Effects of Feminizing Hormones on Sperm Production and Malignant Changes: Microscopic Examination of Post Orchiectomy Specimens in Transwomen.

OBJECTIVE: To examine post-orchiectomy specimens of transgender individuals to better understand the reproductive implications of hormonal therapy and to look for potential malignant or premalignant changes. MATERIALS AND METHODS: A retrospective chart review was performed on the orchiectomy specimens from 135 TG individuals who underwent bilateral simple orchiectomy (54) or vaginoplasty with combined orchiectomy (81) at a single institution from 2014-2017. Factors examined included microscopic evidence of spermatogenesis, weight of specimens, evidence of malignant or premalignant changes, and patient demographic information. RESULTS: Four percent (6/135) of all orchiectomy specimens had normal spermatogenesis in both testicles. Twenty-one percent (28/135) demonstrated some stage of spermatogenesis, of which 61% (17/28) were in maturational arrest. The median patient age at surgery was 30 years (range 18-76). Median overall testicle weight was 24 g (range 10.4-71.1), compared with 24 g (range 10-71g) in testicles without evidence of spermatogenesis and 26 g (range 17.9-40.9) in testicles with normal spermatogenesis. None of the specimens demonstrated premalignant or malignant changes. CONCLUSION: Up to 21% of individuals undergoing a gender affirming surgery had microscopic evidence of spermatogenesis in varying stages. Furthermore, 4% of individuals had normal spermatogenesis. None of the specimens had malignant or premalignant changes. These findings may have implications for counseling transgender individuals on sexual and reproductive health and highlight the need for further research in this sector.

The estrogenicity of methylparaben and ethylparaben at doses close to the acceptable daily intake in immature Sprague-Dawley rats.

The estrogenicity of parabens at human exposure levels has become a focus of concern due to the debate over whether the estrogenicity of parabens is strong enough to play a role in the increased incidence of breast cancer. In this study, the uterotrophic activities of methylparaben (MP) and ethylparaben (EP) at doses close to the acceptable daily intake as allocated by JECFA were demonstrated in immature Sprague-Dawley rats by intragastric administration, and up-regulations of estrogen-responsive biomarker genes were found in uteri of the rats by quantitative real-time RT-PCR (Q-RT-PCR). At the same time, the urinary concentrations of MP and EP, as measured by gas chromatography-mass spectrometry (GC-MS) in rats that received the same doses of MP and EP, were found to be near the high urinary levels reported in human populations in recent years. These results show the in vivo estrogenicity of MP and EP at human exposure levels, and indicate that populations exposed to large amounts of MP and EP may have a high burden of estrogenicity-related diseases. In addition, a molecular docking simulation showed interaction between the parabens and the agonist-binding pocket of human estrogen receptor α (hERα).

Types of combined oral contraceptives used by US women.

BACKGROUND: We sought to estimate the prevalence of types of combined oral contraceptives (COCs) used among US women. STUDY DESIGN: We analyzed interview-collected data from 12,279 women aged 15-44 years participating in the National Survey of Family Growth, 2006-2010. Analyses focused on COC use overall, by pill type, across sociodemographics and health factors. RESULTS: The prevalence of current COC use (88 different brands) was 17%. The majority of COC users used earlier-formulation COCs: ≥30 mcg (67%) versus <30 mcg estrogen (33%), monophasic (67%) versus multiphasic (33%) dosages and traditional 21/7 (88%) versus extended/other cycle regimens (12%) regimens. Norgestimate (32%) and norethindrone (20%) were the most commonly used progestins. Sociodemographic, gynecological and health risk factors were associated with type of COC use. CONCLUSION: Further investigation of specific COC use and of the factors associated with types of pills used among US women at the population level is needed.

User characteristics and out-of-pocket expenditures for progestin-only versus combined oral contraceptives.

BACKGROUND: Little is known about the proportion of oral contraceptive pill (OCP) users that use progestin-only pills (POPs), factors associated with POP use, and whether out-of-pocket expenditures and dispensing patterns are similar to combined oral contraceptives (COCs). STUDY DESIGN: Observational cohort using 1996-2008 Medical Expenditure Panel Surveys. RESULTS: Among all OCP users, 4% used POPs and changed little between 1996 and 2008. Women were more likely to use POPs if they received postpartum care (p<.001), had a diagnosis of hypertension (p<.001) or resided in the West (p<.01). POP users, compared to COC users, were more likely to pay $15 and more (p<.01) and less likely to obtain more than one pack per purchase (p<.001), controlling for age, race/ethnicity and insurance coverage. CONCLUSION: POP use is very low in the United States. POP users obtained fewer packs per purchase compared with COC users, suggesting that POP may be used as transitional OCPs, particularly during the postpartum period.

