| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Original Articles |
Department of Obstetrics and Gynecology (Y.S., M.C., T.I., K.W.), Toride Kyodo General Hospital, Toride, Ibaraki 302-0022; and Department of Obstetrics and Gynecology (T.A.), Tokyo Medical and Dental University, Tokyo 113-8519, Japan
Address correspondence and requests for reprints to: Yoshiaki Somekawa, M.D., Toride Kyodo General Hospital, Hongo 2-1-1 Toride, Ibaraki 302-0022, Japan. E-mail: pv2t-sigi{at}asahi-net.or.jp
Abstract
The purpose of this study was to evaluate the efficacy of ipriflavone in preventing bone loss, decreasing in serum cholesterol and decreasing the rate of appearance of vasomotor symptoms, as well as the effects of ipriflavone on reduction of myoma volume by estrogen deficiency during treatment with the GnRH analog leuprolide.
One hundred two women (mean age, 44.3 ± 0.53 yr) receiving leuprolide therapy for uterine leiomyoma were randomly allocated to two groups (group A, leuprolide only; group B, leuprolide with ipriflavone). Bone mineral density of the lumbar spine was measured by dual-energy x-ray absorptiometry before and after treatment for 6 months. Levels of serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol (LDL-C) were measured before treatment and after 3 and 6 months of treatment. Subjects were asked to report the appearance of vasomotor symptoms throughout treatment. Myoma node volumes were measured before treatment and after treatment for 6 months.
Bone mineral density was reduced in both groups, with reduction rates of -5.26% in group A and -3.70% in group B (P < 0.01 vs. group A). Changes in bone markers were not significant in either group. TC was significantly increased in both groups, and TG levels were increased significantly after 3 and 6 months of treatment in group A but not in group B. There was no significant difference between these two groups in amount of increase of either TC or TG. LDL-C levels were increased significantly after 3 and 6 months of treatment in both groups, and the differences between the groups (11.7% in group A vs. 7.5% in group B at 3 month and 22.6% in group A vs. 8.4% in group B at 6 month) were significant. Severe vasomotor symptoms were reduced in group B. The rates of reduction of myoma volume were 49.8% in group A and 52.9% in group B; this difference between groups was not significant.
Ipriflavone efficaciously alleviated the adverse effects of estrogen deficiency such as bone loss and increase in LDL-C level, and the ability of leuprolide therapy to reduce myoma volume was not decreased by ipriflavone administration.
ALTHOUGH THE GnRH analog leuprolide is frequently used for pseudo-menopausal therapy, it has deleterious side effects, including the appearance of menopausal symptoms, increase in serum cholesterol level, and moderate reduction of bone mineral densities (BMDs) due to suppression of estradiol levels. A number of studies have demonstrated that add-back therapies such as estrogen replacement (1), PTH (2), ipriflavone (3), vitamin K2 (4), and tibolone (5) are useful in preventing these types of bone loss. However, these studies focused mainly on the prevention of bone loss, and few studies have reported the effects of add-back therapies on lipid profiles and menopausal symptoms (5). Ipriflavone is a derivative of isoflavone, and the structural similarity between these agents suggests that they may have similar properties. Isoflavones such as daidzein and genistein bind to estrogen receptors and have weak estrogenic and antiestrogenic activities (6, 7, 8). The purpose of this study was to evaluate the efficacy of ipriflavone in preventing bone loss, decreasing serum cholesterol and decreasing the rate of appearance of vasomotor symptoms, as well as the effects of ipriflavone on reduction of myoma volume induced by estrogen deficiency during leuprolide therapy.
Subjects and Methods
Study subjects
One hundred two Japanese women aged 24–52 (mean age, 44.3 ± 0.53 yr) with uterine leiomyomas who met the criteria for leuprolide treatment agreed to participate in this study. All the patients had normal cyclic menses. Those who were performing excessive exercise, were heavy smokers, alcoholics, or who had been clinically diagnosed with liver disease, ischemic heart disease, diabetes, renal disease, metabolic, or other endocrine diseases that could influence bone turnover or lipid metabolism, and those with a history of carcinoma were excluded. Those who complained of moderate to severe vasomotor menopausal symptoms before enrollment were also excluded. None of the women had a previous history of metabolic bone disease, and none were receiving medications that could affect calcium absorption or bone turnover. The study was approved by the local Ethics Committee and was performed in accordance with the Declaration of Helsinki. Each subject gave informed consent for participation in the study before participation.
