Effects of cimetidine and ranitidine on splanchnic hemodynamics in patients with chronic liver disease.

Effects of two histamine H2 receptor antagonists, cimetidine and ranitidine, on systemic and splanchnic hemodynamics were studied in patients with chronic liver disease by simultaneous catheterization of the portal vein and the right hepatic vein and measurement of portal venous flow using the ultrasound doppler system or cineangiography. Neither infusion of 200 mg of cimetidine nor 50 mg of ranitidine reduced cardiac output, portal venous pressure, the gradient between wedged hepatic venous pressure and free hepatic venous pressure, hepatic blood flow, and portal venous flow. It is unlikely that histamine is an important modulator of flow via the H2 receptor.