Hormonal contraception and bone metabolism: a systematic review.

BACKGROUND: Although a large amount of studies in the literature evaluated the effects of hormonal contraception on bone, many questions remained still unclear, such as the effect of these therapies on fracture risk. STUDY DESIGN: We performed a systematic search of the published studies from January 1975 through January 2012 on the effects of hormonal contraceptives on bone metabolism. We analyzed the overall effect on bone mineral density (BMD) and on fracture risk of combined oral contraceptives (COCs), progestogen-only contraceptives, transdermal contraceptives and vaginal ring. RESULTS: COC therapy does not seem to exert any significant effect on BMD in the general population. In adolescents, the effects of COCs on BMD seem to be mainly determined by estrogen dose. The use of COCs in perimenopausal women seems to reduce bone demineralization and may significantly increase BMD even at a 20-mcg dose. Use of depot medroxyprogesterone acetate is associated with a decrease in BMD, although this decrease seems to be partially reversible after discontinuation. Data on other progestogen-only contraceptives, transdermal patch and vaginal ring are still limited, although it seems that these contraceptive methods do not exert any influence on BMD. CONCLUSIONS: Hormonal contraceptives do not seem to exert any significant effect on bone in the general population. However, other randomized controlled trials are needed to evaluate the effects on fracture risk since the data available are derived from studies having the effects on BMD as the primary end point, and BMD may not accurately reflect the real fracture risk.

Endocrine-mediated effects of 4,4'-(hexafluoroisopropylidene)diphenol in SD rats, based on a subacute oral toxicity study.

The purpose of this study was to investigate the endocrine-mediated effects of 4,4'-(hexafluoroisopropylidene)diphenol according to OECD test guideline no. 407. The estrogenic properties of this chemical have already been shown on uterotrophic assay, and this chemical is classified as a low-production volume chemical in REACH program. Rats were orally gavaged with 0, 10, 30, and 100 mg/kg/day of test chemical for at least 28 days, beginning at 8 weeks of age. In the 100 mg/kg group of male rats, endocrine-mediated effects, atrophic changes in the mammary glands and testicular Leydig cells, decreased accessory sex organ weights, and hypertrophy of the adrenal zona fasciculata with increased organ weights were seen; there was dysfunction of the estrous cycle in the 30 and 100 mg/kg groups, and increased serum T4 values were observed in the 100 mg/kg groups of both sexes. In addition, we also noted other findings, such as reduced body weight gains in the 30 and/or 100 mg/kg groups of both sexes, dilatation of the large intestinal lumen in the 100 mg/kg groups of both sexes, decreased hematopoiesis in the bone marrow and spleen, and decreased white blood cell counts in the 100 mg/kg group of male rats. Our results demonstrate that in a repeated-dose toxicity study, 4,4'-(hexafluoroisopropylidene)diphenol has various endocrine-mediated effects and its NOAEL (no observed adverse effect level) is 10 mg/kg/day.

A randomized, multiple-dose parallel study to compare the pharmacokinetic parameters of synthetic conjugated estrogens, A, administered as oral tablet or vaginal cream.

OBJECTIVE: A randomized, parallel-design study was conducted to determine the pharmacokinetic profile of synthetic conjugated estrogens A (SCE-A) vaginal cream (0.625 mg SCE-A/g) when administered at intervals (1 g once daily for 7 d, then twice weekly) over a 27-day period as compared with the pharmacokinetic profile of 0.3 mg SCE-A tablets administered once daily orally for 27 days. METHODS: Blood samples were collected 48 hours before initial dosing for baseline levels and at multiple occasions during the study until 48 hours after final study dosing (day 29). Maximum plasma concentration, time to maximum plasma concentration (Tmax), and area under the curve from 0 to 24 hours were calculated at days 1, 7, and 27; in addition, area under the curve from 0 to 48 hours was calculated at days 7 and 27, and area under the curve weekly (AUCweekly) values were calculated for both groups. For purposes of comparison, ratios of AUCweekly values for vaginal cream and oral tablets were analyzed. RESULTS: Compared with an oral daily dose of 0.3 mg SCE-A, the steady-state systemic exposure from vaginal cream application was considerably less, with the cream-to-oral ratio being 0.45 for baseline-adjusted (BA) unconjugated estradiol, 0.30 for BA unconjugated estrone, and 0.04 for unconjugated equilin (AUCweekly). At steady-state, the systemic blood levels of BA unconjugated estrone, BA unconjugated estradiol and unconjugated equilin were significantly lower in women who received biweekly application of 1 gm vaginal cream compared to women who took an oral daily dose of 0.3 mg SCE-A tablet. CONCLUSIONS: After intravaginal application of SCE-A vaginal cream, absorption of estrogens was lower compared with absorption after oral administration. At steady state, the systemic exposure of equilin, estradiol, and estrone was significantly lower after twice-weekly administration of 1 g SCE-A vaginal cream compared with that achieved with an oral daily dose of a 0.3 mg SCE-A tablet.

