rarely available on a stat basis A decrease in the cholinesterase activity of the red blood cells is more specific for organophosphate inhibition than is the plasma assay Although plasma cholinesterase is depressed by liver injury from various causes and a small percentage of the population has a genetically determined deficiency of plasma cholinesterase activity, a depression of 25% or more is a strong evidence of excessive organophosphate absorption However, it is important not to delay treatment until confirmation of plasma cholinesterase Note that children may also encounter acetylcholinesterase inhibitors if they ingest an adult’s medication for Alzheimer or Parkinson disease (i.e., rivastigmine, donepezil, tacrine, and galantamine) The management of a patient who has ingested organophosphates must always include safeguards against exposure for the persons who treat the patient because the organophosphates are readily absorbed through the skin and mucous membranes Patients who have been poisoned by the topical application of organophosphates should immediately receive a thorough scrubbing with a soap solution to prevent further absorption In addition, all contaminated clothing must be removed and stored in a plastic bag to protect emergency personnel After decontamination, antidotal therapy begins with the administration of atropine sulfate given in a dose of 0.02 to 0.05 mg/kg IV (to a maximum of mg) to children and to mg for adolescents and adults This dose should be doubled every minutes as needed to obtain and maintain full atropinization, and then an infusion of 10% to 20% of the total loading dose/hour should be administered Atropinization is indicated by the clearing of bronchial secretions and rales Therapy is continued until all absorbed organophosphate has been metabolized and may require more than 2,000 mg of atropine, via bolus dosing and/or subsequent atropine infusion, over the course of a few hours to several days After atropinization has been instituted, severe poisonings should be treated with the addition of pralidoxime This drug is particularly useful in poisonings characterized by profound weakness and muscle twitching A dose of 25 to 50 mg/kg should be administered in 100 mL of saline by infusion over approximately 30 minutes; adults may receive to g by IV In life-threatening situations, 50% of the initial pralidoxime dose may be infused over minutes, followed by the remainder of the dose over 30 minutes After loading, a 1% concentration may be infused continuously at the rate of 500 mg/hr in adolescents and adults, or approximately 10 mg/kg/hr in children, and can be titrated to clinical effect Occasionally, patients may require more than 48 hours of therapy; the end point should be persistent relief of neurologic and cholinergic signs