Beneficial late administration of obidoxime in malathion poisoning

Early treatment of organophosphate (OP) poisoning with oximes results in reactivation of acetylcholinesterase and patient recovery. Data on efficacy of late administration of oximes, particularly obidoxime, is limited. A 42-y old woman swallowed 60 ml of 50% malathion in a suicide attempt. Characteristic muscarinic, nicotinic and central manifestations of OP poisoning appeared: atropine and 250 mg obidoxime i.v., resulted in marked improvement. Several hours after the last dose, clinical manifestations recurred and ventilation was required. After 10 d cholinesterase was still low and liver enzymes were elevated. Obidoxime was reinstituted after the 9 d interruption and muscle strength improved with the first dose. The patient could be disconnected from the ventilator and within <24 h was extubated. Oxime therapy should be considered even late in the course of untreated or partially treated OP intoxications, especially when the etiologic agent is a lipid-soluble compound (ie malathion) that can cause a protracted course of poisoning. The clinical course of this patient did not support a cause-and-effect relationship between obidoxime and the abnormal liver function.