RESUMEN
An extraction procedure and reversed-phase high-performance liquid chromatographic assay is described and validated for the determination of lamotrigine in human plasma. The method involves extraction with chloroform-isopropanol after alkalinization with a carbonate buffer, back-extraction into 0.05% phosphoric acid and separation by reversed-phase HPLC using a 5-micron Supelco diphenyl column (150 x 4.6 mm I.D.). Quantitation was performed by measurement of the UV absorbance at a wavelength of 265 nm. This method was carried out on 50-200 microliters samples of plasma, depending on whether they were pediatric or adult samples. The lower limit of quantitation was 0.2 microgram/ml using 200 microliters of plasma. A linear response was tested from 0.5 to 20 micrograms/ml. Within- and between-day accuracy and precision were always below 10.0% at all analysed concentrations. The method selectivity towards the most used antiepileptic drugs has been proven. Satisfactory performances were obtained in the evaluation of samples from epileptic patients.
Asunto(s)
Anticonvulsivantes/sangre , Cromatografía Líquida de Alta Presión/métodos , Triazinas/sangre , Adulto , Niño , Humanos , Lamotrigina , Microquímica , Control de Calidad , Sensibilidad y Especificidad , Espectrofotometría UltravioletaRESUMEN
An automated HPLC separation method for the detection of malondialdehyde (MDA) in plasma samples of a healthy population is described. The procedure involves a first step of acidic hydrolysis and complex formation with thiobarbituric acid (TBA), then a protein precipitation step, and finally the separation of TBA-MDA adducts through a complete HPLC apparatus with spectrofluorometric quantification. This procedure is very useful for a routine laboratory because of its rapidity (tR = 1.7 min), simplicity and applicability, and the method gives very good results with respect to linearity (0.1-12 mumol/l), precision (within-assay C.V.%: 8, between-assay C.V.%: 10) and accuracy (recovery average: 91.66%).
Asunto(s)
Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Adolescente , Adulto , Anciano , Cromatografía Líquida de Alta Presión , Humanos , Indicadores y Reactivos , Peroxidación de Lípido , Persona de Mediana Edad , Estándares de Referencia , Valores de Referencia , Espectrometría de Fluorescencia , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
BACKGROUND: Despite the fact that high-dose cyclophosphamide (CP) is currently used for both cancer treatment and bone marrow transplantation, its pharmacokinetics is not well defined. METHODS: Serum and urine concentrations of CP were determined in 19 patients who received 2 or more high doses of CP before bone marrow transplantation. RESULTS: Urinary recovery ranged between 1% and 32% and was essentially the same after the first and the second CP dose. In contrast, the pattern of disappearance from the serum of the two doses of CP was substantially different. The serum half-life of the first dose varied over a wide range (4.4 to 25.0 h, mean 8.7 +/- 4.6 h), while the half-life of the second dose was always shorter (1.7 to 6.0 h, mean 3.6 +/- 0.9 h). Accordingly, the CP area under the curve (AUC) of the first dose was much more variable and was always much higher than the CP AUC of the second dose. Therefore, prior administration of CP resulted in a very significant increase of CP metabolism. CONCLUSIONS: These differences can be relevant to the outcome of treatment, and suggest that the metabolism of CP can be manipulated and can be made more homogeneous, either by giving a priming dose of CP (leading to a lower CP AUC, to a faster conversion into activated metabolites and to the exposure of host cells to a higher concentration of the metabolites for a shorter time) or by giving the drug as a continuous infusion over a longer time, to obtain the opposite results.