genotoxicity and carcinogenicity studies of antihistamines

REVIEW ARTICLE

Genotoxicity and carcinogenicity studies of antihistamines

Giovanni Brambilla • Francesca Mattioli •

Luigi Robbiano • Antonietta Martelli

Received: 12 November 2010 / Accepted: 25 January 2011 / Published online: 17 February 2011

� Springer-Verlag 2011

Abstract This review provides a compendium of the

results of genotoxicity and carcinogenicity assays per-

formed on marketed antihistamines. Of the 70 drugs

examined, 29 (41.4%) have at least one genotoxicity and/or

carcinogenicity test result: 12 tested positive in at least one

genotoxicity assay, six in at least one carcinogenicity

assay, and four gave a positive response in both at least one

genotoxicity assay and at least one carcinogenicity assay.

Of 19 drugs with both genotoxicity and carcinogenicity

data, eight were neither genotoxic nor carcinogenic, two

were carcinogenic in at least one sex of mice or rats but

tested negative in genotoxicity assays, five tested positive

in at least one genotoxicity assay but were non-carcino-

genic, and four gave a positive response in at least one

genotoxicity assay and in at least one carcinogenicity

assay. Only 12 (17.1%) of the 70 drugs examined have all

data required by present guidelines for testing of pharma-

ceuticals, but it should be considered that a large fraction of

them were developed and marketed prior the present reg-

ulatory climate.

Keywords Antihistamines � Genotoxicity �Carcinogenicity

Introduction

Antihistamines are drugs used frequently in an intermittent

manner in the treatment of cough, allergic rhinitis,

insomnia, migraine, motion sickness, orticaria, and vertigo.

Among the various adverse reactions that these drugs may

cause, the occurrence of genotoxic and/or carcinogenic

effects cannot be excluded. In order to assess the potential

risk to humans of these effects, the regulatory authorities of

USA, Europe, and Japan recommend that genotoxicity and

carcinogenicity studies are performed before the applica-

tion for marketing approval of pharmaceuticals. Current

guidelines for genotoxicity testing of pharmaceuticals (US

Department of Health and Human Services S2A 1996; S2B

1997; Muller et al. 1999) indicate a standard test battery

that consists of the following: (1) a test for gene mutation

in bacteria, (2) an in vitro test with cytogenetic evaluation

of chromosomal damage with mammalian cells or an in

vitro mammalian cells gene mutation assay, (3) an in vivo

test for chromosomal damage using rodent haematopoietic

cells. Guidelines for carcinogenicity testing of pharma-

ceuticals (US Department of Health and Human Services

S1A 1996; S1B 1997) indicate that long-term carcinoge-

nicity studies in rodents should be performed for all

pharmaceuticals whose expected clinical use is continuous

for at least 6 months as well as for pharmaceuticals used

frequently in an intermittent manner in the treatment of

chronic recurrent conditions. In long-term carcinogenicity

assays, the highest dose should be at least 25-fold higher,

on an mg/m2 basis, than the maximum recommended

human daily dose or represent a 25-fold ratio of rodent to

human AUC.

Antihistamines are extensively used. From the 2007

edition of the Martindale: The Complete Drug Reference

(2007), it can be inferred that 71 drugs of this family are on

the market, and the majority of them are used in several

countries. The International Agency for Research on

Cancer (IARC 1972–2007) in the 91 volumes of IARC

Monographs on the Evaluation of the Carcinogenic Risks

G. Brambilla (&) � F. Mattioli � L. Robbiano � A. Martelli

Department of Internal Medicine, Division of Clinical

Pharmacology and Toxicology, University of Genoa,

Viale Benedetto XV 2, 16132 Genoa, Italy

e-mail: [email protected]

123

Arch Toxicol (2011) 85:1173–1187

DOI 10.1007/s00204-011-0659-4

to Humans published from 1972 to 2007 examined more

than 200 drugs, but these included only one antihistamine,

doxylamine succinate, judged not classifiable as to its

carcinogenicity to humans (IARC 2001). In a review of

Snyder and Green (2001) on the genotoxicity of marketed

pharmaceuticals, based on information obtained from the

1999 edition of the Physicians’ Desk Reference as well as

from peer-reviewed published literature, only 17 antihis-

tamines were examined, but no data are reported for four of

them, and for other five the information is quite limited.

These premises indicate that in prescribing most antihis-

tamines the evaluation of the benefit/genotoxic–carcino-

genic effects ratio is impossible. Therefore, we deemed

useful to examine whether data allowing more complete

information can be retrieved.

This review is a compendium of all the genotoxicity and

carcinogenicity data that have been found in an extensive

search. This search was conducted primarily in peer-

reviewed journals using Medline, Toxline, and the Registry

of Toxic Effects of Chemicals Substances (US Depart-

ment of Health and Human Services 1988). Additional

unpublished data were obtained from the following

websites: http://www.toxnet.nlm.nih.gov, http://www.

ntp.server.niehs.nih.gov, http://www.potency.berkeley.edu,

http://www.fda.gov/cder, http://www.scirus.com, http://

www.inchem.org, http://www.updateusa.com, http://www.

osha.gov. Concerning data that are not published in peer-

reviewed journals, in some cases the tests were conducted

under the oversight of authorative bodies, such as the US

National Toxicology Program; in the other cases, the

genotoxicity and carcinogenicity data are those reported by

the Physician’s Desk Reference (2005) or in the final

package insert approved by the Center for Drug Evaluation

and Research of the Food and Drug Administration.

Unfortunately, this additional unpublished information if

often incomplete; in particular, the results of genotoxicity

assays are usually reported without any information of the

doses that have been tested. Moreover, often no informa-

tion is given whether the in vitro genotoxicity assays were

performed in both the presence and the absence of an

exogenous metabolic system; in these cases, taking into

account that this procedure is required by the guidelines, in

the absence of a specific indication the result is reported in

the tables as obtained in both these experimental

conditions.

