Possible Interaction: Norepinephrine and Quinidine

“In man, quinidine levels of 1.2 mg/l caused vasodilatation in forearms of six to eight subjects and significantly reduced constrictor responses to intravenous norepinephrine and to lower body negative pressure.”

“ Quinidine reduced standing blood pressure, attenuated the Valsalva response, and increased plasma norepinephrine concentrations, suggesting the presence of nonselective alpha-adrenergic blockade.”

“Treatment with iodoacetate or quinidine resulted in increased ratios of intracellular to extracellular concentration of NE , while ethylenediaminetetraacetate decreased this ratio.”

“ NE uptake was also diminished by ouabain, quinidine , and substitution of lithium for sodium in the medium, suggesting the uptake mechanism is related to a sodium pump.”

“Calcium, molar sodium lactate, disodium calcium versenate, methoxamine, levarterenol , and angiotensin were used in an attempt to reverse the hemodynamic alterations induced by quinidine.”

“They showed that treatment with TTX, ranolazine or quinidine (an older antiarrhythmic drug) could all suppress the sodium channel window current and suppress the CAA response to norepinephrine.”

“Both … quinidine also inhibited the active … [3H]5-HT, [3H]noradrenaline and [3H]dopamine into rat brain synaptosomes with IC50 values in the range 0.13-12.4 microM. The … each drug to inhibit [3H]5-HT uptake was significantly higher than that for [3H]noradrenaline or [3H]dopamine.”

“ Quinidine increased the release of norepinephrine from atria but not from the ventricles; this release was greater from the right than from the left atria.”

“Disopyramide at high concentrations potentiated the contractile response of mesenteric arteries to norepinephrine and tyramine, while, in contrast, procainamide and quinidine shifted the dose—response curve for norepinephrine to the right.”

“ Quinidine significantly reduced constrictor responses to sympathetic nerve stimulation, phenylephrine and norepinephrine while responses to a nonadrenergic constrictor drug, 5-hydroxytryptamine, were not reduced, indicating that quinidine interferes with stimuli that activate alpha adrenergic receptors.”