Anticholinergic drugs are agents which block the effects of acetylcholine on cholinergic receptors but conventionally anti-muscarinic drugs are referred to as anticholinergic drugs. Drugs that block the nicotinic receptors are ganglion blockers and neuromuscular blockers. Anticholinergic drugs include atropine, hyoscine and their semisynthetic derivatives and synthetic substitutes. The actions of atropine and scopolamine are similar except that atropine is a CNS stimulant while scopolamine is a CNS depressant and causes sedation. Atropine increases heart rate, reduces secretions, relaxes smooth muscle tone, causes mydriasis and in higher doses stimulates the CNS. Atropine and its derivatives are used as antispasmodics, pre-anesthetic medication, in organophosphorus poisoning, and to produce mydriasis. Hyoscine is used for motion sickness. Derivatives of atropine are preferred for most indications of atropine.