Interactions for Enalapril Antacids: Decrease effeciency of Captopril. Indomethacin: Reduces hypotensive effect. Digoxin: Increases plasma digoxin levels. Potassium preparations & potassium sparing diuretics: Hyperkalaemia and increased risk of renal failure. Lithium: Toxicity due to increased serum concentration of lithium. Immunosuppressive Drugs : Increased risk of bone marrow depression. Antidepressants, diuretics, Beta-blockers, Nitrates, Dopaminergics, Calcium channel blockers, Phenothiazines: Enhance hypotensive effect. Morphine: Enhanced analgesic effect and respiratory depression. Interactions for Hydrochlorothiazide Cholestyramine & Colestipol: decrease absorption of hydrochlorothiazide. Diazoxide: Additive action - may cause hyperglycemia, hyperuricaemia and hypotension. Digitalis: Diuretics induced hypokalaemia may precipitate digitalis toxicity. Lithium: Hydrochlorothiazide potentiates therapeutic and toxic effects by increasing its renal excretion