Effect of respiratory tract disease on pharmacokinetics of tilmicosin in rats.
OBJECTIVE
In rats, murine respiratory mycoplasmosis is caused by Mycoplasma pulmonis. Tilmicosin, a macrolide antibiotic, has good tissue penetration and reaches high concentration in the lungs. Therefore, a model for studying the effects of disease on pharmacokinetics of tilmicosin was developed, using LEW rats.


METHODS
Seventy-two LEW rats were assigned at random to two groups: one group was inoculated with M. pulmonis, and the other served as an uninoculated control group. On postinoculation day 31, all rats received a single dose of tilmicosin (20 mg/kg of body weight, subcutaneously).


RESULTS
Concentration of tilmicosin in the lungs of both groups of rats was significantly higher than serum tilmicosin concentration at all times. Infected rats had significantly higher lung tilmicosin concentration than did noninfected rats. No correlation was found between pH of the lungs and tilmicosin concentration in the lungs in either treatment group, nor did treatment have any effect on pH of the muscle.


CONCLUSIONS
Tilmicosin accumulates in the lungs, and infection/inflammation further improves its tissue penetration.
Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, USA.
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Webb
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Davidson
D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006863:Hydrogen-Ion Concentration; D007279:Injections, Subcutaneous; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D018942:Macrolides; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009174:Mycoplasma / Q000472:pathogenicity*; D009175:Mycoplasma Infections / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D013047:Specific Pathogen-Free Organisms; D014018:Tissue Distribution; D015645:Tylosin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
D000900:Anti-Bacterial Agents; D018942:Macrolides; C052319:tilmicosin; D015645:Tylosin