Characterisation of the Ion Exchange Reaction between Propranolol - H+ or K+ with Amberlite TM IRP 69 Resin by Both, Isothermal Titration Calorimetry and (flame) Photometric Equilibrium Analysis

The model system propranolol hydrochloride (PROP-HCI) / Amberlite TM was studied in terms of equilibrium consentrations and amount drug bound to the ion exhanger, and compared to the system potassium chloride (KCI) / Amberlite TM. It was found that both the affinity and exchange capacity of AmberliteTM for PROP - H+ ions is higher than for K+. Specific heat effects of the exchange reaction measured by isothermal calorimetry and spectroscopy revealed that even at the lowest degree of loading with propranolol, the heat effects surprisingly change continuosly with the degree of loading, while they are constant for potassium. Involvement of non-specific forces in the binding of propranolol - H+ to AmberliteTM is discussed as a possible reason to this behavior.