Results of genotoxicity and carcinogenicity assays

Information about genotoxic and carcinogenic effects of

antihistamines were retrieved for 29 (41.4%) of the 70

drugs considered in this review (Table 1). From the 2007

edition of the Martindale: The Complete Drug Reference, it

can be inferred that 67 antihistamines are still on the

market, whereas three have been retired; one of them,

methapyrilene, is among those listed in Table 1, and the

other two, deptropine and setastine, among those without

genotoxicity and carcinogenicity data. Only 12 drugs—

acrivastine, astemizole, azelastine, cetirizine, deslorata-

dine, doxylamine, ebastine, epinastine, fexofenadine,

loratadine, methapyrilene, terfenadine—were examined in

substantial agreement with the indications of the present

guidelines on genotoxicity and carcinogenicity testing of

pharmaceuticals. Astemizole, azelastine, ebastine, fexo-

fenadine, and terfenadine gave negative responses in all

genotoxicity and carcinogenicity assays. Acrivastine and

epinastine induced chromosomal aberrations in vitro but

were not carcinogenic. Cetirizine and desloratadine tested

negative in all genotoxicity assays, but were carcinogenic

in mice, and in mice and rats, respectively. Doxylamine,

loratadine, and methapyrilene gave positive response(s) in

both genotoxicity and carcinogenicity assays. Seven addi-

tional antihistamines were tested for carcinogenicity but to

a limited extent, i.e. not as recommended by present

guidelines, for genotoxicity. Clemastine, promethazine,

and triprolidine gave negative or inconclusive responses in

all genotoxicity and carcinogenicity assays. Chlorphen-

amine, diphenhydramine, and thenyldiamine gave positive

response in some genotoxicity assays, but tested negative

in carcinogenicity assays. Mepyramine gave positive

responses in some of genotoxicity and carcinogenicity

assays. Of 10 antihistamines, only results of genotoxicity

assays were retrieved. Phenyltoloxamine tested positive in

the in vitro micronucleus assay. Dimenhydrinate and tri-

pelennamine gave contradicting results. Chlorcyclizine,

cyproheptadine, diphenylpyraline, methdilazine, mizolas-

tine, phenindamine, and pheniramine gave only negative

response(s). Results of genotoxicity and carcinogenicity

studies were not retrieved for the 41 antihistamines listed at

the end of Table 1.

Discussion

Our survey was performed to examine to what extent

antihistamines have been tested for their genotoxic and

carcinogenic activity. It cannot be excluded that addi-

tional published and unpublished results exist for both

genotoxicity and carcinogenicity, but they are certainly of

difficult retrieval. Therefore, we deem that the informa-

tion provided by this review is sufficient to provide an

overall perspective of the present knowledge in this field,

and to allow some considerations about the possibility of

the scientific community of evaluating the genotoxic–

carcinogenic risk to humans of the 70 drugs of this

family.

1174 Arch Toxicol (2011) 85:1173–1187

123

http://www.toxnet.nlm.nih.gov

http://www.ntp.server.niehs.nih.gov

http://www.ntp.server.niehs.nih.gov

http://www.potency.berkeley.edu

http://www.fda.gov/cder

http://www.scirus.com

http://www.inchem.org

http://www.inchem.org

http://www.updateusa.com

http://www.osha.gov

http://www.osha.gov

Table 1 Genotoxic and carcinogenic effects of antihistamines

Test system Resultsa Doseb (LED or HID) Reference

Without e.m.s. With

e.m.s.

1. Acrivastine (87848-99-5)

S. typhimurium, reverse mutation - - NR 1

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - NR 1

Chromosomal aberrations, human lymphocytes in vitro ? - NR 1

Chromosomal aberrations, rat bone-marrow cells in vivo - 1,000 mg/kg po 1

Long-term carcinogenesis assay, mice - (938)c 250 mg/kg/day 1

Long-term carcinogenesis assay, rats - (912.2) 40 mg/kg/day 1

2. Astemizole (68844-77-9)


Drosophila melanogaster, sex-linked recessive lethal mutations - NR 3

SCE, human lymphocytes in vitro ? ? 10 lM 2, 4

Micronucleus test, male Wistar rats in vivo ? NR 2, 5

Dominant lethal test - NR 2

Long-term carcinogenesis assay, Swiss mice - (919.2) 400 ppm in diet 6, 7

Long-term carcinogenesis assay, mice - (938) 80 mg/kg/day 2

Long-term carcinogenesis assay, rats - (965) 80 mg/kg/day 2

Long-term carcinogenesis assay, Wistar rats - (978) 800 ppm in diet 6, 7

3. Azelastine (58581-89-8)


UDS, rat primary hepatocytes - NR 2

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - NR 2

Micronucleus test, mice in vivo - NR 2

Chromosomal aberrations, rat bone-marrow cells in vivo - NR 2

Long-term carcinogenesis assay, mice - (9438) 25 mg/kg/day 2

Long-term carcinogenesis assay, rats - (91068) 30 mg/kg/day 2

4. Cetirizine (83881-51-0)

S. typhimurium, reverse mutation - - NR 1, 8

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - NR 1, 8

Chromosomal aberrations, human lymphocytes in vitro - - NR 1, 8

Micronucleus test, male rats in vivo - NR 1, 8

Long-term carcinogenesis assay, male mice ? (liver tumors) 16 mg/kg/day 1

Long-term carcinogenesis assay, Wistar rats - (915) \ 20 mg/kg/day 1

5. Chlorcyclizine (82-93-9)

S. typhimurium, reverse mutation - NR 8

UDS, rat primary hepatocytes - 0.1 mM 8, 9

Gene mutation, mouse lymphoma L5178Y cells, TK locus - NR 8

Micronucleus test, Chinese hamster lung V79 cells in vitro - 30 lg/ml 8

6. Chlorphenamine (132-22-9)

S. typhimurium TA98, TA100, TA1537, reverse mutation - - 3,333 lg/plate 6, 10

S. typhimurium TA1535, reverse mutation - - 10,000/3,333 lg/plate 6, 10

DNA strand breaks, rat primary hepatocytes ? 0.5 mM 11


Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 250/230 lg/ml 6, 10, 12

Gene mutation, Chinese hamster ovary cells, hprt locus - NT 400 lg/ml 6, 10

SCE, Chinese hamster ovary cells in vitro (?) - NR 10

Micronucleus test, Chinese hamster lung V79 cells in vitro ? ? 500 lg/ml 8

Chromosomal aberrations, Chinese hamster ovary cells in vitro - ? 400/750 lg/ml 6, 13

Long-term carcinogenesis assay, B6C3F1male mice - (923.3) 50 mg/kg/day 10

Arch Toxicol (2011) 85:1173–1187 1175

123

Table 1 continued


Without e.m.s. With

e.m.s.

