Effect of sildenafil citrate in nicotine-induced ischemia: An experimental study using a rat model

Recent experimental and clinical studies have demonstrated the negative effects of nicotine on the viability of skin flaps. Necrotic damage to skin flaps can result in significant complications including delayed wound healing, dehiscence and wound contraction. Phosphodiesterase type 5 inhibitors, such as sildenafil citrate, have a protective effect in ischemic injuries of the brain, kidney, myocardium, spinal cord, ileum and testes. In the present study, the authors evaluated the effect of sildenafil citrate on the viability of skin exposed to nicotine-induced ischemia in Sprague Dawley rats. In the preoperative period, the rats were divided into three groups of 10 rats each. Group C was treated with subcutaneous saline and group S and group N were treated with 2 mg/kg nicotine, administered subcutaneously twice per day for 28 days. McFarlane flaps were created in all experimental animals using an incision measuring 7 cm × 3 cm. Postoperative treatment varied among the groups: group S was treated with 20 mg/kg/day sildenafil citrate, while group C and group N were treated with equivalent doses of saline for seven days. A laser Doppler flow meter was used to monitor the microvasculature. Preoperative measurements of the microvasculature revealed decreased blood flow in group N and group S, both of which were treated with subcutaneous nicotine. During the postoperative evaluation, a trend toward increased blood flow was observed in group S compared with the group with nicotine-induced ischemia treated with saline alone postoperatively (group N). A visual fluorescein dye test was used to predict skin viability and demonstrated diminished skin viability in group N and group S (P<0.05) during the preoperative period. Following treatment with sildenafil for seven days, a statically significant improvement in skin viability was observed in group S (P<0.05). Nicotine decreased blood flow within the skin and impaired skin viability, while postoperative application of sildenafil significantly ameliorated the ischemic effects of nicotine and improved skin viability. Future studies will be required to evaluate the clinical use of sildenafil for the improvement of blood flow in ischemic injury of the skin.