Toxicology Flashcards
Initial naloxone dose for young/opioid naive children
0.1mg/kg
Initial naloxone dose for adolescent/at risk of withdrawal
0.04mg
Maximal therapeutic dose acetaminophen
Children - 90mg/kg/d
Adults - 4g/d
Toxic dose acetaminophen
150mg/kg in < 24hrs
10g in < 24hrs
What is the toxic metyabolite of acetaminophen that causes hepatotoxicity?
NAPQI
What produc detoxifies NAPQI?
glutathione
How does NAC work?
= glutathione precursor
What are the stages of acetaminophen toxicity?
Stage 1 - 0.5-24hrs post-ingestion. Asymptomatic or GI symptoms, possible ALOC and elevated anion gap acidosis
Stage 2- 24-72 hours. Hepatotoxic signs with RUQ pain, possible AKI but improvement of GI symptoms
Stage 3 - 72-96hrs. Fulminant hepatitis with return of GI symptoms, possible encephalopathy, metyabolic acidosis, AKI, coagulopathy, possible multisystem dysfunction and death
Stage 4 - 4d-2wks. Recuperation
If patient comes in with ingestion > 8hrs ago or unknown time, how do you manage?
Start NAC immediately and refer to nomogram once results available
What are the criteria for being able to use the nomogram?
Single ingestion or over < 8hrs
bloodwork done 4-24hrs post-ingestion
What are indications for use of NAC?
APAP > 66
Abnormal transaminases (do at least 2 checks)
When can NAC treatment be stopped?
If APAP dose not toxic based on nomogram
At end of treatment if acetaminophen negative and normal transaminases
What are secondary effects of NAC?
elevated INR
flushing
urticaria
angioedema
dyspnea/hypotension
What is the therapeutic dose of activated charcoal?
1g/kg, max 50g
When would you consider more than one dose of activated charcoal?
large quantity of ingested pills, especially if salicylate
ingestion of substance that slows gastric emptyin
extended release pill
enterosoluble pill
blood concentration of substance continues to increase
What are contraindications to use of charcoal?
lithium, heavy metals, alcohols
inadequate protection of airways
intestinal occlusion
ingestion of corrosive substance
What substances warrant repeated charcoal doses?
theophylline, caffeine, phenobarbital, carbamazepine, dapsone, quinine, amatotoxine (mushrooms)
What are the doses for repeated activated charcoal?
1g/kg q4h or 0.5g/kg q2h
What bloodwork should be done if not able to get history in comatose/ALC patients?
CBC, uric acid, Cr, lytes, transaminases, gas, serum osmolality, EtOH, ECG, APAP/ASA dosing
What is the calculation for anion gap?
Na - (Cl + HCO3)
What are the substances that cause elevated anion gap metabolic acidosis
Methanol
Uremia
Diabetic ketoacidosis (DKA)
Paraldehyde, phenformin;
Iron, isoniazid
Lactic (ie, carbon monoxide [CO], cyanide)
Ethylene glycol
Salicylates
How do you calculate osmolality?
2Na + Glucose + BUN (2 salts and a sugar bun)
What is a normal osmolar gap value?
< 10
What toxins cause elevated osmolar gap?
Ketones
Alcohols**