Long-term carcinogenesis assay, B6C3F1 female mice ? (993.2) 200 mg/kg/day 10

Long-term carcinogenesis assay, F344 male rats - (921.3) 30 mg/kg/day 10

Long-term carcinogenesis assay, F344 female rats - (943) 60 mg/kg/day 10

Long-term carcinogenesis assay, F344 rats - (947) 1,000 ppm in diet 14

7. Clemastine (15686-51-8)

Micronucleus test, Chinese hamster lung V79 cells in vitro - - 50 lg/ml 8


Long-term carcinogenesis assay, mice - (9123) 206 mg/kg/day 6, 8

Long-term carcinogenesis assay, rats - (9102) 84 mg/kg/day 6, 8

8. Cyproheptadine (129-03-3)


Micronucleus test, Chinese hamster lung V79 cells in vitro - - 30 lg/ml 8

Chromosomal aberrations, human lymphocytes in vitro - NT 0.2 mM 8, 15

9. Desloratadine (100643-71-8)


E. coli, reverse mutation - - NR 1

Chromosomal aberrations, human lymphocytes in vitro - - NR 1


Long-term carcinogenesis assay, male mice - (928) 16 mg/kg/day 2

Long-term carcinogenesis assay, female mice - (914) 32 mg/kg/day 2

Long-term carcinogenesis assay, male miced ? (liver tumors) 40 mg/kg/day 1

Long-term carcinogenesis assay, female miced - (945) 40 mg/kg/day 1

Long-term carcinogenesis assay, male ratsd ? (liver tumors) 10 mg/kg/day 1, 2

Long-term carcinogenesis assay, female ratsd ? (liver tumors) 25 mg/kg/day 1, 2

10. Dimenhydrinate (523-87-5)

S. typhimurium TA97, TA98, TA100, TA1535, TA1537, reverse

mutation

- - 2,000/3,333 lg/plate 6, 16

S. typhimurium TA1535, reverse mutation ? - 2,000/3,333 lg/plate 6, 16

DNA strand breaks, rat primary hepatocytes - 0.1 mM 17

UDS, rat primary hepatocytes - 0.1 mM 17

11. Diphenhydramine (58-73-1)

S. typhimurium TA98, TA100, TA1535, TA1537, reverse mutation - - 3,333 lg/plate 6, 8, 18

S. typhimurium TA98, TA100, TA1535, TA1538, reverse mutation - - 250 lg/plate 19

S. typhimurium TA98, TA100, TA1535, TA1537, reverse mutation - - 1,000 lg/plate 6, 16

DNA strand breaks, rat primary hepatocytes (?) 0.1 mM 17



Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 1,000/150 lg/ml 8, 17, 18

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 120/150 lg/ml 6, 18

SCE, Chinese hamster ovary cells in vitro - - NR 6, 18

Micronucleus test, Chinese hamster lung V79 cells, in vitro ? NT 1.18 mM 20


Chromosomal aberrations, Chinese hamster ovary cells in vitro ? - 150/300 lg/ml 6, 8, 21

Chromosomal aberrations, human cells in vitro ? NT NR 8

Long-term carcinogenesis assay, B6C3F1 mice - (92.9) 313 ppm in diet 6, 18, 22

Long-term carcinogenesis assay, F344 rats - (939) 2,000 ppm in diet 6, 14, 22

Long-term carcinogenesis assay, F344 male rats ? (912.2) 635 ppm in diet 18, 22

Long-term carcinogenesis assay, F344 female rats ? (96.1) 313 ppm in diet 18, 22

12. Diphenylpyraline (147-20-6)

1176 Arch Toxicol (2011) 85:1173–1187

123

Table 1 continued


Without e.m.s. With

e.m.s.

Binding covalent to E. coli DNA in vitro - - 100 lM 23

13. Doxylamine (469-21-6)

S. typhimurium TA98, TA100, TA1535, TA1537, reverse mutation - - 10,000 lg/plate 6, 8, 16

UDS, rat primary hepatocytes (?) 0.5 mM 8, 24

Micronucleus test, Chinese hamster lung V79 cells in vitro - - 1,000 lg/ml 8

SCE, human lymphocytes in vitro - - 15,930 lg/ml 8, 25

SCE, fetal mouse cells - 300 mg/kg 9 1 8, 25

Micronucleus test, fetal mouse - 300 mg/kg 9 1 8, 25

Chromosomal aberrations, fetal mouse ? 150 mg/kg 9 1 8, 25

Micronucleus test, Chinese hamster bone-marrow cells in vivo - 400 mg/kg 9 1 8, 25

Long-term carcinogenesis assay, B6C3F1 mice ? (liver and thyroid

tumors)

375–750 ppm in diet 6, 22, 26

Long-term carcinogenesis assay, F344 male rats (?) (liver tumors) 115 mg/kg/day 6, 22, 27

Long-term carcinogenesis assay, F344 female rats - (956) 144 mg/kg/day 6, 22, 27

14. Ebastine (90729-43-4)


Gene mutation, Chinese hamster ovary cells, hprt locus - - NR 8



Long-term carcinogenesis assay, mice - NR 8

Long-term carcinogenesis assay, rats - NR 8

15. Epinastine (80012-43-7)

S. typhimurium, reverse mutation - - NR 1, 2

Gene mutation, Chinese hamster lung V79 cells, hprt locus - - NR 1, 2

Chromosomal aberrations, Chinese hamster lung V79 cells in vitro (?) NT NR 1, 2

Chromosomal aberrations, human lymphocytes in vitro (?) NT NR 1, 2


Cell transformation, Syrian hamster embryo cells - NR 1, 2

UDS, rat hepatocytes in vivo - NR 1, 2

Micronucleus test, mice in vivo - NR 1, 2

Chromosomal aberrations, Chinese hamster cells in vivo - NR 1, 2

Long-term carcinogenesis assay, mice - (910.7) 40 mg/kg/day 1, 2

Long-term carcinogenesis assay, rats - (921.7) 40 mg/kg/day 1, 2

16. Fexofenadine (138452-21-8)


Gene mutation, Chinese hamster ovary cells, forward mutation hprt locus - - NR 1

Chromosomal aberrations, rat lymphocytes in vitro - - NR 1


Long-term carcinogenesis assay, micee - (96.0) 150 mg/kg/day of

terfenadine

1

Long-term carcinogenesis assay, ratse - (912.2) 150 mg/kg/day of

terfenadine

1

17. Loratadine (79794-75-5)


UDS, rat primary hepatocytes - NR 6

Gene mutation, Chinese hamster ovary cells, forward mutation hprt locus NT - NR 6

Gene mutation, mouse lymphoma L5178Y cells, TK locus ? - 10 lM 6



Arch Toxicol (2011) 85:1173–1187 1177

123

Table 1 continued


Without e.m.s. With

e.m.s.

