An Expensive Phosphoprotein phosphatase Conspriracy

915 (0.86�C0.95, p?PF-06463922 analysis were also acceptable as described below: Bioassay?=?0.742(HPLC)?+?0.026; R2?=?0.871, with a coefficient of correlation?=?0.931; n?=?61 runs (Fig.?2). We describe and compare two different methodologies, HPLC and a bioassay, for posaconazole quantification from clinical samples. Both methods offer interesting advantages. HPLC has been described as a more accurate, precise and faster methodology, being a useful tool for therapeutic drug monitoring and pharmacokinetic studies [19]. We found in our study that the HPLC method offers superior precision and accuracy compared with the microbiological method (Table?2). Additional advantages such as a simple sample pre-treatment procedure (single-step protein precipitation with acetonitrile [13]), the use of ravuconazole as ES (with similar chemical profile to ensure a comparable chromatographic behaviour) or the use of a simple mobile phase without buffers or additives [11,13,20,21] make this a valuable method for posaconazole quantification. However, such facilities might not be available in all clinical microbiology laboratories whereas bioassay facilities are almost certainly available. The proposed bioassay has been shown to be a simple, Bafilomycin A1 datasheet inexpensive and reliable method for posaconazole quantification. Our data demonstrate sufficient accuracy and precision in spite of the intrinsic variability described for this methodology (natural antifungal serum activity [22,23] or the inhibition zones measurement bias). However, it is worth noting that Phosphoprotein phosphatase bioassay has important limitations; first, bioassay quantifies the antifungal activity, but fails to identify the drug or its active metabolites. In addition, total inhibition zones can be modified by concomitant antifungal drugs, and therefore they might not represent correctly the serum antifungal concentration. In this study, we found that results are comparable using these two different methodologies (ICC value 0.915). Linear regression analysis also shows a good correlation value between bioassay and HPLC (coefficient of correlation?=?0.931) and comparable results (slope 0.742). Values in the HPLC are slightly greater, probably because of the accuracy of the chromatographic method compared with that of the bioassay, where an agar diffusion procedure occurs before drug quantification. Another point to consider is that although the lower limit of quantification (0.125?��g/mL) of these two methods is relatively high compared with that of the other reported methods such us ultra-performance liquid chromatography-UV or liquid chromatography�Ctandem mass spectrometry [13,15,21,24], the linearity range described here effectively covers what is currently believed to be the clinically relevant range for posaconazole concentrations in serum or plasma (the Food and Drug Administration briefing document recommends a goal posaconazole average serum drug concentration of 0.