Pharmaco-economic aspects of the treatment of hypertension

The Periotron is an instrument designed to quantify submicrolitre volumes of fluid sampled on a filter paper strip. To date 3 models have been manufactured: the Periotron 600 (1976), the Periotron 6000 (1983) and more recently the Periotron 8000 (1995). This paper investigated for the first time the calibration characteristics and reliability of the Periotron 8000. The fluids under investigation were: de-ionised water, human serum, fetal bovine serum and an ultrafiltrate of fetal bovine serum. Quantitative analysis was studied by recording a series of Periotron readings over a volume range of 0-1.0 microliters for each fluid. The average of 5 Periotron values for each particular fluid was then plotted versus the respective fluid volume. Qualitative changes in fluid composition versus Periotron Scores were also analysed. Volume conversion for Periotron scores using both Periotron MLCONVRT software and a best fit equation selected from TableCurve 2D software compared well. The results of this study revealed that: 1) differences in calibration fluid composition (e.g. protein content) are reflected in the Periotron scores; 2) positioning of filter paper strip between the jaws of the Periotron should be standardised, 3) calibration of the Periotron 8000 seems to be consistent over a 1-wk interval.