كتاب Enrofloxacin serum bioactivity in bottlenose dolphins, Tursiops truncatus, following oral administration of 5 mg per kg in whole fish

Enrofloxacin serum bioactivity in bottlenose dolphins, Tursiops truncatus, following oral administration of 5 mg per kg in whole fish من كتب طب بيطرى INTRODUCTION Enrofloxacin is a fluoroquinolone antimicrobial agent structu- rally related to nalidixic acid and norfloxacin and is licensed for veterinary use only. The fluoroquinolones have a bactericidal spectrum encompassing gram-negative, gram-positive aerobic bacteria and mycoplasmas (Reeves et al ., 1984; Scheer, 1987a). Enrofloxacin is an important antimicrobial agent that is proving to be very useful in treatment of infectious diseases in many domestic animal species (Scheer, 1987a; Jenkins & Friedlander, 1988; Prescott & Yielding, 1990; Van Landuyt et al ., 1990). The primary mechanism of action of the fluoroquinolones appears to be interference wit ht he bacterial enzyme DNA gyrase (Vancutsem et al ., 1990; Hooper & Wolfson, 1991). This unique mechanism of action differs from that of b ±lactams, tetracy- clines, aminoglycosides, macrolides, chloramphenicol and folic acid antagonists and could explain the lack of cross-resistance between these other antimicrobial agents and the fluoroquino- lones (Scheer, 1987a). Enrofloxacin has close to 100% oral bioavailability and attains excellent body tissue and fluid compartment concentrations in canines and felines (Scheer, 1987b). These characteristics make this antimicrobial, when given orally, particularly promising in use with marine mammals. Although there have been infre- quent reports of neurological, haematological, gastrointestinal and cartilaginous toxicities associated wit henrofloxacin, t he drug has been very well tolerated in a variety of domestic animal species (Altreuther, 1987; Jenkins & Friedlander, 1988). In this study we investigated the serum antimicrobial activity concentrations (SAAC) attained when enrofloxacin tablets were given to bottlenose dolphins in their morning ration of fish. This protocol would determine if this method of dosing enrofloxacin is feasible and would assist veterinarians involved in marine mammal practice to expand their antimicrobial treatment armamentarium. MATERIALS AND METHODS Study design Following approval from the Animal Care Committee at our facility, eight healthy adult bottlenose dolphins, Tursiops truncatus (six male, two female) were selected for this study. They ranged in weight from 154 to 331 kg and were on no other medical treatments. Eac hanimal received a single oral dose of enrofloxacin at a dosage of 5 mg/kg body weight. The dose was rounded to the nearest half tablet or 34 mg increment (68 mg tablets) and placed intact (not crushed) into a whole fish and administered wit ht he morning fis hration. Experimental drug received from Bayer Corporation for our study consisted of the original `purple tablet' oral preparation of enrofloxacin, which dissolves rapidly in water. The new chewable tablets now available do not disintegrate as easily as the former purple tablets and therefore may cause a greater lag between administration and absorption. This method of drug delivery with these animals is standard practice which is convenient and eliminates drug loss # 1999 Blackwell Science Ltd 170 J. vet. Pharmacol. Therap. 22, 170±173, 1999. PHARMACOKINETICS Enrofloxacin serum bioactivity in bottlenose dolphins, Tursiops truncatus , following oral administration of 5 mg/kg in whole fish Linnehan, R. M., Ulrich, R. W., Ridgway, S. Enrofloxacin serum bioactivity in bottlenose dolphins, Tursiops truncatus , following oral administration of 5 mg/kg in whole fish. J. vet. Pharmacol. Therap. 22, 170±173. Eight adult bottlenose dolphins Tursiops truncatus (six male, two female) were employed in a single-dose study of orally administered enrofloxacin dosed at 5 mg/kg body weight. Blood samples were obtained from all animals at 0, 2, 4, 8, 12 and 24 h following administration of the dose in the animals morning ration of fish. Serum antimicrobial activity concentrations (SAAC) were determined using bioassay. The mean elimination half-life ( t ‰ ) of enrofloxacin and its major metabolites was 6.4 + 2.0 h with a range of 3±9.4 h. The time of maximal serum concentration ( t max ) occurred at approximately 4 hwit ha range of 2±8 h following a single oral dose of 5 mg/kg. This variation in t max most likely resulted from individual differences in absorption because of variations in the storage and digestion of the fish ration containing the drug dose within the compartmentalized cetacean stomach. (Paper received 18 December 1997; accepted for publication 5 Marc h1999) Robert W. Ulrich, University of Southern California, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA 90033, USA
-
من كتب طب بيطرى - مكتبة كتب الطب.