Antidotes
A number of antidotes have been used in the clinical setting for Amanita phalloides poisoning to limit intracellular uptake of amatoxin by the liver; however, evidence for their efficacy is limited. These antidotes include silibinin, rifampicin and high-dose benzylpenicillin. The typically long delay before starting treatment may limit the effectiveness of antidotal therapies.
If the patient presents with gastrointestinal symptoms, start antidotal therapy as soon as possible. Seek advice on the choice of antidote from a clinical toxicologist or hepatologist. Silibinin is the preferred antidote; however, access may be limited to tertiary centres, toxicology units and poisons information centres1. Specific dosing for children has not been established, but the same dose as for adults is likely to be effective. If available, for adults and children, use:
silibinin 5 mg/kg intravenously, over 1 hour amanita phalloides mushroom poisoning
FOLLOWED BY
silibinin 20 mg/kg/24 hours by intravenous infusion for up to 4 days.
If silibinin is not available, use:
1 benzylpenicillin 3 g (child: 60 mg/kg up to 2.4 g) intravenously, every 4 hours amanita phalloides mushroom poisoning benzylpenicillin
OR
1 rifampicin 600 mg (child: 15 mg/kg up to 600 mg) intravenously over 1 to 3 hours, daily. amanita phalloides mushroom poisoning rifampicin
If acute liver injury is resolving or not severe, stop antidotal therapy in consultation with a clinical toxicologist or hepatologist.