Therapeutic drug monitoring of posaconazole in hematology adults under posaconazole prophylaxis: influence of food intake.

Posaconazole (PCZ) is given at 200 mg three times daily as a fungal prophylaxis in neutropenic hematologic malignancy patients. A relationship between exposure, plasma concentration, and efficacy is suggested. The objectives of this prospective study were to analyze the PCZ plasma concentration in hematology adults at high risk of developing invasive fungal infections (IFIs), and factors that could have an impact on the PCZ plasma concentration. PCZ plasma concentrations were measured after 2, 7, 10, 14, and 21 days of PCZ prophylaxis. Factors such as gender, age, body weight, posology, treatment duration, mucositis, proton pump inhibitor (PPI) use, and food intake were studied. Sixty-three patients were included, with a median age of 52 years (range 17-70) and a median weight of 75 kg (range 47-150). The median PCZ plasma concentration of the 63 patients ranged from 0.42 to 0.48 mg/L. At day 2, 30% of PCZ plasma concentration were under 0.35 mg/L, and at day 7, 74% were <0.70 mg/L. PCZ plasma concentrations were not affected by gender, age, body weight, or treatment duration. We found that food intake had a high influence on PCZ plasma concentrations (p = 0.0049). PCZ was well tolerated. One patient has developed a probable IFI, probably related to a low exposure to PCZ. PCZ therapeutic drug monitoring (TDM) is essential in order to early detect patients with low concentrations, to assess the etiology of such results, and to decide on the treatment strategy to apply.

Inherited long QT syndrome revealed by antifungals drug-drug interaction.

A 14-year-old Tahitian girl with acute myeloid leukaemia and a suspected mucormucosis infection was treated with intravenous voriconazole and caspofungin. Because of worsening of fungal infection, voriconazole was switched to posaconazole. During the switch, the patient presented with QT interval prolongation with 'torsades de pointes' and reversible cardiac arrest. Voriconazole plasma level measured 15 h after the last administration was 7 mg/L. Genotyping suggested that the patient was an extensive metabolizer with respect to CYP2C9 and CYP2C19. The association of antifungal agents with pro-arrhythmogenic drugs and other risk factors led to torsades de pointes and the revealing of inherited QT syndrome.

Variability in the clinical pattern of cutaneous side-effects of drugs with systemic symptoms: does a DRESS syndrome really exist?

OBJECTIVE: To improve the definition of the various clinical patterns of patients with drug-induced cutaneous side-effects with systemic symptoms, and their possible relationships with the triggering medication, with the ultimate goal of helping in the identification of the causal drug in difficult situations when the patient is taking several drugs. METHODS: Cases of drug-induced cutaneous side-effects associated with various systemic syndromes related to anticonvulsants (carbamazepine, phenytoin and phenobarbitone), minocycline, allopurinol, abacavir and nevirapine were collected retrospectively from the French Pharmacovigilance database (FPD) over a period of 15 years (1985-2000). The clinical patterns typical of the causative drugs were described and compared with data from the literature. RESULTS: Two hundred and sixteen patients with symptoms and signs consistent with cutaneous drug reactions with systemic symptoms were reported to the FPD during this period of time. Their pattern was similar to published data for these drugs, with fever, cutaneous eruption, hepatic abnormalities and eosinophilia being the most prominent but inconstant symptoms. There are clues suggesting that some particular lesional patterns may exist for some drugs. CONCLUSIONS: Although some trends emerge from these retrospective data, they suggest that no clear, unified outline can currently be defined for these multi-organ drug-induced reactions. Instead, a constellation of various symptoms and signs were recorded, that might be sorted in different patterns according to the causal drug, a finding that might indeed improve accurate identification of the causative drug in patients receiving several principal medications at a time. A national prospective study systematically collecting standardized data is required better to define the outlines of these severe adverse drug reactions and to evaluate prognostic data.

Performance analysis of a rapid HPLC determination with the solvent demixing extraction of HIV antiproteases and efavirenz in plasma.

A rapid and simple high-performance liquid chromatographic method without internal standardization is evaluated for the drug-level monitoring of most marketed antiproteases and efavirenz. Following plasma deproteinization with acetonitrile, the analytes are extracted into the solvent while it is demixed by the addition of a saturating amount of neutral salt. The organic supernatant is diluted by half with water up to the polarity of the mobile phase before being injected. The isocratic mobile phase is unbuffered water-acetonitrile (52:48), and the stationary phase is LiChrospher 100 RP-8 (5 microm). Analytes are eluted between 4 min (amprenavir and indinavir) and 20 min (nelfinavir). A spreadsheet program including analysis of variance (ANOVA) and regression is used for both the overall validation of milligrams-per-liter determinations and the performance evaluation of analytical steps from chromatographic raw data. Extraction shows acceptable 5% repeatability and nearly 100% recovery, although it is somewhat concentration-dependent. The calibration function is better fitted by bilogarithmic than arithmetical regression, and the ANOVA of raw data is found quite predictive of the quality of the final determinations.

