Acute toxicity induced by 2-aryl-N-methylsuccinimides

Nephrotoxicity induced by C- and N-arylsuccinimides

The succinimide ring is incorporated into hundreds of compounds that are widely used as agricultural, industrial, and pharmaceutical agents. Some succinimide derivatives that contain an aryl group on the ethylene bridge of the succinimide ring (C-arylsuccinimides) or on the nitrogen atom (N-arylsuccinimides) induce nephrotoxicity in humans and/or laboratory animals. Acute toxicity induced by this general class of compounds is typically characterized as polyuric renal failure, while chronic nephrotoxicity is seen as chronic interstitial nephritis. In this review, the structure-nephrotoxicity relationships, biotransformation, and mechanisms of nephrotoxicity for the C- and N-arylsuccinimides are examined.

Role of chloride groups in the nephrotoxic potential of N-(3,5-dichlorophenyl)-2-hydroxysuccinimide, an oxidative metabolite of N-(3,5-dichlorophenyl)succinimide

Although the addition of chloride groups to the phenyl ring of N-phenylsuccinimide (NPS) is known to enhance the nephrotoxic potential of NPS, the mechanism of this enhancement is unknown. One chlorinated NPS derivative, N-(3,5-dichlorophenyl)succinimide (NDPS), is a potent nephrotoxicant which induces marked proximal tubular necrosis at i.p. doses of 0.4 mmol/kg or greater. The purpose of this study was to compare the nephrotoxic potential of 2-hydroxy-N-phenylsuccinimide (HNPS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS), an oxidative and nephrotoxicant metabolite of NDPS, to determine the importance of the chloride groups for the nephrotoxic potential of NDHS. Male Fischer 344 rats (4/group) were administered a single i.p. injection of HNPS (1.0 or 1.5 mmol/kg), NDHS (0.1 mmol/kg) or vehicle (25% dimethyl sulfoxide in sesame oil), and renal function measured at 24 and 48 h. HNPS was a nonnephrotoxicant at both doses tested, while NDHS induced marked nephrotoxicity characterized by diuresis, increased proteinuria, glucosuria, elevated blood urea nitrogen (BUN) concentration and kidney weight, decreased organic ion accumulation by renal cortical slices and proximal tubular necrosis. In vitro, HNPS reduced p-aminohippurate (PAH) and tetraethylammonium (TEA) accumulation beginning at HNPS bath concentrations of 0.05 and 0.5 mM, respectively. The results of this study indicate that although HNPS has direct effects on renal function in vitro, HNPS is not a nephrotoxicant in vivo at doses up to 15 times the minimal nephrotoxicant dose of NDHS. Therefore, the chloro groups present on NDHS play an essential role in the nephrotoxic potential of NDHS and contribute to aspects of the nephrotoxic mechanism of NDPS beyond NDPS oxidation to form NDHS.

Role of para-hydroxylation in phensuximide-induced urotoxicity in the Fischer 344 rat

Phensuximide (PSX) is an antiepileptic agent which has been shown to induce hemorrhagic cystitis and mild nephrotoxicity following repeated administration in man or rats or when acutely administered to phenobarbital-pretreated rats. The purpose of this study was to explore the role of para-hydroxylation of the phenyl group of PSX in PSX-induced urotoxicity. Two PSX derivatives, 2-(4-fluorophenyl)-N-methylsuccinimide (FMPS) and N-methyl-2-(4-methylphenyl)succinimide (MMPS), were synthesized and evaluated for urotoxic potential. Male Fischer 344 rats (four rats/group) were administered intraperitoneally (i.p.) a succinimide (0.4 or 1.0 mmol/kg) or vehicle and renal function monitored for 48 h. In a separate experiment, rats were pretreated with phenobarbital (75 mg/kg/day; 3 days, i.p.) prior to succinimide or succinimide vehicle. In non-phenobarbital pretreated rats, acute FMPS or MMPS treatment had little effect on renal function or morphology at the doses tested. Hematuria (+) was noted in the FMPS (1.0 mmol/kg) group on post-treatment day 2. However, in the phenobarbital-pretreated rats, FMPS (0.4 or 1.0 mmol/kg) induced marked hematuria (++) and increased proteinuria while having little or no effect on other renal functional parameters or renal morphology. At killing, bladders of treated rats were distended with bloody urine and exhibited hemorrhagic areas within the bladder wall. In phenobarbital-pretreated rats, MMPS administration had little effect on any renal functional parameter measured or urological morphology. These results suggest that para-hydroxylation does not contribute to the hemorrhagic cystitis induced by PSX.