RESUMO
Closantel (CLS) is currently used in programs for the strategic control of gastrointestinal nematodes. CLS is extralabel used in different dairy goat production systems. From available data in dairy cows, it can be concluded that residues of CLS persist in milk. The current work evaluated the concentration profiles of CLS in plasma and milk from lactating orally treated dairy goats to assess the residues pattern in dairy products such as cheese and ricotta. Six (6) female Saanen dairy goats were treated orally with CLS administered at 10 mg/kg. Blood and milk samples were collected between 0 and 36 days post-treatment. The whole milk production was collected at 1, 4, 7, and 10 days post-treatment to produce soft cheese and ricotta. CLS concentrations in plasma, milk, cheese, whey, and ricotta were determined by HPLC. The concentrations of CLS measured in plasma were higher than those measured in milk at all sampling times. However, the calculated withdrawal time for CLS in milk was between 39 and 43 days postadministration to dairy goats. CLS residual concentrations in cheese (between 0.93 and 1.8 µg/g) were higher than those measured in the milk used for its production. CLS concentrations in ricotta were sixfold higher than those in the milk and 20-fold higher than those in the whey used for its production. The persistent and high residual concentrations of CLS in the milk and in the cheese and ricotta should be seriously considered before issuing any recommendation on the extralabel use of CLS in dairy goat farms.
Assuntos
Antinematódeos/farmacocinética , Queijo/análise , Resíduos de Drogas/análise , Cabras/metabolismo , Leite/química , Salicilanilidas/farmacocinética , Animais , Antinematódeos/análise , Antinematódeos/sangue , Feminino , Doenças das Cabras/tratamento farmacológico , Doenças das Cabras/parasitologia , Doenças das Cabras/prevenção & controle , Salicilanilidas/análise , Salicilanilidas/sangueRESUMO
The family of ATP-binding cassette (ABC) transporters is composed of several transmembrane proteins that are involved in the efflux of a large number of drugs including ivermectin, a macrocyclic lactone (ML) endectocide, widely used in human and livestock antiparasitic therapy. The aim of the work reported here was to assess the interaction between three different anthelmintic drugs with substrates of the P-glycoprotein (P-gp) and the breast cancer resistance protein (BCRP). The ability of ivermectin (IVM), moxidectin (MOX) and closantel (CST) to modulate the intestinal transport of both rhodamine 123 (Rho 123), a P-gp substrate, and danofloxacin (DFX), a BCRP substrate, across rat ileum was studied by performing the Ussing chamber technique. Compared to the controls, Rho 123 efflux was significantly reduced by IVM (69%), CST (51%) and the positive control PSC833 (65%), whereas no significant differences were observed in the presence of MOX (30%). In addition, DFX efflux was reduced between 59% and 72% by all the assayed drug molecules, showing a higher potency than that observed in the presence of the specific BCRP inhibitor pantoprazole (PTZ) (52%). An ex vivo intestinal transport approach based on the diffusion chambers technique may offer a complementary tool to study potential drug interactions with efflux transporters such as P-gp and BCRP.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Anti-Helmínticos/metabolismo , Mucosa Intestinal/metabolismo , Animais , Anti-Helmínticos/química , Transporte Biológico/fisiologia , Corantes Fluorescentes/farmacocinética , Fluoroquinolonas/farmacocinética , Humanos , Masculino , Ratos , Ratos Wistar , Rodamina 123/farmacocinéticaRESUMO
The role of the transporter P-glycoprotein (P-gp) in the disposition kinetics of different drugs therapeutically used in veterinary medicine has been demonstrated. Considering the anatomo-physiological features of the ruminant species, the constitutive expression of P-gp (ABCB1) along the sheep gastrointestinal tract was studied. Additionally, the effect of repeated dexamethasone (DEX) administrations on the ABCB1 gene expression in the liver and small intestine was also assessed. The ABCB1 mRNA expression was determined by real-time quantitative PCR. P-gp activity was evaluated in diffusion chambers to determine the efflux of rhodamine 123 (Rho 123) in the ileum from experimental sheep. The constitutive ABCB1 expression was 65-fold higher in the liver than in the intestine (ileum). The highest ABCB1 mRNA expression along the small intestine was observed in the ileum (between 6- and 120-fold higher). The treatment with DEX did not elicit a significant effect on the P-gp gene expression levels in any of the investigated gastrointestinal tissues. Consistently, no significant differences were observed in the intestinal secretion of Rho 123, between untreated control (Peff S-M = 3.99 × 10(-6) ± 2.07 × 10(-6) ) and DEX-treated animals (Peff S-M = 6.00 × 10(-6) ± 2.5 × 10(-6) ). The understanding of the efflux transporters expression and activity along the digestive tract may help to elucidate clinical implications emerging from drug interactions in livestock.