Activity of tolmetin on levels of cyclic nucleotides in experimental pleurisy.

Experimental pleurisy induced in rats with an intrapleural injection of 0.2 ml of 2% acetic acid, was used to test the effect of some non-steroidal anti-inflammatory drugs. During the acute phlogistic reaction there is a variation of the cAMP/cGMP ratio, with a sharp increase of the cGMP concentration and a parallel decrease of the cAMP level in the exudate. Indometacin and 1-methyl-5-p-toluoylpyrrole-2-acetic acid (tolmetin, Tolectin), two non-steroidal anti-inflammatory drugs, injected intrapleurally 1 h before the acetic acid injection were able to reduce the inflammatory response, affecting the cAMP and cGMP ratio. That is there is an increase of the cAMP level and a decrease of the cGMP level.