Inhibition of COX-1 leads to which effect on the gastric mucosa?

• A. Loss of gastric lining protection
• B. Increased mucus production
• C. Reduced acid secretion
• D. Enhanced mucosal defense

Answer: (A)

In this scenario, the key idea is that COX-1 makes protective prostaglandins in the stomach, especially PGE2. These prostaglandins boost the gastric mucosal defense by stimulating mucus and bicarbonate secretion, supporting blood flow to the mucosa, and aiding epithelial repair. When COX-1 is inhibited, those protective prostaglandins drop, so mucus and bicarbonate production decline, mucosal blood flow decreases, and repair processes slow. The gastric lining becomes more vulnerable to injury from acid, leading to erosion and ulcers. That’s why the effect is loss of gastric lining protection. Increased mucus production or reduced acid secretion would not fit this mechanism, and enhanced mucosal defense would be the opposite of what COX-1 inhibition does.