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Regulação da Expressão Gênica/fisiologia , Intestino Delgado/metabolismo , Fígado/metabolismo , Ovinos/fisiologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Animais , Masculino , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Topical formulations have achieved worldwide acceptance in veterinary medicine because their administration is an easy, less labor-intensive and nonstressing form. Any chemical compound that comes in contact with the skin has the potential to be locally and/or systemically absorbed. However, many factors related to the features of animal skin, composition of the topical formulation and to the drug itself can determine marked differences in the percutaneous absorption process. The aim of the current work was to characterize the pattern of in vitro percutaneous absorption for moxidectin (MXD) and doramectin (DRM), two of the most worldwide used topical macrocyclic lactone antiparasitic compounds in cattle. The work included the development of a simple and inexpensive in vitro assay useful to predict in vivo drug percutaneous absorption in cattle. Both drugs were administered as the commercial formulations intended for their topical administration to cattle. The in vitro studies were carried out using modified Franz-type vertical diffusion cells. Cattle skin slices of 500 µm thickness were prepared using a dermatome to separate the stratum corneum and upper epidermis from dermis and subcutaneous tissue. The receptor medium was sampled up to 72 h postadministration and drug concentrations were measured by HPLC. The parameters used to estimate the comparative in vitro skin permeation showed marked differences between DRM and MXD. A 5.29-fold longer lag time (T(lag)) was observed for DRM. Similarly, the flux (J) (2.93-fold) and the permeation coefficients (K(p) ) (2.95-fold) in cattle skin were significantly higher (P < 0.05) for DRM compared to those obtained for MXD. Additionally, the data obtained from the in vitro permeation studies was correlated with the plasma concentrations of both compounds achieved in vivo in cattle treated with the same topical formulations. Correlation coefficients between percentage of drug permeated in vitro vs. percentage of drug absorbed in vivo (up to 48 h post-treatment) were 0.856-0.887 (MXD) and 0.976-0.990 (DRM). However, the highest in vitro-in vivo correlations for both molecules were observed up to 24 h post-treatment A rapid screening method for testing different topical formulations can be achieved with the simple in vitro cattle skin permeation technique described here, which has been successfully adapted to test the comparative percutaneous absorption of MXD and DRM.
Assuntos
Bovinos , Inseticidas/química , Ivermectina/análogos & derivados , Absorção Cutânea , Administração Tópica , Animais , Bioensaio , Ivermectina/química , Macrolídeos/química , PermeabilidadeRESUMO
The effects of repeated administrations of dexamethasone (DEX) (3 mg/kg/day by i.m. route for 7 days) on the gene expression profile of a cytochrome P450 (CYP) 3A28-like isoenzyme, on the expression of a CYP3A-immunoreactive protein and on CYP3A-dependent metabolic activities in sheep liver and small intestinal mucosa were evaluated in the current work. CYP 3A-dependent metabolic activities (erythromycin and triacetyl-oleandomycin N-demethylations) were assessed in microsomal fractions. The mRNA expression of CYP3A28-like, glucocorticoid receptor, constitutive androstane receptor, pregnane X receptor and retinoic X receptor alpha (RXRα) was determined by quantitative real-time PCR. The expression of a CYP3A-immunoreactive protein was measured by Western blot analyses. In the liver, DEX treatment increased CYP3A28-like mRNA levels (2.67-fold, P<0.01) and CYP3A apoprotein expression (1.34-fold, P<0.05) and stimulated CYP3A-dependent metabolism. High and significant correlation coefficients between CYP3A-dependent activities and CYP3A28-like gene (r=0.835-0.856, P<0.01) or protein (r=0.728-0.855, P<0.05) expression profiles were observed. Among the transcriptional factors, DEX only stimulated (2.1-fold, P<0.01) the mRNA expression of RXRα. In sheep small intestine, DEX caused a slight increment (34.6%, P<0.05) in erythromycin N-demethylase activity in the jejunal mucosa and a significant enhancement (P<0.05) of CYP3A apoprotein level in the duodenal mucosa.
