The thickness of the visceral pleura in the animals given the lower concentration of DOXY (group 4) was 0.95 ±0.07 mm as compared with 0.56 ±0.14 mm in those given higher concentrations (group 2). The difference, however, was not significant. The overall cellularity score and the percentage of macrophages, lymphocytes, and polymorphonuclear leukocytes were not affected by the changes in concentration of DOXY (Table 1).
Intrapleural DOXY, neutralized with NaOH to a pH of 7.6, was administered to ten rabbits (at concentrations of 35 or 10 mg/kg) and compared with results obtained with DOXY at the usual pH of 2.0. At the acid pH, the visceral pleural thickness averaged 0.67±0.10 mm as compared with a value of 0.70 ±0.13 mm in the rabbits sclerosed with DOXY at a neutral pH. These differences were not statistically significant Canadian Family Pharmacy.
The left lungs showed moderate to severe atelectasis commensurate with the degree of pleural thickening. No evidence of alveolar edema, pneumonia, interstitial fibrosis, or diffuse alveolar damage was evident. Both left and right lungs showed mild vascular congestion which was possibly an agonal event. Intrapleural DOXY causes substantial deposition of fibrin and collagen in the pleural space and pleural connective tissue of previous healthy rabbits. The extent of fibrosis and adhesions was similar in the animals treated with DOXY or with TCN.
Complete obliteration of the pleural space occurred in 80 percent of the rabbits in each of the five treatment groups. The high and moderate concentrations of DOXY produced equivalent histologic changes in pleural connective tissue. Previous studies of TCN in rabbits showed that doses of 35 mg/kg were necessary for successful pleurodesis although doses of 20 mg/kg have been effective in clinical trials. The few clinical reports using DOXY have recommended daily doses of 500 mg.