Intravenous acetylcysteine is the treatment of choice for acetaminophen poisoning and more recently for anticonvulsant-induced hypersensitivity syndrome. N-acetylcysteine is a known precursor of glutathione involved in detoxification from several drugs.
0.2 to 3% of courses of intravenous acetylcysteine.
Deaths reported (overdose is likely).
Intravenous use (no report following oral administration).
(occurring 20 minutes after starting of treatment)
General: anaphylactic shock, fever (inhalation therapy).
Cutaneous: rash, pruritus, urticaria, angioedema.
Respiratory: bronchospasm (sometimes in asthmatic patients by intravenous or inhalation route).
Hypotension seems to result from a vasodilator action on resistance vasculature (dose-dependent).
Direct non immunological histamine release.
Non life-threatening anaphylactoid reactions to intravenous N-acetylcysteine are easily treated: flushing requires no treatment; urticaria should be treated with antihistamines; angioedema and respiratory symptoms require antihistamines and symptomatic therapy.
In cases of angioedema and respiratory symptoms, N-acetylcysteine should be stopped but can be started again one hour after administration of antihistamines.
Oral methionine and mercaptamine may be used as alternative antidotes.