toxins/pharmacology Flashcards
What 4 toxins are not removed with charcoal?
CALM = cyanide, alcohol, lithium and heavy metals
What is the appropriate dosing of activated charcoal?
0.5-1 g/kg (max 100g)
A 3 y/o swallowed a battery 3 days ago. He is asymptomatic. What do you do?
Endoscopy. If in the esophagus or stomach it must be removed
When should swallowed coins be removed?
If proximal esophagus - endoscopy ASAP!
If middle to lower esophagus, observe 24 hours if asymptomatic and if does not pass then endoscopy needed
What are 3 initial manifestations of Tylenol toxicity?
Anorexia, nausea and vomiting
How long is the latent phase of acetaminophen toxicity?
1-4 days with significant rise of liver enzymes
What are the important 4hr post Tylenol ingestion levels to remember?
>150 = moderate toxicity >300 = severe toxicity
Female ingested Tylenol 2 days ago. Acetaminophen level 4 hr post ingestion was 250 and she was treated with N acetylcysteine. Today LFTs are normal. What is her prognosis?
LFTs can be normal until 4 days after ingestion even after severe overdose! Pt is still in danger…
What is the initial management of acetaminophen ingestion ?
Charcoal then 4 hour post ingestion level
If >150mg/kg has been ingested, what should you do?
Immediately give N acetylcysteine, even before obtaining post ingestion levels
If a patient had wintergreen odor on breath, what should you be concerned about?
Aspirin ingestion
What is the initial treatment of salicylate ingestion?
Charcoal then 3-6hr post ingestion level
How do you manage ibuprofen ingestion ? What should you NOT do?
Do give supportive care and test for co-ingestion of aspirin or Tylenol
Do not give ipecac or gastric lavage,
What occurs physiologically after aspirin ingestion?
Respiratory alkalosis due to increased breathing –> buildup of organic acids and anion gap metabolic acidosis
What is the formula for anion gap?
Na - (Cl + bicarb)
What is the treatment for anion gap metabolic acidosis secondary to aspirin ingestion and why?
Sodium bicarb to alkalinize the urine
Which ingestion is associated with hypoglycemia ?
Ethyl alcohol
At what blood alcohol level can coma, respiratory depression and death occur?
> 0.4
What products contain methanol?
Rubbing alcohol, Windshield washer fluid, cooking fuel, perfumes and antifreeze
Clinical presentation of methanol ingestion …
Acidosis, increased anion gap and CNS depression
What is the antidote to methanol toxicity and why?
4-methypyrazole or ethanol –> alcohol dehydrogenase antagonist which slows conversion to formaldehyde
What are the classic symptoms of opiate toxicity?
Responsive to painful stimuli
Pinpoint but reactive pupils
Respiratory depression
Bradycardia, hypotension and low temperature
How can you differentiate opioid toxicity from dka?
Dka has rapid deep breathing with no miotic pupils
Opiates cause shallow breathing with miotic pupils
How can you differentiate opioid toxicity from organophosphate poisoning?
Both have pinpoint pupils but only organophosphate shave sweating, tearing and wheezing
What toxicity would be suspected in a person with dilated pupils and violent behavior?
Pcp
What is propoxyphene and what can it cause ?
Narcotic analgesic that can cause ventricular arrhythmia, seizures and pulmonary edema
What is the mechanism of action of organophosphates?
Acetylcholinesterase inhibitor
What are the classic signs of organophosphate poisoning?
DUMBBELS = diarrhea, urination, miosis, bronchospasm, bradycardia, emesis, lacrimation, salivation
What are the muscarinic effects of cholinergics and how are they treated?
Bronchospasm and increase pulmonary secretions - give atropine
What are the nicotinic effects of cholinergics and how are they treated?
Neuromuscular effects / treat with pralidoxime
What are the life threatening signs associated with TCA ingestion and when does this occur?
Dysthymia and hypertension occurs within 24 hours
What medications classically are known to have anticholinergic side effects?
Tricyclics, pupil dilator agents and antispasmodics
What are the anticholinergic signs?
Blind as a bat (dilated pupils) Red as a beet Hot as a hare Dry as a bone Mad as a hatter Bowel and bladder lose their tone Heart runs alone
How do you manage TCA ingestion?
Charcoal
alkalinization of urine
EKG monitoring for wide QRS
How do you treat a widening QRS after TCA poisoning?
Sodium bicarb boluses until QRS <100 msec
What are symptoms of beta blocker ingestion?
Depressed sensorium, bradycardia, hypotension and diaphoresis
What types of testing is invalid if a patient is taking TCAs and why?
TCAs render allergy testing unreliable because they interfere with histamine response
What occurs on labs and imaging after hydrocarbon ingestion?
Hypoxemia and ARDS (diffuse bilateral infiltrates on cxr)
How do you treat an asymptomatic patient after hydrocarbon ingestion?
