Tongyangxiao Lotion for Postoperative Wound Healing After Anal Fistula Surgery

This prospective, single-blind, randomized controlled trial was conducted at two hospitals in China (The First Affiliated Hospital of Hebei University of Chinese Medicine and The First Affiliated Hospital of Henan University of Chinese Medicine) from June 2023 to June 2024. The study enrolled 115 patients aged 18-65 years with low simple anal fistula who underwent low anal fistulectomy. Patients were randomly assigned to either the Tongyangxiao (TYX) group (n=58) or the potassium permanganate (PP) group (n=57). Starting on postoperative day 2, the TYX group received a 15-minute sitz bath once daily with 1500 mL of TYX decoction (40°C) for 14 days. The TYX decoction contains ten herbs: Huangbai, Kushen, Danggui, Cangzhu, Qinjiao, Xixin, Fangfeng, Chuanjiao, Mingfan, and Mangxiao. The PP group received a 15-minute sitz bath with 1:5000 potassium permanganate solution (40°C) for the same duration.

The primary outcome was wound healing time (days from surgery to complete epithelialization). Secondary outcomes included wound area (measured by ImageJ at days 5,7,14), exudate score, pain by visual analog scale (VAS, days 5,10,14), serum and tissue levels of inflammatory cytokines (TNF-α, IL-6, IL-1β) by ELISA and immunohistochemistry, expression of PI3K-Akt-mTOR pathway proteins (p-PI3K, p-Akt, p-mTOR) by Western blot and immunohistochemistry, and collagen I/III expression by Western blot, qPCR, and immunohistochemistry. Safety was monitored by recording adverse events.

In parallel, network pharmacology predicted PI3K-Akt as a core pathway. An in vitro experiment using human fibroblast HFF-1 cells treated with TNF-α (50 ng/mL) was performed to model inflammation. Cells were treated with TYX lyophilized powder (0.1 or 0.5 mg/mL), the PI3K activator 740Y-P, or their combination. Cell migration was assessed by Transwell assay; pathway protein expression and collagen were measured by Western blot and immunofluorescence.

The study was approved by the Ethics Committee of Hebei University of Chinese Medicine (YXLL2021010) and the sub-center (2021HL-248-01). All patients gave written informed consent. No U.S. government funding or IND/IDE was involved.

Results demonstrate that TYX significantly shortened wound healing time, reduced pain and exudate, decreased inflammatory cytokines, and upregulated PI3K-Akt-mTOR phosphorylation and collagen deposition. In vitro, TYX reversed TNF-α-induced suppression of fibroblast migration and pathway activity. These findings support the clinical use of TYX lotion to accelerate postoperative wound healing in anal fistula surgery by activating the PI3K-Akt-mTOR signaling pathway.

Inclusion criteria

Age 18 to 65 years

Diagnosis of low simple anal fistula according to the Chinese expert consensus on diagnosis and treatment of anal fistula (2020 edition)

Traditional Chinese medicine pattern of damp-heat downward infusion

Underwent low anal fistulectomy

No surgical contraindications

Exclusion criteria

Complex or high anal fistula

Inflammatory bowel disease, diabetes mellitus, or severe cardiac / liver / renal dysfunction

Allergy to any component of Tongyangxiao lotion or potassium permanganate

Pregnancy or lactation

Participation in another clinical trial within 3 months