Long-term carcinogenesis assay, male mice ? (liver tumors) 40 mg/kg/day 6

Long-term carcinogenesis assay, female mice - (919.2) 40 mg/kg/day 6

Long-term carcinogenesis assay, male rats ? (liver tumors) 10 mg/kg/day 6

Long-term carcinogenesis assay, female rats ? (liver tumors) 25 mg/kg/day 6

18. Mepyramine (pyrilamine) (91-84-9)

S. typhimurium TA100, TA1535, reverse mutation - NT 1,000 lg/plate 6, 16



UDS, rat primary hepatocytes ? 10 lM 8, 24

UDS, rat primary hepatocytes ? 10 lM 9

Gene mutation, mouse lymphoma L5178Y cells, TK locus - ? 600/500 lg/ml 29

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 250/350 lg/ml 30


Long-term carcinogenesis assay, B6C3F1 mice - (99.6) 1,500 ppm in diet 31

Long-term carcinogenesis assay, Sprague–Dawley female rats - (913) 1,000 ppm in dr.wt. 6, 32


Long-term carcinogenesis assay, F344 rats - (952) 2,000 ppm in drink.wat. 34


Long-term carcinogenesis assay, rats ? (liver tumors) NR 8

19. Methapyrilene (91-80-5)


S. typhimurium, reverse mutation (?) (?) NR 8, 36


mutation

- - 10,000 lg/plate 8, 37

S. typhimurium TA1535, reverse mutation (?) - 5,000 lg/plate 8, 19, 37

E. coli WP2 uvrA, reverse mutation - - 10,000 lg/plate 37


UDS, rat primary hepatocytes - 20 mM 24

UDS, rat primary hepatocytes - 550 lg/ml 30

UDS, rat primary hepatocytes ? 1 mM 38

UDS, rat primary hepatocytes - ? 0.1 mM 9

Gene mutation, mouse lymphoma L5178Y cells, TK locus - ? 750/400 lg/ml 8, 29

Gene mutation, mouse lymphoma L5178Y cells, TK locus NT ? 350 lg/ml 39

Gene mutation, mouse lymphoma L5178Y cells, TK locus NT ? 200 lg/ml 35

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 550 lg/ml 30

Gene mutation, Chinese hamster ovary cells, hprt locus NT - 10 lM 40

SCE, Chinese hamster ovary cells in vitro - - 40 lg/ml 41

SCE, Chinese hamster lung V79 cells in vitro - - 40 lg/ml 41


Micronucleus test, Chinese hamster lung V79 cells in vitro ? NT 1.9 mM 20

Chromosomal aberrations, mouse lymphoma L5178Y cells in vitro - ? NR 35

Cell transformation, Syrian hamster embryo cells ? ? NR 35

Cell transformation, BALB/C-3T3 mouse cells ? NT NR 35

Urine from animals, S. typhimurium reverse mutation - NR 35

UDS, rat hepatocytes in vivo - 300 mg/Kg 35, 42

UDS, mouse hepatocytes in vivo - 225 mg/Kg 42

SCE, Fisher male rats bone-marrow cells in vivo - 80 mg/Kg 41

DNA covalent binding rat liver in vivo - 2 g/Kg 43

DNA covalent binding in vitro - ? 500 lg/ml 8, 23

1178 Arch Toxicol (2011) 85:1173–1187

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Table 1 continued


Without e.m.s. With

e.m.s.

DNA covalent binding in vitro NT - 500 lg/ml 39, 43

DNA covalent binding E. coli ? 30 lM 23

Long-term carcinogenesis assay, F344 rats ? (liver tumors) 125 ppm in diet 36

20. Methdilazine (1982-37-2)


mutation

- - 67–333 lg/ml 6, 44

Chromosomal aberrations, Chinese hamster ovary cells in vitro - - 20 lg/ml 6, 45

UDS, rat hepatocytes in vivo - 320 mg/kg 42

21. Mizolastine (108612-45-9)


E. coli WP2 uvrA, reverse mutation - - 5,000 lg/plate 6, 46

22. Phenindamine (82-88-2)

Binding covalent to E. coli DNA in vitro - - 0.5 mM 23

23. Pheniramine (86-21-5)


24. Phenyltoloxamine (92-12-6)

Micronucleus test, Chinese hamster lung V79 cells in vitro ? ? 125/250 lg/ml 8

25. Promethazine (60-87-7)

S. typhimurium TA98, reverse mutation - NT 5,000 lg/ml 6, 47

S. typhimurium TA97, TA98, TA100, TA1535, reverse mutation - - 666 lg/plate 6, 48, 49

S. typhimurium TA1537, reverse mutation - - 100/333 lg/plate 6, 49

S. typhimurium TA2637, reverse mutation (black light) - NT 20 lg/ml 48

Drosophila melanogaster, sex-linked recessive lethal mutations - 1,000 ppm injected 48

Drosophila melanogaster, sex-linked recessive lethal mutations - 3,000 ppm feed 48

DNA strand breaks, rat primary hepatocytes - 0.1 mM 17


Gene mutation, Chinese hamster lung V79 cells, hprt locus - NT 20 lg/ml 50

Gene mutation, Chinese hamster lung V79 cells, ouabain resistance - NT 20 lg/ml 50


SCE, Chinese hamster ovary cells in vitro - ? NR 49

Chromosomal aberrations, Chinese hamster ovary cells in vitro - - 20/50 lg/ml 45

Chromosomal aberrations, human leukocytes in vitro - NT 100 lg/ml 48

UDS, rat hepatocytes in vivo - 400 mg/kg 42

Long-term carcinogenesis assay, B6C3F1 male mice - (92.2) 45 mg/kg/day 49

Long-term carcinogenesis assay, B6C3F1 female mice - (90.7) 15 mg/kg/day 49

Long-term carcinogenesis assay, F344/N rats - (93.2) 33.3 mg/kg/day 49

26. Terfenadine (50679-08-8)

S. typhimurium TA98, TA1537, TA1538, reverse mutation - - 1,000 lg/plate 6, 51

Micronucleus test, Chinese hamster V79 cells in vitro - - 10 lg/ml 8

Micronucleus test, mice in vivo - 2,000 mg/kg/day 6, 51

Long-term carcinogenesis assay, mice ? (96.0) 150 mg/kg/day 6, 51

Long-term carcinogenesis assay, rats ? (912.0) 150 mg/kg/day 6, 51

27. Thenyldiamine (91-79-2)

S. typhimurium TA98, TA100, TA1535, TA1538, reverse mutation - - 1,000 lg/plate 18

S. typhimurium TA98, TA100, TA1535, reverse mutation - - 10,000 lg/plate 16

S. typhimurium TA1537, reverse mutation - - 3,333/10,000 lg/plate 16

UDS, rat primary hepatocytes ? 1 mM 24

Long-term carcinogenesis assay, Sprague–Dawley rat - 1,000 ppm in drinking water 32

Long-term carcinogenesis assay, F344 male rats - (9173) 17.6 mg/kg/day 22

Arch Toxicol (2011) 85:1173–1187 1179

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Table 2 provides information on the number of anti-

histamines tested in the various types of genotoxicity

assays: 25 for bacterial mutagenicity, 14 for gene mutation

in mammalian cells, 22 for in vitro cytogenetics, 13 for in

vivo cytogenetics, 16 for DNA lesions, and 3 in other types

of genotoxicity assays. With respect to carcinogenicity

assays, 17 antihistamines were tested in both mice and rats,

and 2 only in rats, but 11 of them (no. 1, 2, 4, 6, 9, 11, 16,

17, 18, 25, 26 of Table 1) gave negative responses in

assays performed at doses to various extent lower than that

recommended by present guidelines.

