Carcinogenicity Studies of Astemizole in Mice and Rats
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(CANCER RESEARCH 55. 5589-5594. December I. 19951 Carcinogenicity Studies of Astemizole in Mice and Rats Johanna Benze,' Ludo Gypen, John Vandenberghe, Ann Lampo, Roland De Coster, Charles Bowden, and Herman Van Cauteren Janssen Research Foundation, Division offanssen Pharmaceutica N. V., Turnhoutseweg 30. B-2340 Beerse, Belgium ABSTRACT The results from both an 18-month mouse study and a 2-year rat study establish clearly that astemizole is not carcinogenic. We have pub The histamine H1 antagonist astemizole (Hismanal) was tested for lished our findings in response to claims made recently by Brandes et carcinogenicity in Swiss mice and Wistar rats. Astemizole was adminis a!. (7) that astemizole, amongs other H1 antagonists, promotes the tered with the food to mice for 18 and to rats for 24 consecutive months. The doses given—approximately5,20, and 80 mg/kg body weightday growth of experimentally induced tumors in mice. were equivalent to 25, 100, and 400 times, respectively, the recommended human dose of 10 mg/day. Survival of both mice and rats was comparable MATERIALS AND METHODS between groups. Peto's age-adjusted, dose-related trend analysis for the tumor-bearing rats did not reveal a statistically significant difference for Test Animals and Animal Care. A total of 400 Swiss mice from our own males or females. There was no evidence that astemizole led to an in permanent noninbred laboratory colony and 400 specific pathogen-free rats of creased incidence of spontaneously or unusually occurring neoplastic the Wistar substrain, purchased from Charles River (Sulzfeld, Germany), were lesions in either mice or rats. used in the studies. All animals were approximately 5 weeks old at the start of Special attention was given to the effect ofastemizole on the progression the studies. of spontaneously occurring mammary gland adenomas and fibroadeno Mice were housed individually in macrolon cages with a wire mesh roof mm. Peto's analysis applied to the number of female rats bearing these (24 X 14 X 13 cm), and rats were housed individually in stainless steel mesh benign mammary gland tumors disclosed no statistically significant dose cages (20 X 20 X 20 cm) in air-conditioned rooms (temperature, 18—22°C; related trend. There was no positive trend for the onset ofthis tumor type, alternating 12-h light and dark cycles; relative humidity, 50—70%). and the median size of the tumor over time per rat was also not statisti Both mice and rats were given free access to fresh tap water dispensed from cally significantly different in a comparison of the control group with each drinking bottles. Mice received Huybrechts' powdered mice food, which was of the dosed groups. pelleted and administered in self-raising hoppers. Rats received Huybrechts' The findings from these carcinogenicity studies suggest that astemizole powdered rat food supplemented with a vitamin premix. is not tumorigenic and that it does not promote tumor growth. Test Article and Study Design. The test article, astemizole, was synthe sized by Janssen Pharmaceutica. Batches A2201 and C0401 (both pharmaceu tical grade) were used in the mouse and rat carcinogenicity studies, respec INTRODUCTION rively. Astemizole was administered to the animals in food pellets (mice) or powdered food (rats) available ad libitum. Astemizole was mixed into the Astemizole, 1-(4-fluorophenylmethyl)-N-[l-(2-(4-methoxyphenyl)- animals' food at concentrations of 0 (control group), 2.5, 10, or 40 mg/l00 g ethyl l)-4-pipiridinyl]-1H-benzimidazole-2-amine, is a potent and food for mice and 0 (control group), 5, 20, or 80 mg/100 g food for rats. The @ long-acting histamine receptor antagonist devoid of central, sed concentrations of astemizole were equivalent to approximately 5, 20, and 80 ative, and anticholinergic effects (1). At a once-daily administration of mg/kg body weightday.3 The low dose level of S mg/kg body weightday was 10 mg, astemizole is indicated for the treatment of perennial and chosen as a multiple (approximately 25-fold) of the recommended human dose seasonal allergic rhinitis, allergic conjunctivitis, chronic urticaria, and of 10 mg/day (i.e., 0.20 mg/kgday for a 50-kg man or 0.14 mg/kgday for a other allergic conditions (2). Astemizole and other second-generation 70-kg man), and the high dose of 80 mg/kg body weightday was chosen to I receptor antagonists have a more favorable benefit:risk ratio than produce adverse effects on the basis of findings in previously conducted first-generation histamine receptor blockers with regard to the toxicity studies in mice and rats. In both species, each study group comprised 50 males and 50 females. absence of CNS2 effects. They do not cross the blood-brain barrier Dosing started on March 4, 1980, and continued for 18 consecutive months readily and do not potentiate the CNS effects of alcohol and other in the mouse study. For rats, dosing started on March 21, 1984, and continued CNS-active chemicals (3). Adverse experiences associated with for 2 years (105 weeks). astemizole, such as dry mouth, gastrointestinal