Effects of microdose norgestrel on endogenous gonadotropic and steroid hormones, cervical mucus properties, vaginal cytology, and endometrium

Inhibition ratio (I.R.) and transformation index (T.I.): new indexes to compare the effectiveness and clinical behaviour of modern progestin-only pills (POP)

Progestin-only pills (POPs) have emerged as a crucial contraceptive option for women, particularly those contraindicated to oestrogens. This opinion paper introduces two new indices, the Inhibition Ratio (I.R.) (cyclical and daily) and the Transformation Index (T.I.), to evaluate and compare the efficacy and clinical behaviour of modern POPs. The I.R. quantifies the ratio between the progestin dosage in a POP and the minimum dose required to inhibit ovarian function, providing insights into contraceptive efficacy. The T.I., on the other hand, assesses its clinical impact by considering the ratio between the total progestin dose and the dose required to induce endometrial luteinising changes. Both indices thus offer valuable tools for comparing progestins even at significantly different dosages and regimens, providing information on clinical characteristics and drug effects. The newest formulations of POPs (Desogestrel 28 and Drospirenone 24 + 4) have demonstrated higher I.R. and T.I. in comparison to older versions, indicating significant improvements in contraceptive efficacy and clinical impact with better menstrual cycle control. We believe that using these indices will ensure a more informed and personalised choice of progestin not only for contraceptive purposes but also for therapeutic use in gynaecology. The future goal is to develop other progestins with even more advantageous I.R. and T.I., ensuring the best contraceptive efficacy with fewer side effects, even in women at risk (obese, etc.).

Canadian Contraception Consensus (Part 3 of 4): Chapter 8 - Progestin-Only Contraception

OBJECTIVE

To provide guidelines for health care providers on the use of contraceptive methods to prevent pregnancy and on the promotion of healthy sexuality.

OUTCOMES

Overall efficacy of cited contraceptive methods, assessing reduction in pregnancy rate, safety, ease of use, and side effects; the effect of cited contraceptive methods on sexual health and general well-being; and the relative cost and availability of cited contraceptive methods in Canada.

EVIDENCE

Published literature was retrieved through searches of Medline and The Cochrane Database from January 1994 to January 2015 using appropriate controlled vocabulary (e.g., contraception, sexuality, sexual health) and key words (e.g., contraception, family planning, hormonal contraception, emergency contraception). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies published in English from January 1994 to January 2015. Searches were updated on a regular basis in incorporated in the guideline to June 2015. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of the evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). CHAPTER 8: PROGESTIN-ONLY CONTRACEPTION: Summary Statements Recommendations.

The effect of protease inhibitors on the cervical mucus of HIV-positive women taking norethindrone contraception

OBJECTIVE

To compare cervical mucus score (CMS) with and without protease inhibitors (PI) before and after taking norethindrone (NET).

STUDY DESIGN

This two-arm, researcher blinded, non-randomised, prospective study was conducted to evaluate cervical mucus quality in HIV-positive women taking progestin only pills. The study group was taking a PI, and compared to women taking ARV regimens that have demonstrated no significant interaction with NET in prior pharmacokinetic trials with combined oral contraceptives. The women had a cervical mucus score prior to NET administration. Mucus Scoring was repeated after 21 days of steady state exposure to oral NET 0.35 milligrams. Cervical mucus quality was quantified according to the World Health Organisation criteria, which include: volume, consistency, cellularity, spinnbarkeit, and ferning.

RESULTS

Sixteen women took PI and 17 were controls. Baseline CMS were similar (p ≥ 0.1). After 21 days CMS were similar among the two groups (p = 1).

CONCLUSIONS

HIV-positive women taking PI demonstrated thickened cervical mucus with oral norethindrone 0.35 mg and are similar to HIV-positive women taking no PI therapy. This may suggest no difference in contraceptive efficacy of progestin only pills in HIV-positive women taking PI.

The effects of reproductive hormones on the physical properties of cervicovaginal fluid

OBJECTIVE

The purpose of this study was to determine the impact of contraception, menopause, and vaginal flora on the physical and biochemical properties of cervicovaginal fluid (CVF).

