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2012

Volume 4, Number 3September 2012

Online Version ISSN: 1314-412X

Nutrition and Physiology

Pharmacokinetics of tilmicosin in calves after single subcutaneous application

1 2 3D. Dimitrova *, P. Petkov , D. Tsoneva

1Department of Pharmacology, Physiology of Animals and Physiological Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria2Department of Animal Science, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria3Bulgarian Drug Agency, 26 General Zaimov , 1000 Sofia, Bulgaria

Abstract. The aim of this investigation was determination of main pharmacokinetic parameters of tilmicosin after single subcutaneous application of Tilmovet solutio pro imjectionibus 30 % (Biovet LTD Peshtera). Tilmovet solutio pro imjectionibus 30 % was applied subcutaneously, as a 10 mg/kg dose, to 8 (4 male and 4 female, Brown Bulgarian breed) clinically healthy calves, aged 1.5 – months, weighing 71.5 to 91 kg. Blood plasma tilmicosin concentrations were assayed by HPLC. The main pharmacokinetic parameters were calculated. Pharmacokinetic parameters (mean ± SEM) of tilmicosin were as followed: t – 1/2β

32.33 ± 0.99 h, C – 0.976 ± 0.06 μg/mL, T – 1.00 ± 0.00 h, AUC h–18.22 ± 1.23 g.h/mL. Plasma tilmicosin concentrations higher than 0.1 ±0.009 max max 0→72

μg/mL were detected over the entire 72-hour period of observation after the s.c. application.μ

Keywords: pharmacokinetic, tilmicosin, calves

AGRICULTURAL SCIENCE AND TECHNOLOGY, VOL. 4, No 3, pp 211 - 214, 2012

Bulgarian breed) were included in the experiment. Males were not Introductioncastrated, calves weighed 71.5 to 91 kg (measured 24 h prior to the treatment) and were 1.5-3 months of age. Calves were housed in a Tilmicosin, 20-deoxo-20-(3,5-dimethylpiperidin-1-yl) barn in groups of 4, on straw bedding, with individual mangers and desmycosin, is a chemically modified macrolide antibiotic with a appropriate drinking conditions. Each animal received feed ad prolonged effect. It is synthesized from tylosin for veterinary use libitum, free of prophylactic or therapeutic chemical agents. The (Ose and Tonkinson, 1998., Prescott and Baggot, 1988; Kroker et drinking water was freely available. al., 2002). Tilmicosin is mainly active against Gram-positive and

some Gram-negative bacteria (streptococci, staphylococci, Experimental design pasteurellas, mycoplasmas etc.) (Ziv et al., 1995; Crosier et al., The individual dose was determined on the basis of live body 1996). It is concentrated in lung tissue (Thompson and Lawrence,

weight, measured with 0.5 kg precision 24 hours before the 1994; Thompson et al., 1994; Peters et al., 1997; Scorneaux and treatment. Tilmovet solutio pro imjectionibus 30 % was applied Shryock, 1999a, 1999b; Modric et al., 1999), penetrating intra-subcutaneously, once, in the lower third of the neck at a dose of 10 cellularly in alveolar macrophages (Thompson et al., 1994; mg/kg tilmicosin (= 1 ml/30 kg body weight). Scarneaux and Shryock, 1999a, 1999b). The drug is primarily

indicated for treatment of respiratory diseases in large ruminants Blood samplescaused by pasteurellas and mycoplasmas (Ose and Tonkinson, Blood samples (5 ml) were obtained by jugular venipuncture 1988; Crosier et al., 1996; Kroker et al., 2002) and in pigs – for

before (hour 0) the treatment and at post treatment hours 0.17, 0.33, treatment of Actinobacillus pleuropneumoniae, Mycoplasma 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 24, 48 and 72 h. Samples were collected hyopneumoniae, Pasteurella multocida infections (Kroker et al., in heparinized tubes and centrifuged at 1500 x g for 15 min. Blood 2002). The main route of application in large ruminants is plasma was separated in individual Eppendorf tubes and stored at -subcutaneously, at a dose of 10 mg/kg (Lawrence, 1994; Bishop,

о 70 С until analysis. 2005).The purpose of this research was to determine the main

Chemical analysis of samples pharmacokinetic parameters of Tilmovet solutio pro imjectionibus 30 Blood plasma tilmicosin in calves was quantitated by HPLC % ('Biovet' LTD Peshtera) containing tilmicosin, after subcutaneous

