Endometrial safety and tolerability of triphasic sequential hormone replacement estradiol...

Two randomized comparative multicenter studies were conducted to establish the endometrial safety and tolerability of a triphasic sequential hormone replacement estradiol valerate/medroxyprogesterone acetate (E2V/MPA) therapy regimen.

Study 1 was a randomized, double-blind, clinical phase III study in 399 postmenopausal women, following parallel-group design with two groups. The duration of study treatment was 12 or 13 cycles of 28 days. A double-dummy technique was used to ensure blinding in the study. The investigational drugs were E2V/MPA triphasic and E2V/MPA biphasic (Diviseq and Divina, respectively; Orion Pharma). In study 2, a total of 341 subjects were randomly allocated by computer into two parallel groups receiving either E2V/MPA or estradiol/norethisterone acetate triphasic (E2/NETA, Trisequens; Novo Nordisk A/S) for 12-13 cycles. The study was an open, clinical phase III trial with a randomized, parallel-group design. Endometrial biopsies combined with transvaginal ultrasound were undertaken before and at the end of treatment during the progestogen phase. Bleeding patterns and symptom control were assessed throughout both studies.

E2V/MPA triphasic was found to have similar endometrial effects and bleeding patterns to those with E2V/MPA biphasic and E2/NETA triphasic. Climacteric symptoms were relieved as quickly and effectively as with the two comparator treatments. No adverse drug reactions specific to E2V/MPA triphasic were observed. At the end of the study, the proportions of secretory samples were 67.1% for the combined E2V/MPA triphasic groups, 65.6% for the E2V/MPA biphasic group and 71.6% for the E2/NETA triphasic group. One case of hyperplasia occurred in the E2V/MPA triphasic group. Thus the incidence of hyperplasia for the combined groups was 0.33%.

The triphasic E2V/MPA regimen was well tolerated and produced endometrial effects similar to those of the two comparators. Extending estrogen during the so-called treatment-free week with a lower dose of estradiol was effective in controlling vasomotor symptoms.