Partition coefficients (n-octanol/water) of N-butyl-p-aminobenzoate and other local anesthetics measured by reversed-phase high-performance liquid chromatography.
For the determination of the logarithmic partition coefficients between n-octanol and water (log P(o/w)) of local anesthetics, the pH of the aqueous phase needs to be adjusted to high values to ensure that the local anesthetics are in the unionized form. Using the shake-flask or the stir-flask method, this high pH may catalyze hydrolysis, leading to increasing amounts of impurities in time. These impurities exclude non-selective quantification methods like UV spectrometry and require repetitive quantitative analysis of both liquid phases resulting in a tedious and time-consuming method. A rapid reversed-phase HPLC method was developed to measure log P(o/w) of the local anesthetics N-butyl-p-aminobenzoate, methyl-p-aminobenzoate, benzocaine, procaine, mepivacaine, prilocaine, lidocaine, bupivacaine, etidocaine, tetracaine and oxubuprocaine.
Grouls
R J
RJ
Department of Pharmaceutical Services, Catharina Hospital, Eindhoven, Netherlands.
Ackerman
E W
EW
Korsten
H H
HH
Hellebrekers
L J
LJ
Breimer
D D
DD
D020003:1-Octanol; D000779:Anesthetics, Local / Q000737:chemistry*; D001566:Benzocaine / Q000031:analogs & derivatives* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D000442:Octanols; D012995:Solubility; D014867:Water
D000779:Anesthetics, Local; D000442:Octanols; D014867:Water; C004605:butamben; D020003:1-Octanol; D001566:Benzocaine