Toxicology Letters, 53 (1990) 175-177 Elsevier
175
TOXLET 02410
Naproxen and indomethacin: disposition and effects in the isolated perfused rat kidney
Peter G.F. Cox, Miek M. Moons, Frans G.M. Russel and Cees A.M. van Ginneken Department of Pharmacology, University of Ngmegen. Ngmegen (The Netherlands)
Key words: Kidney function; Indomethacin; Isolated perfused rat kidney; Naproxen; Renal handling
INTRODUCTION
The isolated perfused rat kidney (IPK) is a good preparation for studying the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on renal function [l]. The mechanism by which NSAIDs influence renal function is not clear, but inhibition of prostaglandin synthesis and, in relation to this, renal handling, probably play an important role [2,3]. Renal handling of NSAIDs involves glomerular tiltration, active secretion and passive reabsorption. As a consequence of active secretion, NSAIDs may be concentrated in the tubular cells. High intracellular concentrations might lead to nephrotoxicity. The aim of the present study was to investigate the renal handling of naproxen and indomethacin, the effects of both drugs on renal function and the involvement of prostaglandin E2 (PGE2) in these effects. METHODS
Male Wistar rats (225-275 g) were used in all experiments. The experimental time was 150 min. The first 30 min were used as control period for kidney function. Kidney function was monitored by determination of glomerular filtration rate (GFR), urinary flow, and the sodium, potassium, chloride, glucose, magnesium and calcium excretion. Both naproxen and indomethacin concentrations in perfusate and urine samples and in the kidney were determined using high-performance liquid chromatoAddressfor correspondence: P.G.F. Cox, Department of Pharmacology, University of Nijmegen, P.O. Box 9101,650O HB Nijmegen, The Netherlands 0378-4274/90/%3.50 @ 1990 Elsevier Science Publishers B.V. (Biomedical Division)
176 TABLE I FRACTIONAL CLEARANCE AND ACCUMULATION EN IN THE ISOLATED PERFUSED RAT KIDNEY*
Dws
Dose olg)
Perfusate concentrationb
OF INDOMETHACIN
AND NAPROX-
CL/GFR=
K/P ratiod
0.060 + 0.007 0.027 *o.OOs 0.043 +0.010 0.055+o.ot 1 0.037 kO.004 0.033 kO.003
8.8 +0.9 5.2 &OS 3.4 +0.7 2.9 io.4 2.7 _tO.3 1.28f0.06
Olpiml) Indomethacin Naproxen
37.5 375 3.75 37.5 375 3750
0.22 f0.02 2.51 _cO.I8 0.019~0.~2 0.21 +0.02 1.88 kO.19 22.4 kO.7
a n =4 for all doses. b Mean values of the period O-120 min are presented. c Fractional clearance: clearance (CL) divided by GFR. Mean values of the period 30-120 min are presented. d K/P ratio: amount indomethacin per g kidney divided by the perfusate concentration.
graphic methods. For both drugs a very broad concentration range was examined (naproxen 2.5 x 10V4 pg/ml to 25 hg/ml; indomethacin 2.5 x IO-* pg/ml to 2.5 PgJ ml). In experiments in which the influence of PGE2 was investigated, PGEl (133 ng/ml) was added to the perfusate from the moment of isolation. RESULTS AND DISCUSSION
As shown in Table I, fractional clearance of both drugs is very low, indicating extensive reabsorption. Both drugs accumulate in the IPK in a concentration-dependent manner, indomethacin more than naproxen. Accumulation in the tubular cells is probably a result of active secretion across the basolateral membrane, followed by facilitated diffusion across the brush-border membrane [4]_The observed decrease in K/P ratio with increasing perfusate concentration can be explained by saturation of the active secretion mechanism. Indomethacin and naproxen both cause a decrease in urinary flow and electrolyte excretion (Table II). The presence of PGEZ in the perfusate fully opposed these effects on kidney function. The influence of both drugs on renal function, therefore, is the result of the inhibition of prostaglandin synthesis and can be reversed by PGEr. The lowest concentration at which an effect on renal function is seen is about 0.2 pg/ml for naproxen and about 0.002 ,ug/ml for indomethacin. An explanation for this difference might be the much lower indomethacin concentration needed for inhibiting prostaglandin synthesis as compared to naproxen [S]. The higher a~umulation of in-
177 TABLE II EFFECT OF NAPROXEN AND INDOMETHACIN Drug
Perfusate concentrationb
Urinary flow
&g/ml) Control Indomethacin Naproxen
2.43kO.12 2.25f0.18d 1.88+0.19 1.9 +0.2d
0.84_+0.11 0.53 * 0.05* 0.84+0.12 0.57~0.06* 0.72 +0.09
ON KIDNEY FUNCTION* Fractional excretionc Na
Cl
Ca
I.2 kO.2 0.51*0.09* 1.2 f0.3 0.76*0.09* 1.12+0.10
1.3 +0.2 0.58 +0.08* 1.3 rto.4 0.82 &0.08* 1.21 kO.18
1.1 io.2 0.46f0.08* 1.3 kO.4 0.75 * 0.15* 1.03*0.13
a Control (n = 12), indomethacin (n = 4) and naproxen experiments (n = 4). b Mean values of the period O-120 mitt are presented. cMean values of the period 3&120 min are presented. Values are normalized to the control period. d Perfusion fluid contained 133 ng/ml PGE>. * P~0.05vs. control (Student’s t-test).