Study protocol
Subcutaneous leuprolide acetate (Leuprin; provided by Takeda Chemical Industries Co., Ltd., Tokyo, Japan) was administered to the 102 women at a dose of 1.88 mg per month. The first vial of leuprolide acetate was administered early in the follicular phase (second to fifth day of the cycle). These 102 women were nonblindly and randomly allocated to two groups; the first group (group A, n = 51) was given only leuprolide acetate, whereas the second group (group B, n = 51) was given leuprolide acetate together with oral ipriflavone (Osten, 600 mg per day; Takeda Chemical Industries Co. Ltd.). These regimens were continued for 6 months, and bone markers and BMD of the lumbar spine were measured before and at the end of treatment. Variables in the backgrounds of the patients in each group including age, weight, body mass index, age of menarche, gravidity, and parity were compared.
Bone densitometry and bone markers
BMD of the lumbar spine (L2–L4) was measured by dual-energy x-ray absorptiometry using a Hologic QDR-4500 A densitometer (Hologic, Inc., Waltham, MA). BMD was measured before treatment and after treatment with leuprolide for 6 months. We used the mean of three scans to calculate bone mineral content, and lumbar absorptiometries were examined by the same observer. To minimize variation in measured values, differences in total spine areas between two points were set within 5%. Total BMD intra-assay coefficients of variation (CV) for the spine were within 1%.
Serum intact osteocalcin (iOC) was measured as a bone formation marker before treatment and after 6 months of treatment. Serum iOC was measured by a new sandwich enzyme immunoassay, using antibodies to the N- and C-terminal regions of human osteocalcin (9). The values of serum iOC obtained reflect bone formation more precisely than total osteocalcin because unrelated fragments are excluded from measurement. The intra-assay CV for iOC was less than 5.4%.
At the same time, urine total pyridinium cross-links, pyridinoline (Pyr), and deoxypyridinoline (D-Pyr) were measured as bone resorption markers. Urinary concentrations were assessed with urine collected over 2 h (0800–1000 h) and corrected for creatinine excretion. Urinary Pyr and D-Pyr were measured according to a previously described procedure (10). CV were less than 10% for both Pyr and D-Pyr.
Vasomotor symptoms
New appearance of vasomotor symptoms such as hot flashes, sweating, chills of the body or extremities, and palpitations was reported at 4-week intervals. These vasomotor symptoms were stratified into three degrees of severity: grade 1, symptom is present but does not require additional therapy; grade 2, severe symptom is present and requires additional therapy such as Chinese herbal medicine to continue leuprolide treatment; grade 3, patients did not complete leuprolide treatment despite use of additional therapy because of severe vasomotor symptoms.
Lipid and hormone analysis
The values of fasting serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured for evaluation of risk of atherosclerosis. After an overnight fast, blood was collected from each patient for estimation of lipids. TC and TG levels were measured using enzymatic colorimetric methods (Ono Pharmaceutical, Osaka, Japan) and the enzymatic method (Shino-test, Tokyo, Japan). HDL-C levels were measured by a direct method (11) using commercially available kits (Kyowa Medix, Tokyo, Japan) on a Hitachi chemical analyzer (Hitachi Ltd., Tokyo, Japan). LDL-C levels were calculated with Friedewald’s equation (12). The CV for TC, TG, and HDL-C were 0.7%, 1.9%, and 0.7%, respectively. Serum levels of estradiol (E2) were measured before treatment, after 3 months of receiving treatment, and at the end of treatment. The serum level of E2 was measured by RIA (Diagnostic Products Corp., Los Angeles, CA). The intra-assay CV for E2 was 3.2%.
Leiomyoma volumes
Ultrasonographic scans were performed using a Mochida Sonovista-Color II (Mochida Pharmaceutical Co. Ltd., Tokyo, Japan) for the measurement of uterine leiomyoma volumes, coupled with a 5-Mhz probe, and three diameters of the largest myoma node were measured at the beginning of and after 6 months of treatment.
Statistical analysis
Results are given as the mean ± SE. Data
analysis was performed using a Stat View 5.0 software package
(SAS Institute, Inc., Cary, NC). Baseline parameters were
compared between the groups by one-way factorial ANOVA for continuous
variables and by Mann-Whitney test for noncontinuous variables. ANOVA
for repeated measures was used to evaluate the significance of any
changes in the bone markers, serum lipids, and BMD. Differences in
percentage changes between the two groups were also tested by one-way
factorial ANOVA. The 
2 test was used to
evaluate the significance of differences between groups in the
appearance of vasomotor symptoms. Findings of P less than
0.05 were considered significant.
