Effects of Oral Pirfenidone on Colon Anastomosis Healing and Adhesion Formation in Rats.

Introduction: Many experimental studies have examined multiple drugs or treatments to improve the healing of intestinal anastomoses. Synthetic prostacyclin analogs, immunosuppressants, erythropoietin, growth hormone, insulin-like growth factor type 1, synthetic metalloproteinases inhibitors, and hyperbaric oxygen therapy have produced promising results in low-risk models of anastomosis dehiscence. However, in high-risk models, only hyperbaric oxygen therapy has been shown to be useful. Pirfenidone (PFD), a commonly used antifibrosing drug, has not been shown to be effective for this purpose. Our objective was to evaluate the effects of PFD on anastomosis healing and adhesion genesis in a low-risk rat model of dehiscence of colonic anastomosis.

Methods: An experimental study was conducted on 40 healthy Wistar rats randomly assigned to the control group or PFD experimental group (20 rats in each group). Colon anastomosis was performed 3 cm above the peritoneal reflection using the same technique in all animals. Mechanical resistance was studied by measuring bursting pressure. Adhesions were evaluated macroscopic and histologically using common staining techniques. Animals received the first PFD dose 12 h after surgery at a dose of 500 mg/kg one a day (SID) for 5 consecutive days. On day 6, the animals were reoperated on to measure the bursting pressure in situ and to classify adhesions macroscopically, and the anastomosed colon was resected for histological analysis.

Results: There were no deaths, complications, or anastomosis dehiscence in either group. The mean bursting pressure was 120.8 ± 11 mm Hg and 135.5 ± 12.4 in the control and PFD groups, respectively (p < 0.001). The adhesions were less dense and had less inflammatory cell infiltration in the PFD group (p < 0.02 and 0.002, respectively). Collagen content was slightly higher in the PFD group (p = 0.04).

Conclusions: Our results revealed favorable effects of PFD in this low-risk colon anastomosis model; for example, the bursting pressure was higher, and the macroscopic adhesions were soft and exhibited less inflammatory infiltration and higher collagen content in the PFD group than in the control group. The results showing that PFD treatment was associated with better healing of minor adhesions seem to be paradoxical because the therapeutic indications for this drug are directed at treating fibrosing diseases.