Determining the effect of storage conditions on prothrombin time, activated partial thromboplastin time and fibrinogen concentration in rat plasma samples.

Coagulation parameters are usually included in clinical and preclinical safety studies to evaluate the effect of xenobiotics on the extrinsic or intrinsic pathways of coagulation. The analysis is generally performed at the time of terminal sacrifice where many activities are scheduled. Chances of delay in analysis are likely particularly when blood is collected for coagulation via the abdominal vena cava. This experiment was planned to assess the variations in coagulation parameters caused by delay in analysis as well as by storage conditions. Blood was collected from the posterior vena cava under isoflurane anesthesia, and the plasma was separated immediately. Coagulation parameters were evaluated at 0, 6, 24 and 48 h from the plasma stored at room temperature, as well as plasma stored under refrigerated and freezing conditions. Stability of the analytes in blood was also evaluated under refrigerated conditions for 6 h. All parameters were analyzed using a semi-automated coagulometer. Prothrombin time (PT) was stable under all three storage conditions for up to 6 h. Although statistically significant differences were observed for activated partial thromboplastin time (APTT) at room and refrigeration temperatures for up to 6 h, the difference was clinically non-relevant. Fibrinogen was found to be the most stable parameter that showed consistency in results even up to 48 h under all three storage conditions. Plasma for PT can be stored and analyzed without any significant changes for up to 6 h from the actual blood collection, while fibrinogen level testing can be extended for up to 48 h after collection under any storage condition. For reliable APTT results, plasma samples should be run immediately after collection.

Mutagenicity and clastogenicity evaluation of metaphenoxy benzyl chloride by ames and micronucleus assays.

Metaphenoxy Benzyl Chloride (3-PBC; CAS # 53874-66-1) is a commonly used intermediate in organic synthesis and is a widely used chemical building block. There is likelihood of human contact with 3-PBC in the process of organic or pesticide synthesis and even through as impurity in the product. Further, this chemical has been reported to be found in water reservoirs causing a threat to aqueous flaura and fauna. Genotoxic alert has been suspected for the chemical 3-PBC based on its structure hence, the impetus of present work was to assess the mutagenic potential of 3-PBC using Ames bacterial reverse-mutation assay and in vitro micronucleus assay. 3-PBC was tested for mutagenic potential at six different concentrations, with 0.05 (without metabolic activation) and 0.50 (with metabolic activation) µL/plate as the highest concentrations, followed by five lower concentrations with 2-fold spacing. In clastogenic evaluation, 3-PBC was tested at concentrations ranged from 0.31 to 4.88 µL/mL to assess micronucleus induction in mammalian cells viz. Chinese Hamster Ovarian-K1 cells (CHO-K1 cells). In the Ames assay, 3-PBC did not show mutagenicity in all five tester strains of Salmonella typhimurium viz. TA98, TA100, TA102, TA1535 and TA1537 both in the presence and absence of a metabolic activation system and found to be nonclastogenic when evaluated in "CHO-K1 cells".

Effect of moxifloxacin administration on pharmacokinetics of tolfenamic acid in rats

Pharmacokinetics of tolfenamic acid as a single drug (4 mg/kg, intramuscularly) and its co-administration with moxifloxacin (5 mg/kg, intramuscularly) in wistar rats were studied. The plasma drug concentration of tolfenamic acid was assayed by LC-MS/MS. Following intramuscular administration of tolfenamic acid as single drug and in combination with moxifloxacin in male rats, the mean values of observed peak plasma drug concentration (Cmax), area under plasma drug concentration-time curve (AUC(0-¥) ), volume of distribution (Vz), half-life (t½) and clearance (Cl) were 4111.44 ± 493.15 and 3837.69 ± 351.83 ng/ml, 20280.77 ± 3501.67 and 15229.18 ± 678.80 ng.h/ml, 822.17 ± 115.38 and 1249.64 ± 139.52 ml, 2.59 ± 0.16 and 3.27 ± 0.32 hr, and 218.39 ± 25.47 and 265.18 ± 11.36 ml/hr, respectively. The peak plasma drug concentration (Cmax) was significantly higher in female rats compared to male rats. The volume of distribution (Vz) of the drug was significantly higher (P < 0.05) in moxifloxacin-treated male rats compared to female rats. Concomitant administration of moxifloxacin may alter the disposition of tolfenamic acid in male rats.