domethacin in the kidney as compared to naproxen might also contribute to this difference. In conclusion, indomethacin and naproxen both accumulate in the IPK, probably as a result of active secretion. Both drugs cause a decrease in urinary flow and fractional excretion of electrolytes. This influence on renal function is caused by inhibition of prostagiandin synthesis. REFERENCES Cox, P.G.F., Moons, M.M., Russel, F.G.M. and Van Ginneken, C.A.M. (1990) The isolated perfused rat kidney as a tool in the investigation of renal handling and effects of nonsteroidal anti-inflammatory drugs. J. Pharmacol. Methods (in press). Clive, D.M. and Staff, J.S. (1984) Renal syndromes associated with nonsteroidal antiinflammatory drugs. N. Engl. J. Med. 310,563-572. Rainsford, K.D.. Schweitzer, A. and Brune, K. (1981) Autoradiographic and biochemical observations on the distribution of non-steroid anti-inflammatory drugs. Arch. Int. Pharmacodyn. 250,18&194. Jansen, H.M.L., Russel, F.G.M., Wouterse, A.C. Gribnau, F.W.J. and Van Ginneken, C.A.M. (1989) Renal handling of indomethacin: isolated membrane vesicles of proximal tubular cells as an in vitro mode1 system for transport. Neth. J. Med. 35, 137-142. Flower, R.J. (1974) Drugs which inhibit prostaglandin biosynthesis. Pharmacol. Rev. 26,42-49.
175
TOXLET 02410
Naproxen and indomethacin: disposition and effects in the isolated perfused rat kidney
Peter G.F. Cox, Miek M. Moons, Frans G.M. Russel and Cees A.M. van Ginneken Department of Pharmacology, University of Ngmegen. Ngmegen (The Netherlands)
Key words: Kidney function; Indomethacin; Isolated perfused rat kidney; Naproxen; Renal handling
INTRODUCTION
The isolated perfused rat kidney (IPK) is a good preparation for studying the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on renal function [l]. The mechanism by which NSAIDs influence renal function is not clear, but inhibition of prostaglandin synthesis and, in relation to this, renal handling, probably play an important role [2,3]. Renal handling of NSAIDs involves glomerular tiltration, active secretion and passive reabsorption. As a consequence of active secretion, NSAIDs may be concentrated in the tubular cells. High intracellular concentrations might lead to nephrotoxicity. The aim of the present study was to investigate the renal handling of naproxen and indomethacin, the effects of both drugs on renal function and the involvement of prostaglandin E2 (PGE2) in these effects. METHODS
Male Wistar rats (225-275 g) were used in all experiments. The experimental time was 150 min. The first 30 min were used as control period for kidney function. Kidney function was monitored by determination of glomerular filtration rate (GFR), urinary flow, and the sodium, potassium, chloride, glucose, magnesium and calcium excretion. Both naproxen and indomethacin concentrations in perfusate and urine samples and in the kidney were determined using high-performance liquid chromatoAddressfor correspondence: P.G.F. Cox, Department of Pharmacology, University of Nijmegen, P.O. Box 9101,650O HB Nijmegen, The Netherlands 0378-4274/90/%3.50 @ 1990 Elsevier Science Publishers B.V. (Biomedical Division)
176 TABLE I FRACTIONAL CLEARANCE AND ACCUMULATION EN IN THE ISOLATED PERFUSED RAT KIDNEY*
Dws
Dose olg)
Perfusate concentrationb
OF INDOMETHACIN
AND NAPROX-
CL/GFR=
K/P ratiod
0.060 + 0.007 0.027 *o.OOs 0.043 +0.010 0.055+o.ot 1 0.037 kO.004 0.033 kO.003
8.8 +0.9 5.2 &OS 3.4 +0.7 2.9 io.4 2.7 _tO.3 1.28f0.06
Olpiml) Indomethacin Naproxen
37.5 375 3.75 37.5 375 3750
0.22 f0.02 2.51 _cO.I8 0.019~0.~2 0.21 +0.02 1.88 kO.19 22.4 kO.7
a n =4 for all doses. b Mean values of the period O-120 min are presented. c Fractional clearance: clearance (CL) divided by GFR. Mean values of the period 30-120 min are presented. d K/P ratio: amount indomethacin per g kidney divided by the perfusate concentration.
