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Thread: Plasma Protein Binding and Plasma Concentration of Medications

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    Default Plasma Protein Binding and Plasma Concentration of Medications

    Plasma Protein Binding and Plasma Concentration of Medications

    Low Plasma Protein Concentrations

    Low plasma protein concetrations decrease the plasma concentration of bound drug; however, the concentration of free drug generally is unaffected. Therefore, the fraction of drug that is free increases as plasma protein concentraions decrease. Free or unbound drug concentrations are not significantly increased because the free drug that is released into plasma secondary to low plasma protein concentration equilibrates with the tissue compartment.

    Therefore, if the volume of distribution is relatively large, only a minor increase in C free will result.

    Elevated Plasma Protein Concentrations

    Increases in serum albumin are uncommon in the clinical setting. However, many basic drugs are bound to the acute phase reactive protein, α1-acid glycoprotein (AAG). This plasma protein has been know to be significantly decreased and increased under cetain clinical conditions. For example, increases in plasma quinidine concentrations have been observed following surgery or trauma. The change in the quinidine concentration is the result of increased concentrations of the plasma binding proteins (AAGs) and increased bound concentrations of quinidine.

    There appears to be little or no change in the free quinidine level because re-quilibration with the larger tissue stores occurs. In this situation, there would be a decreased in unbound free fraction (fu), and the thearpeutic levels of free or unbound drug should correlate with higher-than-usual drug concentration (bound plus free).

    Other basic compounds with significant binding to AAGs would be expected to be similarly affected.
    For more information, http://www.tomhsiung.com/wordpress/2...of-tdm-report/
    Last edited by admin; Tue 17th March '15 at 3:47pm.

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    Very impressive description.

  3. #3
    PharmD Year 1 TomHsiung's Avatar
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    Yes, very impressive. Thank you, Cheney.

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    I really appreciated your useful description.

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    Administrator admin's Avatar
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    Quote Originally Posted by drugpillstore View Post
    I really appreciated your useful description.
    You are welcome!
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease. Chengdu, Sichuan, China.

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