Drug interactions between enalapril/hydrochlorothiazide and Lasix

enalapril ↔ furosemide

Applies to:enalapril/hydrochlorothiazide and Lasix (furosemide)

MONITOR: Although they are frequently combined in clinical practice, diuretics and angiotensin converting enzyme (ACE) inhibitors may have additive effects. Coadministration makes hypotension and hypovolemia more likely than does either drug alone. Some ACE inhibitors may attenuate the increase in the urinary excretion of sodium caused by some loop diuretics. Some patients on diuretics, especially those on dialysis or a dietary salt restriction, may experience acute hypotension with lightheadedness and dizziness after receiving the first dose of the ACE inhibitor. In addition, ACE inhibitors may cause renal insufficiency or acute renal failure in patients with sodium depletion or renal artery stenosis.

MANAGEMENT: Monitoring of blood pressure, diuresis, electrolytes, and renal function is recommended during coadministration. The possibility of first-dose hypotensive effects may be minimized by initiating therapy with small doses of the ACE inhibitor, or either discontinuing the diuretic temporarily or increasing the salt intake approximately one week prior to initiating an ACE inhibitor. Alternatively, the patient may remain under medical supervision for at least two hours after the first dose of the ACE inhibitor, or until blood pressure has stabilized.

furosemide ↔ hydrochlorothiazide

Applies to:Lasix (furosemide) and enalapril/hydrochlorothiazide

MONITOR: The combination of a thiazide and loop diuretic may produce additive or synergistic effects on diuresis and excretion of electrolytes including sodium, potassium, magnesium, and chloride. Although these agents may be combined therapeutically in some patients with inadequate response to a single agent, the increased risk of dehydration, hypotension, hypokalemia, hypomagnesemia, and hyponatremia should be recognized. The exact mechanism of interaction is unclear but appears to be pharmacodynamic rather than pharmacokinetic.

MANAGEMENT: Caution is advised during concomitant use of a thiazide and loop diuretic. Dosages should be titrated slowly and carefully, and electrolytes, BUN, fluid status, blood pressure, and renal function should be monitored regularly. Patients should be advised to contact their physician if they experience signs and symptoms of fluid and electrolyte depletion such as dizziness, lightheadedness, dry mouth, thirst, fatigue, weakness, lethargy, muscle cramps, decreased urination, postural hypotension, and tachycardia.