Jantien J. Kettenes-van den Bosch

Poly(N‐isopropylacrylamide) with hydrolyzable lactic acid ester side groups: a new type of thermosensitive polymer

N-isopropylacrylamide (NIPAAm) was copolymerized with 2-hydroxyethyl methacrylate-monolactate (HEMA-monolactate). With increasing HEMA-monolactate content in the copolymer, the lower critical solution temperature (LCST) decreases. During incubation in an aqueous solution, the lactate groups are released by hydrolysis, by which the copolymer is converted into poly(NIPAAm-co-HEMA). By this process, the hydrophilicity of the copolymer increases, resulting in increased LCST values.

Simple and selective determination of the cyclophosphamide metabolite phosphoramide mustard in human plasma using high-performance liquid chromatography.

A simple and selective assay for the determination of the alkylating cyclophosphamide metabolite phosphoramide mustard (PM) in plasma was developed and validated. PM was determined after derivatisation by high-performance liquid chromatography (HPLC) with ultraviolet detection at 276 nm. Sample pre-treatment consisted of derivatisation of PM with diethyldithiocarbamate (DDTC) at 70 degrees C for 10 min, followed by extraction with acetonitrile in the presence of 0.7 M sodium chloride. Phase separation occurred due to the high salt content of the aqueous phase. The HPLC system consisted of a C8 column with acetonitrile-0.025 M potassium phosphate buffer, pH 8.0, (32:68, v/v) as the mobile phase. The entire sample handling procedure, from collection at the clinical ward until analysis in the laboratory, was optimised and validated. Calibration curves were linear from 50 to 10,000 ng/ml. The lower limit of quantification and the limit of detection (using a signal-to-noise ratio of 3) were 50 and 40 ng/ml, respectively, using 500 microl of plasma. Within-day and between-day precisions were below 11% over the entire concentration range and the accuracies were between 100 and 106%. PM was found to be stable at -30 degrees C for at least 10 weeks both in plasma and as a DDTC-derivative in a dry sample. A pharmacokinetic pilot study in two patients receiving 1,000 mg/m2 CP in a 1-h infusion demonstrated the applicability of the assay.

Capillary zone electrophoresis–mass spectrometry as a tool in the stability research of the luteinising hormone-releasing hormone analogue goserelin

Abstract A capillary zone electrophoresis (CZE)–MS system for peptide analysis was developed, characterised and applied in the stability research of goserelin, a luteinising hormone-releasing hormone analogue. 10% acetic acid was used as running solution. An important aspect of this CZE–MS system is its relative insensitivity to injection volume size and ions in sample solutions. As a result of the low pH (2.3) of the running solution, the endoosmotic flow was minimal, resulting in mainly electrophoretic movement and, therefore, relatively high resolution. Degraded samples of goserelin at pH 5 and 9 were subjected to analysis with this CZE–MS system. Information was obtained about the degradation of the C-terminal semi-carbazide group. A major difference between CZE and LC is that goserelin epimers are not separated in the CZE system, whereas they are in the RP-HPLC system.

High-performance liquid chromatographic determination of stabilized 4-hydroxyifosfamide in human plasma and erythrocytes

A method using reversed-phase high-performance liquid chromatography (RP-HPLC) is described for the measurement of the stabilized activated metabolite of ifosfamide, 4-hydroxyifosfamide (4-OHIF), in human plasma and erythrocytes. Immediately after sample collection and plasma-erythrocyte separation at 4 degrees C, 4-OHIF was stabilized by derivatization with semicarbazide (SCZ). The sample pretreatment involved liquid-liquid extraction with ethyl acetate. RP-HPLC was executed with a C8 column and acetonitrile-0.025 M potassium dihydrogenphosphate buffer (pH 7.40)-triethylamine (13.5:86:0.5, v/v) as mobile phase. The analyte was determined with UV detection at 230 nm. Complete validation, optimisation and stability studies were performed and the method proved to be specific, sensitive and with a stable analyte in the range of clinically relevant concentrations (0.1-10 microg/ml) after conventional dosing. The lower limit of quantitation was 100 ng/ml using 1.00 ml of sample. Accuracy was between 94.1 and 107.0%. Within-day and between-day precisions were less than 6.2% and 7.2%, respectively. 4-OHIF-SCZ was found to be stable in the biological matrix at -20 degrees C for at least 1 month. A pharmacokinetic study conducted in a patient receiving 9 g/m2 over 3 days by means of a continuous infusion, demonstrated the applicability of this method.

Pharmaceutical development of a parenteral lyophilized formulation of the novel indoloquinone antitumor agent EO9

The aim of this study was to design a stable parenteral dosing form of the investigational cytotoxic drug, encoded EO9. EO9 exhibits poor aqueous solubility and stability characteristics. Freeze-drying was selected as the manufacturing process. Differential scanning calorimetry studies were conducted to determine the freezedrying cycle parameters. A stable lyophilized formulation of EO9 was developed. The prototype, containing 8.0 mg EO9 and 200 mg lactose/vial, was found to be the optimal formulation in terms of solubility, length of the freezedrying cycle, stability, and dosing requirements for phase I clinical trials. Quality control of the freeze-dried formulation showed that the manufacturing process does not change the integrity of EO9. Shelf-life studies demonstrated that the formulation remains stable for at least 1 year when stored at +4°C in a dark environment.

SYNTHESIS AND ELECTROSPRAY MASS SPECTROMETRIC STUDIES ON A CHIRAL, NON-RACEMIC, PHOSPHORAMIDE RECEPTOR MOLECULE

Abstract The synthesis of a class of macrocyclic receptors containing a phosphoramide is described. The preliminary evaluation of this new receptor for interactions with several homochiral amines using electrospray ionisation mass spectrometry is also described.

Pharmaceutical development of a parenteral formulation of the novel anti-tumor agent carzelesin (U-80,244)

SummaryThe aim of this study was to design a parenteral dosage form for the investigational cytotoxic drag carzelesin. A stable formulation in PET (Polyethylene glycol 400/absolute ethanol/Tween 80, 6:3:1, v/v/v) was developed. The prototype, containing 0.50 mg carzelesin in 2.0 ml PET formulation, was found to be the optimal formulation in terms of solubility, stability and dosage requirements in phase I clinical trials. Quality control of the formulation showed that the pharmaceutical preparation of carzelesin in PET is not negatively influenced by the manufacturing process. Shelf life studies demonstrated that the formulation is stable for at least 1 year, when stored at −30°C in the dark. In addition, the stability of carzelesin in the PET formulation is discussed as a function of temperature, additives and after dilution in infusion fluids.