Thermodynamic investigation of biperiden hydrochloride and cyclodextrins supramolecular systems

Isothermal titration calorimetry (ITC) and theoretical calculations were used to investigate the interaction of cyclodextrins (CDs) with biperiden hydrochloride (BPR), a drug for Parkinson’s disease treatment. Among the natural CDs, βCD demonstrated the larger equilibrium constant (Keq = 9,020), demonstrating the cavity size dependency for the interaction. Carboxymethyl-β-cyclodextrin (CMβCD) demonstrated a stronger affinity and higher intermolecular complex stability. Additionally, the Keq for the CMβCD:BPR system varied from 68,100 at 298.15 K to 31,650 at 328.15 K, with a constant standard Gibbs free energy change. The theoretical calculations demonstrated the most stable structure for the CMβCD:BPR inclusion complex.