Pharmacokinetics of a modified-release estrogen tablet.

OBJECTIVE: To determine steady-state plasma concentrations and the pharmacokinetic profile of the essential components of synthetic conjugated estrogens, B (SCE-B), particularly total estrone and delta8,9-dehydroestrone (DHE), after oral administration of a modified-released tablet. STUDY DESIGN: A randomized, multiple-dose, pharmacokinetic study of 28 healthy, postmenopausal women randomly assigned to receive two SCE-B 0.3-mg tablets or one 1.25-mg tablet daily for 14 days. Blood samples were obtained before and after dosing at designated times. Total (conjugated and free) and unconjugated estrogens, namely estrone, equilin, and delta8,9-DHE, were determined, and pharmacokinetic analysis was performed. RESULTS: Steady-state plasma levels of total estrone and total delta8,9-DHE measured on day 14 over a 24-hour period showed minor fluctuations and a similar time to maximum concentration (Tmax): mean Tmax of total estrone = 7.94 and 8.36 hours for 0.3-mg and 1.25-mg tablets, respectively; mean Tmax of total delta8,9-DHE = 7.08 and 8.36 hours for 0.3-mg and 1.25-mg tablets, respectively. Consistency in pharmacokinetic parameters was seen between the two doses of SCE-B. CONCLUSION: SCE-B 0.3-mg and SCE-B 1.25-mg tablets achieved consistent pharmacokinetic parameters and steady-state levels when administered to healthy postmenopausal women. Achieving smooth, predictable levels of component estrogens may result in more consistent relief of menopausal symptoms.

[Effect of estrogens and liposomes on the course of the purulent wounds healing in elderly and senile patients].

The cytological changes dynamics during the process of the purulent wounds healing in elderly and senile patients using estrogens and liposomes in complex of treatment are adduced.

[Low dose estrogens and synthetic estrogens. Options for hormone replacement therapy in climacteric women]. / Estrógenos a dosis bajas y estrógenos de síntesis. ¿Opciones para el reemplazo hormonal en el climaterio?

A significant increase for cardiovascular disease and breast cancer risks was found in the Women's Health Initiative study in 2002, for current users of conjugated equine estrogens in the habitual dose of 0.625 mg for hormone replacement therapy (HRT) for treating menopausal symptoms. This unexpected finding has caused new-found interest in the world to determine if the use of low-dose estrogens or synthetic estrogens can be useful and safer. At present, there is no scientific evidence about the reduction of such risks with the use of low-dose estrogens. Current medical information has showed that HRT is effective to treat climacteric syndrome and to prevent postmenopausal osteoporosis. In addition, HRT reduces significantly the frequency and severity of vaginal bleeding. Currently the Climacteric and Menopause Program at the Instituto Mexicano del Seguro Social only considers the use of conjugated equine estrogens at the standard dose (0.625 mg). The purpose of this paper is to present some results about use of low-dose estrogens and points of view about synthetic estrogens found in current medical literature. This review aims at contributing to the analysis a possible future use of this type of hormone treatment within the institutional program with the goal of giving safer options to clinicians in managing women with menopausal symptoms.

The differential effect of estrogen, estrogen-progestin and tibolone on coagulation inhibitors in postmenopausal women.

