[Negative inotropic action of famotidine]

In a randomized placebo-controlled study, 12 healthy volunteers were treated for one week each with nifedipine 10 mg four times daily or the same dose of nifedipine concurrently with famotidine 40 mg once daily per os. Famotidine did not significantly alter pharmacokinetic parameters of nifedipine. Determination of systolic time intervals showed that pre-ejection period (PEPc) and the ratio of pre-ejection period over left ventricular ejection time (PEP/LVET) were significantly reduced by administration of nifedipine plus placebo. Coadministration of famotidine and nifedipine, however, led to a significant increase in these parameters. Also, administration of famotidine alone to the same subjects led to a significant rise in PEPc and PEP/LVET. In impedance cardiography, stroke volume and cardiac output were significantly reduced by famotidine, whereas the H2-antagonist did not alter heart rate. This observation indicates for the first time that famotidine may exert negative effects on cardiac performance. In our opinion this could be of clinical relevance in elderly subjects or in patients with heart failure.