[Nature of the interaction of voltaren and other pyrazolone and aniline derivatives with prostaglandin endoperoxide synthetase].

A study was made of the nature and mechanism of interaction of voltaren, butadion, analgin, phenacetin and paracetamol with endoperoxide prostaglandin synthetase (PGH-synthetase) of sheep vesicular glands. Activity of the enzyme was measured by polarography with the aid of a Clark's electrode. Butadion and analgin reversibly inhibited PGH-synthetase at concentrations of the order of 10(-4) M, whereas voltaren at those of the order of 10(-6) M. As regards the mechanism of action, butadion and analgin are competitive inhibitors of PGH-synthetase in respect to arachidonic acid and uncompetitive inhibitors in respect to the electron donor adrenaline. Phenacetin administered at concentrations up to 4 X 10(-2) M did not inhibit PGH-synthetase, whereas paracetamol (10(-3)-10(-2) M) increased its catalytic activity, apparently due to the electron donor properties.