The influence of drug presentations in the pharmacokinetics of orally administered enrofloxacin in rheas.

DE LUCAS, JJ; SOLANO J.; DE VICENTE, M.; SAN ANDRES, M. M; MARTELLA, MB; LABAQUE, MC.; NAVARRO, JL; RODRIGUEZ,C

MADRID, ESPAÑA

Congreso; 3r International Ratite Science Symposium; 2005

World´s Poultry Science Association

Pharmaceutical preparations for oral administration are the drug products most frecuently administered to birds. The oral administration of enrofloxacin in the rinking water is an habitual practice in ratites, although therapeutic blood levels cannot be attained due to the following conditions: ratite drinking habits, drug photosensiblity, the use of galvanized water tanks or hard water. For these reasons, direct oral administration is the most satisfactory method since the amount administered can be accurately determined.  Pharmacokinetic (PK) studies are essential to administer a correct oral dosage. In this work,  the comparative evaluation of PK behaviour of two oral formulations (oral and tablets) has been carried out in young rheas (5-month-old). Enrofloxacin (30 mg/kbw /b.i.d. for 5 days) was administered as Baytrilâ 5% o.s. via gastric tube (n=6) or Baytrilâ 150 mg tablets. Enrofloxacin and Ciprofloxacin plasmatic levels were simultaneously quantified using an HPLC/u.v technique. Following the first administration, the mean systemic availability of orally administered tablets (78.13±24.42%) was higher than after oral solution (54.18±13.01%). However, accumulation has been observed after multiple administration of both formulations (AUCD9/AUCD1 were >3 and >5 for tablets and solution, respectively). The permanence of ENR was sligthly higher in solution than tablets (t1/2ßsol=11.56h; t1/2ßtab=11.43h; MRTsol=12.20 h; MRTtab= 9.73 h) but this fact it is not clinically relevant. Based on the PK/PD data from the present study (Cmax/MIC90>10 and AUC0-24/MIC90>125), both oral administration regimens (solution and tablet) had high efficacy against the main bacterial infections present in rhea and they guarantee the absence of bacterial resistance.      *This study was supported by a grant from the UCM (PR3/04-12470).