M. T. Terán

Organochlorine pesticide residues in bovine milk from León (Spain)

Residue levels of the organochlorine pesticides (alpha-HCH, lindane, heptachlor-epoxide, aldrin, endrin, dieldrin, o,p-TDE, p,p-TDE, p,p-DDE and p,p-DDT) were determined in raw bovine milk and compared with the maximum levels allowed by the European Union (EU) in these foods. The highest incidence percentage of the ten insecticides measured was for lindane, followed by alpha-HCH and aldrin. Moreover, the highest mean residue level was for alpha-HCH. None of the samples analyzed exceeded the maximum levels allowed by the EU.

Determination of levamisole by HPLC in plasma samples in the presence of heparin and pentobarbital

Abstract A method which allows for the isolation of levamisole in plasma samples of rabbit which contained pentobarbital and heparin as well, used as an anaesthetic and an anticoagulant respectively, is described in this paper. The subsequent quantification was carried out using a ion-pair high-performance liquid chromatographic method in a reversed and isocratic phase at room temperature, using a UV detection at 225 nm. In our conditions the retention time for the levamisole was about 2.15 minutes and the average percentage of recuperation was that of 73.62%.

Rapid high-performance liquid chromatographic assay of ethynyloestradiol in rabbit plasma.

A method for the determination of ethynyloestradiol in samples of rabbit plasma containing pentobarbital and heparin, the former used as an anaesthetic and the latter as an anticoagulant, has been developed. Quantification was carried out using a reversed-phase high-performance liquid chromatographic (HPLC) method in isocratic mode at room temperature, with electrochemical detection at an applied potential of +1 V vs. Ag/AgCl. Under these conditions, the retention time for ethynyloestradiol was ca. 2.9 min, the average recovery from plasma was 74.5%, and the limit of detection was 10 pg, corresponding to a plasma concentration of 50 pg/ml using 1 ml of plasma. Natural oestrogens, oestriol, oestradiol and oestrone showed peaks that did not interfere with ethynyloestradiol, and retention times of ca. 0.8, 2.4 and 3.4 min, respectively.

Bioavailability of levamisole after intramuscular and oral administration in sheep.

AIMSnTo determine the bioavailability of levamisole in sheep.nnnMETHODSnLevamisole was administered to three groups of six Merino sheep orally and intramuscularly at three dose levels of 5, 7.5 and 10 mg/kg. There was a washout period of 1 week between treatments. Blood samples were collected by jugular venepuncture and plasma was separated immediately by centrifugation and stored at 20 degrees C until analysed. The levamisole concentration in plasma was determined by high performance liquid chromatography with a U.V. detection method. Individual plasma levamisole concentration-time data were analysed using the compartmental method.nnnRESULTSnThe values obtained for k(a), C(max), t(max) and F show a moderate rate and extent of absorption after oral administration of levamisole while, after intramuscular administration, these values demonstrate a high rate and extent of absorption of levamisole. The intramuscular bioavailability was higher than the oral bioavailability (rate of absorption three-fold faster, extent of absorption 25-33% higher and C(max) two-fold higher). The Friedman test involving dose and route of administration showed that the route of administration affects k(a), C(max), t(max) and F; significant differences were found in these parameters.nnnCLINICAL RELEVANCEnOn the basis of these data, the recommended routes for the administration of levamisole in sheep are oral for gastro-intestinal nematodiasis and intramuscular for extragastric nematodiasis.

Organochlorine pesticide residues in muscle tissue of rainbow trout, Oncorhynchus mykiss, taken from four fish farms in León, Spain

Levels of nine organochlorine pesticides (lindane, heptachlor epoxide, aldrin, dieldrin, endrin, o,p-TDE, p,p-TDE, p,p-DDE and p,p-DDT) were determined in muscle samples of rainbow trout, Onchorhynchus mykiss, collected from four fish farms in the province of León, in the north-west of Spain (Europe). The highest incidence percentage was for lindane (67.5%) and heptachlor epoxide (55.0%). Organochlorine residue levels detected contributed slightly to acceptable daily intakes (ADIs) established by the Food and Agriculture Organization of the United Nations and the World Health Organization (lindane 0.22-2.3%; sigma DDT 0.05-0.46%; heptachlor epoxide 10.0-71.4% and sigma dieldrin 16.7-33.3% assuming 300 g of trout muscle as a mean daily intake). The highest concentration found was for heptachlor epoxide (0.043 microgram/g).

Pharmacokinetics of levamisole in sheep after intravenous administration

The pharmacokinetics of levamisole at doses of 5, 7.5 and 10 mg/kg were determined after its intravenous administration to eighteen healthy Merino sheep. Using compartmental analysis, the disposition of the drug best fitted a two-compartmental open model. The mean values for the compartmental volume of distribution at steady state (Vss) were 2.034 +/- 0.23 I, 2.347 +/- 0.720 and 2.001 +/- 0.367 I/kg for each dose, respectively, and values obtained using the statistical moment theory were 2.141 +/- 0.269,2.390 +/- 0.536 and 2.140 +/- 0.345 l/kg for each dose, respectively. There were no dose-related differences (one-way ANOVA) in the constants describing distribution and elimination phases (alpha and beta) or Vss, but significant differences were detected in the total body clearance (Cl) and the area under the plasma concentration-time curve (AUC). After non-compartmental analysis, no significant differences were found when the parameters lambda (the linear terminal slope) and Vss were compared, but significant differences were detected in Cl and AUC. There were no significant differences between the values obtained using the compartmental and non-compartmental analysis when lambda -beta, Cl, Vss, and AUC were compared.