Effect and safety of high-dose dienogest (20 mg/day) in the treatment of women with endometriosis

PURPOSE: Hormonal treatment of endometriosis is often continued for long periods and has the potential to affect many essential metabolic processes. The current study aimed to determine the effects and safety of high-dose dienogest as a medical endometriosis therapy. METHODS: The effects and safety of high-dose dienogest, 20-30 mg/day for 24 weeks, were examined in 21 women aged 18-52 years with laparoscopically and histologically proven endometriosis stage I-IV (according to revised American Society of Reproductive Medicine criteria). At baseline and week 24, sera were obtained and stored at -20°C prior to analysis. RESULTS: The study showed no clinically significant effect of high-dose dienogest on thyroid or adrenal function, electrolyte balance or haematopoiesis. High-dose dienogest therapy also had no appreciable effects on glucose and lipid metabolism, liver enzymes or haemostasis. For instance, although dienogest mediated small increases in the haemostatic variables prothrombin fragment 1 + 2, antithrombin III and protein C, final levels (at week 24) remained within normal reference ranges for these parameters. The exception was the HDL-3 cholesterol concentration at week 24 (0.97 mmol/l), which increased beyond the normal range of 0.28-0.64 mmol/l. CONCLUSIONS: This investigation yielded a unique dataset on the safety of high-dose dienogest in endometriosis stage I-IV. High-dose dienogest (20-30 mg/day) had little influence upon all the parameters measured. It is therefore likely that lower doses of dienogest would have similarly neutral safety effects: an important consideration in the use of dienogest for the treatment of endometriosis.