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Bioavailability: Difference between revisions
→Factors Affecting Bioavailability
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Bioavailability is often assessed through specific pharmacokinetic studies, which evaluate the concentration of a drug in plasma over time. The two key metrics used are absolute and relative bioavailability. | Bioavailability is often assessed through specific pharmacokinetic studies, which evaluate the concentration of a drug in plasma over time. The two key metrics used are absolute and relative bioavailability. | ||
=== | === Absolute Bioavailability === | ||
This measures the bioavailability of a drug compared to its intravenous administration. The formula for calculating absolute bioavailability (F) is: | This measures the bioavailability of a drug compared to its intravenous administration. The formula for calculating absolute bioavailability (F) is: | ||
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where AUC is the [[Area Under the Curve (AUC)|area under the plasma concentration-time curve]] for oral (AUC<sub>oral</sub>) and intravenous (AUC<sub>IV</sub>) administration, and Dose refers to the dose administered via each route. | where AUC is the [[Area Under the Curve (AUC)|area under the plasma concentration-time curve]] for oral (AUC<sub>oral</sub>) and intravenous (AUC<sub>IV</sub>) administration, and Dose refers to the dose administered via each route. | ||
=== | === Relative Bioavailability === | ||
Relative bioavailability compares the bioavailability of a drug in different formulations, typically against a standard or reference formulation. The formula is: | Relative bioavailability compares the bioavailability of a drug in different formulations, typically against a standard or reference formulation. The formula is: | ||
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where AUC<sub>test</sub> and AUC<sub>ref</sub> are the [[Area Under the Curve (AUC)|areas under the curve]] for the test and reference formulations, respectively, and Dose is the dose for each. | where AUC<sub>test</sub> and AUC<sub>ref</sub> are the [[Area Under the Curve (AUC)|areas under the curve]] for the test and reference formulations, respectively, and Dose is the dose for each. | ||
==Factors Affecting Bioavailability== | |||
[[File:Mechanism of micronutrient bioavailability in the human body.png|thumb|Mechanism of micronutrient bioavailability in the human body {{pmid|28344274}}]] | |||
Bioavailability (F) of oral drugs or bioactive food components is influenced by several key stages: liberation, absorption, distribution, metabolism, and elimination. The equation representing bioavailability is: | |||
:<math>F = F_C \times F_B \times F_A \times F_M</math> | |||
Where each factor represents a different aspect of how a substance is processed in the body: | |||
{| class="wikitable" | |||
!F | |||
!Factor | |||
!Description | |||
!Influencing Factors | |||
!Example | |||
|- | |||
|'''F<sub>C</sub>''' | |||
|'''Liberation''' | |||
|The fraction of a micronutrient or drug that becomes available from its food matrix or dosage form in the GIT. | |||
|Physical and chemical form of the substance, processing methods, interactions with other components. | |||
|Reduced liberation of [[Vitamin B12 (Cobalamin)|vitamin B12]] from food sources in the elderly due to decreased stomach acid production, impacting the release and subsequent absorption of B12. | |||
|- | |||
|'''F<sub>B</sub>''' | |||
|'''Bioaccessibility''' | |||
|The portion of the substance that is released from the food product or dosage form and dissolves in the GIT liquids. | |||
|GIT pH and enzyme activity, solubility and stability of the nutrient or drug. | |||
|Dissolution of an omega-3 fatty acid capsule in the intestinal fluid. | |||
|- | |||
|'''F<sub>A</sub>''' | |||
|'''Absorption''' | |||
|The fraction of the substance that passes through the intestinal wall into the systemic circulation. | |||
|Gastrointestinal mucosa integrity, presence of transporters and enzymes, physicochemical properties of the substance. | |||
|Absorption of [[Coenzyme Q10 (CoQ10)]] is generally low due to its large molecular weight and fat solubility, making it better absorbed when taken with meals rich in fats. | |||
|- | |||
|'''F<sub>M</sub>''' | |||
|'''Metabolism''' | |||
|The fraction of the substance that remains in a bioactive form after metabolic transformations. | |||
|Enzymatic activity within the GIT, liver metabolism, systemic circulation, metabolic stability, and enzymatic degradation susceptibility. | |||
|[[Resveratrol]] is rapidly metabolized in the liver into various metabolites, which may have reduced biological activity compared to the parent compound, affecting its overall bioavailability and potential health benefits. | |||
|} | |||
Each of these stages is crucial in determining the overall bioavailability of a substance, and they are influenced by the chemical breakdown of bioactive elements during processing, manufacture, storage, and transport, as well as interactions within the GIT. | |||
==Improving Bioavailability== | ==Improving Bioavailability== | ||
Research and development in pharmaceutical and nutraceutical sciences focus on enhancing bioavailability through various means | Research and development in pharmaceutical and nutraceutical sciences focus on enhancing bioavailability through various means, including advanced delivery systems, chemical modifications, and combinational approaches. | ||
*''' | |||
*'''Chemical Modifications''': Altering the chemical structure of a compound can increase its solubility and absorption. | *'''[[Nano‐Based Delivery Systems|Nano-Based Delivery Systems]]:''' Delivery systems utilizing of nanotechnology (e.g. liposomes, micelles) to enhance the delivery and bioavailability of various nutrients and bioactive components. | ||
*'''Combinational Approaches''': Using adjuvants or combining nutrients with enhancers can improve bioavailability. | *'''Chemical Modifications''': Altering the chemical structure of a compound can increase its solubility and absorption, making the active ingredient more available in the systemic circulation. | ||
*'''Combinational Approaches''': Using adjuvants or combining nutrients with enhancers can significantly improve bioavailability. This approach often involves synergistic combinations that enhance the overall effect of the active ingredients. | |||
==Conclusion== | ==Conclusion== | ||
Understanding and optimizing bioavailability is fundamental for the effectiveness of drugs and nutritional supplements. As research progresses, new methods and formulations continue to emerge, enhancing the efficacy of therapeutic and nutritional interventions. | Understanding and optimizing bioavailability is fundamental for the effectiveness of drugs and nutritional supplements. As research progresses, new methods and formulations continue to emerge, enhancing the efficacy of therapeutic and nutritional interventions. | ||
==See Also== | ==See Also == | ||
*[[Area Under the Curve (AUC)]] | |||
*[[Nano‐Based Delivery Systems]] | |||
*Wikipedia - [[Wikipedia:Bioavailability|Bioavailability]] | *Wikipedia - [[Wikipedia:Bioavailability|Bioavailability]] | ||
==Todo== | |||
*{{pmid text|28344274}} | |||
==References== | |||
<references /> | |||
[[Category:Pharmacokinetics]] | [[Category:Pharmacokinetics]] | ||