Results of older drugs are generally published in peer-

reviewed journals; therefore, the methods used in their

evaluation, as well as the lowest effective dose and the

Table 1 continued


Without e.m.s. With

e.m.s.

Long-term carcinogenesis assay, F344 female rats - (9247) 25.1 mg/kg/day 22

28. Tripelennamine



UDS, rat primary hepatocytes ? 10 lM 17

UDS, rat primary hepatocytes ? 0.5 mM 24

UDS, rat primary hepatocytes ? 50 lM 8, 9

Gene mutation, mouse lymphoma L5178Y cells, TK locus - - 250 lg/ml 30


DNA strand breaks, human primary hepatocytes (?) 33 lM 52

UDS, human primary hepatocytes (?) 33 lM 52

29. Triprolidine (486-12-4)



Long-term carcinogenesis assay, B6C3F1 mice - (9192) 4,000 ppm in diet 54

Long-term carcinogenesis assay, F344/N rats - (9195) 2,000 ppm in diet 55

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32. Habs et al. (1986); 33. Greenman et al. (1995b); 34. Lijinsky (1984b); 35. Mirsalis (1987); 36. Ashby et al. (1988); 37. Oberly et al. (1993); 38. Althaus

et al. (1982); 39. Casciano et al. (1991); 40. Casciano et al. (1984); 41. Iype et al. (1982); 42. Madle et al. (1994); 43. Lijinsky and Yamashita (1988); 44.

Mortelmans et al. (1986); 45. Galloway et al. (1987); 46. Iwase et al. (1998); 47. Motohashi et al. (1997); 48. Gocke (1996); 49. National Toxicology

Program (1993); 50. Fujioka and Maizumi (1983); 51. Gibson et al. (1982); 52. Robbiano et al. (1986); 53. Hensen et al. (1988); 54. Greenman et al.

(1995c); 55. Greenman et al. (1995d)

Antihistamines without retrievable data: alimemazine (84-96-8), azatadine (3964-81-6), bamipine (4945-47-5), bepotastine (125602-71-3), bisulepin

(5802-61-9), bromazine (118-23-0), brompheniramine (86-22-6), buclizine (82-95-1) carbinoxamine (486-16-8), chloropyramine (59-32-5), clemizole

(442-52-4), clocinizine (298-55-5), chlorphenoxamine (27-38-3), cinnarizine (298-57-7), cyclizine (82-92-78), deptropine (604-51-3), dimetindene (5636-

83-9), dimetotiazine (7456-24-8), embramine (3565-72-8), emedastine (8723361-2), flunarizine (52468-60-7), homochlorcyclizine (848-53-3),

hydroxyzine (68-88-2), isothipendyl (482-15-5), levocabastine (79516-68-0), levocetirizine (130018-77-8), mebhydrolin (6153-33-9), meclozine (569-65-

3), mequitazine (29216-28-2), niaprazine (27367-90-4) oxatomide (60607-34-3), oxomemazine (3689-50-7), pirmethixene (314-03-4), piprinhydrinate

((609-90-6), propiomazine (362-29-8), rupatadine (158876-82-5), setastine (64294-95-7), thiethylperazine (1420-55-9), thonzylamine (91-85-0), tri-

methobenzamide (138-56-7), tritoqualine (14504-73-5)a ? Positive, (?) weakly positive, - negative, ? equivocal, NT not tested, without e.m.s. without exogenous metabolic system, with e.m.s. with exogenous

metabolic systemb LED lowest effective dose, HID highest ineffective dose, NR not reported, po oral, ip intraperitoneal, sc subcutaneouslyc The number in parentheses indicates the ratio [high animal dose (mg/m2)/maximum recommended human dose (mg/m2)]d Tested as loratadinee The dose of terfenadine corresponds to an exposure of doses of fexofenadine 3–5 9 MRHD

1180 Arch Toxicol (2011) 85:1173–1187

123

http://www.fda.gov.cder

http://www.toxnet.nlm.nih.gov

http://www.potency.berkeley.edu

highest ineffective dose, are reported. In contrast, the

results of more recent drugs are usually provided by sources

(e.g. Physicians’ Desk Reference, FDA Center for Drug

Evaluation and Research, etc.) which generally give suffi-

cient information on the results of carcinogenicity assays,

but about genotoxicity simply indicate in which assays the

drug tested positive and in which tested negative. We did

not retrieve results of genotoxicity and carcinogenicity

assays of 41 antihistamines, but it is worth noting that the

several of these drugs are marketed in a limited number of

countries. Taken as a whole, these data show that an

assessment of the genotoxic–carcinogenic risk to humans

cannot be performed for the majority of antihistamines. The

introduction of most antihistamines into clinical medicine

took place in the early 1950s, but efforts to develop and

refine methods for genotoxicity and carcinogenicity testing

of pharmaceuticals started approximately 20 years ago, and

current guidelines (US Department of Health and Human

Services S2A 1996; S2B 1997; Muller et al. 1999; US

Department of Health and Human Services S1A 1996; S1B

1997) were published in 1996–1997. This explains why for

the majority of antihistamines results of genotoxicity and

carcinogenicity tests recommended by current guidelines

were not retrieved by our extensive search. At the same

time, it is difficult to justify the present clinical use of

several antihistamines which, due to the absence or paucity

of data, are not classifiable as to their genotoxic and car-

cinogenic risk to humans.

Table 3 provides for each assay type the number of

antihistamines with positive, negative, and discordant

results. It is worth noting the absence of positive drugs in

the bacterial mutagenicity assays, in the gene mutation

assays, and in the in vivo cytogenetics assays. In contrast,

some drugs gave positive results in the in vitro cytogenetics

assays and in the DNA lesions assays. With respect to the

results of long-term carcinogenicity assays, 2 (no. 4, 13 of

Table 1) of 17 antihistamines (11.8%) were carcinogenic to

mice, and 3 (no. 9, 17, 19 of Table 1) of 19 antihistamines

(15.8%) were carcinogenic to rats.