disturbances, rash, and CliniCal Observations and Evaluations. All test animals were observed at increased appetite, occur rarely, and the incidences are comparable to least once daily for signs of waning health, abnormal behavior, unusual those during placebo treatment (4). appearance, occurrences of untoward clinical effects, and manifestations of During the development of astemizole, which was marketed sub toxic and pharmacological responses. All rats underwent a physical examina sequently as Hismanal, numerous preclinical studies were carried out lion once weekly, and the location and size of any palpable cutaneous or s.c. to assess the drug's safety for human use. In laboratory animals, tissue mass were recorded. A scoring system was used to determine the size of astemizole was shown to be safe on single and repeated administra these tissue masses (score 1, 1 cm or smaller; score 2, larger than 1 cm but smaller than 3 cm; score 3, 3 cm or larger). Body weight and food consumption tion. There was no evidence of adverse effects on fertility, and of rats were determined every 4 weeks. Blood samples were taken at necropsy astemizole was devoid of primary embryotoxic, teratogenic, carcino from the carotid artery for hematological analysis from all rats surviving the genic, and mutagenic effects under widely varying test conditions study period. Hematological analysis included hematocrit, hemoglobin, RBC (5, 6). count, and WBC count. The present article provides a detailed account of the findings At the scheduled termination dates, the surviving mice or rats were exam obtained from two carcinogenicity studies conducted with astemizole. med. anesthetized with ether, and killed by exsanguination. A full autopsy was Received 7/5/95; accepted 10/3/95. 3 The concentration of astemizole/lOO g food was kept constant throughout the study The costs of publication of this article were defrayed in part by the payment of page period. In the mouse study, neither food consumption nor actual drug intake were charges. This article must therefore be hereby marked advertisement in accordance with determined, but it is known that an adult mouse of this strain consumes about 6—10g I8 U.S.C. Section 1734 solely to indicate this fact. food/day. In the rat study, the actual drug intake ranges for males receiving astemizole at I To whom requests for reprints should be addressed, at Department of Toxicology, 5, 20, and 80 mg/l0O g food were 2.36—4.59, 9.47—19.2,and 37.3—77.5mg/kg body Janssen Pharmaceutica, Turnhoutseweg 30, B-2340 Beerse, Belgium. weight'day, respectively. The actual drug intake ranges for female rats were calculated as 2 The abbreviation used is: CNS, central nervous system. 3.48—5.32,14.5—20.7,and 61.9—113mg/kg body weight'day. 5589 Downloaded from cancerres.aacrjournals.org on October 1, 2021. © 1995 American Association for Cancer Research. A5TEMIZOLE: CARCINOGENICITY IN MICE AND RATS performed, and all macroscopic changes were noted. On animals that died Table 1 Neoplastic lesions from male micefed months°Treatmentasiemizole for 18 during the study or required killing prematurely, a necropsy was performed as groupC―L soon as possible. During the necropsies, tissue samples were collected for subsequent histological evaluation. Care was taken to collect and identify MHApproximate potentially neoplastic tissue. All tissue samples for histopathology were fixed 2080No. dose (mg/kg)05 in buffered 10% formalin, processed, and examined histologically by means of 5050Survivedof animals5050 4348Survived12 mo4444 standard hematoxylin and eosin-stained sections. Slides of five animals/study 2635No. 18 mo2827 group were reviewed at a time. The order was: (a) control group; (b) low 2730animalsAdrenalof tumor-bearing343 1 dosage group; (c) medium-dosage group; and (d) high-dosage group. Statistical Analysis. In the mouse study, differences concerning mortality, 01Adrenalcortex adenoma01 10pheochromocytomaHematopoieticmedulla01 clinical observations, gross pathology, hyperplastic changes, and neoplastic changes between the control group and each dosed group were analyzed with 79tumorsLiverHepatocellularsystemI I9 @ the two-sided test (8). The same test was used in the rat study for the determination of differences between the control group and each dosed group 1614Hepatocellularadenoma1512 with regard to clinical observations, gross pathology, and nonneoplastic 02Hemangio(endothelio)ma58carcinomaI0 changes. Differences in body weight, food consumption, and hematology were 62Lung, analyzed with the two-sided Mann-Whitney U test (8). For the rat study, Peto's 97Pancreas,primary lung tumor91 1 statistic for a positive dose-related trend (9) was used to analyze mortality, total 02exocrineSoftadenoma,I0 number of tumor-bearing animals, and number of animals bearing a specific tissueFibrosarcoma01 tumor type. As suggested by Peto et a!. (9), the tumor lethality was taken into 01Histiocytoma10 account. An age-adjusted analysis was done for rats bearing fatal tumors and 01Testis, for rats bearing incidental tumors by means of the death rate method and 00ThyroidLeydig cell tumor10 gland adenoma00 prevalence method, respectively.