THE EFFECT OF NONSTEROIDAL ANTIINFLAMMATORY DRUGS ON ELECTROLYTE HOMEOSTASIS AND BLOOD-PRESSURE IN YOUNG AND ELDERLY PERSONS WITH AND WITHOUT RENAL-INSUFFICIENCY

The study objective was to determine the acute and long-term effects o f nonsteroidal antiinflammatory drugs (NSAIDS) on the excretion of sod ium and potassium, blood pressure, and body weight in young and elderl y persons without renal insufficiency, and in elderly persons with mod erate renal insufficiency. We conducted a randomized, open-label, thre e-way, crossover study in which subjects were administered 800 mg ibup rofen three times daily, 20 mg piroxicam daily, and 200 mg sulindac tw ice daily. Measurements included clearance and balance studies of the excretion of sodium and potassium during a 24-hour period, sitting sys tolic and diastolic blood pressures, and body weight measurements. Ibu profen, piroxicam, and sulindac reduced excretion of sodium and potass ium. Maximum decrements in the fractional excretion of sodium and pota ssium were significant for all NSAIDs in each group (P < 0.05). Change in blood pressure was greater with ibuprofen then sulindac both for s ystolic blood pressure (mean difference +/- standard error of mean, 9. 7 +/- 2.3 mm Hg, P = 0.0002) and diastolic blood pressure (mean differ ence, 6.0 +/- 1.6 mm Hg, P = 0.005). Blood pressure increase was assoc iated inversely with sodium excretion after 1 month of NSAID administr ation (P = O.032). Blood pressures increased for elderly persons with renal insufficiency with the administration of ibuprofen. Ibuprofen in creased body weight in young persons (P = 0.006) and in persons with r enal insufficiency (P = 0.001), and piroxicam increased weight in elde rly persons without renal insufficiency. No weight increase was observ ed with sulindac. We conclude that ibuprofen, piroxicam, and sulindac all reduce urinary excretion of sodium and potassium in young and elde rly persons independently of their level of renal function. Ibuprofen elevates blood pressure in elderly persons with renal insufficiency. E levation in systolic blood pressure is explained partial by the reduct ion in sodium excretion produced by NSAIDs. Body weight changes vary b y age, renal function, and type of NSAID administered.