Would N-acetylcysteine (NAC) be able to reverse acetaminophen poisoning from a year ago?

Question

This webpage sugggests that this is possible, but I don't know how long they are talking about :

"NAC is most effective when administered within 8 hours of ingestion. When indicated, however, NAC should be administered regardless of the time since the overdose. Therapy with NAC has been shown to decrease mortality rates in late-presenting patients with fulminant hepatic failure, even in the absence of measurable serum acetaminophen levels."

http://www.emedicine.com/emerg/topic819.htm

Answer 1

I think what the article is suggesting is that even a few days (48 hrs) after overdosing the use of the antidote may be beneficial.

I would highly doubt if after a year the antidote would be effective for the reasons below.

Paracetamol (acetaminophen) is converted to a hepatotoxic (liver damaging) metabolite which also is nephrotoxic (kidney damaging), mainly due to the fact that these "locations" are where the metabolite may be found in high concentrations.

The antidote is thought to work by binding to the toxic metabolite and converting it into a non-toxic substance. Since the half life for paracetamol is relativley short I would highly doubt that remnents from the initial overdosing are still present.

Also if you are on other medications precautions must be taken before taking N-acetylcysteine.

The damage done to your liver/kidneys from that overdose a year ago will not be reversed by this but if you are still uncertain the best thing for you to do it talk to your Pharmacist or GP.

Answer 2

After reading the article I cannot see where the use of NAC post 1 year out .... be of any benefit ..... the damage is done ...

Answer 3

It is only for acute overdoeses and is most effective if administered within the first 24 hrs.