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Diwan BA, Henneman JR, Nims RW. Enhancement of N-Nitrosodiethylamine-lnitiated Hepatocarcinogenesis by Phenytoin in Male F344/NCr Rats at a Dose Causing Maximal Induction of CYP2B. Int J Toxicol 2001. [DOI: 10.1177/109158180102000205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The effect of the clinically important anticonvulsant phenytoin (DPH) on hepatocarcinogenesis of male F344/NCr rats initiated with a single i.p. dose of N-nitrosodiethylamine (75 mg/kg b.w.) was studied. Beginning 2 weeks post-initiation, the rats received control diet or diet containing 500 or 1500 ppm DPH or 500 ppm phenobarbital. At 52 weeks age, the incidences (and multiplicities, in units of tumors per tumor-bearing rat) of hepatocellular adenomas were 0%, 17% (1 ± 0), 42% (1.8 ± 0.8), or 67% (2.5 ± 1.9) in rats exposed to N-nitrosodiethylamine alone, or the carcinogen followed by 500 ppm DPH, 1500 ppm DPH, or 500 ppm phenobarbital, respectively. Between 53 and 79 weeks of age, 39% of rats receiving N-nitrosodiethylamine alone developed multiple (1.5 ± 0.8) hepatocellular adenomas. A similar incidence (41%) occurred in the rats administered the carcinogen followed by 500 ppm DPH. The incidence of hepatocellular adenomas (88% and 89%) was significantly greater in rats exposed to N-nitrosodiethylamine followed by 1500 ppm DPH or 500 ppm phenobarbital, respectively. Multiplicities of hepatocellular adenomas were significantly greater than the control value in rats fed 1500 ppm DPH or 500 ppm phenobarbital (5.9 ± 4.8 and 10.1 ± 6.7, respectively), but not in the rats receiving 500 ppm DPH (2.3 ± 1.6). No rats exposed to N-nitrosodiethylamine alone or the carcinogen followed by 500 ppm DPH developed hepatocellular carcinomas, while hepatocellular carcinomas occurred in 29% or 67% of the rats given 1500 ppm DPH or 500 ppm phenobarbital, respectively, following initiation. Increases in hepatic CYP2B-mediated benzyloxyresorufin O-dealkylation activity in rats exposed to 500 and 1500 ppm DPH for 2 or 23 weeks were ∼50% and ∼100%, respectively, of the maximal induction caused by 500 ppm phenobarbital. Thus, in the rat model, DPH enhanced N-nitrosodiethyl-amine-initiated hepatocarcinogenesis when administered at a dose causing maximal CYP2B induction.
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Affiliation(s)
- Bhalchandra A. Diwan
- Intramural Research Support Program, SAIC Frederick, NCI–Frederick Cancer Research and Development Center, Frederick, Maryland, USA
| | - John R. Henneman
- Intramural Research Support Program, SAIC Frederick, NCI–Frederick Cancer Research and Development Center, Frederick, Maryland, USA
| | - Raymond W. Nims
- Laboratory of Comparative Carcinogenesis, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland, USA
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Bishara RH, Born GS, Anderson VL, Christian JE. Statistical approach to evaluating effect of physical and chemical factors on fecal excretion of chlorophenothane. J Pharm Sci 1973; 62:1420-4. [PMID: 4743083 DOI: 10.1002/jps.2600620904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Hansen JM, Siersbaek-Nielsen K, Kristensen M, Skovsted L, Christensen LK. Effect of diphenylhydantoin on the metabolism of dicoumarol in man. ACTA MEDICA SCANDINAVICA 1971; 189:15-9. [PMID: 4107730 DOI: 10.1111/j.0954-6820.1971.tb04334.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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