Diuretics: Patients on diuretics, especially those in whom diuretic therapy was recently instituted, may occasionally experience an excessive reduction of blood pressure after initiation of therapy with amlodipine besylate and benazepril hydrochloride. The possibility of hypotensive effects with amlodipine besylate and benazepril hydrochloride can be minimized by either discontinuing the diuretic or increasing the salt intake prior to initiation of treatment with amlodipine besylate and benazepril hydrochloride.
Potassium Supplements and Potassium-Sparing Diuretics: Benazepril can attenuate potassium loss caused by thiazide diuretics. Potassium-sparing diuretics (spironolactone, amiloride, triamterene, and others) or potassium supplements can increase the risk of hyperkalemia. If concomitant use of such agents is indicated, monitor the patient's serum potassium frequently.
Lithium: Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors during therapy with lithium. When coadministering amlodipine besylate and benazepril hydrochloride and lithium, frequent monitoring of serum lithium levels is recommended.
Gold: Nitritoid reactions (symptoms include facial flushing, nausea, vomiting and hypotension) have been reported rarely in patient on therapy with injectable gold (sodium aurothiomalate) and concomitant ACE inhibitor therapy.
Other: Benazepril has been used concomitantly with oral anticoagulants, beta-adrenergic-blocking agents, calciumblocking agents, cimetidine, diuretics, digoxin, hydralazine, and naproxen without evidence of clinically important adverse interactions.
In clinical trials, amlodipine has been safely administered with thiazide diuretics, beta-blockers, ACE inhibitors, long-acting nitrates, sublingual nitroglycerin, digoxin, warfarin, nonsteroidal anti-inflammatory drugs, antibiotics, and oral hypoglycemic drugs.
In vitro data in human plasma indicate that amlodipine has no effect on the protein binding of drugs tested (digoxin, phenytoin, warfarin, and indomethacin). Special studies have indicated that the coadministration of amlodipine with digoxin did not change serum digoxin levels or digoxin renal clearance in normal volunteers; that coadministration with cimetidine did not alter the pharmacokinetics of amlodipine; and that coadministration with warfarin did not change thewarfarin-induced prothrombin response time.
Clinical Laboratory Test Findings
Serum Electrolytes: [See Warnings and Precautions (5)].
Creatinine: Minor reversible increases in serum creatinine were observed in patients with essential hypertension treated with amlodipine besylate and benazepril hydrochloride. Increases in creatinine are more likely to occur in patients with renal insufficiency or those pretreated with a diuretic and, based on experience with other ACE inhibitors, would be expected to be especially likely in patients with renal artery stenosis [see Warnings and Precautions (5) ].
Other (causal relationships unknown): Clinically important changes in standard laboratory tests were rarely associated with amlodipine besylate and benazepril hydrochloride administration. Elevations of serum bilirubin and uric acid have been reported as have scattered incidents of elevations of liver enzymes.