Pleurodesis by erythromycin, tetracycline, Aerosil？ 200, and erythromycin plus Aerosil？ 200 in a rat model: a preliminary study

Overall, 75 adult male Spraque-Dawley rats were randomized to 5 treatment groups. Each group received an intrapleural injection via 5 Fr Silastic tubes of one of the following sterile agents: 35mg/kg erythromycin in 2 ml of saline, 35mg/kg tetracycline in 2 ml of saline, 35mg/kg Aerosil？ 200 in 2ml of saline, erythromycin (35mg/kg in 2 ml of saline) plus Aerosil？ 200 (35mg/kg in 2 ml of saline), or 2 ml of saline as a control. The animals were euthanized and necropsied 30 days after injection. The pleurae were assessed for macroscopic and microscopic evidence of surrounding inflammation and fibrosis.The median macroscopic score in the Aerosil？ 200 group was significantly higher than that in the erythromycin group (P？<？0.005). The median microscopic score in the erythromycin group was significantly lower than that in the Aerosil？ 200 and erythromycin plus Aerosil？ 200 groups (P？<？0.005). Furthermore, maximum and minimum pleural fibrosis was observed in the erythromycin plus Aerosil？ 200 and erythromycin groups, respectively (P？<？0.05).This study suggests that Aerosil？ 200 with or without erythromycin may be more potent pleurodesis agent than erythromycin and tetracycline.Obliteration of the pleural space (pleurodesis) to prevent recurrent pleural effusion (mostly malignant) or pneumothorax is chiefly achieved through the use of chemical pleural sclerosants [1]. The best pleural sclerosant should be safe, inexpensive, widely available, and easily administered. However, none of the pleurodesing agents including talc, the sclerosant of choice in clinical practice, fulfil all these criteria [1-3]. Intrapleural administration of the most preferred pleurodesing agent, the talc, is believed to accompany with severe complications such as adult respiratory distress syndrome. On the other hand, parenteral tetracycline which was once the sclerosant agent of choice in clinical practice is no longer commercially available [4]. In addition, intrapleural application of some antineo