Determination of acyclovir in maternal plasma, amniotic fluid, fetal and placental tissues by high-performance liquid chromatography

Acyclovir [9-[(2-hydroxyethoxy)-methyl]-guanosine, Zovirax, ACV] is a synthetic purine nucleoside analog active against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella zoster virus. Acyclovir has frequently been used in HSV-2 seropositive mothers to prevent prenatal transmission of herpes virus to their unborn children. A fast and reproducible HPLC method for the determination of the highly polar acyclvoir in maternal rat plasma, amniotic fluid, placental tissue, and fetal tissue has been developed and validated. Plasma and amniotic fluid samples were prepared by protein precipitation using 2 M perchloric acid and syringe filtering. Tissue samples were homogenized in distilled water, centrifuged, and extracted using a C(18) solid-phase extraction method prior to analysis. Baseline resolution was achieved for acyclovir and the internal standard gancyclovir, an anti-viral of similar structure to acyclovir, using an Agilent Eclipse XDB C(8) column (150 x 2.1 mm, 5 microm). The mobile phase used for the plasma and amniotic fluid was 10 mM acetate/citrate buffer-3.7 mM aqueous octanesulfonic acid (87.5:12.5, v/v) at a flow-rate of 0.2 ml/min. The mobile phase used for the tissue samples was 30 mM acetate/citrate buffer with 5 mM octanesulfonic acid-acetonitrile (99:1, v/v). Both aqueous mobile phase portions were pH adjusted to 3.08. All separations were done using an Agilent 1100 Series HPLC system with UV detection of 254 nm. The assay was validated for each matrix over a range of 0.25-100 microg/ml over 3 days using five replicates of three spiked concentrations. The relative standard deviation and percent error for each validation data set was <15% for middle and high quality control (QC) points and <20% for all low QC points. All calibration curves showed good linearity with an R(2)>0.99. The extraction efficiency for recovery of acyclovir from all matrices was >80%.

High-throughput bioanalytical method using automated sample preparation and liquid chromatography-atmospheric pressure ionspray mass spectrometry for quantitative determination of glybenclamide in human serum

A liquid chromatographic-mass spectrometric (LC-MS) method with rapid automated sample preparation was developed and validated for determination of glybenclamide in human serum. Glybenclamide and its deuterated labelled internal standard were extracted from human serum samples by automated solid-phase extraction. The extract was injected into the LC-MS system for analysis. Glybenclamide and its internal standard were measured in multiple ion monitoring mode. The method was validated over a range of 10-1000 ng/ml with good accuracy and precision and was applicable for pharmacokinetic studies.

Determination of 11-keto-boswellic acid in human plasma

A sensitive, specific, accurate, fast and reproducible GC/MS-method for the quantitative determination of 11-keto-boswellic acid in human plasma using 18alpha-glycyrrhetinic acid as the internal standard was developed and validated. 11-Keto-boswellic acid and the internal standard were separated from acidified plasma by liquid/liquid extraction. The extracted samples were methylated and analyzed by GC/MS in the negative ion chemical ionization mode (NICI) and selected ion monitoring (SIM). The total run time was 8 min between injections. The assay described in this paper demonstrates a validated lower limit of quantification of 0.0100 microg/ml using 1 ml of plasma. The calibration curves are linear in the measured range between 10.0 and 2000 ng/ml plasma. The overall precision (expressed as CV) and accuracy (expressed as bias) for all concentrations of quality controls and standards is better than 15%. No indications were found for possible instabilities of 11-keto-boswellic acid in plasma, in whole blood, in the extraction solvent or after repeated thawing/freezing cycles. The recovery of the extraction method is calculated as 84%. The assay was applied successfully to determine the plasma level of 11-keto-boswellic acid in a clinical pilot study.

Bioequivalence of two brands of ciprofloxacin 750 mg tablets (Sarf and Ciprobay) in healthy human volunteers

An open, randomized, two-way crossover study was carried out in 28 healthy volunteers at Gulf Pharmaceutical Industries (Julphar), as a joint venture with Saqr Hospital, Ras Al-Khaimah, UAE. The two commercial brands used were Sarf (Julphar, UAE) as test and Ciprobay (Bayer AG, Germany) as reference product. The drug was administered to each subject with 240 mL of water after an overnight fasting in two treatment days separated by a one-week washout period. After dosing, serial blood samples were collected for a period of 24 hr and serum was separated and analyzed for ciprofloxacin using a sensitive, reproducible, and accurate high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection. Various pharmacokinetic parameters, including AUC0-t, AUC0-infinity, Cmax, Tmax, t1/2, and lambdaz, were determined from ciprofloxacin serum concentration-time profiles for both formulations and found to be in good agreement with reported values. The parameters AUC0-t, AUC0-infinity, and Cmax were tested for bioequivalence after log-transformation of data. No significant difference was found based on analysis of variance (ANOVA); the 90% confidence intervals (95.73-107.62%, 94.98-108.26%, 92.80-103.90% for AUC0-t, AUC0-infinity, Cmax, respectively) for the test/reference ratios of these parameters were within the bioequivalence acceptance range of 80-125%. Based on this data, it is concluded that both formulations are bioequivalent and are interchangeable in medical practice.

Automated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for the separation and quantitative analysis of pirlindole enantiomers. A 50-microl plasma volume was injected directly onto the pre-column using a mixture of phosphate buffer (pH 5.0) and methanol (97:3; v/v) as washing liquid. By rotation of a switching valve, the analytes were then eluted in the back-flush mode with the LC mobile phase. A complete separation of pirlindole enantiomers was obtained in 22 min on the Chiralcel OD-R column, using a mobile phase made of a mixture of phosphate buffer (pH 5.0) containing 50 mM sodium perchlorate and acetonitrile (65:35; v/v). The flow-rate was 0.6 ml/min and the analytes were detected fluorometrically using 295 and 340 nm as excitation and emission wavelengths, respectively. The method was then validated and was found to be linear in the 2.5-200 ng/ml range. The limit of detection was lower than 1 ng/ml. Repeatability and intermediate precision at a concentration of 50 ng/ml were about 1.5 and 3.5%, respectively.

Validity and use of a non-parallel insulin assay for pharmacokinetic studies of the rapid-acting insulin analogue, insulin aspart

A radioimmunoassay (RIA) for insulin was validated for reliable measurement of the human insulin analogue, insulin aspart, by correction of non-linear measurements. Specificity was equivalent for several species of insulin, except insulin aspart. A non-linear hyperbolic model fitted insulin aspart with a correction formula for non-linearity of: z = 1,503y/ (1,398 - y), where y denotes measured concentration and z denotes true concentration. Matrix-effects were insignificant for human, porcine, and canine heparin-plasma and for human and porcine serum. The coefficient of variation was below 15% for 80-800 pmol/L human and porcine insulin and for 80-600 pmol/L insulin aspart. The limit of detection for insulin aspart was 11.5 pmol/L with a lower limit of quantification of 17.5 pmol/ L. Dilution of serum with Pharmacia dilution media introduced no significant error. In conclusion, this paper demonstrates that a non-parallel radioimmunoassay can be used to estimate accurate concentrations of insulin aspart.

