Rapid simultaneous determination for organophosphorus pesticides in human serum by LC-MS

A simple and rapid method was developed for measuring 10 organophosphorus pesticides (acephate, methidathion, dichlorvos, fenthion, EPN, diazinon, phenthoate, malathion, fenitrothion, and cyanophos) in the serum of acute poisoning patients by LC/MS. Following deproteinization by acetonitrile, an aliquot of the biological sample was injected into a C(18) column using 10mM ammonium formate-methanol as the mobile phase. Extraction recoveries were satisfactory and ranged between 60.0 and 108.1% in serum. The limits of detection (LODs) in serum ranged from 0.125 to 1 microg/ml, and the limits of quantitation (LOQs) ranged from 0.25 to 1.25 microg/ml. An excellent linearity was observed for these LOQs up to 8 microg/ml. Intra- and interassay precision and accuracy were satisfactory for most of the pesticides analyzed. In terms of temperature stability, of all the organophosphorus compounds analyzed, dichlorvos and malathion exhibited the most rapid degradations over 24h at room temperature. Methidathion and diazinon remained relatively stable at all temperatures during the entire 4-week testing period. The present method was successfully applied to one actual case of acute poisoning. In conclusion, this method is simple, accurate, and useful for the determination of organophosphorus pesticides and should benefit both clinical and forensic toxicology.

Rapid simultaneous determination of ephedrines, amphetamines, cocaine, cocaine metabolites, and opiates in human urine by GC-MS

This paper presents a simple and sensitive chromatographic procedure for the simultaneous determination and quantification of ephedrines, amphetamines, cocaine, cocaine metabolites, and opiates in human urine by gas chromatography-mass spectrometry. This method involves enzyme hydrolysis in the presence of a deuterated internal standard, liquid-liquid extraction, and derivatization with pentafluoropropionic anhydride and pentafluoropropanol. The recovery of each compound averaged at 65.8% or more. The limits of detection determined for each compound by using a 2-mL sample volume ranged from 5 to 50 ng/mL. The calibration curves were linear to 100 ng/mL for all compounds when determined using methamphetamine-d4 and MDMA-d5 as internal standards. This method was successfully applied for the analysis of urine samples suspected to contain intoxicants such as methamphetamine and heroin.

A diabetic case with hemoglobin J-Meerut and low HbA1C levels

A diabetic patient with hemoglobin (Hb) J-Meerut and low HbA1C levels is reported. An automatic glycohemoglobin analyzer used for the determination of HbA1C revealed an abnormal peak of the peripheral blood obtained from a Japanese female with diabetes. She showed a lower HbA1C level (3.7%) than expected from her fasting plasma glucose (172 mg/dl). High performance liquid chromatography and isoelectric focusing indicated that her abnormal hemoglobin was Hb J-Meerut [alpha 120(H3)Ala-->Glu] and it accounted for 28.3% of the total hemoglobin. Abnormal hemoglobinemia should be considered when a major discrepancy between the levels of HbA1C and fasting plasma glucose is observed.

[Determination of new anticancer drug, paclitaxel, in biological fluids by high performance liquid chromatography]

A simple and reproducible high performance liquid chromatographic (HPLC) method using an internal standard (I.S.) was developed for the determination of an anticancer drug, paclitaxel, in biological fluids. The sample preparation involves a solid-phase extraction step. HPLC was performed on an ODS column using acetonitrile-2 mM phosphoric acid (45:55) as a mobile phase with detection at 227 nm. A linear relationship was obtained in the range of 0.02-2.0 micrograms/ml in the rat plasma and urine. Since the recovery of the drug was as high as that of I.S. (> 96%), a standard curve generated from the solution of the drug with I.S. in the mobile phase could be used for determination. The method could be applicable for human and dog plasma as well as rat plasma, and the intra- and interday coefficients of variation at 0.05, 2.0 and 10.0 micrograms/ml were less than 7%. This method is useful for pharmacokinetic studies of paclitaxel.

