Solvation and dilution thermodynamics of benzocaine in some aqueous and organic solvents

ABSTRACT

Benzocaine (BZC) is a local anaesthetic commonly used in therapeutics. Based on published thermodynamic quantities of dissolution, partitioning, and sublimation of BZC, the thermodynamic quantities of solvation for this drug in some mutually saturated solvents were calculated. Organic solvents under consideration were cyclohexane (CH), isopropyl myristate (IPM), and 1-octanol (ROH). In all cases, these thermodynamic quantities (i.e. , , and ) were negative, indicating that dissolution is the more favourable state for BZC. Thermodynamic quantities of drug dilution in the organic solvents were also calculated. Accordingly, Gibbs energies of dilution were not favourable in all the three organic solvents (i.e.  > 0). From the obtained values for the different transfer processes, an interpretation based on solute–solute and solute–solvent interactions was developed.

KEYWORDS:

• Benzocaine
• thermodynamics
• solvation
• dilution
• partition coefficient
• organic solvents

Disclosure statement

No potential conflict of interest was reported by the authors.