The effect of orally administered marbofloxacin on the pharmacokinetics of theophylline.

As certain quinolones can interfere with the metabolism of theophylline by competitive inhibition of the hepatic microsomal cytochrome P450 system, concomitant use of these drugs with theophylline could result in theophylline toxicity. This study investigated the effect of orally administered marbofloxacin (2 and 5 mg/kg each once daily) on steady-state plasma pharmacokinetics of theophylline after concomitant oral administration of a sustained release theophylline preparation in dogs. Marbofloxacin caused some alteration in theophylline metabolism. A 2 mg/kg dose of marbofloxacin did not clearly result in an increased area under the concentration--time curve (AUC) or decreased clearance of theophylline, but at a dose of 5 mg/kg, a statistically significant increase in AUC and a decrease in the total clearance of theophylline was found. The 26% reduction in theophylline clearance is probably not clinically significant in healthy dogs, but for dogs with renal impairment, there might be a chance of theophylline accumulation when dosed concomitantly with marbofloxacin.

Delay in processing porcine whole blood affects cytokine expression.

Quantification of cytokine messenger ribonucleic acid (mRNA) in blood samples has become an important tool in the investigation of immune cell activation in a variety of clinical settings. It has been shown that the method of sample collection and processing influences the levels of several cytokine mRNAs. Therefore, it is generally accepted that blood samples for analysis of cytokine expression be processed as soon as possible and under standardised conditions. Since immediate sample processing is not always possible, we investigated the effect of different storage conditions (room temperature (Rt) and 4 degrees C) and storage times (1, 2, 4, 6 and 24 h) on the mRNA level of different cytokines (IL-1alpha, IL-2, IL-6, IL-8, IL-10, IFN-gamma), as well as the IL-2 receptor (IL-2R) in porcine whole blood samples (n=8). Quantification of cytokine expression was performed using simultaneous reverse transcription PCR (RT-PCR) combined with the expression of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a reference. Our data demonstrate that delays in sample processing longer than 1 h result in significant changes of the mRNA levels of individual cytokines. Expression of the monokines IL-1alpha, IL-6 and IL-10 were increased by storage at both room temperature and 4 degrees C. Expression of IL-8 was increased only in the samples stored at room temperature, and expression of IFN-gamma was raised exclusively in the samples stored at 4 degrees C. We conclude that porcine blood samples should be processed within 2 h to prevent undesired stimulatory effects on the cytokine expression pattern. However, if only selected cytokines are investigated, the undesired effects of prolonged storage can be selectively suppressed by choosing the appropriate temperature of sample storage.

Severe hypercalcemia in a dog with a retained fetus and endometritis.

A 10-month-old sexually intact female German Shorthaired Pointer examined because of lethargy, episodes of fever, inappetence, and vomiting was found to have severe hypercalcemia. Results of laboratory testing, radiography, and ultrasonography excluded previously recognized causes of hypercalcemia in dogs. Instead, the dog was found to have purulent endometritis and an incompletely resorbed fetus. Treatment with fluids i.v., diuretics, and calcitonin failed to adequately reduce serum calcium concentration, but serum calcium concentration was normal within 4 days after the dog underwent an ovariohysterectomy. Retention of one or more fetuses and endometritis should be included in the differential diagnosis for dogs with hypercalcemia.