Browsing by Author "McKellar, Quintin A."
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Item Comparative plasma disposition, bioavailability and efficacy of ivermectin following oral and pour-on administrations in horses(Elsevier, 2010-05-28) Gökbulut, Cengiz; Akşit, Dilek; McKellar, Quintin A.; Çırak, Veli Yılgör; Şenlik, Bayram; Durmaz, Murat; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Öncesi Bilimler Bölümü.; 0000-0002-1817-5744; 0000-0003-2964-2245; 6602404057; 9332720500; 16039333100Pour-on formulations of endectocides decrease the risk of injury for both user and animal, and are particularly convenient for animal owners who can apply the product. This study was designed to investigate the plasma disposition and efficacy of ivermectin (IVM) following pour-on, per os and intravenous administrations. Eighteen female horses weighing 510-610 kg were used in this study. The animals were allocated into three groups (per os, pour-on and intravenous groups). The equine paste, bovine pour-on and bovine injectable formulations of IVM were administered orally, topically and intravenously at the dose rates of 0.2, 0.5 and 0.2 mg/kg bodyweight, respectively. Heparinized blood samples and hair samples were collected at various times between 1 h and 40 days. The samples were analysed by high performance liquid chromatography with fluorescence detector. Faecal strongyle egg counts (EPG) were performed by a modified McMaster's technique before and at weekly intervals during 10 weeks after treatment. The results indicated that the plasma concentration and systemic availability of IVM was lower but the plasma persistence was prolonged after pour-on administration compared with per os route. IVM (paste) reduced the EPG by >95% for 10 weeks, whereas the reduction in pour-on group varied from 82 to 97%. EPG reduction in pour-on group was lower than that of per os group. Degradation on the application site, cutaneous biotransformation, binding of IVM to the haircoat and/or sebum are probably responsible for the relatively lower bioavailability of IVM in horses after pour-on administration. In conclusion, the poor plasma availability observed after pour-on administration could result in subtherapeutic plasma concentrations, which may promote the development of drug resistance in parasites.Item Comparative plasma dispositions and bioavailability of ivermectin following oral and pour-on administration in horses(Wiley, 2009-08) Gökbulut, Cengiz; Aksit, Dilek; Durmaz, Murat; McKellar, Quintin A.; Çırak, Veli Yilgör; Şenlik, Bayram; Uludağ Üniversitesi/Veteriner Fakültesi/Parazitoloji Anabilim Dalı.; 0000-0003-2964-2245; 6602404057; 9332720500Item The effects of different ages and dosages on the plasma disposition and hair concentration profile of ivermectin following pour-on administration in goats(Wiley, 2011-02) Gökbulut, Cengiz; Akşit, Dilek; McKellar, Quintin A.; Çırak, Veli Yılgör; Şenlik, Bayram; Uludağ Üniversitesi/Veteriner Fakültesi/Parazitoloji Anabilim Dalı.; 0000-0003-2964-2245; 6602404057; 9332720500The effects of different ages and dosages on the plasma disposition and hair degradation of ivermectin (IVM) were investigated following pour-on administration in goats. Twenty-eight female Saanen goats allocated into two groups of 14 animals according to their ages as young (5-6 months old) and old (12-24 months old) groups. Each age group was divided into two further of seven goats and administered pour-on formulation of IVM topically at the in recommended dosage rate of 0.5 mg/kg bodyweight The recommended cattle dosages rate of 0.5 mg/kg or at the higher dosage of 1.0 mg/kg. Blood samples were collected at various times between 1 h and 40 days. In addition, hair samples (> 0.01 g) were collected using tweezers from the application sites and far from application sites of the all animals throughout the blood sampling period. The plasma and hair samples were analyzed by high performance liquid chromatography (HPLC) using fluorescence detection following solid and liquid phase extractions, respectively. Dose- and age-dependent plasma disposition of IVM were observed in goats after pour-on administration. In addition, relatively high concentration and slow degradation of IVM in hair samples collected from the application site and far from the application site were observed in the present study. The differences between young and old goats are probably related to differences in body condition and/or lengths of haircoat. The systemic availability of IVM following pour-on administration is relatively much lower than after oral and subcutaneous administrations but the plasma persistence was prolonged. Although, the longer persistence of IVM on hairs on the application site may prolong of efficacy against ectoparasites, the poor plasma availability could result in subtherapeutic plasma concentrations, which may confer the risk of resistance development in for internal parasites after pour-on administration in goats.Item The effects of different ages and dosages on the plasma disposition and hair degradation of ivermectin following pour-on administration in goats(Wiley, 2009-08) Gökbulut, Cengiz; Aksit, Dilek; McKellar, Quintin A.; Çırak, Veli Yilgör; Şenlik, Bayram; Uludağ Üniversitesi/Veteriner Fakültesi/Parazitoloji Anabilim Dalı.; 6602404057; 9332720500Item Pharmacological assessment of netobimin as a potential anthelmintic for use in horses: Plasma disposition, faecal excretion and efficacy(Elsevier, 2009-06) Gökbulut, Cengiz; Yıldırım, Funda; McKellar, Quintin A.; Çırak, Veli Yilgör; Şenlik, Bayram; Uludağ Üniversitesi/Veteriner Fakültesi/Parazitoloji Anabilim Dalı.; 0000-0003-2964-2245; 6602404057; 9332720500This study aimed to determine the plasma disposition and faecal excretion of netobimin (NTB) and its respective metabolites as well as the efficacy against strongyles in horses following oral administration. Netobimin (10 mg/kg) was administered orally to 8 horses. Blood and faecal samples were collected from 1 to 120 h post-treatment and analysed by high performance liquid chromatography (HPLC). Using a chiral phase-based HPLC, plasma disposition of ABZSO enantiomers produced was also determined. Faecal strongly egg counts (EPG) were performed by a modified McMaster's technique before and after the treatment. Neither NTB nor ABZ were present and only albendazole sulphoxide (ABZSO) and sulphone metabolites (ABZSO(2)) were detected in the plasma samples. Maximum plasma concentration of ABZSO (0.53 +/- 0.14 mu g/ml) and ABZSO(2) (0.36 +/- 0.09 mu g/ml) were observed at (t(max)) 10.50 and 19.50 h, respectively following administration of NTB. The area under the curve (AUC) of the two metabolites was similar to each other. Netobimin was not detected, and ABZ was predominant in faecal samples. The maximum plasma concentration (C(max)) of (-)ABZSO was significantly higher than (+)ABZSO, but the area under the curves (AUCs) of the enantiomer were not significantly different each other in plasma samples. The enantiomers of ABZSO were close to racemate in the faecal samples analyzed. Netobimin reduced the EPG by 100%, 100%, 77%, 80% and 75% 2, 4, 6, 8 and 10 weeks post-treatment, respectively. The specific behaviour of the two enantiomers probably reflects different enantioselectivity of the enzymatic systems of the liver which are responsible for sulphoxidation and sulphonation of ABZ. Considering the pharmacokinetic and efficacy parameters NTB could be used as an anthelmintic in horses.