Co-Ivyzar Drug Interactions

No significant drug-drug pharmacokinetic (or pharmacodynamic) interactions have been found in interaction studies of irbesartan with digoxin, warfarin and nifedipine.
In vitro studies show significant inhibition of the formation of oxidized irbesartan metabolites with the known cytochrome CYP2C9 substrates/inhibitors sulphenazole, tolbutamide and nifedipine. However, in clinical studies, the consequences of concomitant irbesartan on the pharmacodynamics of warfarin were negligible. Based on in vitro data, no interaction would be expected with drugs whose metabolism is dependent upon CYP450 isozymes 1A1, 1A2, 2A6, 2B6, 2D6, 2E1 or 3A4.
Many of the interactions of hydrochlorothiazide are due to its effect on fluid and electrolyte balance. Diuretic-induced hypokalemia may enhance the toxicity of digitalis glycosides and may also increase the risk of arrhythmias with drugs that prolong the QT interval eg, astemizole, terfenadine, halofantrine, pimozide and sotalol. It may also enhance the neuromuscular blocking action of competitive neuromuscular blockers eg, atracurium. Its potassium-depleting effect may be enhanced by corticosteroids, corticotropin, β2-agonists eg, salbutamol, carbenoxolone, amphotericin B or reboxetine. Hydrochlorothiazide may enhance the nephrotoxicity  of NSAIDs. It has also been reported to diminish the response to pressor amines eg, noradrenaline. It should not be used with lithium to prevent reaching toxic blood level. Increased toxicity has been reported when administered with allopurinol and tetracyclines.