Determination of naphthodianthrones and phloroglucinols from Hypericum perforatum extracts by liquid chromatography/tandem mass spectrometry

Hypericum perforatum L. (St. John's Wort) has long been known as a medicinal plant, and has been used for the treatment of depression and neuralgic disorders. Its main active constituents are believed to be a naphthodianthrone, hypericin, and a phloroglucinol, hyperforin. A sensitive high performance liquid chromatography (HPLC)/electrospray tandem mass spectrometric method for fast simultaneous determination of six major naphthodianthrones and phloroglucinols of Hypericum perforatum extract has been developed. The method, based on multiple dissociation reaction monitoring (MRM), allows the analysis of hypericin, protohypericin, pseudohypericin, protopseudo-hypericin, hyperforin and adhyperforin from the extract in less than 5 min. Good linearity over the range 0.1-1000 ng/mL for hyperforin and 2-500 ng/mL for hypericin was observed. Intra-assay accuracy and precision varied from 2 to 19% within these ranges. Lower levels of quantitation for hyperforin were 0.5 ng/mL and 2 ng/mL for hypericin.

Fluorometric determination of DL-fenfluramine, DL-norfenfluramine and phentermine in plasma by achiral and chiral high-performance liquid chromatography

High-performance liquid chromatography (HPLC) with fluorescence detection has been developed for the simultaneous determination of sympathomimetic amines including ephedrine, norephedrine, 2-phenylethylamine, 4-bromo-2,5-dimethoxyphenylethylamine, phentermine (Phen) and DL-fenfluramine (Fen) in spiked human plasma. Furthermore, an enantioselective HPLC method for the separation of D-Fen (dexfenfluramine) and L-Fen (levofenfluramine) in addition to their active metabolites D- and L-norfenfluramine (Norf) is described. The detection was achieved at emission wavelength of 430 nm with excitation wavelength of 325 nm for both methods. The analytes were extracted from plasma (100 microl) at pH 10.6 with ethyl acetate using fluoxetine as the internal standard. The extracts were evaporated and derivatized with the fluorescence reagent 4-(4,5-diphenyl-1H-imidazole-2-yl)benzoyl chloride in the presence of carbonate buffer (pH 9.0). A gradient separation was achieved on a C18 column for the achiral separation or on a Chiralcel OD-R column for the chiral separation. The methods were fully validated, and shown to have excellent linearity, sensitivity and precision. The chiral method has been applied for the determination of D- and L-enantiomers of Fen and Norf, in addition to Phen in rat plasma after an intraperitoneal administration of DL-Fen and Phen, simultaneously.

Placental transfer of SR49059 in the human dually perfused cotyledon in vitro

SR49059 is an antagonist of vasopressin V(1a)receptors currently developed as a tocolytic drug. We investigated the transplacental transfer of SR49059 in vitro using the single pass dually perfused human cotyledon model. Thirteen placentae were collected from normal term pregnancies immediately after delivery. The placental transfer of SR49059 was tested at steady state at three different concentrations (100 ng/ml, 200 ng/ml and 500 ng/ml) along with that of antipyrine 20 mg/l as a reference substance. Concentrations were assayed by liquid chromatography with UV (antipyrine) or mass spectrometry (SR49059) detection. At steady state, the mean+/-s.d. fetal transfer rate of SR49059 was 10.80+/-4.33 per cent, 9.34+/-4.41 per cent, and 11.78+/-3.26 per cent at 100 ng/ml, 200 ng/ml and 500 ng/ml, respectively. The corresponding clearance indices were 0.29+/-0.14, 0.25+/-0.08, and 0.31+/-0.06, respectively. The absence of saturation kinetics is consistent with a passive mechanism of transfer. Moderate amounts of SR49059 are transferred from the maternal to the fetal circulation. The clearance index of SR49059 appeared to be very similar to that of ritodrine, which is currently used as a tocolytic.

Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis

Albendazole (ABZ) is a benzimidazole anthelmintic drug used in the treatment of neurocysticercosis. After oral administration, ABZ is rapidly oxidized to albendazole sulfoxide (ABZSO), which has an asymmetric sulfur center, and later to albendazole sulfone (ABZSO2). ABZSO is the active metabolite responsible for the therapeutic effect of the drug. Previous studies have demonstrated pharmacokinetic differences between the two enantiomers, with the predominance of (+)-ABZSO in human biological fluids. This article describes for the first time the enantioselective analysis of ABZSO in cerebrospinal fluid (CSF) using capillary electrophoresis. The samples were prepared by liquid-liquid extraction using chloroform:isopropanol (8:2 v/v). The resolution of ABZSO enantiomers was obtained with a fused-silica capillary (60 cm x 75 microm ID) using 20 mmol/L Tris, pH 7.0, with 3.0% w/w sulfated beta-cyclodextrin as running buffer. The coefficient of variations and % relative error obtained for both within-day and between-days assays were lower than 15%. The method was linear over the concentration range of 100 to 2,500 ng/mL for each enantiomer, indicating that it is suitable for the analysis of ABZSO enantiomers in CSF from patients medicated with ABZ.

Analyses of lindane, vinclozolin, aldrin, p,p'-DDE, o,p'-DDT and p,p'-DDT in human serum using gas chromatography with electron capture detection and tandem mass spectrometry

A sensitive, selective and reliable procedure was developed and validated to determine organochlorinated compounds, which present endocrine-disrupting effects, lindane, vinclozolin, aldrin, p,p'-DDT, o,p'-DDT and p,p'-DDE, in human serum. The analytical methodology combines serum extraction with organic solvents, clean-up of the organic extract using acid treatment with H2SO4, elution of the cleaned-up extract through liquid column chromatography system and analysis of the fraction eluted by gas chromatography (GC) with electron capture detection (ECD) and tandem mass spectrometry (MS-MS) detection mode. Performance characteristics, such as linearity, sensitivity, precision, accuracy or recovery, of both chromatographic methods were studied. The proposed analytical methodology was applied to analyse the target compounds in serum samples from women living in agricultural areas of Almería (Spain). Comparison of the MS-MS and the ECD results was made and the advantage of the MS-MS operation mode to determine endocrine disrupting compounds in complex matrices is also presented.

Determination of an arylether antiarrhythmic and its N-dealkyl metabolite in rat plasma and hepatic microsomal incubates using liquid chromatography-tandem mass spectrometry

A method was developed and validated for the quantification of (+/-)-trans-[2-morpholino-1-(1-naphthalene-ethyloxy]cyclohexane monohydrochloride (RSD1070) and its N-dealkyl metabolite in rat plasma and hepatic microsomal incubates. Chromatographic separations were achieved using reversed-phase high-performance liquid chromatography coupled with positive ion electrospray ionization and detection by tandem mass spectrometry. The assay was linear from 2.5 to 100 ng/ml and this range was used for validation. Inter- and intra-assay variability (n=6), extraction recovery, and stability in plasma were assessed. The estimated limit of quantitation was in the range 2.5-3 ng/ml for both analytes in rat plasma. The analytical method was used in a pharmacokinetic study of RSD1070 in rats after a single i.v. bolus of 12 mg/kg.

