Paracetamol and ibuprofen block hydrothorax absorption in mice.

OBJECTIVE

Non-steroidal anti-inflammatory agents (NSAIDs) and paracetamol alter pleural permeability, hindering pleural fluid recycling. The aim of this study was to investigate the effect of different analgesic and anti-inflammatory agents on fluid recycling in an induced hydrothorax model in mice.

METHODS

Hydrothorax was induced in C57BL/6 mice by injecting 500 μl phosphate-buffered saline-bovine serum albumin 1% isosmotic in the right hemithorax. Paracetamol (1 g/kg), ibuprofen (250 mg/kg) and parecoxib (2 mg/kg) were administered systematically by intraperitoneal injections. Each drug group included eight mice, which were sacrificed at 2 h and 4 h, respectively, after injections. The remaining hydrothorax volume and total cells contained were determined.

RESULTS

Regarding the paracetamol and ibuprofen groups, the remaining hydrothorax volume was greater than in the control group (350 ± 61, 348 ± 62 and 270 ± 51 μl, respectively, P = 0.042) when mice were sacrificed within 2 h. Similar observations were made in groups sacrificed after 4 h (202 ± 45 and 198 ± 44 vs 107 ± 56 μl, respectively, P = 0.002). In the parecoxib group, the remaining hydrothorax volume was 122 ± 53 μl (P = 0.038 versus paracetamol and ibuprofen, P > 0.05 versus control group). At the same time, the absorption rate in the paracetamol and ibuprofen groups was lower than in the parecoxib and control groups (P = 0.033). In the parecoxib group, the absorption rate was lower than that in the control group after 2 h (P = 0.042). In the paracetamol and ibuprofen groups, the total cell count and the macrophage and the neutrophils counts were increased, compared with the control and parecoxib groups (P = 0.025, 0.028 and 0.032, respectively).

CONCLUSIONS

Paracetamol and ibuprofen acutely hinder pleural fluid recycling by lowering the fluid absorption rate (higher remaining hydrothorax volume), while they increased total white cell counts. COX-2s presented lower remaining hydrothorax volume without acutely increasing the absorption rate. These findings could present some relevance to the administration of painkillers in patients with pleural effusion after thoracotomy.