An optical isomer of quinine, extracted from the bark of the Cinchona tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular action potential, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission. [PubChem]
For the treatment of ventricular pre-excitation and cardiac dysrhythmias
Quinidine, a hydantoin anticonvulsant, is used alone or with phenobarbital or other anticonvulsants to manage tonic-clonic seizures, psychomotor seizures, neuropathic pain syndromes including diabetic neuropathy, digitalis-induced cardiac arrhythmias, and cardiac arrhythmias associated with QT-interval prolongation.
Mechanism of action
Quinidine acts on sodium channels on the neuronal cell membrane, limiting the spread of seizure activity and reducing seizure propagation. The antiarrhythmic actions are mediated through effects on sodium channels in Purkinje fibers. Quinidine may also act on the slow inward calcium current (ICa), the rapid (IKr) and slow (IKs) components of the delayed potassium rectifier current, the inward potassium rectifier current (IKI), the ATP-sensitive potassium channel (IKATP) and Ito.
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682