The degree of correlation among the results of the var-

ious genotoxicity assays that is shown in Table 4 is not

satisfactory between DNA lesions and the following types

of assays: in vitro cytogenetics (57.1%), bacterial muta-

genicity (60.0%), and gene mutation in mammalian cells

(80%). In contrast, it was excellent (100%) in other couples

of assays, as between bacterial mutagenicity and both gene

mutation and in vivo cytogenetics, as well as between in

vivo cytogenetics and gene mutation and between DNA

lesions and in vivo cytogenetics. It is evident that the

occurrence of discordant results between the different types

Table 2 Overview of genotoxicity and carcinogenicity testing of antihistamines

Drugs with at least one genotoxicity or carcinogenicity tests results (Table 1) 29 (41.4%)a

Drugs without retrievable genotoxicity or carcinogenicity data 41 (58.6%)

Drugs with all genotoxicity and carcinogenicity data required by present guidelines

(Table 1: 1, 2, 3, 4, 9, 13, 14, 15, 16, 17, 19, 26)b12 (17.1%)

Drugs tested not according to present guidelines 17 (24.3%)

Drugs with least one genotoxicity and carcinogenicity test results

(Table 1: 1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 15, 16, 17, 18, 19, 25, 26, 27, 29)

19 (27.1%)

Drugs tested only for genotoxicity (Table 1: 5, 8, 10, 12, 20, 21, 22, 23, 24, 28) 10 (14.3%)

Drugs tested only for carcinogenicity 0

Drugs with at least one results in tests for bacterial mutagenicity

(Table 1: 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 25, 26, 27, 28, 29)

25 (35.7%)

Drugs with at least one results in tests for gene mutation in mammalian cells

(Table 1: 1, 3, 4, 5, 6, 11, 14, 15, 16, 17, 18, 19, 25, 28)

14 (20.0%)

Drugs with at least one results in in vitro tests for SCE, chromosomal aberrations, aneuploidy, or micronucleus

in animal or human cells (Table 1: 1, 2, 4, 5, 6, 7, 8, 9, 11, 13, 14, 15, 16, 17, 18, 19, 20, 24, 25, 26, 28, 29)

22 (31.4%)

Drugs with at least one results in in vivo tests for SCE, chromosomal aberrations, or micronucleus

in animal or human cells (Table 1: 1, 2, 3, 4, 7, 9, 13, 14, 15, 16, 17, 19, 26)

13 (18.6%)

Drugs which underwent testing for DNA binding, DNA damage or DNA repair synthesis

(Table 1: 3, 5, 6, 10, 11, 12, 13, 15, 17, 18, 19, 20, 22, 25, 27, 28)

16 (22.9%)

Drugs which underwent testing in other types of genotoxicity assays (Table 1: 2, 19, 25) 3 (4.3%)

Drugs examined for genotoxicity in human cells (Table 1: 1, 2, 4, 8, 9, 11, 13, 14, 15, 17, 25, 28) 12 (17.1%)

Drugs tested for carcinogenicity in mice (Table 1: 1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 15, 16, 17, 18, 25, 26, 29) 17 (24.3%)

Drugs tested for carcinogenicity in rats (Table 1: 1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 15, 16, 17, 18, 19, 25, 26, 27, 29) 19 (27.1%)

Drugs tested for carcinogenicity in both mice and rats (Table 1: 1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 15, 16, 17, 18, 25, 26, 29) 17 (24.3%)

a Values in parentheses indicate the percentage of the 70 drugs consideredb Number in parentheses are those of drugs of Table 1

Arch Toxicol (2011) 85:1173–1187 1181

123

of genotoxicity assays makes difficult the assessment of the

genotoxic risk. The occurrence of a higher discordance

between the results of bacterial mutagenicity and an in

vitro cytogenetics has been previously reported by Ishidate

et al. (1988); the 90% of the chemicals negative in the

Ames test were positive in the chromosomal aberrations

assay, and only 50% of clastogens were also positive in the

Ames test. When the in vivo micronucleus and the in vitro

cytogenetics assays were compared, 55% of chemicals

positive in vitro were found negative in vivo.

An analysis of the correlation between the results of the

various types of genotoxicity assays and the results of

carcinogenicity assays is reported in Table 5. The drugs

included in this analysis are only those that in the geno-

toxicity assay considered gave only positive result(s) or

only negative or inconclusive result(s), and in carcino-

genesis assays induced tumor development in at least one

sex of mice or rats, or gave only negative or inconclusive

result(s). It is evident that the occurrence of discordant

results in 13 of the 15 couples of assays considered, their

percentage ranging from 11.1 to 46.2%. An analysis of the

correlation between positive results in short-term in vitro

tests and carcinogenicity performed by Tennant et al.

(1987) for 73 chemicals tested in 2-year carcinogenicity

studies indicates that the positive predictivity was 83% for

the Ames test, 73% for the chromosomal aberrations assay,

67% for SCE induction, and 66% for the mouse lymphoma

assay. Similar results, which confirmed that Salmonella is

the most predictive for carcinogenicity, were obtained by

Zeiger et al. (1990). Ishidate et al. (1988), in a comparison

of results from in vitro clastogenicity assays and evaluation

of tumorigenicity, found that among 165 clastogens, 91

(55%) were carcinogens, 56 (34%) were chemicals that had

shown some indications of tumorigenicity, and only 18

Table 3 Summary per assays type of antihistamines with positive, negative, and discordant results

Bacterial mutagenicity

Positive 0

Negative 23 (Table 1: 1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15, 16, 17, 18, 20, 21, 23, 25, 26, 27, 28, 29)

Discordant 2 (Table 1: 10, 19)

Gene mutation in cultured mammalian cells

Positive 0

Negative 11 (Table 1: 1, 3, 4, 5, 6, 11, 14, 15, 16, 25, 28)

Discordant 3 (Table 1: 17, 18, 19)

In vitro cytogenetics

Positive 3 (Table 1: 1, 6, 24)

Negative 16 (Table 1: 2, 4, 5, 7, 8, 9, 13, 14, 16, 17, 18, 20, 25, 26, 28, 29)


In vivo cytogenetics

Positive 0

Negative 12 (Table 1: 1, 2, 3, 4, 7, 9, 14, 15, 16, 17, 19, 26)

Discordant 1 (Table 1: 13)

DNA lesions (in vitro and in vivo)

Positive 4 (Table 1: 13, 18, 27, 28)

Negative 9 (Table 1: 3, 5, 10, 12, 15, 17, 20, 22, 25)


Carcinogenesis in mice

Positive 2 (Table 1: 4, 13)

Negative 13 (Table 1: 1, 2, 3, 6, 7, 11, 14, 15, 16, 18, 25, 26, 29)


Carcinogenesis in rats

Positive 3 (Table 1: 9, 17, 19)

Negative 14 (Table 1: 1, 2, 3, 4, 6, 7, 11, 14, 15, 16, 25, 26, 27, 29)


Carcinogenesis, discordant results in mice and rats 2 (Table 1: 4, 18)

Drugs considered as positive are those that gave only positive results. Drugs considered as negative are those that gave only negative or

inconclusive results. Discordant indicates the number of drugs that gave both positive and negative or inconclusive results in genotoxicity assays

and in carcinogenicity assays performed in the same species or were carcinogenic to mice but not to rats and vice versa. Numbers in parentheses

are those of drugs of Table 1

1182 Arch Toxicol (2011) 85:1173–1187

123

(11%) were evaluated as negative for carcinogenic effects.

