Pharmacokinetics and Dynamics of Heparin in Patients with Proximal Vein Thrombosis

A Bayesian Formulation of the Kalman Filter Applied to the Estimation of Individual Pharmacokinetic Parameters

“…The appropriate therapeutic range depends on the condition being treated. For example, following myocardial infarction, a recommended therapeutic range is 1.5 to 2.5 times the baseline APTT (6,8). Again, useful results may be obtained with as few as one or two APTT results.…”

“…It was noted while running the simulations that the method is relatively insensitive to values of the parameter M. This is most likely due to the fact that the parameters K m and V m , which dominate in Eq. [6], are simply constrained to be positive real numbers. More realistic constraints should improve the sensitivity.…”

“…Initial parameters and variances were based on published data (6,7). The results of a simulation are shown in Table 3.…”

Pharmacokinetics of Heparin and Low Molecular Weight Heparins

“…Commercially available LMWHs main tain some of the kinetic features of low mo lecular components of high-affinity heparin and show a preferential effect against factor Xa [6,12]; when their kinetics are studied through the indirect measure of anti-Xa ac tivity, they show a half-life longer than that of heparin (2.1 -4.4 h) [6] and a higher bio availability after subcutaneous administra tion (90 vs. 20%) [6,[13][14][15], In animal mod els, this higher bioavailaility is associated with a higher and more persistent protection from experimental thrombosis, thus sup porting the relevance of anti-Xa activity for antithrombotic efficacy [5].…”

“…Moreover, it has been shown that heparin has a dose-dependent kinetics [3][4][5], and, therefore, the results obtained in different studies must be compared taking into ac count the doses that have been used. While the metabolism or transfer of heparin is sat urable also at the doses normally adminis tered for therapeutic use, the available evi dence suggests that the kinetics of LMWHs is linear [6,7], and this, from a practical point of view, might simplify dose adjust ments.…”