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Topic: Bioavailability


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  Colloidal Silver Bioavailability
Notice that the definition of bioavailability only concerns the amount of drug (or other substance) that reaches systemic circulation, it does not have anything to do with the ability of the substance to be metabolized by the body.
More factors can affect bioavailability when absorption is slow or incomplete than when it is rapid and complete, so slow or incomplete absorption often leads to variable therapeutic responses.
Bioavailability determinations based on the peak plasma concentration can be misleading, because drug elimination begins as soon as the drug enters the bloodstream.
www.purestcolloids.com /bioavailability.htm   (1481 words)

  
 Soil Bioavailability | US EPA
Bioavailability is the amount of a contaminant that is absorbed into the body following skin contact, ingestion, or inhalation.
Relative bioavailability is how much of a contaminant is absorbed from soil as compared to how much of that contaminant is absorbed from food or water.
Bioavailability is a measure of how much of a contaminant is absorbed when people are exposed to that contaminant through inhalation, skin contact or food intake.
www.epa.gov /superfund/health/contaminants/bioavailability   (225 words)

  
  FeZn Bioavailability
Bioavailability of non-heme iron and dietary zinc is greatly influenced by both dietary inhibitors and enhancers (7, 9).
Bioavailability of trace minerals from cereals and legumes.
Studies on the bioavailability of zinc in humans: effects of heme and nonheme iron on the absorption of zinc.
www.andrews.edu /NUFS/FeZnbioavail.htm   (3466 words)

  
  Bioavailability - Wikipedia, the free encyclopedia
In pharmacology, bioavailability is used to describe the fraction of an administered dose of medication that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs.
Bioavailability is one of the essential tools in pharmacokinetics, as bioavailability must be considered when calculating dosages for non-intravenous routes of administration.
Bioavailability is a measurement of the rate and extent of a therapeutically active drug that reaches the systemic circulation and is available at the site of action.
en.wikipedia.org /wiki/Bioavailability   (445 words)

  
 Linus Pauling Institute at Oregon State University
A study of 12 males (6 smokers and 6 nonsmokers) found the bioavailability of synthetic ascorbic acid (powder administered in water) to be slightly superior to that of orange juice, based on blood levels of ascorbic acid, and not different based on ascorbic acid in leukocytes (white blood cells) (1).
While the bioavailability of ascorbic acid appears equivalent whether it is in the form of powder, chewable tablets, or non-chewable tablets, the bioavailability of ascorbic acid from slow-release preparations is less certain.
Another study in 7 women and 1 man found no difference between the bioavailability of 500 mg of synthetic ascorbic acid and that of a commercially available vitamin C preparation with added bioflavonoids, where the ratio of bioflavonoids to ascorbic acid was 0.05:1 (6).
lpi.oregonstate.edu /infocenter/vitamins/vitaminC/vitCform.html   (1688 words)

  
 Bioavailability of Nutrients - The Nutrition of Micronutrients
Bioavailability is the technical term used to convey the fact that you don't absorb 100% of all nutrients consumed, no matter if you take them in the form of nutritional supplements or as food.
A number of factors affect bioavailability: factors contained in the food itself, factors of human physiology, factors specific to your health status, and factors related to the food processing.
Bioavailability of dietary minerals to humans: the stable isotope approach.
naturalhealthperspective.com /food/bioavailability.html   (1469 words)

  
 The Truth About Bioavailability of Colloidal Silver
Notice that the definition of bioavailability only concerns the amount of drug (or other substance) that reaches systemic circulation, it does not have anything to do with the ability of the substance to be metabolized by the body.
More factors can affect bioavailability when absorption is slow or incomplete than when it is rapid and complete, so slow or incomplete absorption often leads to variable therapeutic responses.Insufficient time in the GI tract is a common cause of low bioavailability.
Bioavailability determinations based on the peak plasma concentration can be misleading, because drug elimination begins as soon as the drug enters the bloodstream.
www.silver-colloids.com /Pubs/bioavailability.html   (1267 words)

  
 2003 CFR Title 21, Volume 5
Criteria for waiver of evidence of in vivo bioavailability or bioequivalence.
Basis for measuring in vivo bioavailability or demonstrating bioequivalence.
Correlation of bioavailability with an acute pharmacological effect or clinical evidence.
www.access.gpo.gov /nara/cfr/waisidx_03/21cfr320_03.html   (176 words)

