Quinidine Amiloride

Chiamvimonvat N, Duff HJ. Amiloride-quinidine interaction adverse outcomes. Clin Pharmacol Ther... 

T Pancreatic insulin release Metformin Peripheral insulin sensitivity hepatic glucose output/production i intestinal glucose absorption Dose Ist-line (naive pts), 1.25/250 mg PO daily-bid 2nd-line, 2.5/500 mg or 5/500 mg bid (max 20/2000 mg) take w/ meals, slowly T dose hold before 48 h after ionic contrast media Caution [C, -] Contra SCr >1.4 mg/dL in females or >1.5 mg/dL in males hypoxemic conditions (sepsis, recent MI) alcoholism metabolic acidosis liver Dz Disp Tabs SE HA, hypoglycemia, lactic acidosis, anorexia, N/V, rash Additional Interactions T Effects W/ amiloride, ciprofloxacin cimetidine, digoxin, miconazole, morphine, nifedipine, procainamide, quinidine, quinine, ranitidine, triamterene,... 

Acebutolol, amiloride, amiodarone, benzthiazide, broxaldine, broxyquinoline, cinchophen, clefamide, clemastine (green rim), cyclopenthiazide, diphenadione, doxycycline, enoxolone, fenbufen, frusemide, halquinol, hydroquinidine, hydroquinine, lorazepam, methyl benzoquate, 5-methyltryptamine, a-methyl-tryptamine, iV-methyltryptamine, metolazone, minocycline, piperacetazine (- red), procyclidine, quinidine, quinine, rimiterol, salbutamol, salinazid, sodium cromoglycate, trichlormethiazide, veratrine (— violet), zomepirac... 

Quinidine has a pharmacodynamic interaction with amiloride, further prolonging the duration of the QRS complex, but not the QT interval (71). 

Na+ Anticonvulsant drugs Class I antiarrhythmics Diuretic drugs Local anesthetic drugs Carbamazepine, phenytoin, valproic acid lA Disopyramide, procainamide, quinidine IB Lidocaine, mexiletine, phenytoin, tocainide IC Encainide, flecainide, propafenone Amiloride Bupivacaine, cocaine, lidocaine, mepivacaine, tetracaine... 

A single study has shown that the antiarrhythmic activity of quinidine can be opposed by amiloride. 

Not understood. The combination of quinidine and amiloride increased the QRS interval, but did not prolong the QT interval more than quinidine alone. 

So far the evidence seems to be limited to this single study but it suggests that amiloride can oppose the antiarrhythmic activity of quinidine. The full clinical implications of this interaction are not yet known, but it would now clearly be prudent to consider monitoring to confirm that the quinidine continues to be effective if amiloride is present. 

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