(Chan et al., 1994; Delepine et al., 1996; Morgan et al., 1997; Hows application to calves. The experiment was conducted in compliance et al., 2000). The method is based on selective extraction of to EC guidelines for preclinical testing of veterinary drugs.tilmicosin from plasma by solid-phase extraction (SPE), chromatographic separation on an octadecylsilyl silica gel column and detection at 287 nm. A Hewlett Packard 1100 HPLC system was

Material and methods used.The assay was validated with respect to specificity, accuracy, precision and limit of quantitation. The limit of quantitation (LOQ)

Eight clinically healthy calves, 4 of both genders (Brown was 0.05 µg/mL. It was validated by analysis of addition of 0.05

211

* e-mail: dj.dimitrova.56@gmail.com

212

µg/mL tilmicosin to six samples and performing the complete the time of maximum plasma concentrations, allowing for direct analytical procedure. detection of C and T values.max max

Pharmacokinetic analysisThe pharmacokinetic analysis after application of Tilmovet

solutio pro imjectionibus 30 % was performed by the TopFit, v.2.0 software. The pharmacokinetic modelling was according to the Akaike's information criterion (AIC) (Yamaoka et al., 1978).Pharmacokinetic analysis was performed on the basis of individual plasma tilmicosin concentrations at each treatment interval, using the non-compartmental model. C and T were obtained directly. max mаx

The area under the concentration-time curve was calculated by the trapezoidal rule. All data were expressed as mean and standard error of the mean (SEM). Harmonic means were determined for biological half-life.

Results

Individual and mean plasma tilmicosin concentrations after single subcutaneous application of Tilmovet solutio pro imjectionibus 30 % are presented in Table 1 and Figure 1. Antibacterial activity was not present in samples obtained prior to the treatment (hour 0). Plasma levels higher than the limit of quantitation

nd(0.05 g/ml) were measured in all treated calves until the 72 post treatment hour. Average tilmicosin concentrations at post treatment hour 0.17 were 0.493±0.024 µg/ml, and by hour 72 – 0.100±0.009 µg/ml.Maximum plasma levels were 0.9760.06 g/ml and occurred one hour after application of Tilmovet. In the subsequent intervals until hour 72, the blood concentrations declined relatively slowly. The areas under the serum concentration curve – AUC and AUC 0→72 h 0→∞

Discussion

The studies on tilmicosin pharmacokinetics in cattle are limited. Nevertheless, there are data available for comparative purposes. The relationship with data obtained in cows after subcutaneous application of 10 mg/kg is also of interest. After application of Tilmovet solutio pro imjectionibus 30 %, blood tilmicosin concentrations between post treatment hours 1 and 72 (0.975±0.062 – 0.100±0.009µg/ml), were similar to those reported by Thompson and Lawrence (1994) in steers and heifers weighing 370.5 and 334 kg, respectively – 0.71±0.30 – 0.12±0.04 µg/ml. Maximum plasma concentrations (C = 0.976±0.006 µg/ml) were max

lower than those published by Ziv et al. (1995) in lactating cows (0.13±0.02 µg/ml) but higher than concentrations in cows weighing 392-483 kg (0.873±0.420 µg/ml) (Modric et al., 1998). Similar relationships were established for T (1.000 h) as compared to data max

of Ziv et al. (1995) – 1.84±0.22h and Modrec et al. (1998)– 0.50±0.67 h. Elimination half-life and mean residence times in our studies (32.33±0.99 h and 42.68±1.52 h, respectively) were higher than those in the experiments of Ziv et al. (1995) (4.18±0,55 h and 7.47±0.92 h) and close to values of Modric et al. (1998) (29.4±6.00 h and 36.5±6.1 h).

The comparisons made showed those pharmacokinetic were 18.22±1.23 µg.h/ml and 22.8±81.80 µg.h/ml respectively. The parameters of tilmicosin after single subcutaneous application of area under the first moment curve – AUC in calves was 0→ ∞

2 Tilmovet solutio pro imjectionibus 30 % were either between or close 995.50±109.83 µg.h /ml, elimination half-life (t ) – 32.33±0.99 h, 1/2βto those calculated in previous investigations. The existing and mean residence time (MRT)–42.68±1.52h. Plasma differences could be attributed to the age, live body weight, site of concentrations vs time curves (Figure 1) exhibited clear peaks near

Table 1. Plasma tilmicosin concentrations (g/ml) in calvesafter single subcutaneous application of Tilmovet solutio proimjectionibus 30 % at a dose of10 mg/kg tilmicosin.

