Irbesartan
Non-Steroidal Anti-Inflammatory Agents Including Selective Cyclooxygenase-2 Inhibitors (COX-2 Inhibitors)
In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, coadministration of NSAIDs, including selective COX-2 inhibitors, with angiotensin II receptor antagonists, including irbesartan, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving irbesartan and NSAID therapy.
The antihypertensive effect of angiotensin II receptor antagonists, including irbesartan, may be attenuated by NSAIDs including selective COX-2 inhibitors.
Dual Blockade of the Renin-Angiotensin System (RAS)
Dual blockade of the RAS with angiotensin-receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Closely monitor blood pressure, renal function, and electrolytes in patients on Irbesartan and Hydrochlorothiazide Tablets and other agents that affect the RAS.
In most patients no benefit has been associated with using two RAS inhibitors concomitantly. In general, avoid combined use of RAS inhibitors.
Do not coadminister aliskiren with Irbesartan and Hydrochlorothiazide Tablets in patients with diabetes. Avoid use of aliskiren with Irbesartan and Hydrochlorothiazide Tablets in patients with renal impairment (GFR <60 mL/min).
Hydrochlorothiazide
When administered concurrently the following drugs may interact with thiazide diuretics:
Alcohol, Barbiturates, or Narcotics: potentiation of orthostatic hypotension may occur.
Antidiabetic Drugs (oral agents and insulin): dosage adjustment of the antidiabetic drug may be required.
Other Antihypertensive Drugs: additive effect or potentiation.
Cholestyramine and Colestipol Resins: absorption of hydrochlorothiazide is impaired in the presence of anionic exchange resins. Single doses of either cholestyramine or colestipol resins bind the hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by up to 85% and 43%, respectively. Irbesartan and Hydrochlorothiazide Tablets should be taken at least one hour before or four hours after these medications.
Corticosteroids, ACTH: intensified electrolyte depletion, particularly hypokalemia.
Pressor Amines (e.g., Norepinephrine): possible decreased response to pressor amines but not sufficient to preclude their use.
Skeletal Muscle Relaxants, Nondepolarizing (e.g., Tubocurarine): possible increased responsiveness to the muscle relaxant.
Lithium: Increases in serum lithium concentrations and lithium toxicity have been reported with concomitant use of irbesartan or thiazide diuretics. Monitor lithium levels in patients receiving Irbesartan and Hydrochlorothiazide Tablets and lithium.
Non-steroidal Anti-inflammatory Drugs: In some patients, the administration of a non-steroidal anti-inflammatory agent can reduce the diuretic, natriuretic, and antihypertensive effects of loop, potassium-sparing, and thiazide diuretics. Therefore, when Irbesartan and Hydrochlorothiazide Tablets and non-steroidal anti-inflammatory agents are used concomitantly, the patient should be observed closely to determine if the desired effect of the diuretic is obtained.
Carbamazepine: concomitant use of carbamazepine and hydrochlorothiazide has been associated with the risk of symptomatic hyponatremia. Electrolytes should be monitored during concomitant use.