Quinapril Hydrochloride/Hydrochlorothiazide

Dual RAS blockade increases risks of hypotension, hyperkalemia, and acute renal failure. Contraindicated in diabetes; avoid in renal impairment (GFR <60).

Increased serum lithium levels and symptoms of lithium toxicity reported with ACE inhibitors; thiazides further reduce lithium renal clearance, increasing toxicity risk.

Nitritoid reactions (facial flushing, nausea, vomiting, hypotension) reported rarely with injectable gold and concomitant ACE inhibitor therapy.

Drug Interactions Agents Increasing Serum Potassium Coadministration of quinapril and hydrochlorothiazide with other drugs that raise serum potassium levels may result in hyperkalemia. Because renal clearance of lithium is reduced by thiazides, the risk of lithium toxicity is presumably raised further when, as in therapy with quinapril and hydrochlorothiazide, a thiazide diuretic is coadministered with the ACE inhibitor. Quinapril and hydrochlorothiazide and lithium should be coadministered with caution, and frequent monitoring of serum lithium levels is recommended.

Drug Interactions Agents Increasing Serum Potassium Coadministration of quinapril and hydrochlorothiazide with other drugs that raise serum potassium levels may result in hyperkalemia. Because renal clearance of lithium is reduced by thiazides, the risk of lithium toxicity is presumably raised further when, as in therapy with quinapril and hydrochlorothiazide, a thiazide diuretic is coadministered with the ACE inhibitor. Quinapril and hydrochlorothiazide and lithium should be coadministered with caution, and frequent monitoring of serum lithium levels is recommended.

Simultaneous administration reduces tetracycline absorption by 28-37%, possibly due to high magnesium content in quinapril tablets.

Other Agents Drug interaction studies of quinapril and other agents showed: Multiple dose therapy with propranolol or cimetidine has no effect on the pharmacokinetics of single doses of quinapril.