STUDY DESIGN

Vaginal swabs, CVF, and cervicovaginal lavage (CVL) were collected from a total of 165 healthy asymptomatic women including: postmenopausal women (n = 29), women in the proliferative (n = 26) or follicular (n = 27) phase, and women using the levonogestrel intrauterine device (n = 28), depomedroxyprogesterone acetate (n = 28) or combined oral contraceptives (n = 27). Vaginal smears were evaluated using the Nugent score. The osmolality, viscosity, density, and pH of CVL samples were measured.

RESULTS

CVL from postmenopausal women and women with abnormal vaginal flora was less viscous and had higher pH than premenopausal women and women with normal flora, respectively. Women using hormonal contraceptives had more viscous CVL as compared with premenopausal women not using hormonal contraceptives, but this increase in viscosity was mitigated in the presence of bacterial vaginosis. Women using depomedroxyprogesterone acetate had less total protein in the CVL as compared with women using the levonogestrel intrauterine device, and had similar protein content when compared with postmenopausal women.

CONCLUSION

The differences in CVL protein content between depomedroxyprogesterone acetate and levonogestrel intrauterine device suggest that type of progesterone and route of delivery impact the vaginal environment. Contraceptive hormone users had more viscous CVL than women not using contraceptives. However, the presence of bacterial vaginosis impacted both the pH and viscosity (regardless of hormonal contraceptive use), demonstrating that vaginal flora has a greater impact on the physical properties of CVF than reproductive hormones.

Comparison of cervical mucus of 24/4 vs. 21/7 combined oral contraceptives

BACKGROUND

Few studies have examined the action of combined oral contraceptives (COCs) on cervical mucus. We hypothesized that midcycle cervical mucus of women taking COCs is of poor quality when compared to their own midcycle mucus prior to initiating COCs. We sought to compare the effect upon quality and sperm penetration of the cervical mucus on the last hormone-free day with a 24/4 regimen to a 21/7 regimen.

METHODS

This is an open-label, investigator-blinded, randomized, controlled, crossover equivalency study. All subjects received, in random order, 2 months of a 21/7 regimen and 2 months of a 24/4 regimen, each containing 20 mcg ethinyl estradiol and 1 mg norethindrone acetate. Analysis of cervical mucus quality (CMQ) and sperm penetration took place midcycle and on the last day of the hormone-free interval during the second month of each COC treatment.

RESULTS

From April 2010 to November 2011, 18 subjects completed all study visits. Mean midcycle CMQ was poor (mean CMQ=1) and did not differ between 24/4 and 21/7 regimens (p=.92). On the last day of the pill-free interval, the quality and sperm penetration were poor with both regimens.

CONCLUSION

This study indicates that thickening of cervical mucus is a major mechanism of contraceptive action of COCs and that both 21/7 and 24/4 regimens result in poor quality and impenetrable mucus on the last day of the pill-free interval.

Effects of the levonorgestrel-releasing intrauterine system on cervical mucus quality and sperm penetrability

BACKGROUND

In levonorgestrel intrauterine system (LNG-IUS) users, the prevention of sperm penetration through cervical mucus has not been demonstrated.

STUDY DESIGN

Subjects were enrolled in an investigator-blinded study to compare quality and sperm penetrability of mid-cycle cervical mucus between LNG-IUS users and hormone-free controls. Cervical mucus was microscopically examined using World Health Organization (WHO) cervical mucus analysis (CMA). CMA score ≥10 of 15 points indicated cervical mucus favoring sperm penetration. Mucus was incubated with sperm using the WHO simplified slide test (SST) and Kremer sperm cervical mucus penetration test (SCMPT).

RESULTS

Data from 14 LNG-IUS users and 16 controls showed 14% of LNG-IUS users had CMA score ≥10% vs. 69% of controls (p=.004). SST showed no sperm penetration for LNG-IUS users, significantly less than controls (0% vs. 64.3%, p<.001). SCMPT demonstrated no sperm mucus penetration for LNG-IUS users at 2 and 6 h (0% vs. 85% in controls with 2-h score ≥6, p<.001; 6 h 0% vs. 79% in controls, p<.001).

