A Class Ia agent that blocks the fast sodium channel which depresses the phase 0 depolarization (reduces Vmax), and prolongs the action potential duration. It has been used in its intravenous formulation to treat malaria, particularily in the USA as the FDA has not licensed a preparation of iv quinine. It is less toxic than quinine but not as effective against some strains of falciparum malaria.
This reduced due to the risk of ventricular arrhythmia and death. Paradoxically this then resulted is better definition of its indications which because they were more limited and specific has caused troubles with drug availability.
- Ventricular tachyarrythmias
- Brugada syndrome and short-QT syndrome
Quinidine also blocks the slowly inactivating Na current and the slow ICa current, the rapid IKr and slow (IKs) components of the delayed potassium rectifier current, the inward potassium rectifier current (IKI) and the ATP-sensitive potassium channel (IKATP).
Cautions and Interactions
It is a reasonably active platelet-activating factor inhibitor.
- ↑ Yang F, Hanon S, Lam P, Schweitzer P. Quinidine revisited. The American journal of medicine. 2009 Apr; 122(4):317-21.(Link to article – subscription may be required.)