Assuntos
Citocromo P-450 CYP3A/metabolismo , Dexametasona/farmacologia , Mucosa Intestinal/metabolismo , Fígado/enzimologia , Ovinos/metabolismo , Animais , Biomarcadores , Western Blotting , Citocromo P-450 CYP3A/genética , Eletroforese em Gel de Poliacrilamida/veterinária , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Masculino , RNA/genética , RNA/metabolismo , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Triclabendazole (TCBZ) is a flukicidal halogenated benzimidazole compound extensively used in veterinary medicine. Liver fluke control in lactating dairy cattle is difficult because treatment should be implemented only during the dry period to avoid milk residues. However, control in endemic areas is usually implemented as regular treatments three to four times a year, even during the lactating period. Thus, information on TCBZ milk excretion and the risk of the presence of drug residues in fluid milk and milk-derivate products is essential. The experimental aims were to evaluate the comparative disposition kinetics of TCBZ and its sulpho-metabolites in plasma and milk in lactating dairy cattle after the oral administration (12 mg kg(-1)) of TCBZ and to assess the pattern of residues in cheese made with milk from treated dairy cows. Both TCBZ sulphoxide and sulphone metabolites but not TCBZ were detected in milk (up to 36 and 144 h, respectively) and plasma (up to 144 h) after oral administration of TCBZ. Residual concentrations of TCBZ sulpho-metabolites were found in cheese made with milk from treated animals. The total average residual concentration in fresh cheese was 13.0-fold higher than that obtained in milk used for its elaboration. The high concentrations of TCBZ sulpho-metabolites recovered in fresh cheese should be seriously considered before milk from treated cows is used for making dairy products.
Assuntos
Anti-Helmínticos/análise , Benzimidazóis/análise , Bovinos/metabolismo , Queijo/análise , Resíduos de Drogas/análise , Leite/química , Drogas Veterinárias/análise , Animais , Anti-Helmínticos/sangue , Anti-Helmínticos/farmacocinética , Benzimidazóis/sangue , Benzimidazóis/farmacocinética , Biotransformação , Cromatografia Líquida de Alta Pressão/veterinária , Feminino , Contaminação de Alimentos , Meia-Vida , Lactação , Limite de Detecção , Reprodutibilidade dos Testes , Sulfonas/análise , Sulfóxidos/análise , Distribuição Tecidual , Triclabendazol , Drogas Veterinárias/sangue , Drogas Veterinárias/farmacocinéticaRESUMO
Metabolic activities of several xenobiotic metabolizing enzymes were evaluated in both hepatic and enteric subcellular fractions obtained from Corriedale × Merino crossbreed rams by using a biochemical approach. Microsomes obtained from the different segments of sheep small intestinal mucosa displayed cytochrome P450 (CYP)-dependent N-demethylations but not O-deethylase activities apparently occurred. CYP-mediated N-demethylations neither decreased nor increased along the small intestinal mucosa. Percentages of activity for erythromycin N-demethylase in the small intestine were between 29% (duodenum) and 45% (ileum) from that measured in the liver, whereas those determined for triacetyl-oleandomycin N-demethylation ranged between 10% (duodenum) and 15% (jejunum) of the same hepatic activity. Conversely, metabolic rates for aminopyrine and chlorfeniramine N-demethylations in the gut mucosa ranged between 3% and 7% compared to their respective hepatic enzyme activities. Sheep enteric mucosa also displayed metabolic reactions typically mediated by flavin-containing monooxygenases (FMOs), carbonyl reductases (CBRs), carboxylesterases (CES), glutathione S-transferases (GSTs) and uridine diphosphoglucuronyltransferases (UGTs). The FMO-mediated sulfoxidation of methimazole was 2.6-fold higher (P < 0.01) in the ileal compared to the duodenal mucosa. Percentages of activity for the microsomal CBR-dependent biotransformation of menadione were between 12% (ileum) and 19% (duodenum-jejunum) of the total activity measured in the liver; metabolic rates measured in duodenum and jejunum were â¼1.7-fold higher (P < 0.05) than that observed in the ileum. The microsomal CES activity (using p-nitrophenyl acetate as substrate) was around twofold higher in duodenum (P < 0.05) and jejunum (P < 0.01) in comparison to the ileum. Cytosolic GST-dependent activities (toward 1-chloro, 2,4-dinitrobenzene) were similar in the mucosa of duodenum, jejunum and ileum. Microsomal UGT activities (toward 1-naphthol) in duodenum and jejunum were three- and fourfold higher, respectively, compared to that measured in the ileum. The small intestinal mucosa may play a critical defensive role due to its involvement in the detoxification of toxic compounds prior to absorption. In addition, gut metabolic reactions may contribute to the presystemic metabolism of orally administered drugs. These results are a further contribution to the understanding of the relevance of the extra-hepatic metabolism of xenobiotics in ruminant species.