graphic methods. For both drugs a very broad concentration range was examined (naproxen 2.5 x 10V4 pg/ml to 25 hg/ml; indomethacin 2.5 x IO-* pg/ml to 2.5 PgJ ml). In experiments in which the influence of PGE2 was investigated, PGEl (133 ng/ml) was added to the perfusate from the moment of isolation. RESULTS AND DISCUSSION
As shown in Table I, fractional clearance of both drugs is very low, indicating extensive reabsorption. Both drugs accumulate in the IPK in a concentration-dependent manner, indomethacin more than naproxen. Accumulation in the tubular cells is probably a result of active secretion across the basolateral membrane, followed by facilitated diffusion across the brush-border membrane [4]_The observed decrease in K/P ratio with increasing perfusate concentration can be explained by saturation of the active secretion mechanism. Indomethacin and naproxen both cause a decrease in urinary flow and electrolyte excretion (Table II). The presence of PGEZ in the perfusate fully opposed these effects on kidney function. The influence of both drugs on renal function, therefore, is the result of the inhibition of prostaglandin synthesis and can be reversed by PGEr. The lowest concentration at which an effect on renal function is seen is about 0.2 pg/ml for naproxen and about 0.002 ,ug/ml for indomethacin. An explanation for this difference might be the much lower indomethacin concentration needed for inhibiting prostaglandin synthesis as compared to naproxen [S]. The higher a~umulation of in-
177 TABLE II EFFECT OF NAPROXEN AND INDOMETHACIN Drug
Perfusate concentrationb
Urinary flow
&g/ml) Control Indomethacin Naproxen
2.43kO.12 2.25f0.18d 1.88+0.19 1.9 +0.2d
0.84_+0.11 0.53 * 0.05* 0.84+0.12 0.57~0.06* 0.72 +0.09
ON KIDNEY FUNCTION* Fractional excretionc Na
Cl
Ca
I.2 kO.2 0.51*0.09* 1.2 f0.3 0.76*0.09* 1.12+0.10
1.3 +0.2 0.58 +0.08* 1.3 rto.4 0.82 &0.08* 1.21 kO.18
1.1 io.2 0.46f0.08* 1.3 kO.4 0.75 * 0.15* 1.03*0.13
a Control (n = 12), indomethacin (n = 4) and naproxen experiments (n = 4). b Mean values of the period O-120 mitt are presented. cMean values of the period 3&120 min are presented. Values are normalized to the control period. d Perfusion fluid contained 133 ng/ml PGE>. * P~0.05vs. control (Student’s t-test).
domethacin in the kidney as compared to naproxen might also contribute to this difference. In conclusion, indomethacin and naproxen both accumulate in the IPK, probably as a result of active secretion. Both drugs cause a decrease in urinary flow and fractional excretion of electrolytes. This influence on renal function is caused by inhibition of prostagiandin synthesis. REFERENCES Cox, P.G.F., Moons, M.M., Russel, F.G.M. and Van Ginneken, C.A.M. (1990) The isolated perfused rat kidney as a tool in the investigation of renal handling and effects of nonsteroidal anti-inflammatory drugs. J. Pharmacol. Methods (in press). Clive, D.M. and Staff, J.S. (1984) Renal syndromes associated with nonsteroidal antiinflammatory drugs. N. Engl. J. Med. 310,563-572. Rainsford, K.D.. Schweitzer, A. and Brune, K. (1981) Autoradiographic and biochemical observations on the distribution of non-steroid anti-inflammatory drugs. Arch. Int. Pharmacodyn. 250,18&194. Jansen, H.M.L., Russel, F.G.M., Wouterse, A.C. Gribnau, F.W.J. and Van Ginneken, C.A.M. (1989) Renal handling of indomethacin: isolated membrane vesicles of proximal tubular cells as an in vitro mode1 system for transport. Neth. J. Med. 35, 137-142. Flower, R.J. (1974) Drugs which inhibit prostaglandin biosynthesis. Pharmacol. Rev. 26,42-49.