Results
There were no significant differences between the groups in
background parameters, baseline BMD, or serum lipid levels (Table 1
). Mean E2 levels
were under 20 pg/mL after 3 and 6 months of treatment in both groups
and did not differ significantly between the groups. BMD was
significantly reduced in both groups, with reduction rates of -5.26%
in group A and -3.70% in group B (P < 0.05
vs. group A). Percent change in bone formation marker (iOC)
tended to be higher and bone resorption markers (urine Pyr and urine
D-Pyr) tended to be lower after 6 months of
treatment in the ipriflavone-added group (group B), but these
differences between groups were not significant. (Fig. 1)
|
|
, A and B).
|
2 = 3.94;
Fig. 3). Severe vasomotor symptoms were
reduced in the ipriflavone-added group (group B).
|
Discussion
Although the basis for GnRH analog treatment of uterine leiomyoma is the dependence of myoma cells on E2 for growth, the severe hypoestrogenic state induced by GnRH analog has deleterious adverse effects such as decrease of BMD, appearance of vasomotor symptoms, and increase in serum LDL-C. Ipriflavone is a derivative of isoflavone, and the dose of ipriflavone we administered, 600 mg, is ultimately metabolized to 60 mg daidzein (13). For this reason, ipriflavone may have had effects similar to those of isoflavones. The findings of our study suggest two intriguing points.
The first is related to the reason why the results of several studies differ as to effects of ipriflavone on bone mass, lipid profiles, and vasomotor symptoms. Several studies have reported that ipriflavone is effective in promoting bone mass and preventing bone loss (3, 14, 15). Gambacciani et al. (3) reported that ipriflavone administration prevented the decrease of BMD induced by GnRH analog treatment and that no significant change was seen in BMD after 6 months of treatment in an ipriflavone administration group in Italy. This result differed from that of our study in Japan, in that the effect of decrease in BMD after 6 months of treatment persisted in our ipriflavone administration group. One possible explanation of this divergence in findings is differences in food culture between Italy and Japan, in that Japanese women consume more than 50 mg per day of isoflavones while western individuals consume 1–3 mg per day (16, 17). Provided that ipriflavone, a derivative of isoflavones, acts through the same mechanism as isoflavones, Japanese people may have acquired less responsiveness to the synthetic phytoestrogen ipriflavone due to long exposure to isoflavones. If this is the case, short-term administration of ipriflavone may be insufficient to obtain satisfactory effects. Unlike ipriflavone, recent studies have reported that soy phytoestrogens are only minimally or not effective in preventing bone loss in surgically postmenopausal cynomolgus monkeys (18) and postmenopausal women (19). Isoflavones and ipriflavone may have different effects and mechanisms of such effects on bone metabolism.
On the other hand, few studies of associations between ipriflavone, menopausal symptoms, and lipid profiles have been performed. Several studies of isoflavones have reported inconsistent effects on serum lipids. One study reported a significant reduction in TC in premenopausal women consuming isoflavones, compared with an isoflavone-free control period (20), but another study reported no significant effects of isoflavone on cholesterol level (21, 22). Recent studies have reported that purified soy isoflavones administered without an adequate dose of soy protein does not affect plasma lipid concentration (23, 24). This soy protein may explain the contradictory findings described in these reports. Japanese women consume considerable amounts of soy product (16), and in our study ipriflavone efficaciously alleviated the adverse effects of estrogen deficiency such as bone loss and increase in serum LDL-C level with soy peptide intake.
Concerning associations between isoflavones and menopausal symptoms, hot flashes are thought to occur less frequently in Japan than in Canada, possibly because of the high phytoestrogen intake from soy foods in Japan (21, 25). Although ipriflavones somewhat lessen vasomotor symptoms, their reduction of the appearance of vasomotor symptoms was too small to be clearly determined in our study, suggesting that the estrogenic effects of ipriflavone were very weak and insufficient to compensate for the lack of estrogens induced by leuprolide during the study period. Use of vasomotor symptoms implies subjective evaluation to some extent, and, thus, our study has a methodological limitation in detection of these minimal effects of ipriflavone. Results of our study suggest that short-term administration of this weak phytoestrogen has mild effects and that chronic administration of it may be required to obtain clinically sufficient effects. The estrogenic binding activities of isoflavones are reported to be on the order of only 1/100 to 1/1000 that of 17ß-estradiol (6, 7, 8), and the estrogenic properties of ipriflavone are also thought to be as weak as those of isoflavones (26). The estrogenic activities of isoflavones and ipriflavone should, thus, not be exaggerated.