[Pharmacokinetics of paclitaxel in experimental animals. Part 2. Tissue distribution]

In S 180 bearing male mice, paclitaxel was rapidly distributed to various tissues within 10 minutes. The highest AUC was seen in the liver, and relatively high in the pancreas, kidney, thymus, intestine, stomach and lung. The concentration of paclitaxel in tumor tissue was not so high early time after administration, but was sustained for a long time with a half life of 12.3 hr. Elimination from the testis and thymus was also slow. The drug level in the brain was very low. In M 109 bearing female CDF1 mice, the distribution and elimination profile of paclitaxel was comparable to that in S 180 mice. The concentration of paclitaxel in the ovary, lung and uterus decreased slowly. In M 109 tumor, which was very sensitive to paclitaxel, the drug had a higher and long lasting distribution compared with S 180 tumor. In S 180 tumor bearing mice pretreated with CCl4, the paclitaxel level was found to be lower in the liver and higher in the other tissues including tumor, plasma, urine and bile than in non-treated mice.

[Pharmacokinetics of paclitaxel in experimental animals. Part 1. Blood level]

The plasma disposition of paclitaxel in rabbits (7 mg/kg, 1 h i.v. inf.) was biphasic with half-lives of 0.36 and 6.36 h, and AUC was 9.46 micrograms.hr/ml. K12 value was larger than K21 and V2 was larger than V1, suggesting that paclitaxel had a favorable distribution profile in tissues. In S 180 bearing male ICR mice (30 mg/kg, i.v. bolus), the biphasic plasma disposition was also observed. The half-lives and AUC were 0.25 h, 2.23 h and 117.93 micrograms.hr/ml. Paclitaxel distributed widely in plasma rather than blood cells. The biliary level of paclitaxel in the enlarged gallbladder of ICR mice was markedly high, about 10-fold higher than the urinary level and 100-fold higher than the plasma level. The bioavailability with oral administration to ICR mice was poor. AUC(oral)/AUC(i.v.) ratio in the bile, liver, tumor and plasma was 18.91, 6.71, 0.83 and 0.45%, respectively.

Clinical pharmacokinetics of carboplatin

The pharmacokinetics of carboplatin were investigated in cancer patients after single, IV infusion doses of 75, 150, 247.5, 300, 375, and 450 mg/m2. Total plasma and urine platinum and plasma ultrafilterable platinum concentrations were determined by atomic absorption spectrometry. Carboplatin was analyzed in plasma by a specific high-performance liquid chromatography (HPLC) procedure. Total plasma platinum, which represented free carboplatin, protein-bound platinum and metabolites, declined triexponentially; plasma half-lives (t1/2 lambda 1, 0.2 to 0.4 hr; t1/2 lambda 2, 1.3 to 1.7 hr; t1/2 lambda 3, 22 to 40 hr) and total body clearance (CLTB 2.8 +/- 0.5 L/m2/hr) were dose independent. Maximum plasma concentrations (Cmax) and area under the plasma concentration time curve (AUC) increased proportionally with dose. Plasma ultrafilterable platinum and carboplatin concentrations at doses of 375 and 450 mg/m2 declined in a biphasic manner. Plasma carboplatin elimination (t1/2 lambda 1, 0.50 hr; t1/2 lambda 2, 2.2 hr) and CLTB (4.4 to 5.6 L/m2/hr) were also independent of dose; AUC and Cmax increased proportionally to dose. Plasma free platinum was essentially all carboplatin for 8 or 12 hours after administration. Carboplatin did not bind to plasma protein in vitro but did degrade (t1/2-26 hours) to yield a reactive intermediate that bound rapidly and irreversibly to protein. The long terminal elimination half-life of plasma platinum was associated with irreversible binding of a platinum metabonate to plasma protein. The urinary excretion of platinum (0 to 24 hours) accounted for 58 to 72% of doses in 12 to 24 hours. The remainder of the dose is slowly excreted. The pharmacokinetics, in vivo stability, protein binding, and elimination of carboplatin are distinct from the first-generation analog cisplatin.