Poly( N-isopropylacrylamide) copolymers for constant temperature controlled drug delivery

In the course of the development of a new drug delivery concept, four thermosensitive copolymers of poly( N-isopropylacrylamide) (PNIPAAm), with phase transition temperature slightly higher than 37 °C, were synthesised and used as time-controlled drug delivery agents. For this purpose, compression-coated tablets coated with the thermosensitive copolymers and containing Na 2SO 4 were prepared and in vitro dissolution tests were performed at constant physiological temperature, the lag time before drug release being controlled by the amount of Na 2SO 4 incorporated into the form. Due to the salting out effect, the lag time was increased by up to 80–90% for PNIPAAm-co-NVA and PNIPAAm-co-MVA coated tablets.