Zeitschrift für Bioanalyse und Biomedizin

A simple and validated liquid chromatographic–mass spectrometric method (LC-MS) for amlodipine in human plasma was quanti fi ed using LC-MS (ESI). Chromatography was performed on a C 18 analytical column, the mobile phase used was Acetonitrile-10mM Ammonium acetate in the ratio of 90:10%v/v and the retention times were 0.829 and 1.281 min for azithromycin (Internal standard) and amlodipine respectively. The ionization was optimized using ESI (+) and enhanced selectivity was achieved. The method is validated as per FDA guidelines. The analyte was shown to be stable over the timescale of the whole procedure. The pharmacokinetic parameters such as peak plasma concentration (C max ), Time to peak Concentration (t max ), Area under the plasma concentration-time curve (AUC 0-t & AUC 0- ∞ ), elimination rate constant (K eli ), Elimination half-life (t ½ ) were calculated. Log transferred values were compared by Analysis of Variance (ANOVA) followed by classical 90% con fi dence interval for C max AUC 0-t .and AUC 0- ∞ and was found to be within the range. These results indicated that the Test and Reference formulation is bioequivalent.

The disposition kinetics was conducted in fi ve healthy female buffalo calves following single i.v dose (5mg/kg) of gentamicin alone and with paracetamol (40mg/kg,i.v.). The study revealed that the plasma concentrations of gentamicin were signi fi cantly higher when it was given with paracetamol as compared to alone between 0.042 to 0.333 hrs and at 24 hrs. Serum concentrations of gentamicin was detected for longer period (48 hrs) in urine in both groups of experimental animals. In case of urine drug attained its peak level at the same time interval (1.5 hrs) in both groups with the concentration of 83.42±3.14  g/ml after alone and 545.1±25.85  g/ml with paracetamol administration. The extrapolated zero time plasma concentrations during distribution phase (A) and theoretical zero time plasma concentrations (Cºp) were signi fi cantly (p< 0.01) higher 34.48±2.35 and 39.03±2.40  g/ml respectively. Also signi fi cantly higher distribution rate constant (  ) of 1.935±0.1119 h -1 and lower distribution half life (t 1/2  ) of 0.36±0.02 hrs were observed, when gentamicin was given with paracetamol. Elimination half life (t 1/2  ) of 6.67±0.11 hrs was not signi fi cantly higher when gentamicin was given with paracetamol. AUC (62.16±2.82 mg/L.hrs) was signi fi cantly (p< 0.05) higher while MRT (6.93±0.36hrs) was not signi fi cantly higher when gentamicin was given with paracetamol. The values of K 12 , K 21 and Kel were calculated to be 1.088±0.111 h -1 , 0.323±0.028 h -1 and 0.628±0.024 h -1 respectively when gentamicin was given concurrently with paracetamol. T~P (5.04±0.16) was signi fi cantly (p< 0.01) higher, while Vd area (0.78±0.03L/Kg) and ClB (1.35±0.06 ml/Kg/min) were not signi fi cantly higher when gentamicin was given with paracetamol. The present investigation established that both gentamicin and paracetamol interacted with altered their kinetic behaviour. The combination with paracetamol may be beni fi cial because paracetamol reduced the maintenance doses of gentamicin which may be much advantageous in the fi eld of veterinary practice in the dose of 5 mg/kg daily by systemic route and 36 hourly when given with paracetamol in urinary tract infection.

The brine shrimp Artemia franciscana is one of the most common live-feed organisms for use in the larval culture of marine fi sh production. Bioencapsulation of fl orfenicol, an antibacterial agent, in Artemia nauplii was investigated as a potential carrier for this drug to marine larvae. Florfenicol was delivered directly to the organisms as particles, and the doses ranged from 100 to 2000 mg/l. Analysis of fl orfenicol concentrations in Artemia sp. nauplii were performed using high performance liquid chromatography (HPLC). The uptake of fl orfenicol in Artemia nauplii increased with particle size, dose, and exposure time, obtaining the highest concentration of 5.02 ng/nauplius, using a dose of 300 mg/l AQUAFLOR premix and 10 min exposure time. However, to obtain reproducible results, an enrichment time of at least 60 min is recommended.