The use of conductometric assessments for development of pulsed release of lidocaine hydrochloride from thermosensitive N-isopropylacrylamide microgels.

The aim of present work was preliminary assessment of the conductivity changes in aqueous compartment, consisting oflidocaine hydrochloride, and N-isopropylacrylamide derivative microgel, during increasing the temperature between 25 degrees and 42 degrees C, as a prerequisite to demonstrate the possibility of applying this microgel for pulsed release of lidocaine hydrochloride, when increased temperature is applied. Conductivity of respective systems composed of polymer and lidocaine hydrochloride were assigned as PNM I-LD, PNM II-LD, and PNM III-LD: obtained values were in the ranges: 39,91 microS/cm - 53,30 microS/cm in the 25 degrees C temperature, 46,14 microS/cm - 56,16 microS/cm in the temperature of 32 degrees C, and 53,30 microS/cm - 118,42 microS/cm at 42 degrees C. During heating or cooling of the microgels derivatives of N-isopropylacrylamide, there is possibility to obtain pulsed release of lidocaine hydrochloride from the polymeric bead in the range between 25 degrees C and 42 degrees C, according to the conductivity measurements.