Pirenzepine is used in the treatment of peptic ulcers, as it reduces gastric acid

Gastric acid

Gastric acid is a digestive fluid, formed in the stomach. It has a pH of 1 to 2 and is composed of hydrochloric acid , and large quantities of potassium chloride and sodium chloride...

 secretion and reduces muscle spasm. It is in a class of drugs known as muscarinic receptor antagonists - acetylcholine

Acetylcholine

The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...

 being the neurotransmitter of the parasympathetic nervous system

Parasympathetic nervous system

The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system . The ANS is responsible for regulation of internal organs and glands, which occurs unconsciously...

 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

Blood-brain barrier

The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...

.

Pirenzepine has been investigated for use in myopia

Myopia

Myopia , "shortsightedness" ) is a refractive defect of the eye in which collimated light produces image focus in front of the retina under conditions of accommodation. In simpler terms, myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in...

control.