Applications of new liquid chromatography-tandem mass spectrometry technologies for drug development support

We have evaluated (i) a multiplexed electrospray interface, (ii) serial sample introduction, and (iii) a quadrupole time-of-flight mass spectrometer for quantitative bioanalysis in compliance with good laboratory practice. These evaluations were done using a 96-well plate liquid chromatography-tandem mass spectrometry method for the quantitation of loratadine and its metabolite, descarboethoxyloratadine. The assay has a dynamic range of 1-1000 ng/ml with 5.56 pg of each analyte being injected on-column at the limit of quantitation. For the four-channel multiplexed electrospray experiments, one-run validations were performed simultaneously in rat, rabbit, mouse and dog plasma. In the four-stream serial experiments, the total run time of the assay was reduced from 3.5 to 0.35 min, resulting in a net acquisition time of 11 s. Four simulated validation runs with standard and quality control solutions were analyzed. Precision and accuracy for standards and quality control samples met US Food and Drug Administration recommended criteria for both the drug and the metabolite using those two approaches. In addition, a quadrupole time-of-flight mass spectrometer was used as a detector in the tandem mass spectrometry mode for the loratadine assay. Our results demonstrated that a dynamic range of three orders of magnitude could be achieved using the quadrupole time-of-flight mass spectrometer, making it useful for quantitation in preclinical toxicology studies.

Determination of mephenoxalone in human plasma sample by high-performance liquid chromatography-fluorescence detection

A simple and sensitive high-performance liquid chromatographic method involving fluorescence detection was developed for the determination of mephenoxalone in human plasma. A Cosmosil 5C18-MS column (250 mm x 4.6 mm I.D., 5 microm) was used as stationary phase and the mobile phase consisted of water-acetic acid-acetonitrile (200:1:300) at a flow-rate of 1.0 ml/min. The fluorescence absorbance was monitored at 280 nm for excitation wavelength and 310 nm for emission wavelength. Temperature control was kept at 40 degrees C for the column. The limit of quantitation achieved was 10 ng/ml, and the standard curve was found to be linear in the concentration range of 10-10,000 ng/ml. Under these analytical conditions, a sufficient mephenoxalone plasma concentration profile could be obtained for pharmacokinetic study.

Identification of the highest dose of docetaxel associable with active doses of epirubicin. Results from a dose-finding study in advanced breast cancer patients

PURPOSE

To determine the maximum tolerated dose (MTD) and the dose limiting toxicity (DLT) of docetaxel in combination with fixed doses of epirubicin.

PATIENTS AND METHODS

Women with locally advanced or metastatic breast cancer were given docetaxel, 60 mg/m2 in escalated doses by steps of 10 mg/m2, in association with two fixed doses of epirubicin (90 mg/m2, and 75 mg/m2). Since neutropenia was foreseen to be the most likely DLT, a third group with prophylactic G-CSF support was planned to define the MTD of docetaxel with 90 mg/m2 of epirubicin. Selected patients underwent pharmacokinetic evaluation of docetaxel.

RESULTS

Fifty-eight patients entered the study. At the first step (90 mg/m2 of epirubicin) the MTD was obtained at 60 mg/m2 of docetaxel. At the second step (75 mg/m2 of epirubicin) the MTD of docetaxel was 80 mg/m2. At the third step (epirubicin 90 mg/m2) G-CSF allowed a safe escalation of docetaxel up to 90 mg/m2. Neutropenia was the most common hematological adverse event. Without G-CSF, grade 4 neutropenia occurred in 69% of cycles, of which 11% was complicated by fever. In G-CSF group, grade 4 neutropenia and neutropenic fever occurred in 31% and 3%, respectively. Most frequent non-hematological adverse effects were asthenia (45%), nausea (39%) and mucositis (36%). No patient developed congestive heart failure. Two toxic deaths occurred. Overall response rate was 73% in 42 out of 58 patients, with no apparent epirubicin dose-related effect. No statistically significant effect of the two doses of epirubicin was observed in docetaxel pharmacokinetics.

CONCLUSIONS

On the basis of the toxicity profile, the docetaxel pharmacokinetics and the response rate observed, epirubicin 75 mg/m2 combined with docetaxel 80 mg/m2 can be recommended for further studies.

Simultaneous determination of etoposide and its catechol metabolite in the plasma of pediatric patients by liquid chromatography/tandem mass spectrometry

The anticancer drug etoposide is associated with leukemias with MLL gene translocations and other translocations as a treatment complication. The genotype of cytochrome P450 3A4 (CYP3A4), which converts etoposide to its catechol metabolite, influences the risk. In order to perform pharmacokinetic studies aimed at further elucidation of the translocation mechanism, we have developed and validated a liquid chromatography/electrospray/tandem mass spectrometry assay for the simultaneous analysis of etoposide and its catechol metabolite in human plasma. The etoposide analog teniposide was used as the internal standard. Liquid chromatography was performed on a YMC ODS-AQ column. Simultaneous determination of etoposide and its catechol metabolite was achieved using a small volume of plasma, so that the method is suitable for pediatric patients. The limits of detection were 200 ng ml(-1) etoposide and 10 ng ml(-1) catechol metabolite in human plasma and 25 ng ml(-1) etoposide and 2.5 ng ml(-1) catechol metabolite in protein-free plasma, respectively. Acceptable precision and accuracy were obtained for concentrations in the calibration curve ranges 0.2--100 microg ml(-1) etoposide and 10--5000 ng ml(-1) catechol metabolite in human plasma. Acceptable precision and accuracy for protein-free human plasma in the range 25--15 000 ng ml(-1) etoposide and 2.5--1500 ng ml(-1) etoposide catechol were also achieved. This method was selective and sensitive enough for the simultaneous quantitation of etoposide and its catechol as a total and protein-free fraction in small plasma volumes from pediatric cancer patients receiving etoposide chemotherapy. A pharmacokinetic model has been developed for future studies in large populations.

Pharmacokinetics and tissue distribution of the anticholinergics tiotropium and ipratropium in the rat and dog

Ipratropium, a current treatment for chronic obstructive pulmonary disease (COPD) and tiotropium, a longer acting anticholinergic bronchodilator currently being developed for COPD are structurally related to atropine. In this study, the intravenous (i.v.), oral (p.o.) and intratracheal (i.tr.) single dose pharmacokinetics (PK) of tiotropium and ipratropium were determined in rat and dog. In rats, concentration-time profiles of tiotropium and ipratropium after single i.v. bolus administration of 7-8 mg kg(-1) are similar. Both drugs are highly cleared (Cl between 87 and 150 ml min(-1) kg(-1)) and extensively distributed into tissues (volume of distribution V(ss) between 3 and 15 l kg(-1)). In dogs, this holds also true for both drugs (Cl between 34 and 42 ml min(-1) kg(-1), V(ss) between 2 and 10 l kg(-1)), although different dose regimen were applied (i.v. bolus of 0.08 mg kg(-1) vs. infusion of 0.1 mg kg(-1) h(-1) for 3 h). Tiotropium plasma concentrations increased linearly in rats over a wide dose range following single i.v. administration. Both ipratropium and tiotropium showed a comparable terminal elimination half-life in rat urine (21-24 h) after single i.v. administration, which was much longer than the corresponding half-life in plasma (6-8 h). Whole body autoradiography in rats revealed a broad and rapid tissue distribution of [(14)C]tiotropium radioactivity after single i.v. administration. A comparable distribution pattern has also been reported earlier for ipratropium.

