A pulse radiolysis study of the interaction of ephedrine with carrageenans

Pulse radiolysis has been used to determine the thermodynamic parameters (delta G', delta H' and delta S') governing the binding of ephedrine to three carrageenans. For each interaction an increase in drug binding occurred as the temperature was increased from ambient. However, a transition temperature was observed (49 degrees C) above which the drug was progressively released as the temperature was increased. These observations are discussed in terms of conformational changes induced in the polymers below and above their melting temperatures.