The role of N-hydroxyphenetidine in phenacetin-induced hemolytic anemia

doi:10.1016/0041-008X(91)90128-2

Toxicology and Applied Pharmacology

Volume 111, Issue 1, October 1991, Pages 1-12

https://doi.org/10.1016/0041-008X(91)90128-2 Get rights and content

Abstract

Phenacetin is well known to cause hemolytic anemia and methemoglobinemia in humans. Early mechanistic studies clearly established a causal role for active/reactive drug metabolites in the process but did not unequivocally identify these metabolite(s) or resolve the question of whether these two hemotoxicities are mechanistically linked. As part of ongoing studies on the mechanism underlying arylamine-induced hemotoxicities, we have recently shown that the arylhydroxylamine metabolites of aniline and dapsone mediate the hemolytic activity of aniline and dapsone, respectively. The present study was undertaken to determine if N-hydroxyphenetidine (PNOH), the known arylhydroxylamine metabolite of phenacetin, is responsible for phenacetin-induced hemolytic anemia. As measured by decreased survival of ⁵¹Cr-labeled erythrocytes in rats, phenacetin, p-phenetidine, and PNOH were all hemolytic in vivo, with PNOH being significantly the most potent of the three. In vitro exposure of ⁵¹Cr-tagged erythrocytes to PNOH, followed by transfusion into isologous rats, resulted in a concentration-dependent reduction in erythrocyte survival, indicating that PNOH is a directacting hemolytic agent. Phenacetin and p-phenetidine were inactive. Phenacetin, p-phenetidine, and PNOH all produced dose-dependent methemoglobinemia in rats. In parallel in vitro studies, PNOH elevated methemoglobin levels, p-phenetidine and phenacetin did not. However, attempts to identify PNOH in the blood of phenacetin- and p-phenetidine-treated rats were unsuccessful, despite the use of a highly sensitive analytical method. Hemotoxic concentrations of PNOH were found to be highly unstable in the presence of red cells, though relatively stable in the buffer vehicle alone. Inhibitors of acetylation (p-aminobenzoic acid [PABA]) and deacetylation (bis-[p-nitrophenyl]phosphate [BNPP]), used to alter the cyclic interconversion of phenacetin and p-phenetidine, caused changes in phenacetin hemotoxicity that indicated the hemotoxin was a deacetylated metabolite distal to p-phenetidine. These data are consistent with the hypothesis that PNOH, formed during the metabolic clearance of phenacetin, mediates phenacetin-induced hemolytic anemia and methemoglobinemia through direct toxic actions in the erythrocyte.

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¹: Present address: Biochemical Toxicology Department, GL992, Toxicology Division, Lilly Research Laboratories, Eli Lily & Co., P.O. Box 708, Greenfield, IN 46140.

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The role of N-hydroxyphenetidine in phenacetin-induced hemolytic anemia

Abstract

Blood

Pathology

Chem. Biol. Interact.

J. Chromatogr.

Drug-induced hemolytic anemia

Pharmacol. Rev.

The effect of sodium nitrite and paraaminopropriophenone administration on blood methemoglobin levels and red blood cell survival

Blood

Glucose-6-phosphate dehydrogenase deficiency

Biomonitoring of aromatic amines. II. Hemoglobin binding of some monocyclic aromatic amines

Arch. Toxicol.

The fate of acetophenetidin (phenacetin) in man and methods for the estimation of acetophenetidin and its metabolites in biological material

J. Pharmacol. Exp. Ther.

N-hydroxylation ofp-acetophenetidide as a factor on nephrotoxicity

J. Med. Chem.