High-performance liquid chromatographic assay with fluorescence detection for the determination of cephaeline and emetine in human plasma and urine

A high-performance liquid chromatographic assay method for the quantitation of ipecac alkaloids (cephaeline and emetine) in human plasma and urine is described. Human plasma or urine was extracted with diethylether under alkaline conditions following the addition of an internal standard. Concentrations of alkaloids and internal standard were determined by octadecylsilica chromatographic separation (Symmetry C18 columns, plasma analysis; 15 cmx4.6 mm I.D., 5 microm particle size, urine analysis; 7.5 cmx4.6 mm I.D., 5 microm particle size). The mobile phase consisted of buffer (20 mmol/l 1-heptanesulfonic acid sodium salt, adjusted to pH 4.0 with acetic acid)-methanol (51:49, v/v). Eluate fluorescence was monitored at 285/316 nm. The lowest quantitation limits of cephaeline and emetine were 1 and 2.5 ng/ml, respectively, in plasma, and 5 ng/ml in urine. Intra- and inter-day relative standard deviations were below 15%. The assay is sensitive, specific and applicable to pharmacokinetic studies in humans.

Determination of unbound concentration of the novel anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid in human plasma by ultrafiltration followed by high-performance liquid chromatography with fluorimetric detection

The novel anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is a highly protein bound drug with narrow therapeutic window. We report a simple HPLC method with fluorimetric detection for the determination of free DMXAA concentration in human plasma. Sample preparation involves the ultrafiltration of plasma by a Centrisart device for 30 min at 2000 g and extraction with acetonitrile: methanol mixture. The method was validated with respect to recovery, selectivity, linearity, precision, and accuracy. Calibration curves for DMXAA were constructed at the concentration range of 0.5-40 microM in blank plasma and phosphate buffer. The difference between the theoretical and calculated concentration and the relative standard deviation were less than 10% at all quality control (QC) concentrations. The HPLC method has been used for the analysis of preclinical studies.

Determination of the covalent adducts of the novel anti-cancer agent 5,6-dimethylxanthenone-4-acetic acid in biological samples by high-performance liquid chromatography

The reversed-phase HPLC methods were developed to determinate the covalently bound protein adducts of the novel anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) via its glucuronides after releasing aglycone by alkaline hydrolysis in human plasma and human serum albumin (HSA). An aliquot of 75 microl of the mixture was injected onto a Spherex C18 column (150x4.6 mm; 5 microm) at a flow-rate of 2.5 ml/min. The mobile phase comprising of acetonitrile:10 mM ammonium acetate buffer (24:76, v/v, pH 5.8) was used in an isocratic condition, and DMXAA was detected by fluorescence. The method was validated with respect to recovery, selectivity, linearity, precision, and accuracy. Calibration curves for DMXAA were constructed in the concentration range of 0.5-40 microM in washed blank human plasma or HSA prior to alkaline hydrolysis. The difference between the theoretical and calculated concentration and the relative standard deviation were less than 10% at all quality control (QC) concentrations. The limit of detection for the covalent adduct in human plasma or HSA is 0.20 microM. The methods presented good accuracy, precision and sensitivity for use in the preclinical and clinical studies.

Determination of calcium dobesilate in human plasma using ion-pairing extraction and high-performance liquid chromatography

A rapid, simple reversed-phase high-performance liquid chromatographic method with ultraviolet absorbance detection has been developed for the determination of calcium dobesilate in human plasma. Sample processing is based on an ion-pairing extraction with tetra-n-butylammonium hydroxide as cationic pairing ion and dichloromethane. Separation of the investigated calcium dobesilate and 2,4-dihydroxybenzoic acid as internal standard was achieved on a Discovery RP-Amide C16 analytical column with 50 mM, pH 2.5, potassium dihydrogenphosphate buffer-acetonitrile (75:25, v/v) mobile phase. The wavelength was set at 305 nm. The limit of quantitation is 100 ng/ml and the calibration curve is linear up to 50 microg/ml. Within-day and between-day precision expressed as the relative standard deviation is about 10% and the accuracy of the determination did not deviate from 100% by more than +/-10%. The developed method was found to be suitable for application in human bioequivalence studies.

Methadone and EDDP in hair from human subjects following a maintenance program: results of a pilot study

A specific method has been developed for the quantitative determination of methadone (MTD) and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), in hair.An amount of 50mg hair samples were incubated in 0.01M HCl overnight at 60 degrees C and deuterated internal standards of MTD and EDDP were added before extraction. Hydrolyzed solutions were extracted by automated solid-phase extraction procedure and analyzed on a gas chromatography (GC) coupled to a ion trap mass spectrometer (MS). Positive chemical ionization was used with acetonitrile as liquid reagent. The different validation parameters, linearity, repeatability, recovery and detection limits are presented. A relative standard deviation (R.S.D.) of 12 and 11% was obtained for the repeatability of MTD and EDDP, respectively. The limits of quantification (LOQ) was 0.05ng/mg for MTD and 0.2ng/mg for EDDP.A number of 26 hair samples from human subjects following a long-term MTD therapy were analyzed by this method. Blood samples of these subjects were analyzed with a routine method using a liquid-liquid extraction and GC/nitrogen phosphorus detector (NPD). MTD was quantified in blood and hair samples and EDDP found in 50% of the hair sample.A comparison was made between the concentrations found in blood or in hair and the dose administrated. This study could demonstrate that there is no relation between the administrated dose and MTD or EDDP concentrations in hair.

High-performance liquid chromatography with electrochemical detection for the determination of 7-monohydroxyethylrutoside in plasma

MonoHER (7-monohydroxyethyl rutoside) is a semisynthetic flavonoid, which can be used as a modulator for doxorubicin-induced cardiotoxicity. To study the pharmacokinetics of monoHER in mice and human an HPLC procedure was developed to measure the level of monoHER in plasma. After extraction of monoHER with methanol, the supernatant was equally diluted (v/v) with 25 mM phosphate buffer (pH 3.33). This solution was analysed by HPLC, using a reversed-phase ODS column, with a mobile phase consisting of 49% methanol and 51% of an aqueous solution containing 10 mM sodium dihydrogen phosphate (pH 3.4), 10 mM acetic acid and 36 microM EDTA. The retention time of monoHER was about 5.2 min. The lower limit of quantification of monoHER was set at 0.3 microM and the calibration line was linear up to 75 microM. The within-day accuracy and precision of the quality control samples (0.45, 1.0, 10 and 40 microM) were better than 15 and 13%, respectively. The between-day accuracy and precision were less than 3, 20%, respectively. The recovery of monoHER (using quality control concentrations) was concentration independent and ranged from 90.5 to 95.3% except for the lowest quality control, 0.45 microM, of which the recovery was 85%. The concentration of monoHER in plasma decreased with 10% when stored at -80 degrees C for one month and with 20% when stored at -20 degrees C for 3 weeks. The repeated injection of monoHER in aliquots of 10 microM, stored in the autosampler tray (4 degrees C), showed a consistent decrease during a run: 15% over 24 h. To compensate for this decrease, sample duplicates were analysed in a mirror image sequence.