Mean ± SEMTime (h)

0.17

0.33

0.50

1

1.5

2

3

4

6

8

10

24

48

72

0.493 0.024

0.674 ± 0.028

0.821 ± 0.033

0.976 ± 0.062

0.869 ± 0.035

0.731 ± 0.033

0.655 ± 0.031

0.582 ± 0.025

0.507 ± 0.022

0.443 ± 0.021

0.395 ± 0.020

0.239 ± 0.019

0.165 ± 0.015

0.100 ± 0.009

±

β΄– t1/2β

elimination half-life; MRT mean residence time; AUC – 0

area under the serum concentration curve from time 0 to infinity; AUC – area under the serum concentration 0→72 h

curve from hour 0 to hour 72; AUMC – area under the 0→∞

first moment curve from time 0 to infinity; T – time to max

reach maximum plasma concentration; C – maximum max

plasma concentration.

hybrid rate constant of the elimination phase; –

→∞

Mean ± SEM

Table 2. Some pharmacokinetic parameters (non-compartmental analysis) of tilmicosin in calves after singlesubcutaneous application of Tilmovet - solutio proimjectionibus 30 % at a dose of 10 mg/kg tilmicosin.

Parameters Units

Tilmovet - solutio pro imjectionibus

30 % (n = 8)

β΄

t1/2β΄

MRT

AUC0→∞

AUC0→

AUMC0→

Tmax

Cmax

72 h

∞

0.02158 ± 0.00069

32.33 ± 0.99

42.68 ± 1.52

22.88 ± 1.80

18.22 ± 1.23

995.50 ± 1.98

1.00 ± 0.00

0.976 ± 0.06

-1h

h

h

µg.h/ml

µg.h/ml

µg.h /ml

h

µg/ml

2

213

injection, climatic or other conditions related to experimental Referencesdesigns. At the same time, the results add to existing information for this specific category of cattle with regard to the breed, age and body Anonymous, 2001. Guidelines for the Conduct of Bioequivalence weight. Studies for Veterinary Medicinal products, EMEA/CVMP/016/00-

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Figure 1. Kinetics of individual plasma tilmicosin concentrations in calves after single subcutaneous application of Tilmovet solutio pro imjectionibus 30 % at a dose of 10 mg/kg tilmicosin.

Time (h)

1.4

0.17 0.33 0.5 1 1.5 2 3 4 6 8 10 24 48 72

1.2

1

0.8

0.6

0.4

0.2

0

Con

cent

ratio

ns, u

g / m

l

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parenthesis after the bibliographic reference (Bulgarian = Bg, Russian = Ru, Serbian = Sr, if in the Cyrillic, Mongolian = Мо, Greek = Gr, Georgian = Geor., Japanese = Jа, Chinese = Ch, Arabic = Аr, etc.)The following order in the reference list is recommended:Journal articles: Author(s) surname and initials, year. Title. Full title of the journal, volume, pages. Example:Simm G, Lewis RM, Grundy B and Dingwall WS, 2002. Responses to selection for lean growth in sheep. Animal Science, 74, 39-50Books: Author(s) surname and initials, year. Title. Edition, name of publisher, place of publication. Example: Oldenbroek JK, 1999. Genebanks and the conservation of farm animal genetic resources, Second edition. DLO Institute for Animal Science and Heal th, Netherlands.Book chapter or conference proceedings: Author(s) surname and initials, year. Title. In: Title of the book or of the proceedings followed by the editor(s), volume, pages. Name of publisher, place of publication. Example: Mauff G, Pulverer G, Operkuch W, Hummel K and Hidden C, 1995. C3-variants and diverse phenotypes of unconverted and converted C3. In: Provides of the Biological Fluids (ed. H. Peters), vol. 22, 143-165, Pergamon Press. Oxford, UK.Todorov N and Mitev J, 1995. Effect of level of feeding during dry period, and body condition score on reproductive perfor-

thmance in dairy cows,IX International Conference on Production Diseases in Farm Animals, Sept.11 – 14, Berlin, Germany, p. 302 (Abstr.).Thesis:Penkov D, 2008. Estimation of metabolic energy and true digestibility of amino acids of some feeds in experiments with muscus duck (Carina moshata, L). Thesis for DSc. Agrarian University, Plovdiv, 314 pp.

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Volume 4, Number 3September 2012