OBJECTIVES: Hormone therapy increases the risk of venous thromboembolism, possibly through a negative effect on coagulation inhibitors. The aim of the study was to assess the effect of conjugated equine estrogens alone or in combination with medroxyprogesterone acetate, low-dose 17beta-estradiol combined with norethisterone acetate and tibolone on inhibitors of coagulation. METHODS: Two hundred and sixteen postmenopausal women received orally either conjugated equine estrogens 0.625 mg (CEE, n=24) or tibolone 2.5 mg (n=24) or CEE+medroxyprogesterone acetate 5 mg (CEE/MPA, n=34) or 17beta-estradiol 1 mg+norethisterone acetate 0.5 mg (E2/NETA, n=66) or no therapy (control, n=68) for 12 months. Plasma antithrombin, protein C and total protein S were measured at baseline and at 12 months. RESULTS: CEE, CEE/MPA and E2/NETA treatment were associated with a significant decrease in antithrombin levels (CEE: baseline 235.6+/-47.6 mg/l, follow-up 221.3+/-48.3 mg/l, p=0.0001; CEE/MPA: baseline 251.1+/-38.6 mg/l, follow-up 225.0+/-42.6 mg/l, p=0.009; E2/NETA: baseline 257.1+/-59.4 mg/l, follow-up 227.1+/-50.4 mg/l, p=0.007; tibolone: baseline 252.6+/-62.4 mg/l, follow-up 261.9+/-59.1 mg/l, p=0.39). Protein C decreased significantly in the CEE and CEE/MPA groups (CEE: baseline 3.64+/-1.17 mg/l, follow-up 2.48+/-1.47 mg/l, p=0.004; CEE/MPA: baseline 3.24+/-1.23 mg/l, follow-up 2.61+/-1.38 mg/l, p=0.001; E2/NETA: baseline 3.24+/-1.10 mg/l, follow-up, 3.15+/-1.11 mg/l, p=0.08; tibolone: baseline 3.26+/-1.25 mg/l, follow-up 3.09+/-1.32 mg/l, p=0.37). Protein S decreased significantly only in the CEE/MPA group (CEE: baseline 19.4+/-2.76 mg/l, follow-up 18.0+/-2.45 mg/l, p=0.56; CEE/MPA: baseline 18.4+/-3.42 mg/l, follow-up 14.5+/-3.43 mg/l, p=0.005; E2/NETA: baseline 19.0+/-3.11 mg/l, follow-up 19.5+/-3.43 mg/l, p=0.18; tibolone: baseline 18.5+/-3.09 mg/l, follow-up 18.0+/-4.09 mg/l, p=0.32). CONCLUSIONS: Estrogen and estrogen-progestin therapy are associated with a reduction in coagulation inhibitors, the extent of which depends on the regimen administered. Tibolone appears to have no effect on inhibitors of coagulation.

Topical vaginal oestrogen cream used for treatment of burn injury of vaginal mucosa after misapplication of 100% acetic acid in a perimenopausal woman: a case report.

BACKGROUND: Three to five per cent acetic acid is commonly used in the field of gynaecology for colposcopic examinations of the cervix. It gives an 'acetowhite' effect that may assist clinicians in identifying neoplastic areas. CASE: A perimenopausal woman was treated with acetic acid for abnormal Pap smear report (cervical intraepithelial neoplasia 1). During application, the patient complained of burning sensation of vagina and vulva. The vagina was saline-irrigated after realising that the acetic acid had not been diluted. Following this incident, the patient was seen weekly and treated with conjugated vaginal oestrogen cream. The patient recovered and the vagina mucosa healed within two weeks. CONCLUSION: Acetic acid is corrosive and may cause vagina bleeding. Oestrogen cream can be used in an attempt to minimise the adverse reaction and speed the healing process.

Combined effect of bis-beta-chloroethylamine estrogen derivatives and doxorubicin on proliferation of sensitive and resistant MCF-7 cells.

The sensitivity of normal (MCF-7/WT) and doxorubicin-resistant (MCF-7/R) breast cancer cells to the antiproliferative effect of ethynylestradiol 11alpha-derivatives with the cytostatic residue in the 3-position of the steroid ring (antiestrogen cytostatics) was studied by evaluating cell viability using methylthiazole tetrazolium staining. The antiproliferative effects of these agents on cell lines in the presence of doxorubicin were compared. Antiestrogen cytostatics produced weaker cytostatic effect on MCF-7/WT cells, but more potent cytostatic effect on MCF-7/WT cells compared to those of doxorubicin. Moreover, administration of these agents in combination with doxorubicin more significantly suppressed proliferation of tumor cells. Accumulation and efflux of cytostatic doxorubicin in MCF-7/R cells were studied in the presence and absence of antiestrogen cytostatic Po716. Confocal laser microscopy showed that doxorubicin accumulation in MCF-7/R cells in the absence of Po716 took 20 min, while in the presence of antiestrogen cytostatic this process took 5 min. The rate of doxorubicin transport from tumor cells was much lower in the presence of the test antiestrogen cytostatic. Our results suggest that antiestrogen cytostatics increase the sensitivity of resistant MCF-7/R cells to doxorubicin by modulating the mechanisms of multidrug resistance of tumor cells.