Development and validation of an automated method for the liquid chromatographic determination of sotalol in plasma using dialysis and trace enrichment on a cation-exchange pre-column as on-line sample preparation

A fully automated method for the determination of sotalol in human plasma was developed, involving dialysis through a cellulose acetate membrane, clean-up and enrichment of the dialysate on a strong cation-exchange pre-column and subsequent liquid chromatographic (LC) analysis with UV detection. All sample handling operations were carried out by means of an ASTED system. Before starting dialysis, the trace enrichment column (TEC) was conditioned. The plasma sample, to which the internal standard (atenolol) was automatically added, was then loaded in the donor channel and was kept static while the dialysis liquid, consisting of 0.017 M acetic acid, was passed through the acceptor channel in successive pulses. After each pulse, the dialysate was dispensed onto the TEC. When dialysis was discontinued, the analytes were eluted from the TEC by the LC mobile phase by rotation of a switching valve and transferred to the analytical column packed with octyl silica. The LC mobile phase was a mixture of methanol and pH 7.0 phosphate buffer containing 1-octanesulfonate at a concentration of 7.5 x 10(-4) M (19:81; v/v). The UV detection was performed at 230 nm. The influence of several parameters of the dialysis and trace enrichment processes on analyte recovery and method selectivity was investigated. The method was then validated. The mean absolute recovery for sotalol was about 60%. The limit of quantitation was 25 ng/ml and R.S.D. for repeatability and intermediate precision obtained at a concentration level of 50 ng/ml were 4.3 and 5.8%, respectively.

Bioequivalence evaluation of lansoprazole 30-mg capsules (Lanfast and Lanzor) in healthy volunteers

The bioequivalence of two lansoprazole 30-mg capsules was determined in healthy human, adult volunteers after a single dose in a randomized cross-over study. The study was conducted at Pharmaconsult, Flemington Pharmaceutical Corp., New Jersey, USA. Reference (Lanzor, Laboratoires Houde, Paris, France) and test (Lanfast, Julphar, UAE) were administered to volunteers with 240 ml water after overnight fasting. Blood samples were collected at specified time intervals, plasma was separated and analyzed for lansoprazole using a validated HPLC method. The pharmacokinetic parameters AUC(0-t), AUC(0-~), C(max), T(max), T(1/2) and elimination rate constant were determined from plasma concentration-time profile of both formulations and found to be in good agreement with previously reported values. The calculated pharmacokinetic parameters were compared statistically to evaluate bioequivalence between the two brands, using the statistical modules recommended by the Food and Drug Administration. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals fell within the acceptable range (80-120%) for bioequivalence. Based on these statistical inferences it was concluded that the two formulations exhibited comparable pharmacokinetic profiles and that Julphar's Lanfast is bioequivalent to Lanzor of Lab. Houde.

A high-performance liquid chromatography-tandem mass spectrometric method for the determination of pharmacokinetics of ganaxolone in rat, monkey, dog and human plasma

A method for determining concentration levels of ganaxolone in rat, monkey, dog and human plasma was validated in the range of 5-1500 ng/ml using a 200-microl plasma sample volume. This validation report describes the linearity, specificity. sensitivity, reproducibility, accuracy, recovery and stability of the analytical method. The inter-day C.V. ranged from 0.5 to 9.2%, intra-day C.V. from 0.7 to 8.8% and intra-day accuracy (mean absolute percentage difference) ranged from 0.0 to 14.0% for rat, monkey, dog and human plasma. The method was used for the routine analysis of ganaxolone in rat, monkey, dog and human plasma and summary of the pharmacokinetic data are presented.

Bioequivalence assessment of Azomycin (Julphar, UAE) as compared to Zithromax (Pfizer, USA)--two brands of azithromycin--in healthy human volunteers

Two studies have been performed to assess the relative bioavailability of Azomycin (Julphar, UAE) as compared with Zithromax (Pfizer, USA) at the International Pharmaceutical Research Center (IPRC), Amman, Jordan. One study involved Azomycin capsules and the other Azomycin suspension. Each study enrolled 24 volunteers and in both studies, after an overnight fasting, the two brands of azithromycin were administered as single dose on two treatment days separated by a 2 weeks washout period. After dosing, serial blood samples were collected for a period of 192 h. Plasma harvested from blood, was analysed for azithromycin by HPLC coupled with electrochemical detection. Various pharmacokinetic parameters including AUC(0-t,) AUC(0-infinity,) C(max), T(max), T(1/2) and K(elm) were determined from plasma concentrations for both formulations and found to be in good agreement with the reported values. AUC(0-t), AUC(0-infinity) and C(max) were tested for bioequivalence after log-transformation of data. No significant difference was found based on ANOVA; 90% confidence intervals for the test/reference ratios of these parameters were found within the bioequivalence acceptance range of 80-125%. Based on these statistical inferences it was concluded that Azomycin capsule is bioequivalent to Zithromax capsule and Azomycin suspension is bioequivalent to Zithromax suspension.

Determination of perfluorobutane in rat blood by automatic headspace capillary gas chromatography and selected ion monitoring mass spectrometry

A new contrast agent (Sonazoid; NC100100) for ultrasound imaging has been developed. It is an aqueous suspension of lipid stabilised perfluorobutane (PFB) gas microbubbles. An automatic headspace capillary gas-chromatographic mass spectrometric method using electron impact ionisation was developed for analysis of Sonazoid PFB in rat blood. The calibration standards were gaseous PFB dissolved in ethanol in the range of 0.5-5000 ng PFB. Fluorotrichloromethane (CFC 11) was used as an internal standard of the method and the MS detector was set to single ion monitoring of the base fragment ions of PFB (m/z 69 and 119) and CFC 11 (m/z 101). The calibration graph, made by plotting the peak area ratios of PFB (m/z 69) to CFC 11(m/z 101) against the amount of PFB, was fitted to a second-order polynomial equation with weighting 1/y2 and found to be reproducible. The limit of quantification of the method was set to 0.4 ng PFB. The between-day variation of the method was below 9.2% relative standard deviation (RSD) and the within-day variation of the method was below 7.6% RSD. The accuracy of the method, as compared to Coulter counter, was estimated by determination of PFB in samples where Sonazoid was added to saline and found to range from 91.5% to 105.2%. PFB, added as Sonazoid, was found to be stable for at least 7 months in rat blood samples when stored at -20 degrees C.

