Toxicology

Intravenous acetylcysteine is advantageous because of its decreased overall administration time (21

hours vs. 72 hours for oral) and minimal GI adverse effects. If intravenous acetylcysteine formulation

is not available and cannot be obtained in a timely fashion, poison control centers can be contacted for

instructions on compounding the inhalational acetylcysteine formulation for intravenous use. It is not

recommended to use this strategy except for emergencies.

Oral acetylcysteine is dosed for 18 total doses; doses may be repeated if emesis occurs within 1 hour

of a dose. Two oral formulations exist. One preparation is an effervescent tablet that must be dissolved

in water before administration, and the other is a liquid preparation that may be diluted in juice or

carbonated beverages to improve palatability. Antiemetics may be administered if significant nausea

or vomiting occurs. Table 4 discusses the dosing strategies for oral and intravenous administration of

acetylcysteine.

For exceptionally large ingestions (e.g., over 30 g), some studies have recommended alternative

approaches:

An increased dose of acetylcysteine (Med J Aust 2020;212:175-83).

ii.

Given that acetaminophen is dialyzable, intermittent hemodialysis is an option (Clin Toxicol

2014;52:856-67). This approach would also require an increase in the acetylcysteine dose (i.e.,

2-fold) due to its concurrent increased clearance (Clin Toxicol 2016;54:519-22). However, a

dosing adjustment does not appear to be necessary in the setting of continuous veno-venous

hemofiltration (Clin Toxicol. 2015;53(10):941-949).

Although treatment guidelines recommend 18 total doses of acetylcysteine administered throughout

72 hours for oral acetylcysteine therapy and 21 hours of the intravenous infusion of acetylcysteine,

many poison control centers recommend early discontinuation if the following conditions are met (or

Serum acetaminophen concentrations are undetectable or less than 10 mcg/mL.

ALT concentrations are normal (60 IU/L or less) or improving. Some clinicians also advocate for

an international normalized ratio (INR) of 1.3 or less.

The patient is clinically improved.

Adverse effects (intravenous): Anaphylactoid reactions (rash, urticarial, pruritus) that are often infusion

rate-associated, hyponatremia, hypervolemia, seizures (pediatric patients with unadjusted volume)

Adverse effects (oral): Nausea, vomiting, anaphylactoid reactions (rare)

with diphenhydramine, and acetylcysteine therapy can be resumed.

70). Common errors include delays in therapy, incorrect dosages, and incorrect infusion rates. To

mitigate these errors, some institutions have developed a a 2-step, and even 1-step, intravenous regimen