CONCLUSIONS

Mid-cycle cervical mucus of LNG-IUS users is poor quality and prevents endocervical sperm transport in vitro.

The mechanism of action of hormonal contraceptives and intrauterine contraceptive devices

Modern hormonal contraceptives and intrauterine contraceptive devices have multiple biologic effects. Some of them may be the primary mechanism of contraceptive action, whereas others are secondary. For combined oral contraceptives and progestin-only methods, the main mechanisms are ovulation inhibition and changes in the cervical mucus that inhibit sperm penetration. The hormonal methods, particularly the low-dose progestin-only products and emergency contraceptive pills, have effects on the endometrium that, theoretically, could affect implantation. However, no scientific evidence indicates that prevention of implantation actually results from the use of these methods. Once pregnancy begins, none of these methods has an abortifacient action. The precise mechanism of intrauterine contraceptive devices is unclear. Current evidence indicates they exert their primary effect before fertilization, reducing the opportunity of sperm to fertilize an ovum.

Temporal relationship between Uniplant insertion and changes in cervical mucus

This study was undertaken to determine the time required by a single implant containing nomegestrol acetate to affect cervical mucus production and sperm penetration in women. All subjects were investigated and, if necessary, treated for any kind of cervicitis or vaginitis prior to starting cervical mucus study. The subjects had not used hormonal contraception for at least three months prior to investigation. They were counseled to use condoms during this study and also to refrain from intercourse during the period of cervical mucus sampling. Follicular development and endometrial thickness were analyzed by transvaginal sonography. Cervical mucus examination, sperm penetration test, and transvaginal sonography were performed during the control cycle and during the first cycle of Uniplant use. Blood samples were taken for the measurement of estradiol, LH, and progesterone. Cervical mucus and sperm penetration tests were evaluated according to the World Health Organization (WHO) criteria. In the treated cycle, when cervical mucus reached a score of 8-10, Uniplant was inserted, independent of the day of the cycle. Cervical mucus was then collected at 0, 4, 8, 12, 24, 48, and 96 h later until a marked change in volume, consistency, ferning spinnbarkheit, and cellularity was observed. All samples were also used for sperm penetration test. Preovulatory estradiol and LH peak decreased significantly compared to pre-implant insertion. Progesterone levels were within the normal limit. Cervical mucus and sperm penetration tests were not affected by Uniplant in the first 12 h. Twenty-four hours after Uniplant insertion, cervical mucus and sperm penetration tests were affected in 70.6% of the women. Forty-eight hours after implant insertion, the women were affected. Follicular rupture occurred in the majority of the women 48 h after implant insertion. Based on these results, it is possible to conclude that Uniplant can affect estradiol and LH preovulatory peaks and disrupt the process of cervical mucus production and sperm penetration, but it was unable to prevent ovulation when inserted in the preovulatory phase.

Cervical mucus concentration of prostaglandins E2 and F2 alpha after pretreatment with mifepristone in the first trimester of pregnancy

Cervical dilatation and softening after pretreatment with mifepristone are well documented. As this effect is similar to that observed after local application of prostaglandin E2 (PGE2) it is tempting to speculate that the effect of mifepristone is mediated via an increase of the endogenous secretion of prostaglandins from the cervical mucosa. Eighteen healthy women in the first trimester of pregnancy were treated with oral mifepristone (200 mg) 48 and 24 hours before legal abortion by vacuum aspiration and 18 women in the same age of gestation without any pretreatment served as controls. Cervical mucus was collected for measurement of prostaglandins by radioimmunoassay before administration of the drug and in connection with vacuum aspiration. The cervical dilatation at the time of surgery was significantly increased in women given mifepristone as compared with untreated women (7.6 versus 5.8 mm). The wet weight of collected cervical mucus was significantly increased in mifepristone treated women. The amount of PGE2 and prostaglandin F2 alpha per sample was unchanged in mifepristone-treated women, whereas the concentration was lower as an effect of dilution due to an increased yield in cervical secretion observed after mifepristone treatment. The present observation does not give any support to the hypothesis that mifepristone-induced cervical maturation is mediated via an increase in cervical prostaglandin production.