The second point concerns the reason why this synthetic phytoestrogen alleviated leuprolide-induced deleterious effects on bone mass, vasomotor symptoms, and lipids, whereas it had no effect on myoma node size. Isoflavones such as daidzein and genistein bind to estrogen receptors and have weak estrogenic and antiestrogenic activities (6, 7, 8). In our study, the weak estrogenic effects of ipriflavone may have ameliorated adverse effects of severe hypoestrogenic states resulting from GnRH analog treatment. One possible explanation for this is the difference in sensitivities to estrogen between target organs. Robert (27) reported the estrogen threshold hypothesis for hormone treatment of endometriosis, in his proposal of a hierarchy of sensitivity to E2 in various tissues. A concentration of E2 in the range of 30–45 pg/mL produced by low-dose estrogen replacement added to GnRH analog treatment may be associated with partial prevention of bone loss without the growth of endometriotic lesions. E2 concentration must be in the range of 15–25 pg/mL to reduce myoma volume in premenopausal women by 50% (28, 29), but according to the estrogen threshold hypothesis, concentrations of E2 in which vasomotor symptoms and lipids are responsive are higher than those at which myomas are responsive. If ipriflavone has weak estrogenic activities that can affect myoma volume size, and given the lack of change in myoma node volume reduction rate observed in our study, its estrogenic activities in the group administered by leuprolide with oral ipriflavone in our study must have been less than the range of 15–25 pg/mL as E2 level, whereas vasomotor symptoms and lipids are not responsive at this E2 level. The findings that ipriflavone has estrogenic effects on vasomotor symptoms and LDL-C without affecting myoma node volume reduction seem to be inconsistent. Weak estrogenic effects and the estrogen threshold hypothesis are not sufficient to explain this relief of these deleterious adverse effects without effects on reduction of myoma node volume.
Another possible explanation for these discrepancies in effects is the
theory of selective estrogen receptor modulators (SERMs). Recent
studies have indicated that there are at least two types estrogen
receptors (ER
and ERß), and ER is known to be present in the
uterus whereas ERß is predominantly present in bone (30, 31). Genistein, which is one of the most typical isoflavones and
is thought to have properties similar to those of ipriflavone, binds
weakly with ER but complexes with ERß nearly as well as estrogens
(32). Arjmandi et al. (33)
speculated that ipriflavone binds to ERß and has positive effects on
bone. The report of Kuiper et al. (26)
indicating that the estrogenic potency of phytoestrogens is
significant, and more so for ERß than for ER, supports this
explanation. Ipriflavone may act in a fashion analogous to SERMs and
has antiestrogenic effects on uterus, resulting in similar rates of
reduction of uterine myoma node volumes with or without ipriflavone
treatment. Effects of ipriflavone on bone mass, lipid metabolism, and
menopausal symptoms may be estrogenic, and this SERM-like property may
be the reason why ipriflavone has not affected observed reduction of
myoma node volume, whereas it causes differences in bone mass, lipid
metabolism, and menopausal symptoms. Our result indicates one direction
of add-back therapy with GnRH analogs for the treatment of uterine
leiomyoma.
Acknowledgments
We gratefully thank the patients who agreed to participate in this study and Hiroshi Hirasawa and Kazuyoshi Hosoya for assistance with laboratory procedures.
Footnotes
1 Presented in part at the 7th World Congress of Endometriosis,
London, United Kingdom, 2000. 
Received September 28, 2000.
Revised January 11, 2001.
Revised March 19, 2001.
Accepted March 20, 2001.
References
and ß. Endocrinology. 138:863–870.This article has been cited by other articles:
 |
|
 |
|
  S. Palomba, F. Orio Jr, T. Russo, A. Falbo, T. Cascella, P. Doldo, C. Nappi, G. Lombardi, P. Mastrantonio, and F. Zullo Long-term effectiveness and safety of GnRH agonist plus raloxifene administration in women with uterine leiomyomas Hum. Reprod., June 1, 2004; 19(6): 1308 - 1314. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Palomba, T. Russo, F. Orio Jr, A. Sammartino, F. M. Sbano, C. Nappi, A. Colao, P. Mastrantonio, G. Lombardi, and F. Zullo Lipid, glucose and homocysteine metabolism in women treated with a GnRH agonist with or without raloxifene Hum. Reprod., February 1, 2004; 19(2): 415 - 421. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. C. Register, M. J. Jayo, and M. S. Anthony Soy Phytoestrogens Do Not Prevent Bone Loss in Postmenopausal Monkeys J. Clin. Endocrinol. Metab., September 1, 2003; 88(9): 4362 - 4370. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Palomba, F. Orio Jr., M. Morelli, T. Russo, M. Pellicano, C. Nappi, P. Mastrantonio, G. Lombardi, A. Colao, and F. Zullo Raloxifene Administration in Women Treated with Gonadotropin-Releasing Hormone Agonist for Uterine Leiomyomas: Effects on Bone Metabolism J. Clin. Endocrinol. Metab., October 1, 2002; 87(10): 4476 - 4481. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
,
P < 0.05 compared with baseline;
