Oral Absorption

  • Siamak Cyrus KhojastehEmail author
  • Harvey Wong
  • Cornelis E. C. A. Hop


The most common route of drug administration is the oral route. As such, an understanding of factors that influence oral absorption is important. For a drug to enter the systemic circulation following oral administration, the drug must first dissolve, cross the intestinal membrane, and pass through the liver. This chapter gives a general overview of oral absorption and include concepts such as first-pass metabolism.


Extraction Ratio Oral Absorption Biopharmaceutics Classification System Permeation Rate Absorption Rate Constant 
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List of Abbreviations


Biopharmaceutics classification system


Biopharmaceutics drug disposition classification system


AUC following an oral dose


AUC following an intravenous dose


Extraction ratio of the gut


Extraction ratio of the liver




Fraction of drug absorbed from the intestinal lumen


Fraction of orally administered drug escaping intestinal metabolism


Fraction of orally administered drug escaping hepatic metabolism/elimination


Maximum absorbable dose


  1. Chen JZ, Xie M, Bao L et al (2006) Characterization of rat stomach pH following famotidine and pentagastrin pre-treatment. AAPS J 8(S2):Abstract T2301Google Scholar
  2. Davies B, Morris T (1993) Physiological parameters in laboratory animals and humans. Pharm Res 10:1093–1095PubMedCrossRefGoogle Scholar
  3. Lentz KA, Quitko M, Morgan DG et al (2007) Development and validation of a preclinical food effect model. J Pharm Sci 96:459–472PubMedCrossRefGoogle Scholar
  4. Lui CY, Amidon GL, Berardi RR et al (1986) Comparison of gastrointestinal pH in dogs and humans: implications on the use of the beagle dog as a model for oral absorption in humans. J Pharm Sci 75:271–274PubMedCrossRefGoogle Scholar
  5. Rowland M, Tozer TN (2011) Clinical pharmacokinetics and pharmacodynamics: concepts and applications. Wolters Kluwer/Lippincott Williams & Wilkins, Baltimore, MDGoogle Scholar
  6. Wu CY, Benet LZ (2005) Predicting drug disposition via application of BCS: transport/absorption/elimination interplay and development of a biopharmaceutics drug disposition classification system. Pharm Res 22:11–23PubMedCrossRefGoogle Scholar

Additional Readings

  1. Amidon GL, Lennernas H, Shah VP et al (1995) A theoretical basis for a biopharmaceutical drug classification: the correlation of in vitro drug product dissolution and in vivo bioavailability. Pharm Res 12:413–420PubMedCrossRefGoogle Scholar
  2. Ehrhardt C, Kim KJ (2008) Drug absorption studies: in situ, in vitro and in silico models. Springer Science and Business Media, LLC, New York, NYGoogle Scholar
  3. Gu C-H, Li H, Levons J et al (2007) Predicting effect of food on extent of drug absorption based on physicochemical properties. Pharm Res 24:1118–1130PubMedCrossRefGoogle Scholar
  4. Horter D, Dressman JB (2001) Influence of physicochemical properties on dissolution of drugs in the gastrointestinal tract. Adv Drug Deliv Rev 46:75–87PubMedCrossRefGoogle Scholar
  5. Sugano K, Okazaki A, Sugimoto S et al (2007) Solubility and dissolution profile in drug discovery. Drug Metab Pharmacokinet 22:225–254PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Siamak Cyrus Khojasteh
    • 1
    Email author
  • Harvey Wong
    • 1
  • Cornelis E. C. A. Hop
    • 1
  1. 1.Genentech, Inc.San FranciscoUSA

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