Is the contraceptive effect of 300 micrograms of norethisterone mainly peripheral or central?

The effect of norethisterone (NET) on pituitary function was evaluated by measuring circulating follicle stimulating hormone (FSH) and luteinizing hormone (LH) during the mid follicular phase as well as before and after removal of the corpus luteum (CL) in 30 untreated women and 43 women treated with 300 micrograms of NET daily for three months. All untreated women exhibited significantly elevated FSH levels after removal of the CL irrespective of the stage of the luteal phase. In the NET-treated women, the levels of FSH were significantly raised in women with luteal activity but these levels were not influenced by the operative procedure in those women without luteal activity. The LH levels remained unchanged after removal of the CL in both untreated and NET-treated women. The results suggest that a low dose of gestagen exerts variable effects on pituitary function. The main contraceptive effect seems to be through direct interference with ovarian function.

Effects of intranasal administration of norethisterone on folliculogenesis, cervical mucus, vaginal cytology, endometrial morphology and reproductive-endocrine profile in women

The effects of intranasal administration of norethisterone (NET) on menstrual cycle length, folliculogenesis, serum levels of estradiol, FSH, LH and progesterone, vaginal cytology, cervical mucus and endometrial morphology were studied in 8 volunteers (age 28 to 39 years, weighing between 46 and 54 kg). The study period comprised 4 consecutive menstrual cycles. In the first cycle (pretreatment cycle), only the vehicle (alcohol, propylene glycol, water; 3:3:4) was sprayed intranasally (100 microliters in each nostril), using a metered nebulizer, once daily from day 3 to the last day of menstrual cycle. In the next two cycles (treatment cycles), NET (300 micrograms/day) was administered once daily, starting from day one of menstrual cycle, between 9 and 10 a.m. The fourth cycle was a post-treatment cycle in which the volunteers were monitored for recovery. Blood samples (about 5 ml each) were collected once daily from day 8 to 24 and thereafter on alternate days until the last day of cycle during all the 4 cycles. Levels of estradiol, FSH, LH and progesterone were measured in the serum samples by radioimmunoassay methods. Cervical mucus samples and vaginal smears were collected once daily starting from day 7 or 8 of each cycle until the mucus was very scanty. Serial pelvic ultrasonography was performed starting from day 7 or 8 until the growing follicle disappeared or throughout the cycle in case a growing follicular cyst was observed. Endometrial aspirates were collected once around day 22 in each cycle and processed for routine histological examination.

Morphometric studies of the endometrium, the fallopian tube and the corpus luteum during contraception with the 300 micrograms norethisterone (NET) minipill

Biopsy specimen from endometrium, Fallopian tube and corpus luteum were obtained from 35 women treated with 300 micrograms norethisterone daily and from 10 untreated, normally menstruating women. Peripheral levels of LH, progesterone and estradiol were measured. In the norethisterone-treated women four different ovarian reactions were identified. Ovarian activity was completely suppressed (Type A) in 3 women, follicular activity only (Type B) in 10 women, follicular activity was followed by insufficient luteal function (Type C) in 12 women, and peripheral estradiol and progesterone levels compatible with normal ovulation (Type D) in 10 women. The histology of the endometrium varied between atrophy (3 subjects), suppressed proliferation (9 subjects), proliferation (8 subjects), irregular secretory changes (12 subjects) and apparently normal secretory activity (3 subjects). When the histology of endometrium and Fallopian tube was compared with the peripheral hormonal levels and the corpus luteum steroid production in vitra, no correlation was found. Nor was a correlation found between the histologic changes of corpus luteum, endometrium and Fallopian tube. Thus, these target organs seem to react independently to norethisterone treatment.

Effects of various IUDs on the composition of cervical mucus

The influence of three different intrauterine devices on the composition of cervical mucus was studied. The amount of mucin, albumin and immunoglobulin G was estimated. After the insertion of an inert IUD, a decrease in mucin was observed. During copper-IUD use the content of mucin, albumin and IgG was increased in cervical mucus, while weight was not affected. In the levonorgestrel-IUD users, ovulation was inhibited in 2 out of 8 women. Mucus weight was increased. The amounts of mucin, albumin and IgG were not changed. In an in vitro experiment the effect of copper-IUDs on autooxidation of cholesterol was studied. There was an extensive conversion of cholesterol but addition of albumin quenched the oxidation of cholesterol. It is suggested that the increased secretion of albumin induced by copper-IUD users may offer protection against copper-induced cell damage.

