In cases of cholinergic overdose, which muscarinic antagonist is used?

In cases of cholinergic overdose, atropine is the muscarinic antagonist of choice. Atropine works by competitively inhibiting the action of acetylcholine at muscarinic receptors, reversing the excessive stimulation caused by high levels of acetylcholine due to overdose. This is crucial in alleviating symptoms related to cholinergic toxicity, such as excessive salivation, bronchial secretions, and bradycardia.

Atropine's rapid onset and effectiveness make it the preferred agent in emergency situations. It is particularly useful for counteracting the effects of organophosphate poisoning and other cholinergic crises, where its ability to increase heart rate and reduce secretions can be life-saving.

The other agents mentioned, while they are muscarinic antagonists, are not typically used for treating cholinergic overdoses. For example, scopolamine is primarily used for motion sickness and nausea, dicyclomine is mainly prescribed for gastrointestinal motility disorders, and benztropine is utilized in managing Parkinson's disease and drug-induced extrapyramidal symptoms. None of these options can effectively counter the acute symptoms of cholinergic toxicity as efficiently as atropine.