pH partition theory

Book Chapter

Authorship

TALEVI, ALAN ; BELLERA, CAROLINA LETICIA

Date

2021

Publishing House and Editing Place

Springer Nature Switzerland AG

Book

The ADME Encyclopedia. A Comprehensive Guide on Biopharmacy and Pharmacokinetics (pp. 1-8)
Springer Nature Switzerland AG

ISBN

978-3-030-51519-5

Summary Information provided by the agent in SIGEVA

The pH partition theory (or pH partition hypothesis, also referred to sometimes as the theory of nonionic diffusion) was conceived during the first half of the twentieth century upon prior observations which suggested that only lipophilic chemical species could cross lipoid biological barriers. The theory states that since most drugs are weak electrolytes, only the nonionized species will be able to permeate across biological barriers; subsequently, weak bases would preferably distribute to aci... The pH partition theory (or pH partition hypothesis, also referred to sometimes as the theory of nonionic diffusion) was conceived during the first half of the twentieth century upon prior observations which suggested that only lipophilic chemical species could cross lipoid biological barriers. The theory states that since most drugs are weak electrolytes, only the nonionized species will be able to permeate across biological barriers; subsequently, weak bases would preferably distribute to acidic body compartments, whereas weak acids would preferably remain in basic ones. The tendency of an ionizable molecule to accumulate in those cells or organelles where the ionized species predominates is known as ion trapping.