Mechanism of action of gestagens

In the mid-1950s it was shown that ovulation can be inhibited by oral administration of progesterone or of synthetic progestogens such as norethynodrel. The idea that progestogens may interfere with fertility even when administered in doses so small, that they do not invariably inhibit ovulation was launched in the mid-1960s by a group of Mexican investigators. Since then a large number of studies have been conducted on the mechanism of action of gestagens when used as contraceptives. The objective of this communication is to review the information collected so far on this topic.

Pharmacodynamics of a contraceptive vaginal ring releasing 3-keto-desogestrel

The pharmacodynamic effects of a new type of 3-keto-Desogestrel [3kDOG] releasing vaginal ring was studied in a group of 20 normally ovulating women during a period of 21 days continuous use. Peripheral blood samples were taken for the estimation of progesterone and oestradiol levels, ultrasound tracking for follicular growth and cervical mucus sampling for scoring [modified Insler] and sperm penetration testing during a control, treatment and recovery period. Additional blood samples were taken for the estimation of 3kDOG levels during the treatment period. After a control cycle, twenty normally ovulating women were selected and randomly divided into two groups. Group A were given a vaginal ring on day 5 of the menstrual cycle releasing 30 ug/24 hours of 3kDOG and group B a similar ring releasing 15 ug/24 hours of kDOG. Of the treatment cycles, none showed an ovulatory pattern in group A and there was only one in group B, the respective mean plasma levels of 3kDOG were 0.38 and 0.25 pmol/ml. The formation of "cysts" or persistent follicles was common to both groups, 6 out of 10 subjects in group A and 8 out of 10 subjects in group B had "cysts" greater than 25mm in diameter in the treatment cycle, this had become 5 out of 10 and 8 out of 10, respectively, in the recovery cycle. A comparison of the cervical mucus scores and sperm penetration of cervical mucus showed a significant reduction between the control and treatment groups but no significant difference between the two groups. The bleeding profiles showed an increase in percentage of bleeding days in both treatment groups to 25% in group A and 21.7% in group B [cf, 17.1%, 15.9%, respectively, in control month]; there being no statistical difference between groups. In conclusion, it is believed that given the efficacy demonstrated and the low level of menstrual disturbances found, this system warrants further investigation as a means of contraception as it appears to offer a better compromise than previous vaginal ring systems.

Treatment with Norplant subdermal implants inhibits sperm penetration through cervical mucus in vitro

Attempts were made to collect several samples of cervical mucus in each of thirty-three cycles of women using NORPLANT subdermal implants, in seven cycles from NORPLANT-2 rod users, and in 33 control cycles. The attempts to collect a mucus sample were successful on 20 of 77 and 7 of 14 occasions in NORPLANT capsule and rod users, respectively, due to the scanty amount and stickiness found in the majority. All 59 attempts in control subjects were successful. The distance travelled by the fastest sperm and by the bulk of spermatozoa through the cervical mucus in vitro was assessed after 10 min of incubation with a normal semen sample. The best score for each cycle was considered for the comparison between treated and control cases. Sperm penetration was greatly impaired in mucus samples of implant users with penetration by the fastest sperm exceeding 10 mm in only two instances and exceeding 20 mm in none. In 30 of 33 control samples, the fastest sperm travelled 21 mm or more and in 28, the bulk of spermatozoa travelled further than 10 mm. Unsuccessful attempts to collect mucus and poor sperm migration were observed in NORPLANT implant users even when circulating estradiol levels were comparable to those seen in the late follicular phase of the normal menstrual cycle. These results suggest that the principal mechanism by which NORPLANT implants prevent pregnancy is by interference of sperm migration through cervical mucus.

