Release cumulative fraction

Figure 8. In Vitro Cumulative Fraction Release of Prazosin from PHPG-Prazosin Conjugate.

The performance of this system is shown in Figure 17 for the release of nifedipine from the GITS system [47], The reproducibility of the release rates is remarkable. Also note that the fractions released over time from three separate doses are basically superimposable. It should also be noted that these systems have an inherent delay in the onset of drug delivery which arises from the time required to build up a sufficient hydrostatic pressure to permit release of the gel that is formed within the tablet during delivery. Figure 18 shows the comparison of the in vitro and in vivo cumulative fraction released for the 30 mg system. Clearly, the in vitro performance is mirrored in the in vivo data. 

Figure 6 shows these cumulative leach fractions from the top waste glass section. A ranking of the elements studied, based on the fraction released after 639 days of solution contact, is given in Table II. This order of leaching can also be seen in Figures 3a and 3b. 

Figure 9.11 Release of bovine serum albumin from EVAc matrices. Controlled release of BSA from an EVAc matrix. Solid particles of BSA either (a) 45 to 75 /rm or (b) 150 to 250 /rm in diameter were dispersed within EVAc by solvent evaporation to achieve final protein loadings from 10, 20, 30, 40, or 50%. In each case five identical slabs, each 70 mg and 1 mm thick, were incubated in cacodylate-buffered water containing 0.02% gentamicin. Periodically, the buffered water was replaced, and the amount of protein released from the matrix was determined by measuring the concentration of protein in the solution that was removed. Each symbol represents the average cumulative fraction of protein released (cumulative mass of protein released/initial mass of protein within the matrix) for the five samples error bars indicate the standard deviation, which in some cases are smaller than the symbols. Data from [16].

Figure 1 Release of ferritin (500-kDa protein) from a matrix of EVAc. (a) The cumulative fraction of mass released from matrices containing 35% ( ) or 50% ( ) ferritin by mass is plotted versus time, (b) The same cumulative mass fraction released from the 50% loaded matrices is plotted versus the square root of time. The dashed line represents the fit to the linear model of desorption from a slab, Eq. (5). Data points represent the mean cumulative fraction of mass of ferritin released from four EVAc matrices incubated in buffered saline at 37 °C. The error bars represent 1 SD of the mean. Some error bars are smaller than the symbols.

For cumulative fractions released of <0.6, an approximate solution can be used ... 

Figure 3. Retardation of release from a matrix. The cumulative fraction released from a 1-mm-thick matrix is plotted versus the square root of time for different assumed values of the difiusion coefficient. As the diffusion coefficient decreases, the release rate decreases. The diffusion coefficient is an appropriate parameter for characterizing the rate of release from these systems.

Figure 5. Cumulative Fraction Naltrexone Release from P(HPG/LEU)-Naltrexone-14-acetate Conjugate Particles of Various Sizes (Loading 8.4%w/w).

Cumulative Fraction Prazosin Release Prazosin (mg/Day/lOOmg Particles)... 

Plasma Naltrexone (ng/ml/mg conjugate) Cumulative Fraction Clonidine Released... 

The cumulative sums of selected major and trace metals extracted by the two SSD procedures from representative arid-zone soils are shown in Fig. 4.6. As can be seen from the figure, the Rehovot procedure is stronger in attacking desired fractions, such as the carbonate bound, Mn oxide bound and organically bound fractions. Extraction of certain major elements, indicating selectivity, specificity and completeness of extraction of given soil components, was found to differ between the two procedures. Calcium and Mg were more completely extracted from the carbonate fraction in arid zone soils by the Rehovot procedure. Calcium and relevant trace elements bound in the carbonate fraction, which were not completely dissolved by the Bonn procedure at this step, were released at the following steps, such as the ERO, OM or RO fractions. 

Abbreviations-. BEST, beta-blocker evaluation survival trial CAPRICORN, caiveclilol postinfarct suivival control in left ventricular dysfunction C1B1S II, Cardiac Insufficiency Bisoprolol Study II COMET, Carvedilol or Metoprolol European Trial COPERNICUS, carvedilol prospective randomized cumulative survival HF, heart failure LVEF, left ventricular ejection fraction MDC, metoprolol in dilated cardiomyopathy MERIT-HF, metoprolol controlled-release randomized intervention trial in congestive heart failure fJYHA, New York Heart Association. 

