A class of drugs also referred to as antimuscarinics that are used as smooth muscle antispasmodics and antisecretory drugs. Anticholinergic medications include the natural belladonna alkaloids (atropine and hyoscine) and synthetic and semisynthetic derivatives. The synthetic and semisynthetic derivatives are separated into tertiary amines (i.e. dicyclomine), and quaternary ammonium compounds, (i.e. hyoscine butylbromide and glycopyrrolate). The quaternary ammonium compounds are less lipid soluble than the natural alkaloids, and are therefore less likely to cross the blood-brain barrier and cause side effects such as agitation and hallucinations.