Page 558 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

VetBooks.ir Chapter 41

Amitraz

Ayhan Filazi and Begum Yurdakok-Dikmen

INTRODUCTION used in diabetic animals because it adversely affects glu-
cose and insulin levels even if it used topically (Hsu and
0
Amitraz (N,N -[(Methylimino)dimethylidyne]di-2,4-xylidine)
Schaffer, 1988). Mainly, the stimulation of α-adrenergic
(Fig. 41.1), is a formamidine derivative pesticide (USEPA,
receptors is held responsible for its adverse effects in
1996). Although it is particularly significant with its
mammals. Low blood pressure, hypothermia, lethargy,
acaricide effects, today, amitraz is widely used as a pesti-
anorexia, vomiting, high blood glucose levels, and diges-
cide for various purposes. Many formulations such as
tive tract disorders may develop in exposed animals.
wettable powder (WP), emulsified concentrate (EC), solu- Dogs may also develop cutaneous or mucosal irritations
ble concentrate/liquid or impregnated collar (for dogs) are
resulting itching, eczema, alopecia, or conjunctivitis due
available for insecticide purposes (USEPA, 1996). It is
to the collars containing this substance (Grossman, 1993;
used widely to control all stages of plant parasites and as
Peter et al., 2006; Tarallo et al., 2009).
an ectoparasiticide in cattle, sheep, pigs, and dogs exclu-
sively topically (Peter et al., 2006). It has been reported
that other animal species such as horses, cats, and dog PHARMACOKINETICS/TOXICOKINETICS
breeds like Chihuahua and Pomeranian should not be trea-
Amitraz is absorbed rapid and easily by dermal or oral
ted with amitraz because of its adverse effects (Tarallo
administration due to its highly lipophilic property; which
et al., 2009). Despite this, due to its effectiveness, low
makes it potentially hazardous for animals and humans.
price and malpractice of the veterinary surgeon, it might
Studies on the pharmacokinetics of amitraz in different
still be used in these species and cause poisonings. As a
species have shown that 53% 80% is excreted in urine
result of this, many cases of poisoning have been reported
when it is delivered orally in mice, rats, dogs, baboons,
for horses, cats, dogs, and humans (Grossman, 1993;
and humans within the first 24 h. Two hours after oral
Gunaratnam et al., 1993; Yilmaz and Yildiztas, 2003). In
application in mice and rats, the highest residual concen-
this chapter, amitraz poisonings that occur in animals will
trations were detected in the liver, kidney, and muscle tis-
be discussed.
sues, and its levels rapidly decreased afterward. Gender
did not affect the excretion route or speed. It was shown
BACKGROUND that 92% of the amitraz applied to rats topically could be
cleansed by washing the skin even after 10 h postapplica-
Amitraz is a broad-spectrum insecticide and acaricide that tion, that only 3% remains on the skin for 24 h and that
is used globally in agriculture and veterinary medicine. It this ratio drops to 1.4% after 5 days. A small portion of
has a rapid effect on the control of animal ectoparasites amitraz was absorbed during these 5 days (approximately
such as scabies, ticks, and lice. Tick collars that contain 3% 8% of the amitraz applied) which is excreted in urine
9% of amitraz are rather widely used in veterinary medi- and feces (USEPA, 1996).
cine (Hugnet et al., 1996). All dip solutions containing The metabolism of amitraz is quite similar in rats,
amitraz that are used for tick infestations in cattle and mice, cats, dogs, baboons, cows, and humans. It is ini-
sheep contain xylene and 12.5% 20% amitraz as an tially hydrolyzed into N-(2,4-dimethylphenyl)-N -methyl
0
active substance. While amitraz is also used to control formamidine (BTS-27271) and 2,4-dimethyl formanilide
ectoparasites in cattle, sheep, goat, and pigs, it is not (BTS-27919). The compounds contain a 2,4-dimethylani-
recommended for use in horses, cats, and small breed line (2,4-DMA) ring. The end product of its metabolism
dogs such as Chihuahua and Pomeranian (Peter et al., is 4-amino-3-methylbenzoic acid (BTS-28369) that is
2006; Tarallo et al., 2009). Also, amitraz should not be rapidly conjugated and excreted. Besides these, it also
Veterinary Toxicology. DOI: http://dx.doi.org/10.1016/B978-0-12-811410-0.00041-6
Copyright © 2018 Elsevier Inc. All rights reserved. 525