	Bradycardia
o	Hypotension

Antidote: naloxone

What is the most life threatening effect of opioid toxicity?
• Respiratory depression

After treatment with antidotal therapy for opioid overdose, when is a patient safe for discharge?
• About 4 hours

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14
Q

Describe when the following interventions are indicated: syrup of ipecac

A

Not supported → causes lots of vomit

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15
Q

Describe when the following interventions are indicated: activated charcoal

A

o Most effective within 1 hour of ingestion
o Only use in alert patients

o Binds toxins in gut: (PHAILS) pesticides, hydrocarbons, acids/akali, iron, lithium, solvents

o Multiple doses = interrupts entero-hepatic circulation: (AABBCD) antimalarials (quinine) and aminophylline (theophylline), barbituates (phenobarbital) and beta blockers (nadolol), carbamazepine, dapsone

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16
Q

Describe when the following interventions are indicated: gastric lavage

A

o No longer indicated except if within 1 hour of life-threatening ingestion and no alternative
o But = no solid evidence on outcomes
o Complications: aspiration, esophageal perforation
o Contraindications: ingestion of corrosive substance or hydrocarbon

17
Q

Describe when the following interventions are indicated: whole bowel irrigation.

A

o Polyethylene glycol via nasogastric tube

o Used for lead ingestion (paint chips)

18
Q

Describe when the following interventions are indicated: urinary alkalization

A

(aspirin & phenobarbital overdose)

19
Q

Describe when the following interventions are indicated:hemodialysis

A

(acute aspirin, toxic alcohol, lithium toxicity)

20
Q

Name the antidote(s) for the following poisonings: parathion, diphenhydramine, oxycodone, methanol, acetaminophen, lead.

A
  • Parathion (organophosphate = cholinergic): atropine, pralidoxine
  • Diphenhydramine (antihistamine = anticholinergic): physostigmine
  • Oxycodone (opioids): naloxone
  • Methanol: fomepizole, ethanol
  • Acetaminophen: n-acetylcysteine
  • Lead: succimer, BAL, CaNa2EDTA
21
Q

Anion Gap Metabolic Acidosis

A

How do you calculate an anion gap?
• AG = Na+ - (Cl- + HCO3-)
• Normal: 8-12 mEq/L

What is the differential diagnosis for a patient with a high AGMA? 
•	(MUDPILES)
•	Methanol (formic acid)
•	Uremia 
•	Diabetic ketoacidosis
•	Propylene glycol
•	Iron tablets or INH
•	Lactic acidosis 
•	Ethylene glycol (oxalic acid)
•	Salicylates

When is dialysis indicated for patients with AGMA?
• Life-saving for salicylate and toxic alcohol poisoning

22
Q

How do you calculate an osmolar gap?

A

OG = 2(Na+) + (glucose/18) + (BUN/2.8)

23
Q

Describe the mechanism and features of antifreeze toxicity.

A

• Antifreeze = ethylene glycol, 1,2-ethanediol

Mechanism of injury
o	Absorbed in proximal GI tract
o	Converted to 3 major metabolites (via hepatic alcohol dehydrogenase)
•	Glycoaldehyde
•	Glycolic acid
•	Glyoxylic acid

Treatment = ethyl alcohol
• Slows glycoaldehyde formation by saturating alcohol DH → less toxic metabolites
• Allows time for urinary excretion of ethylene glycol

Toxicity
o Ethylene glycol = not directly toxic
o Metabolites (glycolic acid and oxalic acid) = TOXIC
1) Glycolic acid
• Forms in high amounts
• Causes elevated anion gap metabolic acidosis
2) Oxalic acid
• Relatively small amounts
• Highly reactive and toxic
• Reacts with Ca2+ containing molecules → calcium oxalate crystals → deposit in kidney → can lead to renal failure

24
Q

Cocaine: metabolism

A

(p450) –> norcocaine
(EtOH) –> ethylcocaine (stronger biologic activity, longer 1/2 life)
(smoking/crack) –> methylecgonidine

Primary metabolite = benzoylecgonine

25
Q

Cocaine: toxicity

A

o Blocks cellular reuptake of NE, DA, and serotonin
o Blocks Na+ channel conductance
o Targets CNS and cardiovascular systems
o Note: risk of death is NOT entirely dose dependent

26
Q

Cocaine: complications

A

o Cardiac arrhythmia, premature coronary atherosclerosis
o Intracranial hemorrhage, seizure, coma
o Aortic dissection, coronary artery spasm
o Hypertensive crisis, hyperthermia
o Acute psychosis, chronic schizophrenic psychosis
o Obstetric complications: abruptio placenta, fetal hypoxia, low birth weight, neonatal cocaine addiction

FM 4 (2 decks)

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