Quantitative measurement of propofol and in main glucuroconjugate metabolites in human plasma using solid phase extraction-liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatographic method coupled with tandem mass spectrometry detection has been developed for the determination of propofol and its main glucuroconjugate metabolites (propofol-glucuronide (PG), 1-quinol-glucuronide (1-QG) and 4-quinol-glucuronide (4-QG) in human plasma. All compounds were extracted with a single solid phase extraction procedure using Max Oasis cartridges. Propofol and thymol (internal standard) were analyzed using a C8 reversed-phase column with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.025% NH(4)OH. Chromatography of glucuroconjugate metabolites and phenyl-beta-d-glucuronide (internal standard) was performed using a hydrophilic interaction liquid chromatography (HILIC) and a mixture of acetonitrile/water/ammonium acetate buffer (100 mM, pH 5, 87/1/12, v/v/v). Both chromatographic separations were achieved in isocratic mode allowing a rapid analysis without re-equilibration of the phase. The method is specific and sensitive with a range of 10-1500 ng mL(-1) for propofol and 1-QG, 20-3000 ng mL(-1) for PG and 25-3750 ng mL(-1) for 4-QG. The regression curves were linear for all compounds. The method is accurate and precise with intra-assay and inter-assay precision <8% and bias < or =6% for all compounds. This assay has allowed the successful measurement of propofol and its main glucuroconjugate metabolites in human plasma from 24 patients undergoing anaesthesia for elective partial hepatectomy surgery.

Is vitamin K1 supplementation necessary in long-term parenteral nutrition?

BACKGROUND: I.v. lipid emulsions contain vitamin K in substantial quantities and in 1989, we therfore stopped supplying vitamin K1 to patients receiving home parenteral nutrition (HPN). METHODS: Nine patients (group I) receiving HPN before 1989 (10 mg i.v. vitamin K1 supplementation weekly until 1989, which was discontinued thereafter) and six patients with an initial low plasma vitamin K1 concentration (related to their malabsorption) (group II) receiving HPN after 1989 were studied. Prothrombin time (PT), plasma vitamin K1 concentration, and vitamin K1, content in lipid emulsions were measured throughout the period of HPN. RESULTS: All lipid emulsions, except for Eurolip 20% and Clinoleic 20% (Baxter SA, Maurepas, France) contained vitamin K1, with concentration ranges from 179 +/- 39 to 353 +/- 78 ng/L. Group I patients had an initial high plasma vitamin K1 concentration due to the vitamin K1 supplementation. After this supplementation was discontinued, plasma vitamin K1 decreased and remained in normal ranges with a normal PT. Throughout the HPN period after 1989, patients received 255 +/- 104 micrograms of vitamin K1 weekly through lipid emulsions. The PT and plasma vitamin K1 concentrations in group II patients were restored by lipid emulsions, which contained 418 +/- 143 micrograms/wk of vitamin K1. CONCLUSIONS: In patients receiving i.v. lipids (except for Eurolip and Clinoleic), a normal vitamin K1 status can be maintained during long-term HPN without vitamin K1 supplementation. However, vitamin K supplementation cannot be abandoned until the vitamin K content of emulsions is standardized by manufacturers. A weekly supply of 250 to 400 micrograms of vitamin K1 is enough to maintain and even restore a normal vitamin K1 status in HPN.

Hepatic concentration of vitamin K active compounds after application of phylloquinone to chickens on a vitamin K deficient or adequate diet.

Liver and serum concentrations of vitamin K active compounds were measured in two groups of (deficient and normal) broilers after administration of phylloquinone 1 mg/kg. Assays were performed by HPLC after extraction and purification of these compounds. The only menaquinone found in the chicken was menaquinone-4. In the deficient group, the chickens exhibited hepatic concentrations of vitamin K1, vitamin K1 epoxide and menaquinone-4 markedly lower than those of the control group. After administration of phylloquinone, vitamin K and vitamin K epoxide levels fell sharply. There is no hepatic storage of vitamin K comparable to that of vitamin A. However, while menaquinone levels were found to be stable in the control group, they rose significantly in the deficient group after vitamin K injection. The question is: is there a transformation of vitamin K into menaquinone and/or is there a preferential utilization of one of the vitamin K active compounds?

Quantification of docetaxel and its main metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Docetaxel is an antineoplastic agent widely used in therapeutics. The objective of this study was to develop and validate a routine assay, using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), for the simultaneous quantification of docetaxel and its main hydroxylated metabolites in human plasma. A structural analogue, paclitaxel, was used as the internal standard. Determination of docetaxel and four metabolites (M1, M2, M3 and M4) was achieved using only 100 microL of plasma. Liquid-liquid extraction was used for sample preparation, with extraction efficiency of at least 90% for all analytes. Detection used positive-mode electrospray ionization in selected reaction monitoring mode. The lower limit of quantification (LLOQ) was 0.5 ng/mL for all analytes. The assay was linear in the calibration curve range 0.5-1000 ng/mL and acceptable precision and accuracy (<15%) were obtained with concentrations above the LLOQ. This method was sufficiently selective and sensitive for quantification of metabolites in plasma from cancer patients receiving docetaxel chemotherapy, and is suitable for routine analyses during pharmacokinetic studies.

Changes in hepatic vitamin K1 levels after prophylactic administration to the newborn.

We undertook a study of hepatic concentrations of vitamin K (vitamin K1 or phylloquinone, vitamin K1-epoxide, and menaquinones) in 18 infants, ages 1-8 days, with or without vitamin K1 supplementation. The infants who had no supplementation had a total hepatic storage ranging between 0.1 and 0.9 micrograms. Also, hepatic storage of phylloquinone was poor (< 1 microgram) when compared with daily requirements. Moreover, we did not detect any menaquinone in the livers of these infants in our study. The prophylaxis applied to the other infants was very efficient. Hepatic vitamin K1 concentrations, obtained < 24 h after administration, were very high (62.8-93.5 micrograms/g). Vitamin K1-epoxide concentrations were high, which proved the efficiency of the vitamin K cycle. In contrast, the decrease in vitamin K1 concentrations was also very rapid, since the median value after 48 h was 8.4 micrograms/g and only 2.9 micrograms/g 5 days after administration. However, hepatic total storage after 5 days in one infant with vitamin K1 supplementation was much higher (112 micrograms) than in infants who had not received supplementation. In conclusion, hepatic phylloquinone storage at birth was poor (< 1 microgram). The newborn infant might be in a situation of potential deficiency. After prophylactic oral administration of phylloquinone, uptake by the liver was quite satisfactory, but concentrations dropped quickly. However, phylloquinone hepatic storage remained elevated (112 micrograms) after 5 days.