Real-time monitoring of metabolic reactions by microdialysis in combination with tandem mass spectrometry: hydrolysis of CS-866 in vitro in human and rat plasma, livers, and small intestines

Microdialysis combined with tandem mass spectrometry was used to monitor the rapid hydrolysis of CS-866, a new prodrug-type angiotensin II receptor antagonist, in vitro in rat and human plasma as well as in hepatic and intestinal preparations. No chromatographic separation was conducted, and the ion intensity of CS-866 in MS/MS was directly used to perform data acquisition at intervals not longer than several seconds. A methanol-dialyzing medium, flow rate of dialysate, and adoption of sheath liquid were contrived to facilitate this method of measurement. The use of the methanol-dialyzing medium resulted in the effective extraction of the lipophilic analyte through the dialyzing membrane and a substantial reduction of inorganic substances introduced into the ion source. The calibration curve for CS-866 was linear over a concentration range from 0.2 to 20 microM (R(2) = 0.9998), and the intraassay precision was at an acceptable level of not more than 15% in coefficient of variation percentage. CS-866 was hydrolyzed very rapidly to RNH-6270, the pharmacologically active metabolite, in rat and human plasma and rat liver microsomes, and the hydrolysis proceeded extremely rapidly in human plasma with a half-life of less than several seconds.

Development and validation of a semi-automated method for L-dopa and dopamine in rat plasma using electrospray LC/MS/MS

A semi-automated alumina-based extraction method for the determination of L-dopa and dopamine in plasma using liquid chromatography mass spectrometry was validated. The method exploited the use of a Tomtec Quadra 96 liquid handing robot to expedite aluminum oxide extraction for sample clean up. Two 96-well sample plates can be processed in less than 2 h and extracts, collected in a 96-well plate format, can be directly injected onto the ESI/LC/MS/MS instrumentation. Chromatographic separation of the analytes was performed on a reverse-phase ODS column (TosoHaas ODS-80) with a mobile phase of acetonitrile/0.1% formic acid (5/95 v/v) at a flow rate of 0.22 ml/min. Analytes were detected by a triple-quadruple mass spectrometer equipped with an electrospray ionization source (ESI). Recoveries were evaluated for a number of pH modifiers and elution solvents. Under optimized conditions, the mean recoveries of L-dopa and dopamine were 56 and 67%, respectively. Intra-run and inter-run precision, calculated as percent relative standard deviation of replicate quality controls, was in the range of 1.45-10.8% for both L-dopa and dopamine. Intra-run and inter-run accuracy, calculated as percent error, was in the range -2.5 to 6.69% for both analytes. The limit of quantitaiton was 2.5 ng/ml for both L-dopa and dopamine when 100 microl of plasma was extracted. The method is simple, rapid, accurate and suitable for the quantification of L-dopa and dopamine in plasma or other biological fluid samples from clinical, preclinical, or pharmacological studies.

Quantitation of basic fibroblast growth factor by immunoassay using BIAcore 2000

A sensitive, accurate, and efficient immunoassay using a BIAcore 2000 biosensor instrument for the quantitation of basic fibroblast growth factor (bFGF) in HEPES-buffered saline containing 100 microg/ml heparin (HHBS) has been developed and validated. In this method, anti-bFGF monoclonal antibody 48.1 (MAb 48.1) was selected as a binding ligand and immobilized to the matrix surface of Sensor Chip CM5 by amine coupling. A high immobilization level of MAb 48.1 (12643+/-816 RU, mean +/- S.D., n = 5) was achieved with high reproducibility (i.e. coefficient of variation (CV) was 6.5%). This immobilized MAb 48.1 sensor surface was used to detect and quantity bFGF. This assay has a range of reliable BIAcore response from 5.65 to 1440 ng/ml bFGF in HHBS. which was well fitted with a sigmoidal model. The immobilized MAb 48.1 was found to be stable for at least 150 regeneration cycles and for at least 9 days at room temperature. Intra- and interassay CVs ranged from 0.9 to 5.9%, and from 2.7 to 8.5%, respectively. Matrices such as serum, bovine serum albumin (BSA), and two pharmaceutical excipients (Pluronic F127 surfactant and sodium carboxymethylcellulose) did not interfere with bFGF analysis over the sensor surface. Therefore, this validated assay has good precision, accuracy and specificity, and has been found useful in quantifying bFGF in several research and development studies.

Validation of a highly sensitive ICP-MS method for the determination of platinum in biofluids: application to clinical pharmacokinetic studies with oxaliplatin

ELOXATIN (Oxaliplatin) is a novel platinum containing anti-cancer agent with a diaminocyclohexane carrier ligand which has been approved in several major European countries. Clinical studies have demonstrated that the compound exhibits marked activity against colorectal cancers in combination with 5-fluorouracil (5-FU). The aim of this work was to develop and validate a highly sensitive inductively coupled plasma mass spectrometry assay for the determination of oxaliplatin-derived platinum in plasma ultrafiltrate, plasma and whole blood and to apply this technique to clinical pharmacokinetic studies with oxaliplatin. Ultratrace detection of platinum in plasma ultrafiltrate was achieved using ultrasonic nebulisation combined with ICP-MS. This technique allows detection of platinum at the 0.001 microg Pt/ml level in only 100 microl of matrix. Assays in blood and plasma utilised a standard Meinhardt nebuliser and spray chamber, achieving detection limits of 0.1 microg Pt/ml in 100 and 200 microl of matrix, respectively. The assays were validated (accuracy and precision within +/- 15%) over the concentration ranges: 0.001-0.250 microg Pt/ml in plasma ultrafiltrate and 0.1-10 microg Pt/ml for plasma and whole blood. The effect of sample digestion. dilution, long term frozen storage and quantitation in the presence of 5-FU were also investigated and validated. The method was used to monitor platinum exposure following oxaliplatin administration (130 mg/m2) to cancer patients. Following a 2 h i.v. infusion, peak platinum levels declined in a triphasic manner in all blood compartments. Free platinum was detected in plasma ultrafiltrate at low levels (0.001 0.010 microg Pt/ml) for up to 3 weeks. In conclusion, a highly sensitive and specific assay has been developed for the determination of platinum in biofluids. This method enabled characterisation of the long term exposure to platinum in patients following oxaliplatin treatment.

Pharmacokinetic studies of neuromuscular blocking agents: good clinical research practice (GCRP)

In September 1997, an international consensus conference on standardization of studies of neuromuscular blocking agents was held in Copenhagen, Denmark. Based on the conference, a set of guidelines for good clinical research practice (GCRP) in pharmacokinetic studies of neuromuscular blocking agents is presented. Guidelines include: design of the study; relevant patient groups to investigate; test drug administration, sampling and analysis; pharmacokinetic analysis; pharmacokinetic/pharmacodynamic modeling; population pharmacokinetics; statistics; and presentation of pharmacokinetic data. The guidelines are intended to aid those working in this research area; it is hoped that they will assist researchers, editors of scientific papers, and pharmaceutical companies in improving the quality of pharmacokinetic studies.

