The following agents may increase certain actions or side effects of anticholinergic drugs. amantadine
antiarrhythmic agents of class (e.g. quinidine), antihistamines antipsychotic agents (e.g. phenothiazines),
benzodiazepines. MAO inhibitors, narcotic analgesics (e.g., meperidine), nitrates and nitrites, sympathomimetic
agents, tricyclic antidepressants, and other drugs having anticholinergic activity.
Anticholinergics antagonize the effects of antiglaucoma agents. Anticholinergic drugs in the presence of increased
intraocular pressure may be hazardous when taken concurrently with agents such as corti costeroids..
Anticholinergic agents may affect gastrointestinal absorption of various drugs, such as slowly dissolving dosage
forms of digoxin; increased serum digoxin concentrations may result.
Anticholinergic drugs may antagonize the effects of the drugs that alter gastrointestinal motility, such as
metoclopramide. Because antacids may interfere with the absorption of anticholinergic agents, simultaneous use of
these drugs should be avoided.
The inhibiting effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents
used to treat achlorhydria and those used to test gastric secretion.