Stability of thermosensitive gel. Hydrochloric acid is an aqueous solution of hydrogen chloride. It is a strong monobasic inorganic acid and has a wide range of industrial uses. In the experiments on the dissolution and release of berberine hydrochloride thermosensitive gel, the principle of sustained release is the stability of the thermosensitive gel. Thermosensitive hydrogel is a block polymer of poly-N-isopropylacrylamide and polyethylene glycol. It is liquid at low temperatures and condenses at high temperatures. This state change is reversible with temperature. .