Synthesis of the impurities during the manufacture of bulk drug midazolam and separation of these impurities by HPLC.

During the manufacture of bulk drug midazolam various impurities arised that can be the related products or degradation products. Structures of eight impurities that can arise during the manufacture of bulk drug midazolam were proposed. In the present work, synthesis of these impurities and their characterization by different spectroscopic techniques have been done. HPLC method was developed for the separation of impurities from the bulk drug. The developed method separates midazolam from its eight impurities/degradation products within a run time of 45 min.

Synthesis of stable isotope labelled internal standards for drug-drug interaction (DDI) studies.

The syntheses of stable isotope labelled internal standards of important CYP-isoform selective probes, like testosterone 1, diclofenac 3, midazolam 5, and dextromethorphan 7, as well as their corresponding hydroxylated metabolites 6ß-hydroxytestosterone 2, 4'-hydroxydiclofenac 4, 1'-hydroxymidazolam 6 and dextrorphan 8 are reported. Microwave-enhanced H/D-exchange reactions applying either acid, base, or homogeneous and heterogeneous transition metal catalysis, or combinations thereof proved to be highly efficient for direct deuterium labelling of the above mentioned probes. Compared to conventional stepwise synthetic approaches, the combination of H/D exchange and biotransformation provides the potential for considerable time- and cost savings, in particular for the synthesis of the stable isotope labelled internal standards of 4'-hydroxydiclofenac 4 and 1'-hydroxymidazolam 6.

Microbial production of phase I and phase II metabolites of midazolam.

Midazolam, a potent benzodiazepine derivative and a typical substrate of CYP3A4/3A5, is essentially metabolized in human into 1'-hydroxymidazolam, then eliminated as the corresponding phase II metabolite, the 1'-O-ß-D-glucuronide derivative. A high yield alternative to the current multistep synthesis of 1'-hydroxymidazolam is described, using a biotransformation of midazolam by a fungal microorganism, Beauveria bassiana. The corresponding phase II metabolite, 1'-hydroxymidazolam-1'-O-ß-D-glucuronide, has been then prepared by chemical synthesis (3 steps, 20% yield), or by microbial glucuronidation (one step, 20% yield) using a Streptomyces sp. strain. The use of the same Streptomyces strain allows a direct and expeditive synthesis of the same glucuronide conjugate from midazolam itself in an advantageous 17% yield.

Development and formulation of a 0.2% oral solution of midazolam containing gamma-cyclodextrin.

In absence of dedicated children formulation, intravenous formulations of midazolam, which exhibit strong bitterness, are occasionally used for oral or sublingual administration. In order to improve the quality and the acceptance by children of a midazolam anesthesia premedication, a new 0.2% (w/v) aqueous solution for oral administration has been prepared. The final formulation was obtained by the adjunction of a sweetener (sucralose), an aroma (orange aroma) and gamma-cyclodextrin to a citric acid solution of midazolam. The gamma-cyclodextrin forms an inclusion complex with the hydrophobic midazolam as evidenced using nuclear magnetic resonance spectroscopy (stoichiometry 1:1, K=283 M(-1)). A sterile filtration method was selected for the formulation microbial preservation using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). Finally, a routine high performance liquid chromatography (HPLC) method is proposed for the quantitative determination of global midazolam amount in the pharmaceutical preparation.

In-process control of midazolam synthesis by HPLC.

A high-performance liquid chromatographic assay coupled with UV detection (239 nm) has been developed for the determination of midazolam and its synthesis precursors. The separation of the analytes was performed on a Kromasil C8 column (15 cm x 4.6 mm i.d., 5 microm) at 30 degrees C. The mobile phase [ammonium chloride (pH 5.5, 1 g l(-1))-methanolacetonitrile (45:22:33, v/v/v)] was pumped at a flow-rate of 1.5 ml min(-1). This method is rapid (less than 11 min), sensitive (limit of detection (LOD) ranged between 0.05 and 0.5 mg l(-1)) and selective for the determination of midazolam, and it could be used for monitoring different synthetic routes.

Estudio de compatibilidad galénica de mezclas anestésicas pPpofol-Midazolam / Study of pharmacotechnical compatibility of Popofol-Midazolam anesthetic mixture

Se realiza el estudio de compatibilidad galénica de una mezcla de propofol y midazolam con: objeto de determinar su posible formulación y acondicionamiento en jeringas precargadas previamente a la perfusión de la misma, o si por el contrario resulta necesaria su preparación extemporánea. En la muestra se llevan a cabo análisis del pH, del diámetro promedio y distribución de las gotitas lipídicas; así como un estudio fotomicrográfico y visual al inicio del ensayo y a intervalos de dos horas con objeto de detectar posibles variaciones significativas de dichos parámetros: Estas pueden resultar indicativas del grado de inestabilización físico-química del sistema. Las tomas de muestra se prolongan durante 36 horas que corresponden al vaciado de 3 jeringas precargadas con la emulsión anestésica previamente elaborada, en condiciones análogas a las de perfusión al paciente. La variación observada tanto en el pH como en el tamaño medio de gotitas, así como la ausencia de precipitados en el transcurso del ensayo, evidencian que no existen problemas de estabilidad físico-química de la mezcla anestésica en las condiciones habituales de aplicación a nivel hospitalario (AU)