Effect of teriparatide [rhPTH(1-34)] on BMD when given to postmenopausal women receiving hormone replacement therapy.

UNLABELLED: The effects of teriparatide when given in combination with HRT were studied in postmenopausal women with low bone mass or osteoporosis. The data provide evidence that the adverse event profile for combination therapy with teriparatide + HRT together is consistent with that expected for each treatment alone and that the BMD response is greater than for HRT alone. INTRODUCTION: Teriparatide [rhPTH(1-34)], given as a once-daily injection, activates new bone formation in patients with osteoporosis. Hormone replacement therapy (HRT) prevents osteoporosis by reducing bone resorption and formation. Combination therapy with these two compounds, in small clinical trials, increased BMD and reduced vertebral fracture burden. The purpose of this study was to determine whether teriparatide provided additional effect on BMD when given in combination with HRT. MATERIALS AND METHODS: A randomized, double-blind, placebo-controlled study was conducted in postmenopausal women with either low bone mass or osteoporosis. Patients were randomized to placebo subcutaneous plus HRT (n = 125) or teriparatide 40 microg/day (SC) plus HRT (TPTD40 + HRT; n = 122) for a median treatment exposure of 13.8 months. Approximately one-half of the patients in each group were pretreated with HRT for at least 12 months before randomization. Patients received 1000 mg calcium and 400-1200 IU of vitamin D daily as oral supplementation. BMD was measured by DXA. RESULTS: Compared with HRT alone, TPTD40 + HRT produced significant (p < 0.001) increases in spine BMD (14% versus 3%), total hip (5.2% versus 1.6%), and femoral neck (5.2% versus 2%) at study endpoint. BMD, in whole body and ultradistal radius, was higher, and in the one-third distal radius was lower, in the combination therapy but not in the HRT group. Serum bone-specific alkaline phosphatase and urinary N-telopeptide/Cr were increased significantly (p < 0.01) in the women receiving TPTD40 + HRT compared with HRT. A similar profile of BMD and bone markers was evident in both randomized patients as well as in subgroups of patients not pretreated or pretreated with HRT. Patients tolerated both the treatments well. Nausea and leg cramps were more frequently reported in the TPTD40 + HRT group. CONCLUSIONS: Adding teriparatide, a bone formation agent, to HRT, an antiresorptive agent, provides additional increases in BMD beyond that provided by HRT alone. The adverse effects of teriparatide when added to HRT were similar to the adverse effects described for teriparatide administered alone. Whether teriparatide was initiated at the same time as HRT or after at least 1 year on HRT, the incremental increases over HRT alone were similar.

Efficacy of tibolone and transdermal estrogen therapy on psychological symptoms in women following surgical menopause.

OBJECTIVE: This study investigated the efficacy of tibolone and transdermal estradiol therapy on menopausal and psychological symptoms in women following surgical menopause. METHOD: Seventy-five women who had undergone surgical menopause were randomized to a 6-month double-blind interventional study treatment with oral 2.5 mg/day tibolone, transdermal 3.9 mg/week estradiol or oral placebo. The patients were assessed using Kupperman's Scale, Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating Scale (HARS) before and at the end of the 6 months of treatment. RESULT: Sixty-five subjects completed the study: 23 on tibolone, 21 on transdermal estradiol and 21 on placebo. At the end of the 6 months of therapy, highly significant improvements in menopausal symptoms, depression and anxiety scores were observed in both groups (tibolone and transdermal estradiol groups) as compared with baseline values (p<0.001). However, in the placebo group, there were no significant differences on changes from baseline to the end of treatment (p>0.05). CONCLUSION: These results suggest that tibolone and transdermal estradiol therapy significantly improve menopausal and psychological symptoms in women following surgical menopause.

