Oral Antimicrobial Medication
Pharmacokinetics in Pigs

by
DGS Burch BVetmed MRCVS
Octagon Services Ltd   Copyright © December 2001
On-line at: www.octagon-services.co.uk

Notes to assist use of this spreadsheet:
These data give an overall pattern for an antimicrobial, obviously each reference or study has been carried out in a different way so the results may vary between studies.
1. Dose rate is usually given by gavage as a bolus dose in classical pharmacokinetic studies but for practical use in water and in feed studies are described. Estimated dose rates have an 'e' denoting them for comparative use.
2. Cmax is the peak level found in serum after administration and is the highest level that can be achieved with a certain antimicrobial at a certain dose.
Administration by water and feed usually gives a much lower figure because the drug is given over a 24-hour period and feed slows the passage and sometimes affects the absorption of some compounds.
3. C 12hours is the level of antimicrobial found in the blood 12 hours after administration. Products with a fast clearance usually have gone by 12 hours. When given in feed levels may be lower but can persist for longer periods.
4. Steady state is the level achieved after in water or infeed use and the average level that is achieved over a 24 hour period.This is the most important level for many antimicrobials as they act by inhibiting the growth of the bacteria and require a prolonged exposure. Concentrations in other target tissues like lung or gut contents are also important when dealing with infections in those areas.
5. Protein binding of an antimicrobial is important as it can affect the effective concentration of that particular antimicrobial against an organism. High binding is therefore not usually good.
6. Bioavailability is the comparison of the absorption of a product from the gut in comparison with a dose given intravenously (assumed 100%). It is important if you want an antimicrobial to go from the gut to a target in the body. A high bioavailability means a drug is likely to work systemically although other factors can affect this. Feed may interfere with the absorption and bioavailability of a product.
7. Lung concentration is important if you want to treat an infection in the lung. Some antibiotics specifically concentrate in lung tissue and nasal mucosa.
8. Colon contents concentration is important to treat swine dysentery or colitis for example. High concentrations in the ileum are useful for ileitis treament. Poor absorption can be an advantage.
 
Overall, understanding the pharmacokinetics of an antimicrobial, knowing its level at the site of infection and the Minimal Inhibitory Concentration (MIC) of an organism to treat, can help the veterinarian to decide on what product, what dose, how it should be administered, for how long and improve the therapeutic control of the disease and thereby reduce the chances of developing antimicrobial resistance.

 

Pharmacokinetics graph for antimicrobials medication

 

The data in the following table are provided free and without obligation, for demonstration purposes
readers should seek expert guidance before taking decisions requiring critical product specifications.
Antimicrobial
 		 Reference
 		 Dose rate
mg/kg bwt
 		 Water
Conc.
ppm		 Feed
Conc.
ppm		 C max
µg/ml
 		 C12hrs
µg/ml
 		 Steady
state
µg/ml		 Protein
bind
%		 Bio-
avail
%		 Lung
conc.
µg/ml		 Colon
content
µg/g		 Other
µg/g
 
