Clidinium (generally found as the bromide salt, clidinium bromide) is an anticholinergic drug. It may help symptoms of cramping and abdominal/stomach pain by decreasing stomach acid, and slowing the intestines. It is commonly prescribed in combination with chlordiazepoxide using the brand name Librax.

Clidinium is an effective anticholinergic agent with activity approximating that of atropine sulfate against spasms induced by acetylcholine in isolated intestinal strips. On oral administration in mice it proved an effective antisialagogue in preventing salivation induced by pilocarpine. Spontaneous intestinal motility in both rats and dogs is reduced following oral dosing with 0.1 to 0.25 mg/kg. Potent cholinergic ganglionic blocking effects (vagal) are produced with intravenous usage in anesthetized dogs.

Oral doses of 23 mg/kg to dogs produced signs of nasal dryness and slight pupillary dilation. In two other species, monkeys and rabbits, doses of 5 mg/kg, po, given three times daily for 5 days did not produce apparent secretory or visual changes.