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- Title
Pharmacokinetics of a New Parenteral Formulation of Tilmicosin-La in Cows.
- Authors
Gutiérrez, Lilia; Soriano, Rodrigo; Martínez-Cortes, Ismael; Miranda-Calderon, Jorge; Sumano, Héctor
- Abstract
The blood serum pharmacokinetics of a Poloxamer-407 based new pharmaceutical preparation of 39% tilmicosin was determined in cows. Two dose levels injected SC, were assessed: 10 mg/kg (Til-LA10) and 26 mg/kg (Til-LA26). Tilmicosin was determined using HPLC, also electrocardiographic (EKG) monitoring in all animals before and at 1, 2 and 4 h after the injection of the drug was performed to measure key EKG parameters, including heart rate. Maximum serum concentration values were 2.6 μg/mL and 1.23 μg/mL, occurring 4.9 and 5.1 h after the injection of Til- LA26 and Til-LA10, respectively. Mean residence time was statistically larger for Til-LA26 (50.4±5.8 h) than Til-LA10 (37.4±4.7 h) (P<0.05), with T1/2el of 39.8 h for Til-LA26 and 33.2 h for Til-LA10. There were no differences in relative bioavailability as adjusted for dose (AUMC of 8663 μg/mLžh2 for Til-LA26 and 2858 μg/mLžh2 for Til-LA10). This new formulation as dosed for Til-LA26 possesses a long T1/2el of tilmicosin and resulted in a lack of changes in the EKG and heart rate. Based on PK/PD ratios tilmicosin is regarded as a time-dependent antibacterial drug. Considering a theoretical minimum therapeutic serum concentration (MTC) of 0.1 μg/mL useful concentrations can be achieved for up to 192 h with Til-LA26 and an AUC/MTC ratio of 1514 without cardiac toxicity. Further studies are necessary to correlate PK/PD parameters obtained with clinical efficacy and a more thorough analysis of cardiac toxicity is required to determine the suitability of this preparation in bovine medicine.
- Subjects
SERUM; PHARMACOKINETICS; ELECTROCARDIOGRAPHS; ELECTROCARDIOGRAPHY; POLOXAMERS
- Publication
Pakistan Veterinary Journal, 2016, Vol 36, Issue 2, p165
- ISSN
0253-8318
- Publication type
Article