Abstract: Aim Pharmaco kinetic profiles of medroxy progesterone acetate after single and multiple administ ration of cyclofem in Chinese women were analy sed to provide pharmacokinetic data for safety evaluation on chronic treatment of this long-acting injectable contraceptive.Methods Nine healthy women received once-a-month injectable cont raceptive cyclofem (aqueous microcry stalline suspension containing 25 mg medroxy progeste rone acetate and 5 mg cypionate)for up to 1 year.Blood samples were collected immediately prior to drug administ ration and to consecutive time points after injection.Int raindividual compa rison was applied in this long itudinal study.Results after 1st, 6th and 12th injection, the maximum concent rations were observed on day 3.4±0.9, 4.3±2.2 and 3.7±2.6, reespectively.C_max of 1st, 6th and 12th treatment cycles were 3.75±1.27, 5.54±1.79 and 5.55±1.80 nmol/L, while A UC0-28were 55.84±28.15, 95.45±26.56 and 98.81±21.84 nmol/(L·d), respectively.There was significant interindividual varia tion in the pharmacokinetic prof ile of MPA after int ramuscular injection of cyclofem.No meaning ful change was observed in MRT.There was a tendency of increase in C_max and AUC_0-28 of MPA during First six mo nths of treatment, whereas no statistically significant difference be tw ee n 6th and 12th injection.Conclusion No obvious drug accumulation was occured after long-term use of cyclofem.

Key words: medroxy progesterone acetate, cyclofem, once-a-month injectable contraceptive, Pharmacokinetics