Hemodynamic studies on cimetidine and ranitidine in anesthetized dogs

Abstract

The cardiovascular effects of the H2-receptor-antagonists cimetidine and ranitidine have been compared in a randomized double-blind crossover study. The experiments were performed in seven anesthetized mongrel dogs. Cimetidine (200 mg) and ranitidine (50 mg) were infused i.v. for 2 min. The time interval between cimetidine and ranitidine application was always 3 h. The direct comparison of the drug effects on blood pressure shows a significant difference between cimetidine and ranitidine (P less than 0.001). Apart from the sequence of application, cimetidine causes a significant decrease (P less than 0.01) in total peripheral resistance (-271 +/- 50 dyn . s . cm-5) resulting in a decrease in mean blood pressure (-9 +/- 1.1 mmHg). In contrast to cimetidine, none of the recorded parameters are altered significantly by ranitidine. Heart rate, left ventricular end-diastolic pressure, myocardial contractility (dP/dtmaxLV), mean right atrial pressure, mean pulmonary artery pressure, and cardiac output are not affected significantly by either drug. Due to our results it might be concluded that the cimetidine-induced hypotension is mediated by peripheral vasodilation.

Anticholinesterase Activity of Histamine H2‐Receptor Antagonists in the Dog: Their Possible Role in Gastric Motor Activity

“…We observed, however, that ranitidine at a dose of 3.0 mg/kg sometimes caused dogs to collapse, and in the anesthetized dogs ranitidine at a dose of 3.0 mg/kg markedly decreased the blood pressure. Previous reports have also shown that cimetidine and ranitidine induce hypotension (25)(26)(27), although such a severe decrease in blood pressure was not observed. Since the decrease in blood pressure was not shown in the case of famotidine, anticholinesterase activity may also he involved in this phenomenon.…”

Gastroprokinetic Activity of Nizatidine during the Digestive State in the Dog and Rat

“…the circular system, gland secretion, intestinal transit, and defecation as adverse events. It has been reported that neostigmine, cimetidine, and ranitidine decrease blood pressure in experimental animals [21,23]. Both in non-clinical and clinical studies on nizatidine, no severe AChE inhibition-related adverse events including a fall in blood pressure and severe diarrhea have been observed [24,25].…”