Potentiometric CheqSol and standardized shake-flask solubility methods are complimentary tools in physicochemical...

Area of Science:

• Pharmaceutical Sciences
• Physical Chemistry
• Drug Delivery

Background:

• Understanding drug solubility is critical for formulation development and predicting in vivo performance.
• Supersaturation is a key phenomenon influencing drug absorption and bioavailability.
• Different analytical methods are needed to fully characterize drug solubility and related phenomena.

Purpose of the Study:

• To comprehensively evaluate the solubility behavior of glimepiride, pioglitazone, and sibutramine.
• To compare the strengths and limitations of the shake-flask (SF) and potentiometric (CheqSol) methods.
• To elucidate the thermodynamic and kinetic solubility aspects, including supersaturation, of the selected drugs.

Main Methods:

• Utilized the shake-flask (SF) method to determine thermodynamic solubility across a pH range.
• Employed the potentiometric (CheqSol) method to assess equilibrium solubility of neutral species and kinetic solubility (supersaturation).
• Characterized solid phases using powder X-ray diffraction and identified aggregation/complexation reactions.

Main Results:

• The SF method provided counterion-dependent thermodynamic solubility and identified solid phases.
• CheqSol method quantified supersaturation extent and duration for 'chaser' compounds.
• Combined data from both methods offered a complete understanding of drug solubility profiles.

Conclusions:

• The synergistic application of SF and CheqSol methods provides a robust approach to characterizing drug solubility.
• Accurate solubility data is essential for optimizing drug formulations and predicting bioavailability.
• This study highlights the importance of considering both thermodynamic and kinetic solubility parameters.