Which mechanism describes H2 receptor blockers?

Which mechanism describes H2 receptor blockers?

• A. They block histamine H2 receptors on parietal cells to reduce acid secretion
• B. They irreversibly inhibit the proton pump
• C. They neutralize gastric acid
• D. They stimulate mucous production

Answer: (A)

H2 receptor blockers work by blocking histamine H2 receptors on gastric parietal cells, which reduces acid secretion. Histamine binding to these receptors normally stimulates a cascade that increases cyclic AMP and activates the proton pumps that secrete stomach acid. By occupying the receptor, these drugs prevent histamine from triggering that cascade, leading to lower acid output, especially reducing basal and nocturnal acid secretion and helping with conditions like GERD and peptic ulcers. This mechanism is competitive and reversible, unlike proton pump inhibitors, which irreversibly inhibit the proton pump; it’s also not about neutralizing acid like antacids or increasing mucus production like protective agents.

H2 receptor blockers work by blocking histamine H2 receptors on gastric parietal cells, which reduces acid secretion. Histamine binding to these receptors normally stimulates a cascade that increases cyclic AMP and activates the proton pumps that secrete stomach acid. By occupying the receptor, these drugs prevent histamine from triggering that cascade, leading to lower acid output, especially reducing basal and nocturnal acid secretion and helping with conditions like GERD and peptic ulcers. This mechanism is competitive and reversible, unlike proton pump inhibitors, which irreversibly inhibit the proton pump; it’s also not about neutralizing acid like antacids or increasing mucus production like protective agents.