An 8 year old child is brought to emergency after accidently swallowing multiple tablets of a drug. The child developed severe diarrhea, urination, sweating and respiratory difficulty. On examination, pupil was constricted and there were crepitations heard on lung auscultation in lower lobes of both lungs. There were no vascular or CNS effects. Which drug can cause these type of effects?

The drug poisoning has cholinergic effects suggested by diarrhea, urination, sweating, miosis and bronchoconstriction and respiratory secretions. However no vascular effect is seen These findings suggest that the drug is an indirect-acting cholinergic agent. So, acetylcholine and bethanechol can be easily ruled out as these are directly acting agents. As the drug lacks CNS effects, means it is not able to enter the brain. So, physostigmine is also ruled out. Neostigmine is a quaternary substance with poor lipid solubility and has little or no CNS effects.