Preparation and evaluation of in situ temperature-controlled heating gel loaded with compound Sophora flavescens decoction for rectal delivery

Abstract

Persistent prostatitis significantly impacts the quality of life for individuals suffering from the condition, while the effectiveness of conventional treatments is suboptimal. An in situ gel with sustained mild heat release under controlled temperature loaded with a compound (Fufang Kushen Tang) for rectal delivery was prepared in the study. Besides, the encapsulation efficiency of n-docosane @ CaCO3 phase change microcapsules (MEPCMs) was between 58.00 % and 64.84 %, the phase change temperature was 42.76–43.12 °C, the latent heat of phase change was between 109.62 and 122.54 J/g, and heat release and effective temperature regulation could last for up to 15–20 min. Moreover, the optimal prescription of in situ rectal heating gel was composed of 22.00 % extracts of Sophora flavescens and Radix Paeonia rubra, 0.75 % borneol, 31.19 % MEPCMs, 5.41 % P407, 0.88 % HPMC K4M, 6.00 % HP-β-CD, 7.50 % ethanol, and 26.27 % water. Furthermore, the gel could continuously heat in the rectum of rats for about 200 s, and the active components (matrine and paeoniflorin) could release 90.00 % within 12 h, and the accumulative penetration through the rectal mucosa of rats was over 85.00 %. Additionally, a pathological examination demonstrated that the gel caused slight irritation to the rectum, which could recover following drug withdrawal, and exhibited no detrimental impact on the prostate. This study developed an in situ gel with two functions drug therapy and hyperthermia for the treatment of chronic prostatitis, which could provide a novel idea for the development of chronic prostatitis medication.