| Interactions related to both valsartan and hydrochlorothiazide Concomitant use not recommended Lithium Reversible increases in serum lithium concentrations and toxicity have been reported during concurrent use of ACE inhibitors and thiazide, including hydrochlorothiazide. Due to the lack of experience with concomitant use of valsartan and lithium, this combination is not recommended. If the combination proves necessary, careful monitoring of serum lithium levels is recommended.Concomitant use requiring caution Other antihypertensive agents Co-Diovan may increase the effects of other agents with antihypertensive properties (e.g ACEI, beta-blockers, calcium channel blockers).Pressor amines (e.g. noradrenaline, adrenaline)Possible decreased response to pressor amines but not sufficient to preclude their use.Non-steroidal anti-inflammatory medicines (NSAIDs), including selective COX-2 inhibitors, acetylsalicylic acid>3 g/day), and non-selective NSAIDsNSAIDS can attenuate the antihypertensive effect of both angiotensin II antagonists and hydrochlorothiazide when administered simultaneously. Furthermore, concomitant use of Co-Diovan and NSAIDs may lead to worsening of renal function and an increase in serum potassium. Therefore, monitoring of renal function at the beginning of the treatment is recommended, as well as adequate hydration of the patient.Interactions related to valsartan Concomitant use not recommended Potassium-sparing diuretics, potassium supplements, salt substitutes containing potassium and other substances that may increase potassium levels If a medicinal product that affects potassium levels is considered necessary in combination with valsartan, monitoring of potassium plasma levels is advised.No interaction In drug interaction studies with valsartan, no interactions of clinical significance have been found with valsartan or any of the following substances: cimetidine, warfarin, furosemide, digoxin, atenolol, indomethacin, hydrochlorothiazide, amlodipine, glibenclamide. Digoxin and indomethacin could interact with the hydrochlorothiazide component of Co-Diovan (see interactions related to hydrochlorothiazide).Interactions related to hydrochlorothiazide Concomitant use requiring caution Medicinal products associated with potassium loss and hypokalaemia (e.g. kaliuretic diuretics, corticosteroids, laxatives, ACTH, amphotericin, carbenoxolone, penicillin G, salicylic acid and derivatives).If these medicinal products are to be prescribed with the hydrochlorothiazide-valsartan combination, monitoring of potassium plasma levels is advised. These medicinal products may potentiate the effect of hydrochlorothiazide on serum potassium (see section 4.4).Medicinal products that could induce torsades de pointes • Class Ia antiarrhythmics (e.g. quinidine, hydroquinidine, disopyramide)• Class III antiarrhythmics (e.g. amiodarone, sotalol, dofetilide, ibutilide)• Some antipsychotics (e.g. thioridazine, chlorpromazine, levomepromazine, trifluoperazine, cyamemazine, sulpiride, sultopride, amisulpride, tiapride, pimozide, haloperidol, droperidol)• Others (e.g. bepridil, cisapride, diphemanil, erythromycin i.v., halofantrin, ketanserin, mizolastin, pentamidine, sparfloxacine, terfenadine, vincamine i.v.)Due to the risk of hypokalemia, hydrochlorothiazide should be administered with caution when associated with medicinal products that could induce torsades de pointes.Digitalis glycosides Thiazide-induced hypokalaemia or hypomagnesaemia may occur as unwanted effects favouring the onset of digitalis-induced cardiac arrhythmias.Calcium salts and vitamin D Administration of thiazide diuretics, including hydrochlorothiazide, with vitamin D or with calcium salts may potentiate the rise in serum calcium.Antidiabetic agents (oral agents and insulin)The treatment with a thiazide may influence the glucose tolerance. Dose adjustment of the antidiabetic medicinal product may be necessary.Metformin should be used with caution because of the risk of lactic acidosis induced by possible functional renal failure linked to hydrochlorothiazide.Beta blockers and diazoxide Concomitant use of thiazide diuretics, including hydrochlorothiazide, with beta blockers may increase the risk of hyperglycaemia. Thiazide diuretics, including hydrochlorothiazide, may enhance the hyperglycaemic effect of diazoxide.Medicinal products used in the treatment of gout (probenecid, sulfinpyrazone and allopurinol)Dose adjustment of uricosuric medications may be necessary as hydrochlorothiazide may raise the level of serum uric acid. Increase of dosage of probenecid or sulfinpyrazone may be necessary. Co-administration of thiazide diuretics, including hydrochlorothiazide, may increase the incidence of hypersensitivity reactions to allopurinol.Anticholinergic agents (e.g. atropine, biperiden)The bioavailability of thiazide-type diuretics may be increased by anticholinergic agents, apparently due to a decrease in gastrointestinal motility and the stomach emptying rate.Amantadine Thiazides, including hydrochlorothiazide, may increase the risk of adverse effects caused by amantadineCholestyramine and cholestipol resins Absorption of thiazide diuretics, including hydrochlorothiazide is impaired in the presence of anionic exchange resins.Cytotoxic agents (e.g. cyclophosamide, methotrexate)Thiazides, including hydrochlorothiazide, may reduce renal excretion of cytotoxic agents and potentiate their myelosuppressive effects.Non-depolarising skeletal muscle relaxants (e.g. tubocurarine)Thiazides, including hydrochlorothiazide, potentiate the action of curare derivatives.Ciclosporin Concomitant treatment with cyclosporin may increase the risk of hyperuricaemia and gout-type complications.Alcohol, anaesthetics and sedatives Potentiation of orthostatic hypotension may occur.Methyldopa There have been isolated reports of haemolytic anaemia in patients receiving concomitant treatment with methyldopa and hydrochlorothiazide.Carbamazepine Patients receiving hydrochlorothiazide concomitantly with carbamazepine may develop hyponatremia. Such patients should therefore be advised about the possibility of hyponatraemic reactions, and should be monitored accordingly.Iodine contrast media In case of diuretic-induced dehydration, there is an increased risk of acute renal failure, especially with high doses of the iodine product. Patients should be rehydrated before the administration. | |