Heparin elimination

Substances other than enzymes can be immobilized. Examples include the fixing of heparin on polytetrafluoroethylene with the aid of PEI (424), the controUed release of pesticides which are bound to PEI (425), and the inhibition of herbicide suspensions by addition of PEI (426). The uptake of anionic dyes by fabric or paper is improved if the paper is first catonized with PEI (427). In addition, PEI is able to absorb odorizing substances such as fatty acids and aldehydes. Because of its high molecular weight, PEI can be used in cosmetics and body care products, as weU as in industrial elimination of odors, such as the improvement of ambient air quaHty in sewage treatment plants (428). 

Alkali-catalyzed cleavage of glycosidic bonds of glycosaminoglycur-onates occurs by way of -elimination.223 By proper choice of the experimental conditions, it seems possible to achieve a controlled degradation of heparin by -elimination, producing fragments apparently preserving... 

Organic samples are usually mineralized to render them soluble in water and to eliminate possible interference from the matrix (for example through adsorption on the electrode surface). Mineralization can be carried out by heating with strong oxidizing acids, by fusion with alkalis or by combustion in an oxygen atmosphere [142]. Blood samples must be treated with heparin if they are not immediately analysed and the content of O2 and CO2 must be carefully maintained otherwise the dissociation equiUbrium of calcium is shifted [78,96]. 

Qassification Idiopathic osteoporosis type 1, occurring in postmenopausal females type 11, occurring in senescent males and females (>70 y). Secondary osteoporosis associated with primary disorders such as Cushing s disease, or induced by drugs, e.g chronic therapy with glucocorticoids or heparin. In these forms, the cause can be eliminated. 

Heparin is highly bound to plasma proteins and has a short elimination half-life of 1-5 hours depending on the dose. It is distributed to the reticuloendothelial system and metabolized in the liver to inactive metabolites. It does not cross the placental barrier, however there is a risk of heparin-induced maternal osteopenia if it is used throughout pregnancy. 

Freeze-dried concentrates of plasma containing prothrombin, factors IX and X, and varied amounts of factor VII (Proplex, etc) are commercially available for treating deficiencies of these factors (Table 34-3). Each unit of factor IX per kilogram of body weight raises its activity in plasma 1.5%. Heparin is often added to inhibit coagulation factors activated by the manufacturing process. However, addition of heparin does not eliminate all thromboembolic events. 

In the ESSENCE trial, the LMWH enoxaparin led to a relative risk reduction of 15% to 16% in the rate of death, Ml, or refractory ischemia as compared to unfractionated heparin at 30 days in UA/NSTEMI patients (38). Nadroparin [FRAXIS study (39)] and dalteparin [FRIC study (40)] did not demonstrate superiority against unfractionated heparin. Human pharmacokinetic data indicate that these differences in clinical efficacy might be explained by different elimination half-lives of antifactor Xa activity (dalteparin 2.8 hours, nadroparin 3.7 hours, enoxaparin 4.1 hours) (41). 

Initially, plasma and oral fluid specimens from patients (n = 21) on different antidepressant treatment were collected twice to assess if any of the studied analytes was likely to show a good correlation. The best results were obtained for venlafaxine (%CV for plasma/oral fluid concentrations ratio (f OF/PL) <21%). Therefore, the study was extended for this antidepressant by analysis of oral fluid and plasma specimens from five patients on venlafaxine treatment collected on four occasions. Daily doses of venlafaxine retard formulations were 75 mg for two patients, and 150 mg for the remaining participants. Collection of oral fluid (direct spitting into polypropylene tubes) and plasma (heparinized tubes) specimens was performed, when possible, before the next dose to ensure the drug was in the elimination phase. The dose and the time of collection was the same on the four different occasions for each patient. For the analysis, oral fluid and plasma specimens were centrifuged at 14 x 103 rpm, and 0.2 mL of the supernatant were extracted. In addition, correlation between the concentrations in the plasmatic free fraction and in oral fluid was also evaluated. Plasmatic proteins were eliminated by filtering 0.5 mL of plasma samples using Microcon filter devices Ultracel YM-3 (Millipore Corp., Billerica, MA, USA). 

The apoE phenotype may be assigned after isoelectric focusing of proteins obtained by delipidating VLDL, obtained either by ultracentrifugation (H19, P2, U5, W4, W6) or heparin-Mn2+ precipitation (U4) of serum. The assignment of a phenotype is usually straightforward (H13) if not, the elimination of sialylated components with neuraminidase may be helpful (H13). 

For the separation of heparin from heparin-protein complexes, Homan and Lens have developed a method which avoids the use of acid media. The heparin-protein complex is dissolved in aqueous solution at pH 7.5 and is extracted with phenol (which removes most of the protein). The method also facilitates the removal of colored impurities wLich are normally difficult to eliminate. Extraction of the heparin-protein-octylamine complex with phenol has been studied. "... 

Pharmacokinetics. Heparin is poorly absorbed from the gastrointestinal tract and is given i.v. or S.C. once in the blood its effect is immediate. Heparin binds to several plasma proteins and to sites on endothelial cells it is also taken up by cells of the reticuloendothelial system and some is cleared by the kidney. Due to these factors, elimination of heparin from the plasma appears to involve a combination of zero-order and first-order processes, the effect of which is that the plasma biological effect alters disproportionately with dose, being 60 min after 75 units per kg and 150 min after 400 units per kg. 

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