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Presystemic Extraction: Mechanisms and Consequences
Author(s) -
Greenblatt David J.
Publication year - 1993
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1993.tb04719.x
Subject(s) - bioavailability , first pass effect , pharmacokinetics , oral administration , pharmacology , gastrointestinal tract , systemic circulation , absorption (acoustics) , extraction (chemistry) , biotransformation , chemistry , medicine , chromatography , biochemistry , enzyme , physics , acoustics
Many drugs have incomplete systemic availability after oral dosage. This can be attributed to incomplete absorption from the gastrointestinal tract, or to presystemic extraction, in which a fraction of an orally administered dose is biotransformed before reaching the systemic circulation. Presystemic extraction can occur either via biotransformation by gastrointestinal mucosa or enteric flora, or via metabolism during the “first‐pass” through the liver. For drugs with low oral bioavailability due to high presystemic extraction, impaired clearance leads to increased peak plasma levels and greater area under the concentration‐time curve, but minimal change in elimination half‐life.