More recently, the sensitivity of four in vitro genotoxicity

assays was evaluated by Kirkland et al. (2005). The anal-

ysis of a data base of 533 carcinogens revealed that the

percentage of them yielding positive results was 58.8% in

the Ames test, 73.1% in the mouse lymphoma assay, 78.7%

in the micronucleus test, and 65.6% in the chromosomal

aberrations assay. However, it should be considered that

recent data (Kirkland et al. 2007; Thybaud et al. 2007) have

shown that in vitro assays commonly employed in regu-

latory screening strategies are often positive for chemicals

considered not to present a significant genotoxic or car-

cinogenic risk in vivo, the rate of positive responses for

non-carcinogens becoming exceptionally high when test

batteries are employed. Moreover, also a positive result in

an in vivo genotoxicity assay does not necessarily support

the conclusion of a genotoxic activity. According to Tweats

et al. (2007), there is growing body of evidence that

compound-related disturbances in the physiology of

rodents can result in increases in micronucleated cells in

the bone-marrow that are not related to the intrinsic

genotoxicity of the compound under test. In contrast, it has

been shown that there are carcinogens that gave negative or

equivocal results in the in vivo micronucleus test. Recently,

Kirkland and Speit (2008) examined the published in vivo

results of UDS, transgenic mutation, and Comet-assay for

67 carcinogens that tested negative in the in vivo micro-

nucleus assay. In general, the UDS test was disappointing

giving positive results with less than 20% of these car-

cinogens; the transgenic mutation assay gave positive

responses with more than 50% of the carcinogens, and the

Comet-assay detected almost 90% of the micronucleus-

negative or equivocal carcinogens. Moreover, based on a

small number of publications with non-carcinogens, the

transgenic mutation and the Comet assays gave negative

results with non-carcinogens in 69 and 78% occasions,

respectively.

Finally, Table 6 indicates, using the same criteria of

inclusion indicated for Table 5, the percentages of anti-

histamines that, according to results obtained in the various

types of genotoxicity assays, may be classified as non-

genotoxic non-carcinogens, genotoxic non-carcinogens,

non-genotoxic carcinogens, and genotoxic carcinogens.

These percentages depend on the genotoxicity assay

considered. For instance, are classified as non-genotoxic

non-carcinogens the 88.9% of antihistamines that tested

negative in the gene mutation assay and only the 42.8% of

those that tested negative in DNA lesions assays. If we

prudently presumed that a drug might be considered

genotoxic if tested positive in at least one genotoxicity

assay and carcinogenic if tested positive in at least one

carcinogenicity assay, 4 of the 19 antihistamines with both

genotoxicity and carcinogenicity tests results—doxyla-

mine, loratadine, mepyramine and methapyrilene—might

be classified as genotoxic carcinogens even if provided in

genotoxicity assays contrasting results. Two antihista-

mines—cetirizine and desloratadine—might be considered

non-genotoxic carcinogens. In a quantitative risk assess-

ment, the capability of distinguishing between genotoxic

and non-genotoxic carcinogens is important for the pre-

diction of the dose–response curve and for the extrapola-

tion of experimental data to relevant levels of human

Table 4 Correlation between the results of genotoxicity assays of antihistamines

Couples of assays considered No. of drugs with

Concordant results Discordant results

Bacterial mutagenicity—gene mutation in

mammalian cells

11 (100%) (Table 1: 1, 3, 4, 5, 6, 11, 14, 15, 16, 25, 28) 0

Bacterial mutagenicity—in vitro cytogenetics 15 (88.2%) (Table 1:

2, 4, 5, 8, 9, 13, 14, 16, 17, 18, 20, 25, 26, 28, 29)

2 (11.8%) (Table 1: 1, 6)

Bacterial mutagenicity—in vivo cytogenetics 10 (100%) (Table 1: 1, 2, 3, 4, 9, 14, 15, 16, 17, 26) 0

Bacterial mutagenicity—DNA lesions 6 (60.0%) (Table 1: 3, 5, 15, 17, 20, 25) 4 (40.0%) (Table 1: 13, 18, 27, 28)

Gene mutation in mammalian cells—in vitro

cytogenetics

6 (75.0%) (Table 1: 4, 5, 14, 16, 25, 28) 2 (25.0%) (Table 1: 1, 6)

Gene mutation in mammalian cells—in vivo

cytogenetics

6 (100%) (Table 1: 1, 3, 4, 14, 15, 16) 0

Gene mutation in mammalian cells—DNA

lesions

4 (80%) (Table 1: 3, 5, 15, 25) 1 (20%) (Table 1: 28)

In vitro cytogenetics—in vivo cytogenetics 8 (88.9%) (Table 1: 2, 4, 7, 9, 14, 16, 17, 26) 1 (11.1%) (Table 1: 1)

DNA lesions—in vitro cytogenetics 4 (57.1%) (Table 1: 5, 17, 20, 25) 3 (42.9%) (Table 1: 13, 18, 28)

DNA lesions—in vivo cytogenetics 3 (100%) (Table 1: 3, 15, 17) 0

Drugs included in these comparisons are those that in the assay considered gave only positive result(s) or only negative or inconclusive result(s).

In parentheses are indicated the corresponding percentages, and the numbers of Table 1

Arch Toxicol (2011) 85:1173–1187 1183

123

exposure. While threshold models are valid for non-geno-

toxic carcinogens, a no-effect level usually cannot be

expected for genotoxic carcinogens.

According to IARC (1987), an agent for which there is

inadequate evidence or no data in humans but sufficient

evidence of carcinogenicity in experimental animals, and

in some instances in the presence of limited evidence of

carcinogenicity in experimental animals together with

supporting evidence from other relevant data, may be

classified as possibly carcinogenic to humans (Group 2B).

