Pharmacology of H2 Receptor Antagonists

H2 Receptor Antagonists

Histamine H2 receptor antagonists are competitive blockers of gastric parietal-cell H2 receptors that suppress basal and stimulated acid secretion and are used for GERD, peptic ulcer disease, hypersecretory states, and selected prophylaxis indications, with famotidine preferred clinically because of potency and safety while ranitidine has been withdrawn for NDMA contamination concerns. The class reduces nocturnal … Read more

Sildenafil: Its Use as a PDE5 Inhibitor for Erectile Dysfunction

sildenafil

Phosphodiesterase type 5 (PDE5) inhibitors are first‑line oral agents for erectile dysfunction that augment the endogenous nitric oxide–cGMP pathway in the corpus cavernosum to facilitate erection with sexual stimulation, and the class includes sildenafil, vardenafil, tadalafil, and avanafil. Standard pharmacology texts detail shared mechanisms with clinically important differences in onset, duration, food effects, selectivity, and … Read more