Automated determination of midazolam in human plasma by high-performance liquid chromatography using column switching.

An automated gradient high-performance liquid chromatographic method using a column-switching technique was developed in order to determine and quantify midazolam (separated from the metabolite alpha-hydroximidazolam) in human plasma. After dilution with an internal standard (flurazepam) solution, containing 20% acetonitrile, 400 microliters of the plasma samples were injected onto a precolumn (17 x 4.6 mm I.D., C18 Corasil 37-53 microns) and retained. Proteins and polar plasma components were washed out using a 0.1 M sodium hydroxide solution, followed by an equilibration with a phosphate buffer of pH 8.0. After column-switching midazolam and flurazepam were eluted and transferred to the analytical column (RP-select B) in the backflush mode, separated by gradient elution and detected at 230 nm by ultraviolet detection. Precision of replicate analyses on the same day was 1.5% for midazolam and 0.7% for flurazepam. Recovery of midazolam was in the range 80-89% and the detection limit was 2 ng/ml plasma.

[Excessive watery diarrhea and pronounced fatigue due to Cyclospora cayetanensis infection in an HIV infected traveler returning from the tropics]. / Exzessive wässrige Diarrhoe und Leistungsminderung durch eine Cyclospora-cayetanensis-Infektion bei einem HIV-infizierten Tropenaufenthalter.

We report the case of a 46-year-old HIV-1 infected patient who acquired a Cyclopsora cayetanensis infection during travel to southeast Asia. He developed excessive watery diarrhoea and pronounced fatigue, which resolved after treatment with cotrimoxazole. The term Cyclospora cayetanensis was first suggested in 1993 for the infectious agent of diarrhoea in tropical and subtropical regions. The infection is usually self-limiting. However, in HIV-1 infected persons the symptoms are often more severe and protracted. Microbiological diagnosis is performed by light microscopy and at X400 magnification of faeces fixed in SAF medium or 10% formalin preservatives.

An evaluation of the Rapid Infusion System.

The performance of the Rapid Infusion System was evaluated in the laboratory. Using a conventional mixture of two units of packed red cells, two units of fresh frozen plasma and 500 ml crystalloid, a single line and a driving pressure of 300 mmHg, the highest flow in our study was 970 ml.min-1 (2.8 mm catheter, no stopcock). With a 1.6 mm venous cannula the measured flow was 640 ml.min-1. Additional diluting of the standard 'blood cocktail' did not add much to the performance of the system. When primed with tap water 21 degrees C (12 degrees C respectively), the fluid at the outlet of the system reached a maximum temperature of 37.8 degrees C (37.4 degrees C) after 6 min at a flow of 400 ml.min-1. At flows higher than 1150 ml.min-1 (priming with 12 degrees C tap water: 800 ml.min-1), the system slowed down to flows of 700 to 1000 ml.min-1 in order to maintain an adequate temperature. We conclude, that the Rapid Infusion System is a valuable tool for situations where a rapid but controlled replacement with warmed blood at rates up to at least 1100 ml.min-1 is needed. The use of large bore intravenous catheters and avoiding additional resistors such as standard 3-way stopcocks is highly recommended.