Table 5 Correlation between the results of genotoxicity and carcinogenicity assays of antihistamines

Couples of assays considered No. of drugs with

Concordant results Discordant results

Bacterial mutagenicity—carcinogenicity in mice 12 (75.0%)

(Table 1: 1, 2, 3, 6, 11, 14, 15, 16, 18, 25, 26, 29)

4 (25.0%)

(Table 1: 4, 9, 13, 17)

Bacterial mutagenicity—carcinogenicity in rats 13 (76.5%) (Table 1: 1, 2, 3, 4, 6, 11, 14,

15, 16, 25, 26, 27, 29)

4 (23.5%)

(Table 1: 9, 13, 17, 18)

Bacterial mutagenicity—carcinogenicity

in both mice and rats

11 (68.7%)

(Table 1: 1, 2, 3, 6, 11, 14, 15, 16, 25, 26, 29)

5 (31.5%)

(Table 1: 4, 9, 13, 17, 18)

In vitro cytogenetics—carcinogenicity in mice 8 (57.1%) (Table 1: 2, 7, 14, 16, 18, 25, 26, 29) 6 (42.9%)

(Table 1: 1, 4, 6, 9, 13, 17)

In vitro cytogenetics—carcinogenicity in rats 8 (57.1%) (Table 1: 2, 4, 7, 14, 16, 25, 26, 29) 6 (42.9%)

(Table 1: 1, 6, 9, 13, 17, 18)

In vitro cytogenetics—carcinogenicity in both

mice and rats

7 (53.8%) (Table 1: 2, 7, 14, 16, 25, 26, 29) 6 (46.2%)

(Table 1: 1, 4, 9, 13, 17, 18)

Gene mutation in mammalian cells—

carcinogenicity in mice

8 (88.9%) (Table 1: 1, 3, 6, 11, 14, 15, 16, 25) 1 (11.1%) (Table 1: 4)


carcinogenicity in rats

9 (100%) (Table 1: 1, 3, 4, 6, 11, 14, 15, 16, 25) 0


carcinogenicity in both mice and rats

8 (100%) (Table 1: 1, 3, 6, 11, 14, 15, 16, 25) 0

In vivo cytogenetics—carcinogenicity in mice 8 (72.7%) (Table 1: 1, 2, 3, 7, 14, 15, 16, 26) 3 (27.3%) (Table 1: 4, 9, 17)

In vivo cytogenetics—carcinogenicity in rats 9 (75.0%) Table 1: 1, 2, 3, 4, 7, 14, 15, 16, 26) 3 (25.0%) (Table 1: 9, 17, 19)

In vivo cytogenetics—carcinogenicity in

both mice and rats

8 (72.7%) (Table 1: 1, 2, 3, 7, 14, 15, 16, 26) 3 (27.3%) (Table 1: 4, 9, 17)

DNA lesions—carcinogenicity in mice 4 (66.7%) (Table 1: 3, 13, 15, 25) 2 (33.3%) (Table 1: 17, 18)

DNA lesions—carcinogenicity in rats 5 (71.4%) (Table 1: 3, 13, 15, 18, 25) 2 (28.2%) (Table 1: 17, 27)

DNA lesions—carcinogenicity in both mice and rats 4 (80.0%) (Table 1: 3, 13, 15, 25) 1 (20.0%) (Table 1: 17)

The drugs included in these comparisons are those that in genotoxicity assay considered gave only positive results or only negative or

inconclusive results and in carcinogenicity assays tested positive in at least one sex of mice or rats or gave negative or inconclusive results in both

species. In parentheses are indicated the corresponding percentages, and the numbers of drugs of Table 1

Table 6 Number of non-carcinogens and of carcinogens that tested negative and positive in the different types of genotoxicity assay

No. of non-genotoxic

non-carcinogens

No. of genotoxic

non-carcinogens

No. of non-genotoxic

carcinogens

No. of genotoxic

carcinogens

Bacterial mutagenicity 12 (70.6%) (1, 2, 3, 6, 11, 14, 15,

16, 25, 26, 27, 29)

0 5 (29.4%) (4, 9, 13, 17, 18) 0

Gene mutation assay 8 (88.9%) (1, 3, 6, 11, 14, 15, 16, 25) 0 1 (11.2%) (4) 0

In vitro cytogenetics 7 (53.8%) (2, 7, 14, 16, 25, 26, 29) 2 (15.4%) (1,6) 4 (30.8%) (4, 9, 17, 18) 0

In vivo cytogenetics 8 (61.5%) (1, 2, 3, 7, 14, 15, 16, 26) 0 5 (38.5%) (4, 9, 13, 17, 19) 0

In vitro and/or in vivo DNA lesion 3 (42.8%) (3, 15, 25) 1 (14.3%) (27) 1 (14.3%)(17) 2 (28.6%) (13, 18)

The data indicate the number of non-carcinogens and carcinogens examined in each genotoxicity assay that tested negative (non-genotoxic) and

positive (genotoxic) in the same assay. In this analysis were considered as non-carcinogens those drugs that did not increase tumor incidence in

mice and/or rats of both sexes, and as carcinogens those drugs that increased tumor incidence in at least one sex of mice or rats. Only the drugs

that gave a single negative or concordant negative results, and the drugs that gave a single positive or concordant positive results in the indicated

genotoxicity assay were considered non-genotoxic and genotoxic, respectively, and were included in this analysis

In parentheses are indicated the corresponding numbers of Table 1

1184 Arch Toxicol (2011) 85:1173–1187

123

On the basis of these indications, three antihistamines—

desloratadine, loratadine, and methapyrilene—perhaps

might be classified as Group 2B. All the other antihista-

mines should be considered, on the basis of available data,

not classifiable as to their carcinogenicity to humans

(Group 3); doxylamine has been already classified in this

group by IARC (2001).

Finally, it should be considered that genotoxic–carcin-

ogenic effects might be produced in humans by the

N-nitroso compounds formed in the gastric environment by

the reaction with nitrite of antihistamines that are theoret-

ically nitrosatable amine drugs (Brambilla and Martelli

2007). In this respect, it should be considered that forma-

tion of N-nitroso compounds by reaction with nitrite has

been found to occur for chlorphenamine, cinnarizine,

clemizole, cyclizine, dimenhydrinate, diphenhydramine,

diphenylpyraline, hydroxyzine, methapyrilene, prometha-

zine, tripelennamine, and triprolidine. In addition, geno-

toxic effects have been found to be produced by the

nitrosation reaction mixture and/or the drug–nitrite inter-

action product(s) of astemizole, cinnarizine, diphenhydra-

mine, hydroxyzine, methapyrilene, and tripelennamine.

The information provided by this review on the geno-

toxic and carcinogenic effects of antihistamines makes

evident that, although the Council Directive 65/65/EEC of

26 January (1965) exists since more than 40 years, the

assessment of the genotoxic and carcinogenic risk to

humans of the majority of the marketed drugs of this family

is still not based on sufficient studies; this also in spite of

the necessity of renewed authorization every 5 years. As a

matter of fact, only 12 of the 70 antihistamines considered

were examined in substantial agreement with the indica-

tions of the current guide lines for genotoxicity and car-

cinogenicity studies indicated in the Introduction. If we

consider that the daily dose of most antihistamines ranges

from 10 to more than 100 mg, an adequate evaluation of

their possible genotoxic and carcinogenic activity should

be considered at least of the same importance to that of

numberless chemicals examined in the 97 volumes of the

IARC Monographs on the Evaluation of Carcinogenic

Risks to Humans, the daily exposure to which is often

lower than 1 mg.

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