Possible Interaction: Quinidine and Quinine

“Both red cell and plasma levels of quinine-quinidine were higher than quinine levels.”

“ Quinidine exhibited stronger inhibition than quinine ; however, these two compounds inhibited the CYP2D6.10-mediated reaction more weakly than the CYP2D6.1 and CYP2D6.2 reactions.”

“The Lineweaver-Burk plots with varying inhibitor concentrations suggested that inhibition by quinidine and quinine was competitive.”

“Thus, the dog expresses a CYP2D ortholog possessing enzymatic activities similar to human CYP2D6, but is affected by the inhibitors quinine and quinidine in a manner closer to that of rat CYP2D1.”

“The mean trough level of quinidine (10 mumol/l) was about 2.5-times less than that of quinine (25 mumol/l).”

“The risks of fast intravenous injection of quinine , the striking prolongation of the electrocardiographic (ECG) QT interval triggered by quinidine , and the lethality of CQ in overdose have separately caused substantial concern.”

“Though common with other potassium channel blockers (ezogabine and quinine ), such discoloration has only rarely been reported with quinidine, all in adults.2 Epileptologists should be aware of this potential complication of quinidine therapy.”

“Moreover, quinidine blocks the entrance of the active pocket of CYP2D6 more closely than quinine does, which explains well why the inhibitory activity of quinidine is of 2 magnitudes larger than quinine.”

“Crossreactivity between quinine and quinidine photoallergy has been reported, but not with chloroquine.”

“In conclusion, we showed that quinine and quinidine coadministered with HF might inhibit its metabolism resulting in the potentiation of HF-induced cardiotoxicity in patients.”