Interaction of some anti-inflammatory analgesic drugs and hydrocortisone on the EEG effects of pentazocine, chlorpromazine and pentobarbital.

Pentazocine administered in doses of 2.5 and 5.0 mg/kg i.v. produced EEG synchronization with dose-dependent relationships. When this drug was associated with anti-inflammatory compounds such as mefenamic acid or indomethacin, the EEG effect was decreased. The same occurred also when pentazocine, 5 mg/Kg, was combined with hydrocortisone. There were no changes on the EEG effects of pentobarbital and chlorpromazine when these drugs were associated with hydrocortisone and sodium salicylate. The significance of these effects is discussed in terms of a possible interaction between the central mechanisms of pentazocine's action and some anti-inflammatory agents and hydrocortisone. Since this interaction does not happen with other drugs which produce EEG synchronization, such as pentobarbital and chlorpromazine, a different mechanism might be involved.