A study in 12 patients showed that 20-40 mg tenoxicam daily had no significant effect on the urinary excretion of sodium or chloride due to 40 mg Furosemide, and blood pressure, heart rate and body weight also were not affected.
Uncertain and complex. It seems almost certain that a number of different mechanisms come into play. One possible mechanism is concerned with the synthesis of renal pro-staglandins which occurs when the loop diuretics cause sodium excretion If this synthesis is blocked by drugs such as the NSAID’s, then both natriuresis and renal blood flow will be altered. Indomethacm is a non-specific inhibitor of cyclo-oxygenase, whereas suhndac selectively inhibits cyclo-oxygenase outside the kidney which might explain why it interacts to a lesser extent.
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