AIMTo observe the metabolic interaction between diphenytriazol and steroid hormone drugs, and provide some useful information for clinical medication.

METHODSThe steroid hormone drugs which may be co-administrated with diphenytriazol were selected, such as mifepriston, estradiol, medroxyprogesterone acetate, progesterone, norethisterone and so on. Diphenytriazol was incubated with each drug in rat liver microsome. The residual concentration of diphenytriazol or steroid hormone drugs in the microsomal incubates was determined by reversed-phase high-performance liquid chromatography, separately. The inhibition constants (K(i)) for each of them were calculated.

RESULTSThe inhibition constant K(is) of diphenytriazol for the metabolism of mifepristone, estradiol, medroxyprogesterone acetate, progesterone and norethisterone were (201.3 +/- 1.0), (94 +/- 4), (128.7 +/- 2.2), (64 +/- 5) and (80 +/- 4) micromol x L(-1), respectively. The inhibition constants K(i) of steroid hormone drugs for the metabolism of diphenytriazol was (66.9 +/- 2.2) micromol x L(-1) for estradiol, (60.0 +/- 2.3) micromol x L(-1) for medroxyprogesterone acetate, (163 +/- 10) micromol x L(-1) for progesterone and (88 +/- 5) micromol x L(-1) for norethisterone, respectively.

CONCLUSIONDiphenytriazol shows metabolism interaction with steroid hormone drugs such as estradiol, medroxyprogesterone acetate, progesterone and norethisterone.