Quinine bisulfate

Quinidine is an antiarrhythmic agent. Quinidine is a potent, orally active, selective cytochrome P450db inhibitor. Quinidine is also a K+ channel blocker with an IC50 of 19.9 μM. Quinidine can be used for malaria research[1][2][3].

Research Areas >> Cancer

Research Areas >> Cardiovascular Disease

Research Areas >> Infection

Signaling Pathways >> Metabolic Enzyme/Protease >> Cytochrome P450

Signaling Pathways >> Membrane Transporter/Ion Channel >> Potassium Channel

Quinidine sulfate is an anti-arrythmic drug which affects ionic currents in heart muscle and which has also been shown to be a potent blocker of several classes of K+ channel in a variety of cell types[1]. Bath application of quinidine sulfate causes a dose-dependent reduction of the peak amplitude of Ik. The Kd for blockade of Ik at 0 mV is estimated to be 41 μM[1]. Quinidine sulfate elicits a dose-dependent increase of the rate of the decay of Ik and this effect is enhanced by membrane depolarization. Quinidine also causes a 5 mV hyperpolarizing shift of the steady-state inactivation curve and increases the half-time for recovery from inactivation. Quinidine does not affect the onset of inactivation measured at -30 mV[1].

Quinidine sulfate is rapidly absorbed, with peak plasma concentrations 60-90 min after an oral dose. Other salts (gluconate, polygalacturonate) are more slowly absorbed, with lower peak concentrations[2]. Quinidine sulfate is approximately 70-90 % bound to plasma proteins. It undergoes hepatic oxidative metabolism to form an N-oxide, a 3-hydroxy form, an O-demethyl form and 2'-quinidinone[2]. Quinidine sulfate inhibits metabolism of amphetamine in rats. Quinidine pretreatment results in a significant decrease in the excretion of p-hydroxyamphetamine at 24 and 48 h to 7.2 and 24.1% of the vehicle-control levels, respectively, accompanied by a significant increase in amphetamine excretion between 24 and 48 h to 542% of the control[3].

[1]. Kehl SJ, et al. Quinidine-induced inhibition of the fast transient outward K+ current in rat melanotrophs. Br J Pharmacol. 1991 Jul;103(3):1807-13.

[2]. Roden DM, et al. Class I antiarrhythmic agents: quinidine, procainamide and N-acetylprocainamide, disopyramide.

[3]. Moody DE, et al. Quinidine inhibits in vivo metabolism of amphetamine in rats: impact upon correlation between GC/MS and immunoassay findings in rat urine. J Anal Toxicol. 1990 Sep-Oct;14(5):311-7.