Application of a standardized coextractive cleanup procedure to routine high-performance liquid chromatography assays of teicoplanin and ganciclovir in plasma.

Deproteinization of plasma samples with acetonitrile followed by coextracting acetonitrile and lipophilic solutes with chloroform, as already proposed for methotrexate, is stressed as a general sample cleanup procedure for liquid chromatography of highly polar drugs, and was validated for two more applications: teicoplanin and ganciclovir. A dedicated "prevalidation" experimental design was used to assess performances of both assays, including sample preparation. Deviations from linearity were less than 10% over the ranges of 3.1 to 50 mg/l (teicoplanin) and 0.2 to 15 mg/l (ganciclovir), respectively, and limits of quantitation were 0.09 and 0.01 mg/l, respectively. Mean chromatographic measurement R.S.D.s were 4.6% and 1.9%, respectively, with an additional mean cleanup R.S.D. of 2% for both. Mean analyte losses ascribable to cleanup were 6% and 2.5%, respectively from water, and 18% and 12%, respectively from the plasma matrix.

Prevalidation statistical design to assess analytical methods. Example of a quick liquid chromatographic assay of itraconazole in serum.

(A) An analysis-of-variance spreadsheet program is presented which allows to readily test and/or quantitate in a single run analytical linearity, matrix effect on recovery, repeatability of measurement and of extraction and the ruggedness of these features for up to three sessions. Owing to napierian logarithmic transformation, ANOVA mean squares directly read as relative standard deviations and checking linearity is straightforward. (B) A quick assay for therapeutic drug monitoring of itraconazole and its main metabolite was devised with the help of the program, and subsequently validated according to current quality control recommendations. The assay involves acetonitrile demixing extraction, reversed-phase HPLC and UV detection and shows acceptable performance from 0.06 to 5.0 mg/l (limit of detection about 0.03 mg/l). The prevalidation design fairly predicted precision and accuracy, was more informative about matrix effect and was even more demanding about analytical linearity.

High-performance liquid chromatographic determination of fluconazole in plasma.

A high-performance liquid chromatographic method with ultraviolet absorbance detection at 260 nm was developed for the analysis of fluconazole in plasma. The method involves sample clean-up by liquid-liquid extraction. The proposed technique is reproducible, selective, reliable and sensitive. Calibration standards were prepared in the range 1.25-20 mg/l. The limit of quantitation was 0.4 mg/l. The coefficients of variation were 5% between measurements of a single extract injected in duplicate, and 7% between two extractions of spiked samples at the same concentrations. The separation between fluconazole and endogenous substances was satisfactory. This method was designed in order to minimise the risk of interference from substances that could be co-administered to critically ill patients undergoing hemodiafiltration. With a run time below 5 min, the present method is rapid and easy to use for later clinical studies, as well as for routine monitoring.

Determination of methotrexate and 7-hydroxymethotrexate by liquid chromatography for routine monitoring of plasma levels.

A high-performance liquid chromatographic (HPLC) method was designed to meet analytical and metrological requirements for routine blood level monitoring of methotrexate (MTX) and its main metabolite 7-hydroxymethotrexate (7OMTX). The metabolite, unavailable as a pure substance, was measured by reference to MTX calibration according to their respective ultraviolet absorbances. Acetonitrile deproteinization and chloroform clean-up provided plasma samples devoid of long-retained contaminants. The precision of the HPLC measurements, reproducibility of clean-up recovery, matrix effects and linearity were assessed by analysis of variance and linear regression in an appropriate experimental design, within a range from 0.205 to 16.7 mg/l of MTX and from 0.084 to 6.83 mg/l of 7OMTX. The clean-up recovery from plasma was 88% for MTX and 72% for 7OMTX, owing to retention on the protein precipitate. The assay was linear, the measurement precision was 3.3% for MTX and 6.2% for 7OMTX and the clean-up reproducibility was 4% for MTX and 3.6% for 7OMTX. By reference to automated fluorescence polarization immunoassay, the HPLC method resulted in plasma MTX values 10% lower, probably owing to the higher specificity of HPLC. Unsystematically sequenced plasma samples from 35 children following 24-h MTX infusions provided estimated half-decay times of 16 and 19 h for MTX and 7OMTX, respectively, and 7OMTX:MTX concentration ratios of 7 at 48 h and of 5 at 72 h from starting infusions.

High-performance liquid chromatographic determination of cis-dichlorodiammineplatinum(II) in plasma ultrafiltrate.

