Procyclidine
Procyclidine is only found in individuals that have used or taken this drug. It is a muscarinic antagonist that crosses the blood-brain barrier and is used in the treatment of drug-induced extrapyramidal disorders and in parkinsonism. The mechanism of action is unknown. It is thought that Procyclidine acts by blocking central cholinergic receptors, and thus balancing cholinergic and dopaminergic activity in the basal ganglia. Many of its effects are due to its pharmacologic similarities with atropine. Procyclidine exerts an antispasmodic effect on smooth muscle, and may produce mydriasis and reduction in salivation.