Formulation of thermoresponsive and bioadhesive gel for treatment of oesophageal pain and inflammation

The aim of this study was the formulation and examination of a novel thermoresponsive and bioadhesive, in situ gelling drug delivery system, which can be used in the treatment of oesophageal pain and inflammation. A bioadhesive cellulose derivative (Metolose® 60SH) was used as a thermoresponsive material, because Metolose® has thermal gelation properties at certain temperature. The thermal gelation temperature (T2) of Metolose® 60SH 2 w/w% solution is above body temperature (65–66 °C), but by using different methods (Metolose® 60SH concentration, auxiliary materials), it can be shifted near to body temperature. The pH alteration between pH = 2–10 and the application of different alcohols did not influence the gelation temperature, but using water-soluble salts and changing the concentration of Metolose® 60SH solution between 2 and 3 w/w% the thermal gelation point could be decreased. Different NSAIDs were used as model drugs and which had not influence on thermal gelation temperature, but difference in in vitro liberation and penetration can be observed. In vitro adhesion test pointed out that the condition of investigated membrane can change the adhesion. Morphological test of oesophageal tissue showed that investigated materials had no irritative or tissue-damaging effect on the oesophageal mucosa even after 12 h.