Sensitive determination of tilmicosin, erythromycin ethylsuccinate and clindamycin by CE with electrochemiluminescence detection using azithromycin as internal standard and its applications.

A sensitive approach for the simultaneous determination of tilmicosin, erythromycin ethylsuccinate and clindamycin was developed by CE coupled with electrochemiluminescence detection with ionic liquid. The parameters for CE, electrochemiluminescence detection and the effect of ionic liquid were investigated systematically. The three analytes were well separated and detected within 8 min. The limits of detection (S/N=3) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.4x10(-9), 2.3x10(-8) and 1.3x10(-8) mol/L, respectively. The precisions (RSD%) of the peak area and the migration time are from 0.8 to 1.5% and from 0.2 to 0.5% within a day and from 1.8 to 2.7% and from 0.6 to 0.8% in 3 days, respectively. The limits of quantitation (S/N=10) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.2x10(-8), 2.9x10(-7) and 9.1x10(-8) mol/L in human urines and 5.5x10(-8), 3.2x10(-7) and 2.1x10(-7) mol/L in milk samples, respectively. The recoveries of three analytes at different concentration levels in urine, milk and drugs are between 90.0 and 104.7%. The proposed method was successfully applied to the determination of three analytes in human urine, milk and drugs.

Effect of albendazole administration on pharmacokinetic aspects of tylosin in lactating goats.

Tylosin concentrations and its disposition kinetics in serum, urine, and milk of lactating goats following a single intravenous (i.v.) or intramuscular (i.m.) injection (10 mg kg(-1) b.wt.) were carried out using high performance liquid chromatography (HPLC).The concentration-time curve of tylosin after i.v. injection could be described by a two-compartment open model. Tylosin was rapidly distributed and eliminated from goat's bodies with t(1/2(beta)) value of 1.25 h. The V((d)) was less than one litre/kg and the MRT was 1.40 h. Concomitant administration with albendazole decreased tylosin concentrations in serum after its i.v. injection and the MRT was 1.17 h. The AUC and AUMC showed a significant decrease in goats given albendazole prior to injection as compared with those given tylosin only. Following i.m. administration, the absorption half-life and the corresponding t(max) revealed rapid absorption rate with systemic bioavailability (F%) of 76.2 %. Albendazole when given concurrently with tylosin decreased its serum concentrations due to lower bioavailability (43.25 %). Following i.v. or i.m. injection, tylosin was excreted rapidly in urine in concentration much higher than those determined in serum and milk. Tylosin administered in goats pretreated with albendazole was excreted at lower concentration in urine, with a significant decrease from 1(st) to 10(th) hours as compared with animals given tylosin only. Following i.v. or i.m. administration of tylosin, the drug was excreted in high concentrations in milk. A significant decrease in milk concentrations was reported in goats pretreated with albendazole.