In vitro drug release from transbuccal disc devices was determined at 37°C using a USP dissolution apparatus connected through a microprocessor-controlled peristaltic pump to a fraction collector. The cumulative amount released as a function of time was calculated from the drug concentration data after compensating for the total amount removed in the collected sample fractions. 

This arbitrary recommendation does not rely on strict theoretical and experimental findings and is based only on the fact that completely different physical conditions have been postulated for the derivation of the equivalent (4.2) and (4.3), while the underlying mechanism in both situations is classical diffusion. In this context, a linear plot of the cumulative amount of drug released q (t) or the fraction of drug released q (f) /f/,Xj (utilizing data up to 60% of the release curve) vs. the square root of time is routinely used in the literature as an indicator for diffusion-controlled drug release from a plethora of delivery systems. 

Intracellular fluxes can be estimated more precisely through 13C tracer experiments. Following 13C feeding to a cell it is possible to analyze metabolic products, such as amino acids, and measure 13C enriched patterns, so to be able to reconstruct the flux distribution from the measured data [91]. To obtain flux data from the labeling patterns, two techniques can be applied NMR [92, 93] and MS [94, 95]. Due to the low intracellular concentration of metabolites, these are often difficult to measure therefore the analysis of the labeling pattern of amino acids in proteins is used as input for flux quantification. Here proteins are hydrolyzed to release labeled amino acids and further analyzed by NMR of GC-MS. Once NMR or MS spectra are recorded, the next step is the quantitative interpretation of the isotopomer data by using mathematical models that describe the relationship between fluxes and the observed isotopomer abundance [96, 97], Some of the mathematical approaches used include cumulative isotopomer (cumomers) [98], bondomers [99], and fractional labeling [100], For a more comprehensive review on the methods we refer to Sauer [91]. 

The importance of other factors additional to amount ofnecrosis has also been studied. In patients with first acute MI treated with PCI, LAD-related MI show for a similar amount of myocardial necrosis as determined by enzymatic infarct size, lower left-ventricular ejection fraction (LVEF) when compared to non-LAD-related MI. LVEF-measured 6-month post-MI showed a decrease, for every 1000 cumulative lactate dehydrogenase release, of 4.8% for LAD and 2.4% for non-LAD-related infarcts (p < 0.0001), and these results remain in the multivariate analysis (Elsman et al., 2006). 

The cumulative release profile of bupivacaine from the various copolymer devices are shown in Figs. 17a and 17b. The drug release occurred very slowly over a period of 15-25 days depending on the polymer used. The fractional agent release (M t/M ,) was very well described by Eq. (2) and the coefficients of the various terms in Eq. (2) were determined by polynomial regression for all the copolymers studied. The equation best describing the release profiles is as shown below ... 

Figure 9.9 Controlled release of ferritin from an EVAc matrix. Release of ferritin (500 kDa protein) from a matrix of EVAc. (a) The cumulative fraction of mass released from matrices containing 35% (circles) or 50 /o (squares) ferritin by mass.

The cumulative fraction of protein released (i.e., the amount released at time t divided by the amount originally dispersed in the matrix) is found by... 

It is critical to point out that cumulative Pb emissions and rates of emissions to the various environmental compartments are not equivalent to lead production and consumption, at least in the near term. Over the long term, i.e., over the hfetime of cultures and societies, aU lead present in human consumption channels can be viewed as potential lead contamination. Overall, and by estimating lead release dispersal across categories of lead production and consumption, a report of the National Academy of Sciences (NAS/NRC, 1980) estimated that at least 50% of cumulative lead production eventually becomes lead emissions. This fraction in quantitative terms translates to 150 million MT of a total global estimate of 300 million MT produced since the invention of successful smelting (Regal and Smith, 1992). 

The current level of lead emissions from mobile sources such as autos, trucks, farm equipment, and aircraft, is a small fraction of the total lead releases nationally and globally that occurred up to the early and mid-1970s. Chapters 3 and 4 detailed and quantified this dramatic reduction. However, lead from mobile sources largely settled in the environmental compartments of soils and dusts, where residence time is on the order of decades. This cumulative tally has been estimated for the United States at over 3 million MT. Furthermore, current lead inputs to existing lead loadings in soils and as dusts even at reduced values occur because of the ready remobilization of small dust particles from leaded soil surfaces. In a number of geographic areas with heavily used traffic arteries, roadside soil lead releases as fine particle dusts can produce significant localized elevations in air lead content. 

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