Background: Present work was designed about the assignation of thermodynamic acid dissociation
constants (pKa) of pravastatin, atorvastatin and rosuvastatin by using RPLC method. In the experiment,
methanol-water binary mixture was chosen as hydroorganic solvent mixture.
Method: Chromatographic study was performed with Nucleosil 300-5C4 column (5µm, 250x4.6 mm,
I.D.) and the flow rate of the experiment was adjusted at 1 mL/min. The thermodynamic acid dissociation
constant values and the intrinsic retention factors were estimated by use of a non-linear least squares fit of
the data. The realibility of the RPLC methodology was investigated statistically using the difference between
the experimental and theoretical results. Aqueous pKa values were also estimated with extrapolation
by means of the Yasuda-Shedlovsky and mole fraction equations.
Conclusion: Availability of present procedure in order to quantitatively determine the studied compounds
was verified by the validation in suitability with the requirements laid down via ICH (International Conference
on Harmonization) guidelines. Results of the analysis show that the method can be used for the
estimation of studied drugs in pharmaceutical formulations, with great recovery, well precision and accuracy.