Assuntos
Intestino Delgado/metabolismo , Ovinos/metabolismo , Animais , Duodeno/enzimologia , Duodeno/metabolismo , Íleo/enzimologia , Íleo/metabolismo , Mucosa Intestinal/enzimologia , Mucosa Intestinal/metabolismo , Intestino Delgado/enzimologia , Jejuno/enzimologia , Jejuno/metabolismo , Masculino , Metimazol/metabolismo , Microssomos/enzimologia , Microssomos/metabolismo , Microssomos Hepáticos/metabolismo , Oxirredução , Farmacocinética , Frações Subcelulares/enzimologia , Frações Subcelulares/metabolismo , Vitamina K 3/metabolismoRESUMO
The role of the drug efflux pump, known as P-glycoprotein, in the pharmacokinetic disposition (host) and resistance mechanisms (target parasites) of the macrocyclic lactone (ML) antiparasitic compounds has been demonstrated. To achieve a deeper comprehension on the relationship between their pharmacokinetic and pharmacodynamic behaviors, the aim of the current work was to assess the comparative effect of loperamide, a well-established P-glycoprotein modulator, on the ivermectin and moxidectin disposition kinetics and efficacy against resistant nematodes in cattle. Fifty (50) Aberdeen Angus male calves were divided into five (5) experimental groups. Group A remained as an untreated control. Animals in the other experimental Groups received ivermectin (Group B) and moxidectin (Group C) (200 microg/kg, subcutaneously) given alone or co-administered with loperamide (0.4 mg/kg, three times every 24 h) (Groups D and E). Blood samples were collected over 30 days post-treatment and drug plasma concentrations were measured by HPLC with fluorescence detection. Estimation of the anthelmintic efficacy for the different drug treatments was performed by the faecal egg count reduction test (FECRT). Nematode larvae were identified by pooled faecal cultures for each experimental group. Cooperia spp. and Ostertagia spp. were the largely predominant nematode larvae in pre-treatment cultures. A low nematodicidal efficacy (measured by the FECRT) was observed for both ivermectin (23%) and moxidectin (69%) in cattle, which agrees with a high degree of resistance to both molecules. Cooperia spp. was the most abundant nematode species recovered after the different drug treatments. The egg output reduction values increased from 23% to 50% (ivermectin) and from 69% to 87% (moxidectin) following their co-administration with loperamide. Enhanced systemic concentrations and an altered disposition of both ML in cattle, which correlates with a tendency to increased anthelmintic efficacy, were observed in the presence of loperamide. Overall, the in vivo modulation of P-glycoprotein activity modified the kinetic behavior and improved the efficacy of the ML against resistant nematodes in cattle. The work provides further evidence on the high degree of resistance to ML in cattle nematodes and, shows for the first time under field conditions, that modulation of P-glycoprotein may be a valid pharmacological approach to improve the activity and extend the lifespan of these antiparasitic molecules.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antinematódeos/farmacologia , Ivermectina/farmacologia , Nematoides/efeitos dos fármacos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/efeitos dos fármacos , Animais , Antinematódeos/administração & dosagem , Antinematódeos/farmacocinética , Área Sob a Curva , Disponibilidade Biológica , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/parasitologia , Resistência a Medicamentos , Fezes/parasitologia , Injeções Subcutâneas/veterinária , Ivermectina/administração & dosagem , Ivermectina/farmacocinética , Loperamida/administração & dosagem , Loperamida/farmacologia , Macrolídeos/administração & dosagem , Macrolídeos/farmacocinética , Macrolídeos/farmacologia , Masculino , Nematoides/metabolismo , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Infecções por Nematoides/veterinária , Contagem de Ovos de Parasitas , Distribuição TecidualRESUMO
