Physostigmine overdose can cause cholinergic crisis. Atropine may be administered at one-half the dose of physostigmine to reverse cholinergic effects. Pralidoxime is of questionable value in carbamate insecticide poisoning. These doses may be repeated in 1 to 2 hours and then every 6 to 12 hours if muscle weakness or coma is not relieved. Isoniazid combines with pyridoxine to form the isonicotinoylhydrazine derivative of pyridoxine, resulting in pyridoxine deficiency.
Seizures associated with isoniazid overdose often respond to pyridoxine administration.
Gm for each gram of isoniazid taken. If the dose of isoniazid is unknown, administer 5 Gm over 30 to 60 minutes. The dose may be repeated in 30 minutes as needed. After 5 days reduce the dose frequency to every 12 hours for an additional 2 weeks. Repeat courses may be necessary if indicated by weekly monitoring of blood lead concentrations.