Micromolar concentrations of 2-methoxyestradiol kill glioma cells by an apoptotic mechanism, without destroying their microtubule cytoskeleton.

The purpose of this study was to investigate the potential effects of 2-methoxyestradiol, a natural mammalian steroid, in glioma cells, since antiproliferative effects of this compound had been shown earlier in several leukemia and carcinoma cell lines. The effects of 0.2, 2 and 20 microM concentrations of 2-methoxyestradiol were measured in three malignant human glioma cell lines (U87MG, U138MG, LN405) and one malignant rat glioma cell line (RG-2) using a microtiter-tetrazolium (MTT) assay. In all cell lines, a significant reduction of the viable cell number by more then 75% occurred ( P < 0.05) for concentrations of 2 and 20 microM 2-methoxyestradiol after 6 days. A concentration of 0.2 microM had smaller effects (10-40% cell reduction), which were significant in two of the cell lines tested. The apoptotic nature of cell death was further analyzed in U87MG and RG-2 cells. Caspase-3 activity was significantly induced to levels between 3.4- and 23-fold after 4 days for the two higher 2-methoxyestradiol concentrations (P < 0.05). In the cell line RG-2 nuclear fragmentation was visible in many nuclei, following stains with Hoechst H33258. A round cell morphology occurred in most treated cells, which was not accompanied by a complete destruction of the microtubule network, as it can be observed with other microtubule targeting drugs.

Progestins and estrogens and Alzheimer's disease.

Sex-specific incidence rates for Alzheimer's disease (AD) are higher in women than men. Many fundamental researches and some clinical investigations have reported therapeutic and preventive effects of estrogens on AD. But WHIMS [S.A. Shumaker, C. Legault, S.R. Rapp, L. Thal, R.B. Wallace, J.K. Ockene, S.L. Hendrix, B.N. Jones IIIrd, A.R. Assaf, R.D. Jackson, J.M. Kotchen, S. Wabertheil-Smoller, J. Wactawsk-Wende, WHIMS investigators, Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women. The women's health initiative memory study: a randomized controlled trial, JAMA 289 (2003) 2651-2662], which used daily continuous hormone replacement therapy (HRT), reported that the hazard ratio of the HRT for probable dementia was 2.05. Effect of progestins, and continuous (not cyclically) HRT, even only with estrogen should be reconsidered. In our clinical study, conjugated equine estrogen (CEE) alone showed good changes of psychiatric tests for AD on the 3rd week, but addition of medroxyprogesterone acetate (MPA) or norethindrone since 4th week suppressed these tests. Using human umbilical vein epithelial cell (HUVEC), levonorgestrel (LNG), norethindrone acetate (NETA), MPA increased intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-secretin but dienogest (DNG) showed no effect. In vitro flow system, estradiol (E2), suppressed adhesion of white cell, but LNG, NETA, MPA increased the adhesions. DNG showed less effect. Non-feminizing estrogen J 861, which has delta8,9 double bond and straight in its structure and has less effect on sexual organs. J 861 has shown ameliorative effects on central nervous system (CNS) (increasing of cholineacetyltransferase immunoreactive cells in substantia innominata (SI), etc.) like E2. More investigations about progestins and estrogens and AD should be done.

Contrasting effects of estradiol and 17 beta-aminoestrogens on blood clotting time in rats and mice.

Estrogens have been associated with thromboembolic events. Our group has described the anticoagulant effect of 17 beta-aminoestrogens in rodents, potentially new alternative estrogenic agents without thrombogenic risk. This work compares the contrasting effects of estradiol and the 17 beta-aminoestrogens (prolame, butolame, and pentolame) on blood clotting time. Ovariectomized CD1 mice received a single injection of 17beta-aminoestrogens, estradiol (20 to 80 mg/kg), or vehicle. Estradiol decreased blood clotting time from -10% to -25% (48 h; P<0.01) and 17 beta-aminoestrogens increased it, differing in latency (approximately 12 h; +48%, P<0.01) and duration (approximately 72 h +58%, P<0.01). In male Wistar rats, similar effects (pentolame +45%; estradiol -31%; P<0.01) were observed 48 h after five consecutive daily injections of 1000 microg/animal/day. The maximum procoagulant effect of estradiol was obtained after 72 h with 10 microg/animal/day (-45%; P<0.01). 17 Beta-aminoestrogens always produced opposite effects to those of estradiol on blood coagulation.