The chemical stability of residues of different antiparasitic macrocyclic lactone compounds in milk subjected to thermal treatment was assessed. Concentrations of ivermectin (IVM), moxidectin (MXD) and eprinomectin (EPM) in sheep milk, equivalent to those measured in vivo in milk excretion studies, were subjected to 65 degrees C over 30 min or to 75 degrees C for 15 s. Residue concentrations of IVM, MXD and EPM in milk were measured by high-performance liquid chromatography (HPLC) (fluorescence detection) before and after heat treatment of the drug-fortified milk samples. No evidence of chemical loss was obtained in either of the thermal treatments under evaluation. The stability of the parent compounds in milk was evidenced by the lack of bioconversion products (metabolites) after both thermal treatments. Only very minor changes on drug concentrations were observed at the end of the treatments, which fell within the limits of the variation of the validated analytical method. In conclusion, residue concentrations of macrocyclic lactones are unaffected by industrial-simulated milk thermal procedures. Based on the reported findings, it can be postulated that residue concentrations of IVM, MXD and EPM measured in raw sheep milk may be used to estimate consumer exposure and dietary intake for these veterinary drugs.
Assuntos
Antiparasitários/análise , Resíduos de Drogas/análise , Contaminação de Alimentos/análise , Macrolídeos/análise , Leite/química , Animais , Antiparasitários/química , Cromatografia Líquida de Alta Pressão/métodos , Resíduos de Drogas/química , Estabilidade de Medicamentos , Análise de Alimentos/métodos , Manipulação de Alimentos/métodos , Temperatura Alta , Ivermectina/análogos & derivados , Ivermectina/análise , Ivermectina/química , Macrolídeos/química , OvinosRESUMO
Understanding the disposition kinetics and the pattern of metabolism is critical to optimise the flukicidal activity of triclabendazole (TCBZ) in ruminants. TCBZ is metabolised by both flavin-monooxygenase (FMO) and cytochrome P450 (P450) in the liver. Interference with these metabolic pathways may be useful to increase the systemic availabilities of TCBZ metabolites, which may improve the efficacy against Fasciola hepatica. The plasma disposition of TCBZ metabolites was evaluated following TCBZ co-administration with FMO [methimazole (MTZ)] and P450 [piperonyl butoxyde (PB) and ketoconazole (KTZ)] inhibitors in sheep. Twenty (20) healthy Corriedale x Merino weaned female lambs were randomly allocated into four experimental groups. Animals of each group were treated as follow: Group A, TCBZ alone (5 mg/kg, IV route); Group B, TCBZ (5 mg/kg, IV) + MTZ (3 mg/kg, IV); Group C, TCBZ (5 mg/kg, IV) + PB (30 mg/kg, IV) and Group D, TCBZ (5 mg/kg, IV) + KTZ (10 mg/kg, orally). Blood samples were taken over 240 h post-treatment and analysed by HPLC. TCBZ sulphoxide and sulphone were the main metabolites recovered in plasma. MTZ did not affect TCBZ disposition kinetics. TCBZ sulphoxide Cmax values were significantly increased (P < 0.05) after the TCBZ + PB (62%) and TCBZ + KTZ (37%) treatments compared to those measured in the TCBZ alone treatment. TCBZ sulphoxide plasma AUCs were higher (P < 0.05) in the presence of both PB (99%) and KTZ (41%). Inhibition of TCBZ P450-mediated oxidation in the liver accounted for the increased systemic availability of its active metabolite TCBZ sulphoxide. This work contributes to the search of different strategies to improve the use of this flukicidal drug in ruminants.