Supplementation responses plasma concentrations

In the total plasma response approach, the bioavailability of a compound is determined by measuring its plasma concentration at different times (up to weeks) after single or long-term ingestion of the compound from supplements or food sources. Generally, a plasma concentration-versus-time plot is generated, from which is determined the area-under-curve (AUC) value used as an indicator of the absorption of the componnd. Here, the term relative bioavailability is more appropriate since AUC valnes of two or more treatments are usually compared. This is in contrast to absolnte bioavailability for which the AUC value of the orally administered componnd is compared to that obtained with intravenous administration taken as a reference (100% absorption). 

ESTRAMUSTINE CALCIUM AND DAIRY PRODUCTS i plasma concentrations of estramustine and risk of poor therapeutic response Due to l absorption of estramustine owing to the formation of a calcium-phosphate complex Administer estramustine 1 hour before or 2 hours after dairy products or calcium supplements... 

In rats, high doses of vitamin Be (10 mg per kg of body weight) lead to decreased oxidative metabolism of tryptophan, presumably as a result of impaired responsiveness to glucocorticoid hormones, an increased plasma concentration of tryptophan, and increased uptake of tryptophan into the brain, leading to an increased rate of serotonin turnover (Bender and Totoe, 1984a). This suggests that vitamin Bg supplements might be a useful adjunct to tryptophan for the treatment of depression. 

It has been suggested that there may be some benefit of using tryptophan in selected patients, particularly those with psychomotor retardation (3). Unfortunately, most of these reports have appeared as letters to the editors of journals (4-6) or as preliminary communications (7). In addition to the possible absence of any consistent effect, there are many plausible reasons to explain the variabihty in response. Tryptophan has been given in both the racemic and monomeric (levorotatory) forms, both alone and together with a number of substances intended to increase the synthesis or availability of serotonin, including monoamine oxidase (MAO) inhibitors (8), potassium or carbohydrate supplements (9), and co-enzymes such as pyridoxine or ascorbic acid (10). It has also been suggested that tryptophan plasma concentrations have a therapeutic window (4), and that repeated administration induces hepatic tryptophan pyrrolase, resulting in lowered plasma concentrations and loss of therapeutic effect after 2 weeks of treatment (8). Attempts have been made to amehorate this problem by coadministration of nicotinamide (4). 

The box plot has proved to be a popular graphical method for displaying and summarizing univariate data, to compare parallel batches of data, and to supplement more complex displays with univariate information. Its appeal is due to the simplicity of the graphical construction (based on quartiles) and the many features that it displays (location, spread, skewness, and potential outliers). Box plots are useful for summarizing distributions of treatment outcomes. A good example would be the comparison of the distribution of response to treatment at different dose levels or exposure (as measured by area under the plasma concentration-time curve) as in Figure 37.3. 

Wise JA, Morin RJ, Sanderson R and Blum K. (1996). Changes in plasma carotenoid, alpha-tocopherol, and lipid peroxide levels in response to supplementation with concentrated fruit and vegetable extracts a pilot study. Curr Ther Res 57(6) 445 t61. 

The effects of wine and its polyphenol constituents on early indicators of coronary heart disease such as elevated levels of plasma lipids, platelets and serum antioxidant activity were discussed in a review by Cooper et al. (2004). This review also addressed whether the polyphenols or alcohol are responsible for the beneficial effects of wine on cardio-vascular health. The authors conclude that red wine polyphenols have little effect on plasma lipid concentrations, but that wine consumption reduces the susceptibility of low-density lipoprotein (LDL) cholesterol to oxidation and increase serum antioxidant capacity. These effects, however, do depend on the amount of wine that is consumed and the period of supplementation. It was suggested that specific polyphenols appear to have endothelium-dependent vaso-relaxing abilities. Red wine phenolics also have an inhibitory effect on platelet aggregation. Evidence suggests that alcohol has a positive synergistic effect with wine polyphenols on some atherosclerosis risk factors. Thus, evidence that wine drinking is beneficial for cardiac health appears positive. 

In human subjects, however, 8 weeks of vitamin E supplementation (800 IU/day) to the diet produced a lowered plasma PGI2 level, as measured by 6-keto-PGF1(X, compared with that in non-supplemented controls [129]. Addition of vitamin E to human platelets in concentrations which resemble normal plasma levels produced a moderately potent but consistent reduction in cyclo-oxygenase activity, with a dose-dependent response up to 1 mM. a-Tocopherol quinone was equally effective in this test [ 130]. 

Burton, G.W. et al., Eluman plasma and tissue alpha-tocopherol concentrations in response to supplementation with deuterated natural and synthetic vitamin E, Am. J. Clin. Nutr., 67, 669, 1998. 

Although there are still some discrepancies in the hterature regarding zinc levels in dialysis patients, most studies have found decreased levels of the element in serum [64,65] and muscles whereas the levels in bone [63] and other tissues seem to be normal or even increased suggesting translocation of the element in uremia. The dialysis treatment itself seems to have little or no effect on the serum zinc concentrations. Zinc deficiency in uremic patients has been associated with anorexia, disturbances in taste and sexual performance [66] whereas decreased plasma zinc seem to correlate with erythrocyte superoxide dismutase levels [67]. As evaluated by Tiirk et al. [68], zinc supplementation did not have any effect on the restoration of immune parameters or enhancement of the antibody response to multivalent influenza vaccine in hemodialysis patients. On the ofher hand however, has zinc supplementation been reported an effective means of improving serum levels of zinc and cholesterol in the hemodialysis patient [69]. 

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