pK(a) Determinations for Montelukast Sodium and Levodropropizine

Abstract

The pK (a) constants and relative abundances of unionized and ionized forms of Montelukast sodium {the sodium salt of 2-[1-[[(1R)-1-[3-[2-(7-chloroquinolin-2-yl)ethenyl] phenyl]-3-[2-(2-hydroxypropan-2-yl)phenyl]propyl]sulfanylmethyl]cyclopropyl]acetic acid} and Levodropropizine {(2S)-3-(4-phenylpiperazin-1-yl)propane-1,2-diol} were determined potentiometrically from measurements at various pHs. These determinations were in order to relate their pK (a) values with their bioavailability and to provide chemical data to be used in their analysis.