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The effects of chronic oral cimetidine therapy on the cardiovascular system in man
Insights
Oral cimetidine, used for peptic ulcers, showed no adverse cardiovascular effects in patients. This study suggests histamine (H2) receptors may not play a significant physiological role in the human cardiovascular system.
Area of Science:
- Cardiovascular Pharmacology
- Gastroenterology
Background:
- Histamine (H2) receptors are present in the human cardiovascular system.
- Cimetidine is a widely used H2 receptor antagonist for peptic ulcer treatment.
Purpose of the Study:
- To assess the cardiovascular effects of oral cimetidine therapy in patients with peptic ulcers.
Main Methods:
- A double-blind, placebo-controlled crossover trial involving 19 patients in symptomatic remission.
- Cardiac parameters were evaluated at rest and during maximal treadmill exercise.
- 24-hour ambulatory monitoring and echocardiography were used to assess cardiac function.
Main Results:
- No significant differences in resting heart rate, blood pressure, or ECG were observed between cimetidine and placebo groups.
- Cimetidine did not affect exercise tolerance, maximum heart rate, or blood pressure during exercise.
- No changes in ventricular ectopics, heart rate variability, left ventricular volume, or contractility were detected.
Conclusions:
- Oral administration of cimetidine (400 mg four times daily) is not associated with demonstrable cardiovascular changes.
- The findings suggest a lack of a significant physiological role for cardiovascular H2 receptors in humans.
Abstract:
1 The demonstration of histamine (H2) receptors in the cardiovascular system in man and the widespread use of the specific H2 receptor antagonist cimetidine for the treatment of peptic ulcer has necessitated assessment of the cardiovascular effects of this drug during oral therapy in man. 2 Consequently, nineteen patients with a history of peptic ulcer but in symptomatic remission underwent a double-blind crossover trial of oral cimetidine v placebo, each treatment period lasting 4 weeks. No significant difference in various cardiac parameters at rest (heart rate, blood pressure, ECG) or following a maximal treadmill exercise test (time-into-protocol, maximum heart rate and blood pressure) was found between the groups. Similarly, cimetidine produced no change in the incidence of ventricular ectopics or in heart rate on 24 h ambulatory monitoring and had no effect on left ventricular volume or contractility as measured by echocardiography. 3 Thus oral administration of cimetidine in a dose of 400 mg four times daily was associated with no demonstrable cardiovascular changes. In addition, since this dose is thought compatible with cardiovascular H2 receptor blockade this study favours the lack of a physiological role for these receptors in man.