Search

Background Skin adverse events associated with D-Penicillamine ( DPA) are common and multi-faceted, although the presence of DPA or its metabolites has never been documented in the skin, because of inherent difficulties in determining its tissue levels. Thus, the association between DPA and DPA-related dermatoses has been only hypothesized on the basis of careful history, clinical observation and typical histopathological findings. Objective To detect DPA in biopsy specimens in a unique case of 25-year-late-onset elastosis perforans serpiginosa and pseudo-pseudoxanthoma elasticum associated with a history of long-term high dose DPA, by applying a recently described analytical method to assess the presence of DPA in skin. Methods We used a reliable analytical method based on high-performance liquid chromatography coupled with amperometric detection to look for the presence of DPA in skin biopsy specimens. Results A chromatographic peak corresponding to DPA was evidenced in some affected skin samples collected from the patient. Conclusion We documented the effective presence and the persistence after 25 years of DPA in the skin of a woman affected by elastotic cutaneous change due to a long-term therapy with DPA. This report provides further evidence of the relationship between DPA deposit in affected skin and clinical manifestation. [ABSTRACT FROM AUTHOR]

A simple and sensitive HPLC (high performance liquid chromatography) method has been developed for the qualitative and quantitative analysis of several CNS (central nervous system) drugs in clinical and forensic toxicology. The leading conditions were studied, namely parameters such as mobile phase pH, organic modifier percentage, and salt concentration. An isocratic HPLC elution, using a mobile phase composed of acetonitrile and pH 2.8 aqueous tetramethylammonium perchlorate and a C8 reversed phase column as the stationary phase, was found to be convenient for the separation of several CNS drugs, and for their detection and quantitation. The identification of the drugs was assured using their relative retention times, together with the peak area ratios at two different wavelengths (230 and 270 nm). A quick pre-treatment of the plasma samples, based on a SPE (solid phase extraction) procedure, with good extraction efficiency and satisfactory selectivity was developed. Under these conditions, a mixture of fifteen CNS drugs (including antipsychotics, antidepressants and antiepileptics) and some selected active metabolites, was well separated for identification and quantitative determination purposes. [ABSTRACT FROM AUTHOR]

An HPLC method with electrochemical detection has been developed for the determination of clozapine and its main metabolites, desmethylclozapine and clozapine N-oxide, in human plasma. An accurate pretreatment of the biological samples was implemented by means of solid phase extraction (SPE) on HLB cartridges. This improved pretreatment, together with a new mobile phase, allows for the accurate determination of clozapine N-oxide, which could not be quantitated by a previous method. The method uses only 100 μL of plasma for one complete analysis and shows good recovery values for all three analytes. The eluates from the SPE procedure were chromatographed in a reversed phase C18 column using a mobile phase composed of phosphate buffer, acetonitrile and methanol. Clozapine, desmethylclozapine and clozapine N-oxide were eluted in less than 10 minutes, without any interference from the biological matrix. Linearity was observed over the 2.50–150 ng mL−1 (clozapine and desmethylclozapine) or 1.25–75 ng mL−1 clozapine N-oxide) range for the three analytes, with satisfactory repeatability values. The limit of detection was 0.3 ng mL−1 for clozapine and desmethylclozapine, samples of patients treated with Leponex gave good results. No interference from other common central nervous system drugs was found. This method seems to be a useful tool for pharmacokinetic studies and for clinical monitoring, because of its need for small plasma samples and its high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5 μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective, has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex® tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as well as for therapeutic drug monitoring. [ABSTRACT FROM AUTHOR]

A sensitive and selective high-performance liquid chromatographic method has been developed for monitoring clozapine levels in human plasma. Chromatography was performed on a reversed-phase column (C8, 150 mm×4.6 mm i.d., 5 μm) with acetonitrile-aqueous sodium acetate solution, 88∶12 ( v/v), as mobile phase; the flow rate was 1 mL min−1. Clozapine oxidation at +800 mV was detected amperometrically. Response was linearly dependent on concentration over the range 50–1500 ng mL−1 clozapine in plasma. Sample preparation by solid-phase extraction before HPLC analysis gave high extraction yield (94%). The accuracy and precision of the method were both very good (recovery: 97%; RSD<3.3%). [ABSTRACT FROM AUTHOR]

The aim of this investigation was the study and development of analytical procedures suitable for the assay of glutathione (GSH) in pharmaceutical formulations. Two are based on isocratic HPLC with a 250 mm×4.6 mm i.d., 5 μm C18 column and UV detection. In the first procedure sample solutions were injected without pretreatment whereas in the second the samples were injected after derivatization with Ellman’s reagent which forms an easily detectable adduct with GSH. Good linearity was obtained over the range 0.12–6.00×10−4M for the direct procedure and 0.25–3.00×10−4M for the derivatization procedure. The precision and rapidity of analysis were also good for both methods. The third method is based on capillary zone electrophoresis (CZE) in a 27 cm×75 μm i.d untreated fused silica capillary containing pH 7 phosphate buffer. All results are in good agreement with a spectrophotometric procedure used as reference method. [ABSTRACT FROM AUTHOR]