Increased serum lithium conc & toxicity. Amlodipine: Increased exposure to simvastatin. Increased plasma conc w/ ketoconazole, itraconazole, ritonavir. Increased exposure w/ grapefruit juice. CYP3A4 inducers eg, rifampicin, Hypericum perforatum
. Valsartan: Increased incidence of hypotension, hyperkalemia & changes in renal function w/ ACE inhibitors, aliskiren. Increased K levels w/ K-sparing diuretics, K supplements, K-containing salt substitutes or drugs increasing K levels eg, heparin. Attenuated antihypertensive effects w/ NSAIDs including COX-2 inhibitors. Increased systemic exposure w/ rifampin, ciclosporin, ritonavir. Hydrochlorothiazide: Potentiated antihypertensive effects of other antihypertensive drugs eg, guanethidine, methyldopa, β-blockers, vasodilators, Ca-channel blockers, ACE inhibitors, ARBs, direct renin inhibitors. Potentiated action of skeletal muscle relaxants. Increased hypokalemic effect w/ kaliuretic diuretics, corticosteroids, ACTH, amphotericin, carbenoxolone, penicillin G, salicylic acid derivatives or antiarrhythmics. Intensified hyponatremic effect w/ antidepressants, antipsychotics, antiepileptics. Altered glucose tolerance of insulin, oral antidiabetics. Thiazide-induced hypokalemia or hypomagnesemia w/ digitalis glycosides. Increased hypersensitivity to allopurinol. Increased risk of ARs by amantadine. Enhanced myelosuppressive effects of antineoplastics. Increased bioavailability w/ anticholinergics. Decreased bioavailability w/ prokinetic drugs. Decreased absorption w/ cholestyramine or colestipol. Potentiated rise in serum Ca w/ vit D or Ca salts. Increased risk of hyperuricemia & gout-type complications w/ ciclosporin. Enhanced hyperglycemic effect of diazoxide. Hemolytic anemia w/ methyldopa. Potentiated orthostatic hypotension w/ alcohol, barbiturates, narcotics. Reduced response to pressor amines.