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A general equation for the ratio of the areas below the blood or plasma concentration time‐curves following intravenous and oral drug administration and its application to inter‐subject variations in drug elimination.
Author(s) -
Vaughan DP,
Trainor A
Publication year - 1975
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1975.tb01582.x
Subject(s) - drug , pharmacokinetics , oral administration , pharmacology , drug metabolism , drug administration , medicine , route of administration , blood plasma , urine , first pass effect , area under the curve , intravenous drug , immunology , human immunodeficiency virus (hiv) , viral disease
1 When a drug is metabolized in the liver the total area under the plasma or blood concentration‐time curve following oral drug administration is less than the area obtained after intravenous drug administration. This difference has been termed the 'first‐pass effect'. 2 General equations for the areas below the blood or plasma concentration‐time curve of a drug following intravenous and oral drug administration are derived. 3 An explicit expression for the ratio of areas below the blood or plasma concentration‐time curves following intravenous and oral drug administration is derived. 4 By the application of the derived equations it is shown that the relative contribution of hepatic drug metabolism and urinary excretion to inter‐ subject variation in drug elimination can be easily ascertained.