A new insulin immunoassay specific for the rapid-acting insulin analog, insulin aspart, suitable for bioavailability, bioequivalence, and pharmacokinetic studies

OBJECTIVES

To validate a specific enzyme-linked immunosorbent assay for the rapid-acting human insulin analogue, insulin aspart, in human serum, human plasma, and porcine plasma.

DESIGN AND METHODS

For the enzyme-linked immunosorbent assay, two murine monoclonal antibodies were developed that bind to two different epitopes on the insulin aspart molecule. Key parameters for validation were imprecision, accuracy, matrix effects, dilution-linearity, and cross-reactivity.

RESULTS

No cross-reactivity was found with human and porcine insulin, human proinsulin, or human C-peptide. The assay is sensitive (limit of quantification = 11.5 pmol/L), accurate (95-107% recovery with human serum, human plasma, and porcine plasma in the range 16-800 pmol/L), and has a 14.7% total imprecision within the entire analytical range. Dilution of samples gave linear results with human serum as the diluent.

CONCLUSIONS

The insulin aspart-specific enzyme-linked immunosorbent assay described in this study is well suited to study the bioavailability, bioequivalence, and pharmacokinetics of this insulin analogue.

Stereoselective pharmacokinetic analysis of valnoctamide, a CNS-active chiral amide analogue of valproic acid, in dogs, rats, and mice

The purpose of this study was to evaluate the stereoselective pharmacokinetics of valnoctamide (VCD) in dogs, rats, and mice; which are the most common animal models for pharmacokinetic, pharmacologic, and toxicologic evaluation; and to compare it with previously published human data. Racemic VCD (mixture of four stereoisomers) was administered intravenously to six mongrel dogs and to rats (five rats per time-point), and intraperitoneally to mice (five mice per time-point). Plasma concentrations of the individual stereoisomers were measured by a stereospecific gas chromatography assay. In dogs, (2S,3R)-VCD had a larger clearance (0.33 L/h x kg) and a larger volume of distribution (0.79 L/kg) than its two diastereomers (0.24-0.25 L/h x kg and 0.65 L/kg, respectively). A tendency toward slightly higher clearance and volume of distribution values for (2S,3R)-VCD was observed in rats and mice as well. Consequently, in all three animal species the half-life (t1/2) of (2S,3R)-VCD was not different from the t1/2 of the other three VCD stereoisomers. The stereoselective pharmacokinetics of VCD as observed in dogs, rats, and mice is in line with the stereoselectivity previously observed in healthy subjects and epileptic patients.

Liquid chromatographic-tandem mass spectrometric method for the analysis of a neurokinin-1 antagonist and its metabolite using automated solid-phase sample preparation and automated data handling and reporting

Pharmacokinetic studies play a vital role during the development of new pharmaceutical substances. Data presented demonstrate an accurate, precise and robust assay for a neurokinin-1 receptor antagonist and its metabolite with HPLC-MS-MS. Sample preparation is performed by solid-phase extraction (SPE) in the 96-well plate format. This process is fully automated with a Tecan Genesis pipetting system using its standard robotic manipulator arm (ROMA). All instruments are fully integrated in a study oriented laboratory information system (LIMS) with an Oracle database that communicates bi-directional with the analytical equipment. Finally, the results are reported by push button operation.

Effect of nucleoside analogues and oligonucleotides on hydrolysis of liposomal phospholipids

The hydrolysis of the bilayer forming phospholipids resulting first of all in lysophospholipids and fatty acids is one limiting factor determining the shelf-life of liposomes. In several studies the influence of pH, buffer, lipid composition and other parameters on the hydrolysis of phospholipids have been demonstrated, but the influence of drugs has not yet been investigated systematically. In this study the influence of nucleoside analogues, especially 2', 2'-difluoro 2'-deoxycytidine (gemcitabine, dFdC) on the degradation of phospholipids was elucidated in more detail. It could be demonstrated that the interaction of dFdC with phospholipid bilayers promotes the hydrolysis of phospholipids in a concentration-dependent manner. Obviously two parts of the molecule, the amino group bound to the pyrimidine moiety and the 2', 2'-difluoro-2'-deoxyribose, seem to be responsible for the forced phospholipid hydrolysis. The dFdC-induced hydrolysis of phospholipids was influenced by pH, buffer, lipid composition and different anions. Optimization of the above parameters resulted in prolonged shelf-life of dFdC liposome dispersions, which is an important prerequisite for clinical practice.

Bioequivalence evaluation of two brands of cefuroxime 500 mg tablets (Cefuzime and Zinnat) in healthy human volunteers

A bioequivalence study of two oral formulations of 500 mg cefuroxime axetil was carried out in 24 healthy volunteers following a single dose, standard two-treatment cross-over design at the College of Pharmacy, King Saud University, Riyadh, Saudi Arabia, working jointly with King Khalid University Hospital. The two formulations used were Cefuzime (Julphar, United Arab Emirates) as the test and Zinnat (Glaxo Wellcome, England) as the reference product. Both test and reference tablets were administered to each subject after an overnight fasting on two treatment days separated by a 1-week washout period. After dosing, serial blood samples were collected for a period of 8 h. Plasma harvested from blood was analysed for cefuroxime by a sensitive, reproducible and accurate high pressure liquid chromatography (HPLC) method. Various pharmacokinetic parameters including AUC(0-t), AUC(0-infinity), C(max), T(max), T(1/2) and K(el) were determined from plasma concentrations of both formulations and found to be in good agreement with reported values. AUC(0-t), AUC(0-infinity) and C(max) were tested for bioequivalence after log-transformation of data. No significant difference was found based on an analysis of variance (ANOVA); 90% confidence interval for test/reference ratio of these parameters were found within bioequivalence acceptance range of 80-125%. Based on these statistical inferences, it was concluded that Cefuzime is bioequivalent to Zinnat.

Enantioselective analysis of levetiracetam and its enantiomer R-alpha-ethyl-2-oxo-pyrrolidine acetamide using gas chromatography and ion trap mass spectrometric detection

A gas chromatographic-mass spectrometric method was developed for the enantioselective analysis of levetiracetam and its enantiomer (R)-alpha-ethyl-2-oxo-pyrrolidine acetamide in dog plasma and urine. A solid-phase extraction procedure was followed by gas chromatographic separation of the enantiomers on a chiral cyclodextrin capillary column and detection using ion trap mass spectrometry. The fragmentation pattern of the enantiomers was further investigated using tandem mass spectrometry. For quantitative analysis three single ions were selected from the enantiomers, enabling selected ion monitoring in detection. The calibration curves were linear from 1 microM to 2 mM for plasma samples and from 0.5 mM to 38 mM for urine samples. In plasma and urine samples the inter-day precision, expressed as relative standard deviation was around 10% in all concentrations. Selected ion monitoring mass spectrometry is suitable for quantitative analysis of a wide concentration range of levetiracetam and its enantiomer in biological samples. The method was successfully applied to a pharmacokinetic study of levetiracetam and (R)-alpha-ethyl-2-oxo-pyrrolidine acetamide in a dog.