Observation x 6 hours with pulse oximetry.
What ingestion should you consider in a patient with confusion and weakness but no fever?
Carbon monoxide
You are presented with a patient who is lethargic, confused and in distress. Vitals are normal. What is the best treatment?
100% oxygen
If suspected carbon monoxide poisoning but no improvement of symptoms despite 100% oxygen what should you consider?
Cyanide poisoning
What are 3 options for treatment of cyanide poisoning ?
Hydroxocobalamin
Sodium thiosulfate
Nitrate
When do you consider hyperbaric treatment after carbon monoxide toxicity?
Pregnancy, acidosis, cardiac involvement or neurological involvement
What might have been ingested in a patient that appears drunk with oxalate crystals on urinalysis?
Ethylene glycol
What is seen in the first phase of ethylene glycol toxicity?
Nausea, tachycardia, hypertension, metabolic acidosis and calcium oxalate crystals with hypocalcemia
What is the cause of coma or cardio respiratory failure during phase 2 of ethylene glycol toxicity?
Large anion gap acidosis and hypocalcemia
What occurs in phase 3 of ethylene glycol toxicity and how is it treated?
Acute tubular necrosis with renal failure requiring dialysis
At what level is iron ingestion considered toxic?
40 mg/kg of elemental iron
What lab findings are consistent with iron toxicity?
4hour post ingestion level > 350 WBC >15 Glucose> 150 Elevated LFTs Metabolic acidosis
What are 4 major multisystem effects of iron ingestion?
Metabolic acidosis
Coagulopathy
Cardiovascular collapse
GI obstruction
What is the appropriate treatment for significant iron toxicity? What is not used for iron toxicity?
Defuroxamine chelation
Not charcoal as poor absorption
What are indications for iron chelation therapy?
Anion gap acidosis
Iron >500
Significant number of pills seen on KUB
When can deferoxamine treatment be stopped?
When clinical improvement and urine no longer pink
What are classic presenting signs on a patient following ingestion of caustic substance?
Coughing, drooling, difficulty swallowing and chest pain
What is the initial management for suspected caustic substance ingestion?
Endoscopy within 48 hours
What is recommended for treatment of alkali ingestion?
Observation 6 hours
Endoscopy if symptoms
No activated charcoal as will inhibit endoscopic exam
What are PCBs and what can they cause?
Synthetic hydrocarbons that cause Pigmentation/rash, Cutting teeth early and Birthweight that is low
How can you differentiate varicella vs smallpox lesions?
Smallpox - starts in face and extremities with lesions in same stage.
Chicken pox - starts centrally and spreads with lesions in varying stages.
What is a lesion that starts as an itchy papule that becomes bullous w central necrosis that is black and painless?
Cutaneous anthrax
What 5 medications are affected with use of St. John’s wort and why?
OCPs Iron Digoxin Anticoagulants Antiretroviral drugs *induction of P450 increases drug elimination
How is echinacea believed to act? When is it contraindicated?
Acts by modulating cellular immunity
Contraindicated in patients on immunosuppressants
What 5 drugs can interact with ginseng?
Anticoagulants Anti platelets Steroids Hypoglycemic medications Diuretics
When should valerian root not be used?
In patients using alcohol or other sedating drugs
Isotretinoin and griseofulvin should be taken with what types of foods?
Fatty foods (the drugs are lipophilic)
Which 3 medications should not be taken with dairy products ?
Tetracycline
Doxycycline
Ciprofloxacin
When is steady state of a drug achieved?
After 4-5 half lives
What 4 drugs cause inhibitory effects on hepatic enzymes and thus increased toxicity of many drugs?
Erythromycin
Ciprofloxacin
Cimetidine
Omeprazole
What 4 medications are considered potent enzymatic inducers which decrease the levels of many other medications ?
rifampin
Phenobarbital
Carbamazepine
Phenytoin
What 2 drugs decrease bioavailability of calcium, iron and magnesium?
Cephalosporins and fluoroquinolones
What two drugs inhibit renal metabolism of digoxin and lead to toxicity?
Quinidine and amiodarone
What is the appropriate medication to give for a patient with adrenal insufficiency who requires stress dosing?
IV hydrocortisone
What are 4 major side effects of beta blockers ?
Sexual dysfunction
Insomnia
Bronchospasm
Bradycardia
What type of drug is acetazolamide and how does it work?
Carbonic anhydrase inhibitor
Blocks teuptake of bicarb causing metabolic acidosis and alkaline urine
What are two major side effects of LASIX use?
Ototoxicity
Renal toxicity
What is the mechanism of action of loop diuretics and what electrolyte changes are seen?
Block absorption of Na and Cl
Wasting of Ca, K and H
Hypochloremic hypokalemic alkalosis
