Reversible increased serum conc & toxicity of lithium. Increased antihypertensive effect w/ baclofen. Attenuated antihypertensive effect w/ NSAIDs ie, ASA, COX-2 inhibitors, nonselective NSAIDs. Increased antihypertensive effect & risk of orthostatic hypotension w/ imipramine-like antidepressants (tricyclics), neuroleptics. Perindopril: Higher frequency of adverse events w/ ARBs, aliskiren & estramustine. Increased risk of angioedema w/ racecadotril, mTOR inhibitors (eg, sirolimus, everolimus, temsirolimus), gliptins (eg, linagliptin, saxagliptin, sitagliptin, vildagliptin); sacubitril/valsartan. Increased risk of hyperkalaemia w/ aliskiren, K salts, K-sparing diuretics (e.g. spironolactone, triamterene or amiloride), ACE inhibitors, AIIAs, NSAIDs, heparins, immunosuppressants (eg, ciclosporin or tacrolimus), trimethoprim, co-trimoxazole. Increased risk of hyperkalaemia, worsened renal function, CV morbidity & mortality w/ aliskiren. Increased risk of severe anaphylactoid reactions w/ extracorporeal treatments. Increased risk of angioneurotic oedema w/ estramustine. Additive hyperkalaemic effects w/ K-sparing diuretics, K salts. Increased blood-glucose lowering effect w/ antidiabetics eg, insulins, oral hypoglycaemic agents. Excessive BP reduction w/ non-K-sparing diuretics. Increased hypotensive effects by antihypertensives & vasodilators. Reduced BP w/ nitroglycerin & other nitrates or other vasodilators. Increased risk of leucopenia w/ allopurinol, cytostatic or immunosuppressive agents, systemic corticosteroids or procainamide. Enhanced hypotensive effects of certain anaesth drugs. Reduced antihypertensive effects w/ sympathomimetics. Nitritoid reactions w/ injectable gold (Na aurothiomalate). Indapamide: Risk of hypokalaemia w/ Torsades de pointes-inducing drugs eg, class IA (eg, quinidine, hydroquinidine, disopyramide) & III (amiodarone, dofetilide, ibutilide, bretylium, sotalol) antiarrhythmic agents, phenothiazines (eg, chlorpromazine, cyamemazine, levomepromazine, thioridazine, trifluoperazine), benzamides (eg, amisulpride, sulpiride, sultopride, tiapride), butyrophenones (eg, droperidol, haloperidol), other antipsychotics (eg, pimozide), others (eg, bepridil, cisapride, diphemanil, IV erythromycin, halofantrine, mizolastine, moxifloxacin, pentamidine, sparfloxacin, IV vincamine, methadone, astemizole, terfenadine). Increased risk of low K levels w/ K-lowering drugs eg, amphotericin B (IV), glucocorticoids & mineralocorticoids (systemic), tetracosactide, stimulant laxatives. Toxic effects due to low K levels may occur w/ digitalis. Increased hypersensitivity reactions to allopurinol. Hypokalaemia or hyperkalaemia w/ K-sparing diuretics eg, amiloride, spironolactone, triamterene. Lactic acidosis due to metformin. Increased risk of acute renal insufficiency w/ high-dose iodinated contrast media. Increased Ca levels w/ Ca salts. Increased creatinine levels w/ ciclosporin, tacrolimus. Reduced antihypertensive effect w/ corticosteroids, tetracosactide (systemic route).