Multicentre evaluation of the Boehringer Mannheim/Hitachi 717 analysis system

We conducted an European multicentre trial to assess the performance of the new Boehringer Mannheim/Hitachi 717 analysis system. The photometer response was linear up to an absorbance of 2.8. The maximal CV of photometric imprecision was 0.5% for the wavelength pair 340/405 nm within the absorbance range 0.9 to 2.4. For the 13 analytes in our study, mean within-run imprecision was less than 2%, and mean between-day imprecision less than 2.5%. The results obtained with the Hitachi 717 instrument correlated closely with those of comparison instruments. Linearity for the various tests was high and exceeded the manufacturer's claims. No drift was detected during an 8-hour work period; carry over could not be detected under the chosen experimental conditions. The new instrument was readily accepted by the evaluators because of its ease of handling and simple daily maintenance.     

A multicentre evaluation of the Boehringer Mannheim/Hitachi 704 analysis system

The selective multitest Boehringer Mannheim/Hitachi 704 analysis system was examined according to the ECCLS guidelines in a multicentre evaluation involving four laboratories. Ten routine parameters, covering most of the application settings of the instrument, were measured in the respective laboratory at temperatures 25, 30 or 37 degrees C. The trial lasted four months and gave more than 40,000 data. It yielded the following results: 1. Within the four laboratories the mean coefficients of variation for three control sera at different concentrations were found to be equal to or better than 1.6% for the within-run imprecision and 2.8% or better for the between-day imprecision. 2. No drift was observed during eight hours. 3. Because of the high linear measuring range a re-run analysis was seldom necessary. 4. Sample-related carry-over was not seen. Reagent-dependent carry-over was measured from cholesterol to uric acid and from triacylglycerols to lipase. Through modification of the cholesterol and triacylglycerol reagents, the carry-over effect was practically eliminated. 5. The recovery of the assigned values of control sera showed average values between 99 and 104%. For bilirubin, creatinine, creatine kinase and alanine aminotransferase some control sera showed deviations greater than 10%. 6. In all cases, regression analysis of the results obtained in comparisons of the present instrument with the Hitachi 705 or 737 yielded slopes close to unity with extreme values of 0.95 and 1.06. 7. During the entire evaluation period there was no malfunction or breakdown of the instruments. The evaluators came to the conclusion that the analytical performance as well as the reliability and practicability of the Hitachi 704 can be rated as excellent.     

User-defined serum aspartate and alanine aminotransferase, cholesterol, triglycerides, urea, and uric acid for the Beckman synchron CX 4/5 using Ames Sera-Pak reagents.

Beckman aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol, triglycerides, urea, and uric acid Liquid Reagents for Synchron CX 4/5 (48, 48, 25, 60, 26, and 30 cents US/test, respectively) are expensive. We have established our own methods for serum AST, ALT, cholesterol, triglycerides, urea, and uric acid (6, 6, 5, 12, 13, and 6 cents US/test, respectively) using Ames Sera-Pak reagents. Linearity of our AST, ALT, cholesterol, triglycerides, urea, and uric acid methods were either similar to or higher than the Beckman methods. The within run and day-to-day run precisions were acceptable. Recovery of our AST, ALT, cholesterol, triglycerides, urea, and uric acid were excellent. Our results for AST, ALT, cholesterol, triglycerides, urea, and uric acid correlated well with the Beckman results. Bilirubin (340.8 mumol/L) did not significantly interfere on our AST, ALT, cholesterol, triglycerides, and urea, while its concentrations of 165.8 mumol/L started giving negative interference on uric acid. Turbidity (2+) did not interfere significantly on our AST and ALT but started giving positive interference on cholesterol, triglycerides, urea, and uric acid. Hemolysis (2+) gave positive interference on our cholesterol, triglycerides, urea, and uric acid. Stability of Ames Sera-Pak working reagents was at least 30 days for AST, ALT, urea, and uric acid and 40 days for cholesterol and triglycerides.     

Development and evaluation of a vancomycin dosing nomogram to achieve the target area under the concentration-time curve. A retrospective study

Although the superiority of vancomycin dosing based on area under the concentration-time curve (AUC_0-24) over that based on trough concentration has been reported, a dosing strategy to achieve the target AUC_0-24 has yet to be developed. The objective of this study was to develop a convenient useable nomogram for vancomycin dosing to obtain the target AUC_0-24 (400 μg h/mL). The nomogram was pharmacokinetically developed in a retrospective manner. The number of enrolled patients and concentrations was 166 and 309 for development of the nomogram, 99 and 181 for evaluation of the nomogram, respectively. The nomogram was developed as doses per personal body weight corresponding to each range of estimated glomerular filtration rate (eGFR), which was identified to be the covariate for vancomycin clearance by non-linear mixed effect modeling. The nomogram described the surrogate trough concentration for the target AUC_0-24 was calculatedly different for each eGFR range (9.3–15.0 μg/mL). The rate of attainment of therapeutic range using surrogate trough concentration to obtain the target AUC_0-24 was 63.8% in the evaluation period. We have developed and evaluated the first convenient useable nomogram of vancomycin dosing to obtain the target AUC_0-24.