 
Tiamulin Laber and Schutze 10 1.03 <lod >90
1977 25 1.82 0.55 >90
50 4.57 1.41 >90
Tiamulin Andersen 1994 6e 60 <0.3 1.11 2.16
Tiamutin 12e 120 <0.3 4.26 5.59
product data 18e 180 <0.3 8.5 18.58
110 <0.3 1.46 2.84
220 <0.3 1.99 8.05
Tiamulin Ibayashi et al 1994 110 <0.3 0.63
Tiamulin Schreiber & Wanner 10 Fast 0.67 <0.05 100
1990 10 Fed 180 0.1 0.1 0.1 35.2
Valnemulin Burch & Ripley1998 3.8 75 >90 0.04 1.68
Econor product data 11.7 200 >90 0.23 5.2
Tilmicosin Thomson et al 1994 10.97 200 <loq 0.59-1.43
21.34 400 0.11-0.23 1.11-2.59
Tilmicosin Stoker et al 1996 19.4 400 0.039 1.69 2.19
Tracheal
epithelium
7.19
Macro-
phages
Spiramycin Nielsen,1997 56.1 Fast 5.2 60
55.9 Fed 1 24
Tylosin Ibayashi et al 1994 5.5e 110 <0.05
Tylosin Aivlosin product data 50 2.1 <loq
Acetyl isovaleryl
tylosin		 Ibayashi et al1994 5.5e 110 0.14
Acetyl isovaleryl
tylosin		 Aivlosin product data 50 8.4 <loq
Lincomycin Nielsen, 1997 33.2 Fast 8.4 73
33.1 Fed 5.1 41
Lincomycin Ibayashi et al1994 2e 44 0.1
5.5e 110 0.85
Lincomycin DeGeeter et al 1980 5.5e 110 0.16 0.66 34.51 47.82
Ileal
contents
11e 220 0.14 1.13 101.01 25.05
Ileal
contents
Spectinomycin Jaglan et al 1994 2 44 3.85 16.98-49.97
Gentamicin Aerts et al 1994 3.3 (Piglets) 0.31 0.14-0.31 1.4-4.5
Tetracycline Nielsen, 1997 46.4 Fast 4 18
46.6 Fed 0.8 5
Chlortetracycline Nielsen, 1997 39.9 Fast 2.4 11
40.1 Fed 0.8 6
Chlortetracycline Anderson et al 1992 28.6 2.2 0.4
Chlortetracycline Del Castillo et al 1997 40e 800 1.6 0.8 13.2
Chlortetracycline Sutter & Wanner 40 dry feed
restricted		 2500 1.95 17.6
1990 40 moist feed
restricted		 2500 2.11 21.3
40 wet feed
restricted		 2500 3.32 28.2
Chlortetracycline Jacobson et al 1994 50 Fed 0.67 0.56
Chlortetracycline Asanuma et al 1986 18e 364 0.35 0.25 0.25 0.45-0.65
Oxytetracycline Nielsen, 1997 45.5 Fast 0.7 3
45.6 Fed 0.4 3
Oxytetracycline Pijpers 1990 50 1.87 0.3 4.8
12.1 400 0.13-0.22
26.4 800 0.19-0.5
Oxytetracycline Pijpers et al 1994 34-39 800 0.67-1.0 0.67-1.18 3.93-5.0
nasal
mucosa
Oxytetracycline Jacobson et al 1994 50 Fed 0.04 0.08
54.5 1600 0.39-1.14
Oxytetracycline Del Castillo et al 1997 40e 800 0.6 0.35 3.8
Oxytetracycline Asanuma et al 1986 18e 364 0.2 <lod 0.08 0.1
Doxycycline Pijpers 1994 10 4.82 0.6 101
Doxycycline Pijpers 1990 6.6 200 0.37-0.89
12.9 400 0.71-1.14
26.1 800 1.62-3.18
Doxycycline Bousquet et al 1997 11.8 250 1
13.3 250 1.5 1.7 2.9
nasal
mucosa
Penicillin V Nielsen 1997 52.6 Fast 3.6 19
51.8 Fed 3 17
Penicillin V Wheeler 1983 25e 500 0.19
Penicillin V del Castillo et al 13 Fast 3.39 41
1996 13 Fed 0.93 49
Penicillin V McKellar et al 1987 10.6 3.3 <lod
Amoxicillin Del Castillo et al 15 Fast 0.125 39
1997 15 Fed 21
Amoxicillin Bes et al 1997 20 3.79 0.06
Amoxicillin Anadon et al 2000 20 6.76 0.3 39
Amoxicillin Anfossi et al 2000 50 2.5 0.2
Trimethoprim Nielsen,1997 8.3 Fast 1.9 90
8.3 Fed 1.5 92
Trimethoprim Mengelers et al 1992 5e 100 0.2-0.3 63
Sulfadiazine Nielsen 1997 39.1 Fast 32 89
38.9 Fed 25 85
Sulfadiazine Villa et al 1997 28
Sulfadimethoxine Mengelers et al 1992 25e 500 66-86 96
Sulfamethoxazole Mengelers et al 1992 25e 500 2.0-4.0 48
Enrofloxacin Nielsen 1997 10.1 Fast 2.4 101
10.5 Fed 1.4 83
Enrofloxacin Richez et al 1994 2.5 Fed 0.23 75
5 100 0.28
Enrofloxacin Banholzer et al 1997 5 150 0.32
Enrofloxacin Zeng & Fung 1997 2.5 1.17 150
Bregante et al 2000 37-43
Enrofloxacin Villa et al 1997 27
Ciprofloxacin Villa et al 1997 35
Ciprofloxacin Fang et al 2000 5 0.6 51.6
Flumequine Villa et al 1997 67
Norfloxacin Park et al 1997 5 0.46 36
Antimicrobial Reference Dose rate Water
Conc.		 Feed
Conc.		 C max
 C12hrs
 Steady
state
 Protein
bind		 Bio-
avail		 Lung Colon
content		 Other
Copyright © Octagon Services Ltd   December 2001
*Antimicrobial sensitivity data for major pig bacterial pathogens

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