Background. Elderly patients suffering from nociceptive pain of locomotive organs and concomitantly from renal impairment represent a target population for painkilling drugs. That is why they are predisposed to nephrotoxic effects non-steroidal anti-inflammatory drugs. The aim of our study was to evaluate cycloxygenase-2 (COX-2) inhibition effect on renal function in elderly with moderate impairment of renal function. Methods and Results. Based on 24-h urine collection we assessed creatinine clearance (CCr), fractional excretion of sodium (FENa), potassium (FEK), chloride (FECl), osmotic active solutes (FEOSM) and 24h urinary excretion of prostaglandin PGE2 and PGF2α. Under conditions of sub-maximal water load fractional excretion of electrolytes, inulin clearance (Cin), serum cystatin C (Scyst) were assessed. In addition basal and stimulated plasma renin activity (PRA) and plasma aldosteron (Paldo) were examined. Using comparison of parameters before and at the end of 7-days rofecoxib treatment we found out Cin 0,82±0,34 vs 0,74±0,18 ml/s/1,73 m2, FENa 1,0±0,3 vs 1,2±0,4 (p=0,02), FEOSM 2,9±0,7 vs 3,7±1,2 % (p=0,03), UPGE2αV 663±528 vs 414±195 (p=0,059), UPGF2V (559±625) vs 205±174 ηg/24h (p=0,02), stimulated PRA 0,94±0,73 vs 0,4±0,27 ±pg/l/h (p=0,019), Paldo 104,56±50,15 vs 56,94±27,08 ηg/l/h (p=0,008). Conclusions. Short-term COX-2 inhibition in patients with moderate renal impairment was associated with significant decrease of tubular transport of sodium, without changing GFR and water excretion.

        Key words: coclooxygenase-2 inhibition, renal function, renal insufficiency.