Intra-uterine pressure and serum ibuprofen: observations after oral administration of 400 mg ibuprofen to a patient with primary dysmenorrhoea.

Intra-uterine pressure was recorded in a dysmenorrhoeic patient for 10 h before and after administration of a single dose of ibuprofen 400 mg. Blood samples were obtained at regular intervals during the recording for determination of the serum concentration of ibuprofen by reverse HPLC. The maximum serum concentration (37.4 micrograms Ml-1) was achieved after 1 h and the terminal half-life of ibuprofen was approximately 2 h. A marked reduction in intra-uterine pressure and the severity of pain was recorded 1.5 h following the administration of ibuprofen. Despite low or non-detectable serum concentrations of ibuprofen after 4 h, intra-uterine pressure never regained the level recorded before treatment.