C17H23N03; dl-tropyl tropate; a racemic mixture of d- and l-hyoscyamine, alkaloids obtained from the leaves and roots ofAtropa belladonna; an anticholinergic, with diverse effects (tachycardia, mydriasis, cycloplegia. constipation, urinaryretention, antisudorific) attributable to reversible competitive blockade of acetylcholine at muscarinic type cholinergicreceptors; used in the treatment of poisoning with organophosphate insecticides or nerve gases. The (-) form is by far themore active. Syn: dl-hyoscyamine, tropine tropate.