Cyclooxygenase-2 and kidney failure

Cyclooxygenase (COX)-dependent prostaglandins are necessary for normal kidney function. These prostaglandins are associated with inflammation, maintenance of sodium and water homeostasis, control of renin release, renal vasodilation, vasoconstriction attenuation, and prenatal renal development. COX-2 expression is regulated by the renin-angiotensin system, glucocorticoids or mineralcorticoids, and aldosterone, supporting a role for COX-2 in kidney function. Indeed, COX-2 mRNA and protein levels as well as enzyme activity are increased, along with PGE2, during kidney failure. In addition, changes in COX-2 expression are associated with increased blood pressure, urinary volume, sodium and protein and decreased urinary osmolarity. Intrarenal mechanisms such as angiotensin II (Ang II) production, increased sodium delivery, glomerular hypertension, and renal tubular inflammation have been suggested to be responsible for the increase in COX-2 expression. Although, specific COX-2 pharmacological inhibition has been related to the prevention of kidney damage, clinical studies have reported that COX-2 inhibition may cause side effects such as edema or a modest elevation in blood pressure and could possibly interfere with antihypertensive drugs and increase the risk of cardiovascular complications. Thus, administration of COX-2 inhibitors requires caution, especially in the presence of underlying cardiovascular disease.

Effect of indomethacin and selective cyclooxygenase-2 inhibitors on proteinuria and renal function in patients with AA type renal amyloidosis

AIMS

Because the cardiovascular system (CVS) side-effects of cyclooxygenase-2 (COX-2) selective inhibitors have recently been questioned, we aimed to compare the renal and haemodynamic effects of cyclooxygenase selective (celecoxib and rofecoxib) and non-selective non-steroidal anti-inflammatory drugs (NSAIDs) (indomethacin) in patients with renal amyloidosis secondary to rheumatological diseases who required anti-inflammatory agents and are taking maximum tolerable dose of angiotensin-converting enzyme inhibitors.

METHODS

The present study was performed on 11 patients with stable proteinuria who were diagnosed as AA amyloidosis secondary to rheumatological diseases confirmed by renal biopsies. The study had three consecutive stages (celecoxib 200 mg/day; indomethacin 100 mg/day; rofecoxib 25 mg/day.) Each was given for 4 weeks and a wash-out phase of 3 weeks was allowed between consecutive stages.

RESULTS

Although the decrease of proteinuria in the celecoxib period was higher than in the rofecoxib and indomethacin periods, the difference was not statistically significant. No statistically significant differences were found between serum urea, creatinine, creatinine clearance and urinary sodium excretion.

CONCLUSION

In this study, no differences were found between indomethacin and the two selective COX-2 inhibitors in respect to proteinuria and renal functions in 11 patients with renal amyloidosis secondary to rheumatological diseases with varying degrees of proteinuria. Routine doses of NSAIDs brought no additional benefit to the ACE inhibitor use in terms of proteinuria and renal functions. The use of selective COX-2 inhibitors should be limited to their anti-inflammatory and analgesic effects in this population.

Nimesulide, a cyclooxygenase-2 preferential inhibitor, impairs renal function in the newborn rabbit

Tocolysis with nonsteroidal anti-inflammatory drugs (NSAIDs) has been widely accepted for several years. Recently, the use of the cyclooxygenase-2 (COX2) preferential NSAID nimesulide has been proposed. However, data reporting neonatal acute renal failure or irreversible end-stage renal failure after maternal ingestion of nimesulide question the safety of this drug for the fetus and the neonate. Therefore, this study was designed to define the renal effects of nimesulide in newborn rabbits. Experiments were performed in 28 newborn rabbits. Renal function and hemodynamic parameters were measured using inulin and para-aminohippuric acid clearances as markers of GFR and renal blood flow, respectively. After a control period, nimesulide 2, 20, or 200 microg/kg was given as an i.v. bolus, followed by a 0.05, 0.5, or 5 microg.kg(-1).min(-1) infusion. Nimesulide administration induced a significant dose-dependent increase in renal vascular resistance (29, 37, and 92%, respectively), with a concomitant decrease in diuresis (-5, -23, and -44%), GFR (-12, -23, and -47%), and renal blood flow (-23, -23, and -48%). These results are in contrast with recent reports claiming that selective COX2 inhibition could be safer for the kidney than nonselective NSAIDs. These experiments confirm that prostaglandins, by maintaining renal vasodilation, play a key role in the delicate balance regulating neonatal GFR. We conclude that COX2-selective/preferential inhibitors thus should be prescribed with the same caution as nonselective NSAIDs during pregnancy and in the neonatal period.