Trial of 17-hydroxyprogesterone caproate (Proluton Depot) in women with long-standing infertility; failure of estrogen positive feedback the following cycle

In open and double-blind studies 40 women with long-standing unexplained infertility were investigated and treated with 17 alpha-hydroxyprogesterone caproate (17HPC, Proluton Depot). In the open study, 16 women with a high index of suspicious abortions were given 500 mg 17HPC imtramuscularly (i.m.) weekly for 6-16 weeks. Six of the women received the drug from a time preceding the expected date of a period; 2 of these conceived that cycle and their pregnancies continued to term, while 4 were not pregnant. Ten women (9 with definite previous abortions) were given 17HPC when they suspected (correctly) that they were pregnant. Their pregnancies continued to term in all but 1, who had a premature delivery (still-birth) at 34 weeks. In the double-blind study 24 women were given injections of 17HPC or placebo i.m. at weekly intervals, from about 4 days before the expected period (day -4), provided that the level of progesterone (Prog) (on days -9 to -7) was greater than 10 nmol/l. After placebo no delay in menstruation or disruption of the succeeding cycle was observed. In 14 of 16 cycles in 14 women given 500 mg 17HPC the withdrawal period was delayed by a few days, and then followed by highly erratic bleeding over the next 1-3 months. The dose was therefore reduced to 250 mg 17HPC but the same problem resulted in 8 of 29 cycles in 16 women (including the above studied in later cycles). Regular cycles were eventually restored in all cases but in 3 this necessitated treatment with the contraceptive pill (Microgynon). In most of the post-treatment cycles there was a progressive and prolonged estradiol (E2) rise, which was not preceded by changes either in serum FSH concentration or in the LH/FSH ratio nor associated with the expected positive feedback rise in LH. We conclude that 17HPC disrupts the following cycle, probably by allowing follicular development while interfering with positive LH feedback. None of the patients of the double-blind study had conceived (as evidenced by undetectable hCG levels). Our study confirmed that this progestogen exerts no direct luteolytic effect. However, in order to establish the efficacy or otherwise of 17HPC given before the end of the cycle, women should be selected with a very high index of suspicion of recurrent early implantation failure or abortion.

Contraceptive efficacy of bioabsorbable pellets of norethindrone (NET) as subcutaneous implants: phase II clinical study

The contraceptive efficacy of norethindrone (NET) fused pellets was evaluated over 12 months in a Phase II clinical study with three and four pellets, each pellet containing 35 mg of NET. Volunteers were healthy, fertile, sexually active women. The release rate of NET from three and four pellets, respectively, was 150.3 +/- 7.2 micrograms and 212.5 +/- 8.6 micrograms NET/day. Following the implantation of NET pellets, serum NET levels did not show any 'burst effect' and were sustained at levels between 0.4 and 0.6 ng NET/ml serum with three pellets and 0.6-0.7 ng NET/ml serum with four pellets. With three and four pellets, respectively, 40% and 27% of the women had normal menstrual cycles; 20% and 14% were amenorrheic; 27% and 37% had mid-menstrual spotting or bleeding; and 13% and 22% had prolonged episodes of bleeding. Cardiovascular, hepatic, and renal functions were normal throughout the study. Ovulation was inhibited in 85% and 92% of the cycles with three and four pellets, respectively. In women using three pellets, two pregnancies occurred, one at the 6th cycle and another at the 12th cycle. In women using four pellets, no pregnancies occurred during the entire period of study.

Phase I comparative clinical trial with subdermal implants--bioabsorbable levonorgestrel or norethisterone pellet fused with cholesterol

