[3] Class Ia drugs increase the time one action potential lasts in the heart.

[4] Prajmaline is a semi-synthetic propyl derivative of ajmaline, with a higher bioavailability than its predecessor.

[5] It acts to stop arrhythmias of the heart through a frequency-dependent block of cardiac sodium channels.

[6] The effects of some Class I antiarrhythmics are only seen in a patient who has a normal heart rate (~1 Hz).

[1][8][9] Patients who are taking other treatments for their symptoms (e.g. beta blockers and nifedipine) have developed minor transient conduction defects when given Prajmaline.

[3] Due to Prajmaline's sodium channel-blocking properties, it has been shown to protect rat white matter from anoxia (82 +/- 15%).