  
 Bioavailability
A nutrient's bioavailability is the proportion of the nutrient that, when ingested, actually gets absorbed by the body.
The remaining amount cannot be metabolized and is removed as waste.
The bioavailability of a nutrient can also increase or decrease if other substances are present.
www.faqs.org /nutrition/Ar-Bu/Bioavailability.html   (136 words)

  
 U.S. Pharmacist - Continuing Education - Bioavailability and Bioequivalence: Selected Issues - Default
The extent of absorption is measured by the bioavailability, or fraction of dose absorbed measured by the area under the concentration-time profile (AUC), whereas the rate of absorption is roughly assessed by measuring the maximum plasma or blood level, Cmax, of a compound.
Changes in absorption and bioavailability may be due to secretion of gastric acid, bile, and pancreatic fluids; modifications of gastric and intestinal motility patterns; and alterations in blood flow.
Influence of a high-fat breakfast on the bioavailability of theophylline controlled-release formulations: an in vitro demonstration of an in vivo observation.
www.uspharmacist.com /NewLook/CE/bioavail/lesson.htm   (4589 words)

  
 Bioavailability: Pharmacokinetics: Merck Manual Professional
Bioavailability refers to the extent to and rate at which the active moiety (drug or metabolite) enters systemic circulation, thereby accessing the site of action.
Bioavailability of a drug is largely determined by the properties of the dosage form (which depend partly on its design and manufacture), rather than by the drug's physicochemical properties, which determine absorption potential.
Bioavailability is usually assessed by determining the maximum (peak) plasma drug concentration, peak time (when maximum plasma drug concentration occurs), and area under the plasma concentration–time curve (AUC—see Fig.
www.merck.com /mmpe/print/sec20/ch303/ch303c.html   (695 words)

  
 Iron Bioavailability - A Summary
Iron bioavailability is the proportion of ingested iron which is absorbedfrom the intestinal lumen and transferred into the circulation.
Bioavailability is one of the crucial links between how much iron anindividual consumes and their final body iron status.
Food fortification: There is a need for accurate data on the bioavailability of iron in specific iron-fortified foods to ensure that iron claims are not made on foods from which very little iron is actually absorbed.
www.ironpanel.org.au /AIS/IBA/iba_text.html   (1394 words)

  
 NOAA GLERL Bioavailability of Sediment-Associated Contaminants Project
The bioavailability of selected organic contaminants from sediment was evaluated based on sediment characteristics and measures of contaminant desorption versus measured bioaccumulation by the worm Lumbriculus variegatus and the amphipod Diporeia spp.
The bioavailability of the contaminants from sediment was proportional to the flux of the contaminants from sediment.
Bioavailability studies were performed with benzo[a]pyrene sorbed to sediments where the duration of contact ranged from 1 week to 13 months (Kukkonen and Landrum, 1998).
www.glerl.noaa.gov /res/Task_rpts/1996/aqland06-3.html   (7008 words)

  
 Bioavailability of Trace Mineral Sources
Mineral bioavailability is defined as the proportion of the element consumed that is utilized for a biochemical or physiologic function (325).
Consequently, it is risky to predict relative bioavailability of different mineral sources without having measured it for the animal in question.
Bioavailability data for the common trace mineral sources has been summarized for swine (327, 357), cattle (328, 337, 357) and poultry (338, 357).
www.saltinstitute.org /47dd.html   (481 words)

  
 The Bioavailability of Different Forms of Vitamin C
Bioavailability refers to the degree to which a nutrient becomes available to the target tissue after it has been administered.
The bioavailability of ascorbic acid appears equivalent whether it is in the form of powder, chewable tablets, or non-chewable tablets.
The ascorbic acid released by the hydrolysis of ascorbyl palmitate appears to be as bioavailable as ascorbic acid alone.
lpi.oregonstate.edu /ss01/bioavailability.html   (1336 words)

  
 Bioavailability of dietary supplements   (Site not responding. Last check: )
Indeed, several speakers provided different definitions, some regarding bioavailability simply as the proportion of a nutrient or bioactive ingredient that was absorbed from the gastrointestinal tract, while others included metabolism, excretion, utilisation and a measure of efficacy in their definitions.
This means that the bioavailability of ingredients in dietary supplements should probably include a measure of efficacy, although there was general agreement at the meeting that bioavailability might need to be defined differently for each ingredient.
Bioavailability would depend on the nutritional and physiological status of the individual, and although it would be useful to have such detailed data, this was not currently practical because measuring bioavailability in individuals was expensive and time consuming.
www.pharmj.com /Editorial/20000219/forum/dietarysupplements.html   (1706 words)

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