The potential for antifertility effect of two bioabsorable pellets, one containing norethisterone (NET) and the other containing levonorgestrel (LNG) fused with cholesterol, was studied in a group of healthy, menstruating but sterilised women. The pellets weighed approximately 30 mg and contain 85% steroid and 15% cholesterol. A single NET pellet was inserted in 4 subjects, out of which 2 were also studied for steroid pattern in blood. After reaching peak levels within 48 hours, the plasma NET levels declined gradually within a fortnight's time, and thereafter, ranged between 200 to 700 mg/ml up to 90 days post-insertion. After this period, occassional spurts of NET release were seen. Bleeding pattern was studied in 37 cycles; mid-luteal progesterone (P) estimation was done in 16 cycles, mid-cycle cervical mucus was studied in 27 cycles and post-coital test (PCT) in 7 cycles. Cycle length with pellet insertion was of 25 to 37 days duration except one cycle of 55 days duration. All cycles studied during the treatment were ovulatory (P greater than 5 ng/ml) and no consistent effect was observed on cervical mucus as well as on PCT. Thus, a single NET pellet does not seem to have a reliable contraceptive potential. A single LNG pellet was inserted in 8 subjects, and steroid patterns were studied in 6 women. Peak levels of LNG were reached within 24 hours of pellet insertion and the levels fell gradually in a week's time. Thereafter, LNG levels ranged between 100-400 pg/ml up to 8 months. In contrast to the observation with NET pellets, only one subject showed frequent spurts of LNG release until the 4th month of treatment. Bleeding pattern was studied in 90 cycles, P was estimated in 52 cycles, mid-cycle cervical mucus studied in 55 cycles and PCT done in 26 cycles. Breakthrough bleeding (BTB) occurred on 15 occasions, 11 episodes being in 2 subjects. Cycle length varied between 21 to 42 days. The LNG pellet did not exert a consistent effect either on ovulation inhibition or cervical mucus or PCT. In their present form, therefore, a single LNG pellet also does not appear to have a reliable contraceptive effect.

Ovarian morphology during and after lynestrenol treatment around menopause

In this histological study, the inhibition of continuous oral administration of lynestrenol 5 mg/day on the ovarian follicle and corpus luteum development was found to be extremely pronounced. Known estrogen - producing structures such as antral, mature follicles and corpora lutea were completely absent during treatment. Structures devoid of cystic function however, as persistent and cystic follicles and follicular cysts, seemed not to be influenced in their histological appearance and frequency. As the recovery of the cyclic ovarian function after cessation of the medication compares favorably with the spontaneous cycle, a continuous lynestrenol treatment of 5 mg/day can be regarded as a safe endocrinological regimen.

Demonstration of an early abortifacient effect of norethisterone (NET) in the primate (baboon)

A long-acting injectable contraceptive which provides continuous controlled release of norethisterone (NET) for three months following a single intramuscular injection was tested for antifertility effects in baboons using a low dose of microcapsules (total NET dose 2.5 mg; daily dose approximately 0.03 mg/day) which has no effect on ovarian function or ovulation. The continuous administration of NET during the cycle of conception had no effect on ovulation, fertilization or implantation as evidenced by the occurrence of nine pregnancies following 23 test matings. Pregnancy was diagnosed by the measurement of baboon chorionic gonadotropin hormone and the maintenance of elevated serum progesterone levels past the normal time of menstruation. Six of the nine pregnancies, however, ended in abortion between days 27 and 35 of pregnancy. The remaining three pregnancies continued to term and normal, healthy babies were delivered. Five control baboons included in this study became pregnant and all delivered normal, healthy infants. The results of this study demonstrate that early abortion should be considered as a mechanism of antifertility action of NET when administered continuously in low doses. These findings are contrary to the generally accepted explanation that low-dose synthetic progestins exert their contraceptive effect by inhibiting sperm transport and/or preventing implantation.

Correlation between the serum norethindrone (NET) levels attained after insertion of a silastic implant releasing norethindrone acetate and the endogenous hormones particularly progesterone

Six normally menstruating women were inserted each with a single silastic implant-D releasing norethindrone acetate (NETA). The levels of endogenous hormones, FSH, LH, E2 and progesterone, were estimated by radioimmunoassay (RIA) procedures in the control and treatment cycles. In addition, the levels of drug in the serum as norethindrone (NET) which is a major metabolite of NETA were also estimated by RIA procedures in the treatment cycles. In all, 12 treatment cycles were studied. In the initial treatment cycles (1st/2nd or 3rd), the serum NET levels were either 1 ng/ml or above. The LH and FSH showed either normal or suppressed mid-cycle peaks, but the progesterone levels were completely suppressed. In the sixth treatment cycles, the serum NET levels were either 0.5 ng/ml or below. The FSH and LH mid-cycle peaks were lower but distinct while the luteal progesterone levels were of normal ovulatory type. These studies lead us to the conclusion that a serum level of NET of the order of 1 ng/ml is required to bring about suppression of luteal progesterone, either as a result of direct action on the ovary or through suppression of pituitary gonadotropins. When the serum level falls to 0.5 ng/ml or below, the suppressive effect is removed and ovulatory pattern of progesterone returns.

