The effects of acidic and nonacidic pyrazoles on arachidonic acid metabolism in mouse peritoneal macrophages.

The effects of acidic and nonacidic pyrazole derivatives and their metabolites on arachidonic acid metabolism have been investigated in mouse peritoneal macrophages stimulated with the calcium ionophore A 23 187 (10(-6) Mol/l). In the group of the acidic compounds with anti-inflammatory properties, phenylbutazone and butyl malonic acid mono (1-phenylhydrazide), the hydrolysis product of mofebutazone, inhibited prostaglandin production in a dose-dependent manner (10(-4)-10(-6) Mol/l). In contrast, mofebutazone itself and its hydroxylation product, 4-OH-mofebutazone, failed to show any activity. Similarly, in the case of bumadizone, an anti-inflammatory drug structurally related to phenylbutazone, no inhibitory effect on prostaglandin release was found either. The nonacidic pyrazole derivatives with antipyretic and anti-inflammatory activity, antipyrine, isopropylaminophenazone, as well as metamizol and its active metabolites 4-methylaminophenazone and 4-aminophenazone, also inhibited prostaglandin release dose-dependently. This was found to be paralleled by an increased leukotriene C4 production. Neither of the main excretory metabolites of metamizol, acetyl- and formylaminophenazone, showed any effect. The concentration levels at which the nonacidic compounds affected arachidonic acid metabolism (approx. 10(-4) Mol/l) were high enough to elicit anti-inflammatory effects. They were far higher, though, than the plasma levels producing antipyretic and analgesic effects that are reached after therapeutic doses.