Determination of Ephedrine Alkaloids in Human Urine and Plasma by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study

A collaborative study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids (i.e., norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, methylephedrine, and methylpseudoephedrine) in human urine and plasma. The amount of ephedrine-type alkaloids present was determined using liquid chromatography (LC) with tandem mass selective detection. The test samples were diluted to reflect a concentration of 5.00–100 ng/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of human urine and eight blind duplicates of human plasma were analyzed by 10 collaborators. In addition to negative controls, test portions of urine and plasma were fortified at 3 different levels with each of the 6 ephedrine-type alkaloids at approximately 1, 2, and 5 μg/mL for urine and 100, 200, and 500 ng/mL for plasma. On the basis of the accuracy and precision results for this collaborative study, it is recommended that this method be adopted Official First Action for the determination of 6 different ephedrine-type alkaloids in human urine and plasma.

Determination of Ephedrine Alkaloids in Dietary Supplements and Botanicals by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study

An interlaboratory study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids [i.e., norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME), and methylpseudoephedrine (MPE)] in dietary supplements and botanicals. The amount of ephedrine-type alkaloids present was determined using liquid chromatography with tandem mass selective detection. The samples were diluted to reflect a concentration of 0.0200 to 1.00 μg/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of dietary supplements or botanicals were analyzed by 10 collaborators. Included was a negative control, ephedra nevadensis, and negative controls fortified at 2 different levels with each of the 6 ephedrine-type alkaloids. The spike levels were approximately 100 and 1000 μg/g for NE, 100 and 600 μg/g for NPE, 6500 and 65 000 μg/g for E, 1000 and 10 000 μg/g for PE, 300 and 3000 μg/g for ME, and 100 and 1000 μg/g for MPE. On the basis of the accuracy and precision results for this interlaboratory study, it is recommended that this method be adopted Official First Action for the determination of 6 different individual ephedrine-type alkaloids in dietary supplements and botanicals.

Postmortal degradation of furazolidone and furaltadone in edible tissues of calves

Rapid and complete postmortal degradation of furazolidone and furaltadone occurred in liver, kidney and muscle tissues of veal calves. Different degradation half-lives were observed between these tissues, the mean ranging from less than 7 minutes to 63 minutes. At 24 h after slaughter the parent nitrofurans were no longer detectable in edible tissues. For residue monitoring purposes plasma and/or urine can be used, if these matrices are treated in a specific way immediately after slaughter; muscle tissues and organs are unsuitable for residue monitoring of parent nitrofurans.

Monitoring milk for chloramphenicol residues by an immunoassay (Quik-card)

An easy to perform immunoassay method (Quik-card) for monitoring milk on the presence of chloramphenicol residues exceeding 5 to 10 ppb is described, as well as an extraction and preconcentration method utilising a Sep-pak silica cartridge, which enables the detection of CAP residues in milk in concentrations exceeding 1 ppb by HPLC and 0.1 ppb by the immunoassay.

Pharmacokinetics, renal clearance and metabolism of ciprofloxacin following intravenous and oral administration to calves and pigs

The pharmacokinetics of ciprofloxacin, a quinoline derivative with marked bactericidal activity against gram-negative bacteria, was studied in calves and pigs following intravenous and oral administration. Ciprofloxacin was rapidly and well distributed in the body, exhibited a short elimination half-life of 2.5 h in both species, and was rapidly absorbed after oral administration (Tmax:2 to 3 h). The oral bioavailability in calves was 53 +/- 14% and for 1 pig 37.3%. The renal clearance of the unbound ciprofloxacin for both species was of the same order, indicated a predominantly tubular secretion pattern, and accounted for about 46% of the total drug elimination. No complete drug mass balance could be demonstrated. Small amounts of two metabolites were detected in the urine of calves, but not in pig urine.

Pharmacokinetics of ciprofloxacin in carp, African catfish and rainbow trout

The plasma disposition of ciprofloxacin was studied in carp, African catfish and trout after intravenous (IV) and intramuscular (IM) administration at a dose rate of 15 mg/kg. Pharmacokinetic analysis of IV data showed that ciprofloxacin was well distributed (distribution volume Vd(area): 3.08-5.59 litre/kg) and exhibited a similar elimination half-life of about 14 h in these 3 fish species. After IM administration to carp and trout a rapid absorption was noticed; the maximum ciprofloxacin plasma concentrations (mean: 3.49 and 2.37 micrograms/ml, respectively), were achieved within 1 h after injection. At the dose level applied, ciprofloxacin has potential therapeutic value for 2-5 days especially against gram-negative bacterial fish pathogens.