4. Gut— antimuscarinic agents

Atropine, methscopolamine, and propantheline were used in the past to reduce acid secretion in acid-peptic disease, but are now obsolete for this indication because they are not as effective as H2 blockers and proton pump inhibitors, and they cause far more frequent and severe adverse effects. The M1-selective inhibitor pirenzepine is available in Europe for the treatment of peptic ulcer. Muscarinic blockers can also be used to reduce cramping and hypermotility in transient diarrheas, but drugs such as diphenoxylate and loperamide are more effective.