The
verapamil analog
falipamil is a new compound with specific bradycardic action on the sinus node. It differs from
verapamil with respect to its electrophysiological and haemodynamic actions.
Falipamil causes a slight prolongation of intraatrial and intraventricular conduction, whereas sinuatrial and AV-node conduction is enhanced. The refractory periods of atrial and ventricular myocardium and ventricular repolarization are significantly prolonged, whereas the refractory period of the AV-node is shortened.
Falipamil fails to influence any haemodynamic parameter significantly at rest, if heart rate is kept constant. In exercise-induced myocardial ischaemia, changes in haemodynamics reflect changes in heart rate. Increased sinus rate at rest is significantly reduced by
falipamil 15%-25%. Around 150 mg
falipamil prove aequieffective to about 40 micrograms
pindolol.
Atropine-induced and
catecholamine-induced
sinus tachycardia is also significantly diminished. Increased sinus rate during exercise is lowered by about 10%. Through reduction of heart rate,
falipamil proves capable of significantly diminishing or even preventing ischaemic ST-segment depression and ischaemia induced increase in pulmonary capillary pressure. Thus
falipamil can be used to normalize sinus rate in patients with
sinus tachycardia of various origin, particularly in
intensive care, in acute ischaemic
heart disease, in anaesthesia and in surgery cases.