Physicochemical properties of amphoteric β-lactam antibiotics. I: Stability, solubility, and dissolution behavior of amino penicillins as a function of pH

A. Tsuji, E. Nakashima, S. Hamano, T. Yamana

Research output: Contribution to journalArticle

122 Citations (Scopus)


The degradation rate, solubility, and dissolution rate of amino penicillins, amoxicillin, ampicillin, epicillin, and cyclacillin, were determined quantitatively as a function of pH. In the pH range studied, 0.30-10.50, the degradation of amoxicillin and epicillin followed pseudo-first-order kinetics to give the same type of pH-rate profiles as those of ampicillin and cyclacillin. Cyclacillin anhydrate was the most soluble, followed in order by ampicillin anhydrate, ampicillin trihydrate, amoxicillin trihydrate, and epicillin anhydrate. These pH-solubility profiles showed U-shaped curves. The dissolution rate constants from the rotating disk were analyzed by the simultaneous chemical reaction and diffusion models. Their relative bioavailability after a single oral administration was assessed from their physicochemical properties determined in vitro.

Original languageEnglish
Pages (from-to)1059-1066
Number of pages8
JournalJournal of Pharmaceutical Sciences
Issue number8
Publication statusPublished - 1978
Externally publishedYes


ASJC Scopus subject areas

  • Molecular Medicine
  • Chemistry(all)
  • Organic Chemistry
  • Drug Discovery
  • Pharmaceutical Science
  • Pharmacology

Cite this