Biopharmaceutics Classification System
Solubility is one of drug physicochemical characteristics which determines
the success of drug formulation process, especially in solution preparation.
Ofloxacin is an antibiotic drug and categorized as class 2 drug in
(BCS). The solubility of ofloxacin is
dependent on pH of the solvent due to its amphoteric properties. The objectives of
this research were to find and to determine the effects of pH and ionic strength on
solubility profile of ofloxacin.
Ofloxacin solubilities were measured at various pH and ionic strengths
ranged from 1.5 to 12.5 and from 0.01 to 0.20 respectively. Solubility experiments
were carried out using shaking thermostatic-waterbath for 3 hours at a temperature
of 37°C � 1°C.
The results showed that ofloxacin solubility increased at a pH values
below the pKa1 (6.08) and above the pKa2 (8.25). However, the solubility
decreased at pH value between pKa1 and pKa2. Changing the pH from 6.2 to 1.5
and 12.5, the ofloxacin solubility increased about 10 times. Ofloxacin solubility in
various ionic strength showed that increasing of ionic strength cause the
increasing of the solubility, that means there was salting in phenomena. Least-
Square Fitting Analysis using Henderson-Hasselbalch equation for amphoteric
compound were insufficient to describe ofloxacin solubility process in a series
of pH