INVESTIGADORES
LANUSSE Carlos Edmundo
artículos
Título:
Doramectin concentration profiles in the gastrointestinal tract of topically-treated calves: influence of animal licking restriction
Autor/es:
SALLOVITZ, J., LIFSCHITZ, A., VIRKEL, G., LANUSSE, C.
Revista:
VETERINARY PARASITOLOGY
Editorial:
Elsevier
Referencias:
Lugar: Amsterdam; Año: 2005 vol. 133 p. 61 - 70
ISSN:
0304-4017
Resumen:
Endectocide compounds are extensively used for broad-spectrum parasite control and their topical administration to
cattle is widespread in clinical practice. Pour-on formulations of moxidectin, ivermectin, eprinomectin and doramectin
(DRM) are marketed internationally for use in cattle. However, variability in antiparasitic efficacy and pharmacokinetic
profiles has been observed. Although the tissue distribution pattern for different endectocide molecules given subcutaneously
to cattle has been described, only limited information on drug concentration profiles in tissues of parasite location after
topical treatment is available. Understanding the plasma and target tissue kinetics for topically-administered endectocide
compounds is relevant to optimise their therapeutic potential. The current work was designed to measure the plasma and
gastrointestinal (GI) concentration profiles of DRM following its pour-on administration to calves. The influence of natural
licking behaviour of cattle on DRM concentration in mucosal tissue and luminal content of different GI sections was
evaluated. The trial was conducted in two experimental phases. In Phase I, the DRM plasma kinetics was comparatively
characterised in free-licking and in 2-day licking-restricted (non-licking) calves. The pattern of distribution of topical DRM
to mucosal and luminal contents from abomasum, duodenum, ileum, caecum and spiral colon was assessed in free-licking
and non-licking calves restricted over 10 days post-administration (Phase II). The prevention of licking caused marked
changes on the plasma and GI kinetics of DRM administered pour-on. In 2-day licking restricted calves, DRM systemic
availability was significantly lower (29%) than in free licking animals during the first 9 days post-treatment. Following a 10-
day long licking restriction period, DRM concentrations profiles in both mucosal tissue and luminal contents of the GI tract
were markedly higher in animals allowed to lick freely. This enhancement in drug concentrations in free-licking compared to
non-licking calves, was particularly pronounced in the abomasal (38-fold higher) and duodenal (six-fold higher) luminal
content. As shown earlier for ivermectin, licking behaviour may facilitate the oral ingestion of topically-administered DRM
in cattle. This would be consistent with the marked lower drug concentration profiles measured in the bloodstream and GI
tract of the animals prevented from licking. The work reported here provides relevant information on the pattern of DRM
distribution to the GI tract after pour-on treatment, and contributes to understand the variability observed in the antiparasitic
persistence of topically-administered endectocides in cattle. The implications of natural licking in topical treatments are