Peripheral prostaglandin metabolite levels in women undergoing therapeutic abortions in the first trimester with and without treatment with prostaglandin synthetase inhibitor

The levels of 11-deoxy-13,14-dihydro-15-keto-11β,16ζ-cyclo prostaglandin E₂ (bicyclo PGEM), 13,14-dihydro-15 keto-prostaglandin F_2α (PGFM) and prolactin were measured in four serial plasma samples collected from thirty women undergoing therapeutic abortions in the first trimester by a suction curettage procedure. Eleven of these women received a preoperative loading dose of sodium meclofenamate, a PG synthetase inhibitor, before the abortion procedure was started and the rest received this medication after the last blood samples were drawn. Prolactin levels increased significantly during the procedure. Sodium meclofenamate treatment had no effect on this increase. Bicyclo PGFM levels did not increase during the procedure in untreated or treated women, whereas PGFM levels increased but only in untreated women. The lack of increase in treated women apparently was not a treatment effect because PGFM levels in corresponding samples of untreated and treated women were similar. Treatment significantly reduced the bicyclo PGEM levels immediately after completion of the procedure as compared to untreated women. This differential PG response to treatment is unprecedented and may be due to sodium meclofenamate inhibition of PGE₂ and not PGF_2α synthesis. Nevertheless, these data demonstrate that sodium meclofenamate treatment of patients undergoing first trimester therapeutic abortion to relieve pain involves selective suppression of PGE₂ synthesis.