Quinidine with digoxin

The interaction of quinidine with digoxin involves displacement of digoxin from tissues. 

The pharmacokinetic interaction of quinidine with digoxin also occurs with quinine (280,281) and hydroxychloroquine (282). However, the effects of these drugs are smaller than those with quinidine. Quinine reduces the extrarenal clearance of digoxin, perhaps by altering its biliary secretion (283). 

The pharmacokinetic interaction of quinidine with digoxin also occurs with quinine and hydroxychloroquine (49). 

Fromm et al. [61] have shown in Caco-2 cells, that the apical to basolateral flux of digoxin is 1.2% per hour, and the basolateral to apical flux is 8.9% per hour. This polarized flux can be normalized by the addition of increasing concentrations of quinidine (with 100 pM quinidine, digoxin flux rates are 2.7% per hour apical to basolateral and 3% per hour basolateral to apical). Such a profile is indicative of... 

Quinidine can increase the plasma concentrations of digoxin, which may in turn lead to signs and symptoms of digitalis toxicity. Gastrointestinal, central nervous system (CNS), or cardiac toxicity associated with elevated digoxin concentrations may occur. Quinidine and digoxin can be administered concurrently however, a downward adjustment in the digoxin dose may be required. 

Concurrent administration of propafenone with digoxin, warfarin, propranolol, or metoprolol increases the serum concentrations of the latter four drugs. Cimetidine slightly increases the propafenone serum concentrations. Additive pharmacological effects can occur when lidocaine, procainamide, and quinidine are combined with propafenone. 

Adenosine does not interact with digoxin, disopyramide, flecainide, or quinidine. 

A placebo-controUed study of the use of propafenone 450-600 mg orally, either alone or in combination with digoxin, has been carried out in 176 patients with atrial fibrillation a further 70 patients were given digitalis plus quinidine (12). There were no significant differences across the groups in terms of percentage conversion to sinus rhjThm,... 

P-gp-mediated transport. These authors underlined their results with P-gp knockout mice studies. Co-administration of digoxin and quinidine to wild-type mice resulted in a 73% increase in digoxin concentrations, whereas the increase for the knockout mice was only 20%. 

Digoxin uptake into rat hver shces showed a temperature-dependent component, compatible with the involvement of carrier-mediated uptake mechanisms. Quinine markedly inhibited the uptake of digoxin, in contrast to its diastereomer quinidine, which only slightly inhibited the digoxin uptake in rat liver slices. This stereoselective inhibition is in line with results obtained in isolated rat hepatocytes and isolated perfused rat hvers [90,91]. These results were also found after cryopreservation of the slices, indicating that carrier-specific phenomena can be studied after cryopreservation [92]. 

UnUke quinidine, disopyramide does not increase the plasma concentration of digoxin in patients receiving a maintenance dose of the cardiac glycoside. Hypoglycemia has been reported with the use of disopyramide, particularly in conjunction with moderate or excessive alcohol intake. 

Amiodarone increases the hypoprothrombinemic response to warfarin (an oral anticoagulant) by reducing its metabolism. Patients receiving digoxin may undergo an increase in serum digoxin concentrations when amiodarone is added to the treatment regimen. Amiodarone interferes with hepatic and renal elimination of flecainide, phenytoin, and quinidine. 

Memantine is not a major substrate for hepatic cytochrome P450 isoenzymes and has not been shown to significantly inhibit or induce these enzymes. However, memantine is partially excreted by renal tubular secretion. Thus, concomitant use of other medications that use the same renal system (i.e., triampterene, hydrochlorothiazide, digoxin, cimetidine, ranitidine, metformin, and quinidine) may affect plasma levels of both drugs (Namenda 2005). Memantine should not be used in combination with other NMDA receptor antagonists, such as amantadine or dextromethorphan, because these combinations have not been formally studied. The clearance of memantine can be reduced when the urine is alkalinized, such as with the concomitant use of sodium bicarbonate or carbonic anhy-... 

Quinidine inhibits the tubular secretion of digoxin which consequently raises the plasma digoxin concentration, which may be associated with toxicity. Certain other drugs also increase the digoxin concentration like verapamil, amiodarone, spironolactone etc. 

Like other aluminium salts, pulmonary aspiration of sucralfate can lead to acute lung injury. There is some systemic absorption of aluminium, which is probably significant only in patients with renal impairment. Administration can be associated with a degree of hypophosphataemia, and there is also interference with absorption of some other drugs, e.g. quinolone antibacterials, digoxin, quinidine, and warfarin. 

Simultaneous administration of sucralfates with other nonantacid medication should be given after an interval of at least 2 hours. Sucralfates interact with rantidine, cimetidine, digoxin, quinidine, theophylline, and warfarin. Sulfasalazine should be administered with caution with antibacterials and antineoplastics.179... 

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