Drug Interactions between Accuretic and aspirin

MONITOR: Concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) and diuretics may adversely affect renal function due to NSAID inhibition of the renal synthesis of prostaglandins that help maintain renal perfusion in dehydrated states. The risk may be increased in patients on dietary sodium restriction. At the same time, hypotensive effect of the diuretics may be reduced because inhibition of prostaglandins can lead to unopposed pressor activity and, consequently, elevation in blood pressure. Natriuretic and diuretic effects may also be reduced, as NSAIDs have been reported to cause sodium and water retention, which may account for the increased risk of congestive heart failure associated with the combination. One study showed an increase in the incidence density of congestive heart failure (in patients over 55 years of age) from 9.3 per 1,000 person-years in patients on diuretics to 23.3 per 1,000 person-years in patients on both diuretic and NSAID therapy. NSAIDs may also increase the risk of hyperkalemia associated with potassium-sparing diuretics.

MANAGEMENT: In patients receiving both diuretic and NSAID therapy, management consists of avoiding dehydration and carefully monitoring the patient's renal function and blood pressure. If renal insufficiency or hyperkalemia develops, both drugs should be discontinued until the condition is corrected.

MONITOR: Some investigators suggest that coadministration with aspirin may attenuate the vasodilator and hypotensive effects of ACE inhibitors. In addition, some have found that the benefits of ACE inhibitors on morbidity and mortality in post-acute myocardial infarction, coronary heart disease, and particularly congestive heart failure may be compromised or even nullified by aspirin. The proposed mechanism is aspirin inhibition of cyclooxygenase, resulting in suppression of prostaglandin synthesis and prostaglandin-mediated hemodynamic effects of ACE inhibitors. However, evidence of a negative interaction is largely contradictory, and interpretation of relevant data has often been complicated by multiple confounding elements as well as the retrospective or post hoc nature of most studies. Available data seem to indicate that low-dose aspirin (less than 236 mg/day, and especially less than 100 mg/day) is unlikely, or at least significantly less likely, to interfere with ACE inhibitor effects, although susceptibility to the interaction may be subject to some degree of interpatient variability.

MANAGEMENT: Based on current data, it is difficult to determine the likelihood of a negative interaction between aspirin and ACE inhibitors and its clinical relevance during long-term therapy, particularly in congestive heart failure. Current recommendations generally do not preclude combination use in patients with cardiovascular diseases or risk factors that might otherwise benefit from the drugs independently. However, patients receiving long-term therapy with the combination should undergo regular blood pressure and other appropriate clinical monitoring such as renal function assessments. The lowest therapeutic dosage of aspirin should be used.

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.