The effect of acid and non-acid antipyretic analgesics on prostaglandin (PG) release from cultured mouse astrocytes and peritoneal macrophages was investigated in order to test the hypothesis that the non-acid compounds are more potent inhibitors of PG formation in brain than in peripheral tissues. Stimulation of the cells by the divalent cation ionophore A 23187 (10(-6) mol/l) induced PG release from astrocytes and macrophages (mainly PGD2 and PGE2, respectively). This PG release was inhibited by acetylsalicylic acid (10(-5) - 10(-6) mol/l) and indomethacin (10(-6) - 10(-9) mol/l) but also by high concentrations (10(-3) - 10(-5) mol/l) of the non-acid compounds 4-methyl-aminophenazone, the main active metabolite of dipyrone (metamizol), and acetaminophen (paracetamol). No difference was found in the inhibitory potency of the drugs in astrocytes and macrophages, suggesting that a specific sensitivity of brain cells toward non-acid antipyretic analgesics does not contribute to their analgesic effect.