Clinical and pharmacological phase I study with accelerated titration design of a daily times five schedule of BBR3464, a novel cationic triplatinum complex

OBJECTIVES

To define the maximum tolerated dose (MTD), the toxicity and pharmacokinetic profile of BBR3464, a novel triplatinum complex.

PATIENTS AND METHODS

Fourteen patients with advanced solid tumors not responsive to previous antitumor treatments received BBR 3464 on a daily x 5 schedule every twenty-eighth day. The drug was given as a one-hour infusion with pre-and post-treatment hydration (500 ml in one hour) and no antiemetic prophylaxis. The starting dose was 0.03 mg/m2/day. A modified accelerated titration escalation design was used. Total and free platinum (Pt) concentrations in plasma and urine were assessed by ICP-MS on days 1 and 5 of the first cycle.

RESULTS

Dose was escalated four times up to 0.17 mg/m2/day. Short-lasting neutropenia and diarrhea of late onset were dose-limiting and defined the MTD at 0.12 mg/m2. Nausea and vomiting were rare, neither neuro- nor renal toxic effects were observed. BBR3464 showed a rapid distribution phase of 1 hour and a terminal half-life of several days. At 0.17 mg/m2 plasma Cmax and AUC on day 5 were higher than on day 1, indicating drug accumulation. Approximately 10% of the equivalent dose of BBR3464 (2.2%-13.4%) was recovered in a 24-hour urine collection.

CONCLUSIONS

The higher than expected incidence of neutropenia and GI toxicity might be related to the prolonged half-life and accumulation of total and free Pt after daily administrations. Lack of nephrotoxicity and the low urinary excretion support the use of the drug without hydration. The single intermittent schedule has been selected for clinical development.

Quantitative determination of endocrine- disrupting polychlorinated biphenyls and organochlorinated pesticides in human serum using gas chromatography with electron-capture detection and tandem mass spectrometry

A sensitive, selective and reliable procedure was developed and validated to determine organochlorinated compounds, which have endocrine-disrupting effects, in human serum. Target compounds were selected between polychlorinated biphenyls and organochlorinated pesticides. Sample workup consisted of (1) extraction of serum with organic solvents, (2) clean-up of the organic extract using acid treatment with H(2)SO(4), (3) elution of the cleaned-up extract through a liquid column chromatographic system and (4) analysis of the fraction eluted by gas chromatography with electron capture detection (ECD) and tandem mass spectrometry (MS/MS) detection. Performance characteristics, such as linearity, sensitivity, precision, accuracy and recovery, of both chromatographic methods were studied. The proposed analytical methodology was applied to determine the target compounds in serum samples from women living in agricultural areas of Almería (Spain). The results show the advantage of MS/MS over ECD in the analysis of real human serum samples where matrix interferences can be confused with target pesticides.

Pharmacokinetics of the M1-agonist talsaclidine in mouse, rat, rabbit and monkey, and extrapolation to man

1. Talsaclidine is an M1-agonist under development for the treatment of Alzheimer's disease. The aim of the study was to investigate the absorption, distribution, metabolism and excretion (ADME) of single intravenous and oral doses of [14C]-talsaclidine in mouse, rat, rabbit and monkey. Previous data in humans showed that the drug was mainly excreted into the urine as the unchanged parent drug. The hypothesis was tested if animal data of drugs, which are mainly excreted renally, could be extrapolated to human. 2. The apparent volume of distribution at steady-state (V(ss)) was comparable in all animal species (2-5 l x kg(-1)) indicating an extensive distribution of the drug into tissues. The plasma protein binding was low and comparable in all species including man (< or = 7%). Elimination in terms of clearance was rapid-to-moderate depending on the species. The total plasma clearance (Cl) decreased in the order: mouse (128 ml x min(-1) x kg(-1))> rat (73.9) > monkey (10.6). Urinary excretion is the dominant route of excretion (> or = 86%). 3. A good correlation was achieved with human and animal data in allometric scaling of CI and V(ss). This confirms the hypothesis that renal filtration is scalable over the species and, given a comparable protein binding, animal data is predictive for man.

Post-column reaction detection of biotin in human plasma ultrafiltrate based on laser-induced fluorescence energy transfer in the far-red spectral region

High performance liquid chromatography followed by post-column reaction detection in the far-red spectral region provides added sensitivity and selectivity. A homogeneous fluorescence energy transfer assay in the competitive mode based on the binding of biotin and streptavidin was developed as an on-line post-column reaction detection system. The labels used for energy transfer were R-Phycoerythrin conjugated to biotin and Cyanine 5 labeled with streptavidin. The energy transfer peak was measured at 670 nm and excitation was achieved using the 488 nm line of an argon ion laser. The biotin concentration in plasma ultrafiltrate ranged from 0.024 to 6.12 ng/mL (n = 6). The precision of the two controls, 0.24 and 2. 44 ng/mL, was found to be 18.70% and 9.92% relative standard deviation respectively. Accuracy was 10.47% and 1.95% difference from spiked, respectively (n = 6). The limit of detection was 21.70 pg/mL (8.90 x 10(-11)M) calculated based on a factor of 2x the standard deviation of the blank (n = 6). The correlation coefficient for the calibration curve was found to be 0.9995. Recovery from plasma ultrafiltrate at 2.44 ng/mL was 103.40% (n = 6). Detection selectivity was indicated by the absence of background fluorescence in six different plasma samples collected from six individual donors. Endogenous levels were detected in two of the six pools of plasma ultrafiltrates.

Validation of high-performance liquid chromatographic assay methods for the analysis of carboplatin in plasma ultrafiltrate

Validation of two HPLC assays for the quantitation of carboplatin in human plasma ultrafiltrate is described. Both assay methods employed a YMC ODS-AQ 3.9 x 150 mm (3 microm) column for the chromatographic separation. The first method utilized direct UV detection, the second method utilized UV detection following post-column derivatization with sodium bisulfite. Structural analogues of carboplatin were synthesized and used as internal standards for the assays. With direct UV detection, sample clean-up using solid-phase extraction on amino cartridges was required prior to injection, with extraction recoveries ranging from 80 to 90%. This extraction procedure was not necessary with the post-column reaction method, which employed a more selective analytical wavelength. Unfortunately, instability of the post-column reagent was a problem and led to greater variability in predicted concentration values. For standard curves, a weighted (1/y2) regression approach was used for plots of peak area or peak height ratio (carboplatin/internal standard) vs. carboplatin concentration. The limit of detection of both assays was 0.025 microg/ml and both were validated for carboplatin concentrations from 0.05 to 40 microg/ml. Accuracy and precision data were generated using three batches of validation samples, each batch consisting of a standard curve and five sets of quality control samples. Stability of carboplatin in blood, plasma, plasma ultrafiltrate, and reconstituted extracts was evaluated. The assay methods were employed for the pharmacokinetic analysis of blood samples drawn from a pediatric patient that received a 400 mg/m2 dose of carboplatin.