Haemodynamic effects of BM 10.188, a new orally active inotropic agent, in healthy volunteers

Uncorrected pre-ejection period: a simple non-invasive measurement for pharmacodynamic screening of inotropic activity

Since heart rate (HR) is an important determinant of the duration of systole, systolic time intervals (STI) from 8 healthy subjects were examined after infusion of atropine. As no overall correlation was found between HR and pre-ejection period (PEP), the results confirm the need for individual estimates of the correction of the left ventricular ejection time (LVET) and the total electromechanical systole (OS2). In the same subjects the sensitivity of PEP to minor negative inotropic effects of mexiletine and disopyramide measured at Cmax was confirmed. Thus, in addition to its simplicity and reliability, the sensitivity of the uncorrected PEP should encourage use of this technique as part of any screening system for the early detection of an inotropic effect of new chemical entities.

Systolic time intervals in evaluation of the negative inotropic effect after single oral doses of mexiletine and disopyramide

A placebo-controlled, single blind, crossover study was done to evaluate the inotropic effects of single oral doses of mexiletine and disopyramide assessed by the measurement of Systolic Time Intervals (STI). Each of 8 healthy volunteers received five treatments in random order: 200 and 400 mg mexiletine, 100 and 200 mg disopyramide, and placebo. There was a significant increase in cumulated PEP after 400 mg mexiletine and 200 mg disopyramide. There was no significant change in LVET and QS2. Peak plasma levels were in the lower range of the reputed antiarrythmic levels. Plasma concentration-effect relationships are discussed. Although the study revealed large inter- and intrasubject variability in the measured STIs, it is concluded that a negative inotropic effect was detected despite the low plasma levels of the minor negative inotropic drugs.

The effect of glyceryl trinitrate ointment on heart rate--corrected systolic time intervals in angina pectoris

1 Individual systolic time intervals (STI) v heart rate regression equations were determined using small doses of intravenous atropine in seven patients with angina pectoris. 2 Regression lines of the form LVET = A + B.HR and QS2 = C + D.HR were calculated. There was no significant correlation between PEP and HR. The values of parameters A C and D were significantly different from a group of previously studied normal volunteers. 3 STI changes were recorded for 5 h after the application of GTN or placebo ointment. The active drug caused shortening of LVET and QS2 with the peak effect occurring between 105 and 180 min. After 180 min neither LVET nor QS2 were significantly shortened. There was no significant effect on PEP or heart rate.