A reproducible, simple and sensitive high-performance liquid chromatographic method was described for the quantitative analysis of cis-diamminedichloroplatinum(II) (CDDP) in ultrafiltrate plasma in the presence of nickel chloride as internal standard. CDDP and the internal standard were chelated by exchange with diethyldithiocarbamate. After derivatization, the mixture was directly injected into the column. Chromatography was performed on an Ultrasphere column and the eluent measured spectrophotometrically at 260 nm for CDDP and at 250 nm for the internal standard. The peak area ratio of CDDP to the internal standard varied linearly with concentration over the range 0.05-10 micrograms ml-1. Precision and reproducibility were both excellent and the limit of quantification was 0.03 micrograms ml-1 using only 0.5 ml of ultrafiltrate. The present method, without extraction, should be entirely automated. This assay may be suitable for therapeutic drug monitoring in patients receiving CDDP.

Performance analysis of a reversed-phase liquid chromatographic assay of lamotrigine in plasma using solvent-demixing extraction.

A reversed-phase column liquid chromatographic assay is described and validated for lamotrigine, a new anticonvulsant drug. The drug and its internal standard were extracted from plasma into acetonitrile according to a previously described solvent-demixing procedure, separated on LiChrospher 100CN, and measured by ultraviolet absorption at 280 nm. The assay performance was evaluated through analysis of variance and of regression with our usual validation design. The method detects ca. 2 ng (55 micrograms/l x 30 microliters) and shows a linear response with a constant 5% coefficient of variation from 1 to 10 mg/l. It is easy and robust, and seems well suited to therapeutic drug monitoring.

Pharmacokinetics of an indomethacin pro-drug: apyramide after intravenous administration in dog.

The pharmacokinetics of apyramide, an ester of indomethacin and acetaminophen (paracetamol), were determined after intravenous administration to nine beagle dogs. Indomethacin and its pro-drug, apyramide, were extracted from acetonitrile-precipitated plasma by a solvent-demixing procedure and the concentration of these two drugs was measured by a reversed-phase liquid chromatographic assay. The kinetic evolution with time of plasma levels of apyramide and of indomethacin resulting from enzymatic hydrolysis was compared with values obtained for indomethacin injected in equimolar dose. Plasma levels of apyramide quickly decreased and the mean (+/- SD) half life was 0.15 +/- 0.08 h. For metabolic indomethacin, the mean (+/- SD) area under curve was 12.36 +/- 4.80 mg.h/l and the mean (+/- SD) half life of terminal phase was 16.71 +/- 9.46 h. After administration of indomethacin, these values were 17.60 +/- 4.12 mg.h/l and 7.89 +/- 2.20 h, respectively.

Carbamazepine and its 10,11-epoxide metabolite in acute mania: clinical and pharmacokinetic correlates.

The study was designed to investigate the antimanic profile of carbamazepine as a first-line drug in affective or schizoaffective disorders, to correlate the clinical efficacy with the plasma level of carbamazepine and its 10,11-epoxide metabolite, and to test the potential value of monitoring the salivary level. It was administered alone for 3 weeks to 21 acute manic inpatients. During the first week, the dosage was rapidly increased to 800 mg/day in order to produce steady-state plasma levels of carbamazepine on Day 7. The individual dose was then adjusted to maintain the therapeutic range of 8-12 mg/l. Plasma and saliva levels of the drug and its metabolite, as well as clinical status were assessed weekly. Overall, there was 62% globally improved patients and 77% in affective disorders. The improvement of manic symptoms was significantly lower in schizoaffective than in affective disorders, whereas the dropout rate and the need for antipsychotic medication was higher in the former group. The antimanic response was significantly correlated with the plasma levels both of carbamazepine and its epoxide metabolite, with a time-lag consistent with a delayed drug effect. Drug and metabolite concentrations in saliva were close to their plasma free fraction and were strongly correlated with their plasma levels, suggesting the potential value of salivary drug monitoring.

Liquid chromatographic assay of heptaminol in serum and its oral pharmacokinetics in the dog.

In order to investigate the pharmacokinetics of heptaminol in dogs, a high-performance liquid chromatographic assay of the drug was devised and it was evaluated in a general purpose validation design through analysis of variance. Heptaminol and its internal standard n-propylamine were salted out from plasma together with acetonitrile, the previously proposed "solvent demixing " extraction procedure. Both amines were derivatised in acetonitrile with the o-phthaldialdehyde, 2-mercaptoethanol procedure of Roth. The adducts were quantitated by reversed-phase high-performance liquid chromatography on Radial-Pak cartridges with ultraviolet detection. Peak height ratios were linearly related to concentrations up to 250 mumol l-1 with a 2% coefficient of variation. Sensitivity was 3.5 mumol l-1 (signal-to-noise ratio of 5). Means of the usual pharmacokinetic parameters in four dogs were: elimination half-life 3.75 h, apparent distribution volume 2.18 l kg-1 and total clearance 0.402 l kg-1 h-1, similar to the results obtained in humans by other authors using radiolabelled heptaminol .