OBJECTIVETo determine the rheological properties of shuanghuanglian in situ gel (SHL-gel) by using dynamic rheological experiments, in order to evaluate its gelling properties shuanghuanglian in situ gel and predict its gelling behavior in vivo.

METHODRheological parameters were determined by scanning of shear rate and frequency at different temperatures. The phase transition process from liquid to semisolid was described by testing of process heating/cooling and acute heating/cooling.

RESULTSHL-gel was Newtonian fluid under the conditions of a phase angle approaching 90 degrees at low temperature or room temperature, with its viscous characteristics dominated. It was shear-thinning pseudoplastic fluid under the conditions of a low phase angle at body temperature, with its elastic characteristics dominated. During the phase transition process, the phase angle delta was getting sharp, with exponential increase of the modulus. The gelling temperature (Tg) was at (35.38 +/- 0.05) degrees C, the phase transition temperature ranged from 33.71 to 37.01%, and phase transition time was 140 s.

CONCLUSIONThe dynamic rheological experiment characterizes the gelling properties of Shuanghuanglian in situ gel so precisely that it can be used as the basis of for in vitro evaluation and quality control of products.