Increased hypotensive effects w/ other antihypertensive agents. Risk of vol depletion & hypotension w/ high dose diuretics. Increased serum conc & toxicity of lithium. K serum disturbances may affect digital glycosides & antiarrhythmics. Irbesartan: Higher frequency of adverse reactions w/ ACE inhibitors, angiotensin II blockers or aliskiren. Increased serum K levels w/ K-sparing diuretics, K supplements, K-containing salt substitutes, or other medicinal products that may increase serum K levels (eg, heparin Na). Attenuation of antihypertesive effect & increased risk of worsening renal function w/ NSAIDs. Hydrochlorothiazide: Potentiated serum K-depleting effect w/ other medicinal products associated w/ K loss & hypokalaemia (eg, other kaliuretic diuretics, laxatives, amphotericin, carbenoxolone, penicillin G Na). Potentiated orthostatic hypotension w/ alcohol. May require dose adjustment of antidiabetic & antigout agents. Impaired absorption w/ cholestyramine & colestipol resins. Increased electrolyte depletion w/ corticosteroid & ACTH. Thiazide-induced hypokalaemia or hypomagnesaemia favour the onset of digitalis-induced cardiac arrhythmias. Possible reduced diuretic, natriuretic & antihypertensive effects w/ NSAIDs. Decreased effects of pressor amines. Increased effect of non-depolarizing skeletal muscle relaxant (eg, tubocurarine). Increased incidence of hypersensitivity reactions to allopurinol. Increased serum Ca levels w/ Ca supplements or Ca-sparing agents. Risk of symptomatic hyponatraemia w/ carbamazepine. Enhanced hyperglycaemic effect of β-blocker & diazoxide. Increased bioavailability w/ anticholinergics (eg, atropine, biperiden). Increased risk of adverse reactions of amantadine. Reduced renal excretion & enhanced myelosuppressive effects of cytotoxic agents (eg, cyclophosphamide, methotrexate).