Pirenzepine (marketed by Merck Marker under the trade-name Gastrozepin) is used in the treatment of peptic ulcers, as it reduces gastric acid secretion and reduces muscle spasm. It is in a class of drugs known as Muscarinic receptor antagonists - acetylcholine being the neurotransmitter of the parasympathetic nervous system which initiates the rest-and-digest state (as opposed to fight-or-flight), the result being an increase in gastric motility and digestion. It has no effects on the brain and spinal cord as it cannot diffuse through the blood-brain barrier.

Pirenzepine has been investigated for use in myopia control.