The effect of daily d-norgestrel (30 micrograms) on serum progesterone in Thai women

Serum progesterone levels were measured by RIA in 23 Thai women during the first 3 of a 6-month treatment period of taking 30 micrograms d-Norgestrel daily and again for a 3-month period after discontinuing its use in order to determine the frequency of ovulation. During the period of use, 11 out of the 23 subjects showed no evidence of ovulation while only 1 subject failed to ovulate during the post-treatment stage. The median time for the post-treatment resumption of ovulation was 20 days with the earliest occurring before day 10 and the latest around day 85. The frequency of ovulation in women who did ovulate during the treatment period appeared to be depressed with an average of 1.8 ovulations/subject as compared to 2.4 during the post-treatment. Menstrual bleeding patterns were not significantly altered.

Effect of short-term cyclic administration of cyproterone acetate on pituitary-ovarian function in the human

Short courses of cyproterone acetate, a compound with progestational and antiandrogenic activities, were administered to normally menstruating women during different phases of the menstrual cycle to suppress growth and maturation of the follicles and corpus luteum function. Postovulatory administration of 20 mg of the drug daily for 8 days to two women delayed menstruation by 4 to 6 days, followed by prolonged bleeding and short post-treatment cycles. Plasma levels of progesterone were suppressed temporarily during therapy, but increased immediately after cessation of treatment. Administration of 10 mg of the drug for 8 days during the early follicular phase to two women resulted in irregular bleeding, short cycles, and decreased plasma levels of progesterone throughout the cycle. Reduction of the dose to 2.5 mg during the early follicular phase in two other women also resulted in irregular cycles. When the 2.5-mg dose was administered to three women from the 8th to the 15th days of the cycle, vaginal bleeding and cycle length were normal. Plasma levels of luteinizing hormone and progesterone were suppressed during therapy. In one subject, cervical mucus was found to be hostile to sperm penetration in all three treatment cycles. The results indicate that, with cyclic administration of low doses of cyproterone acetate to women during the late follicular phase, it may be possible to interrupt pituitary-ovarian function, as well as sperm transport through the cervical mucus.

Low-dose combination oral contraceptives: a controlled clinical study of three different norgestrel-ethinyl estradiol ratios

Three doses of norgestrel-ethinyl estradiol in altered ratios were investigated in a double-blind, randomized study. The estrogen content was maintained at 20 microng or less, while the progestogen dose was increased in 100-microng increments. Two pregnancies were reported for the lowest dose. No pregnancies occurred in the two higher doses. Each dosage increase improved cycle control and lessened bleeding irregularities. The incidence of patients reporting intermenstrual bleeding was inversely proportional to the doses studied. Dropouts for cycle disturbances followed a similar pattern.

Binding of norgestrel to human plasma proteins

Binding of [14, 15-3H](+/-)-norgestrel to human plasma proteins has been investigated. Norgestrel showed greater affinity to plasma than to human serum albumin indicating specific norgestrel binding protein(s) in the plasma. alpha1-acid glycoprotein showed high affinity for norgestrel when compared with human serum albumin. The binding protein was eluted at pH 5.8 by step by step elution on a DEAE-cellulose column. Norgestrel binding to plasma proteins was not affected at 60 degrees C. The optimal binding occurred between pH 7 and 8. Ligand specificity of the binding protein revealed that progesterone was able to compete for the norgestrel binding sites, whereas corticosterone, testosterone, oestradiol, and norethindrone acetate did not show much competition. The molecular weight of the binding protein was found to be approximately 43 000. Sucrose density gradient analysis indicated that norgestrel bound to a macromolecular component of sedimentation coefficient 2.9 S. The association constant (Kass) and dissociation constant (Kdiss) of norgestrel-binding plasma protein was found to be 1.4-10(6) M-1 and 0.7-10(-6) M respectively. The number of binding sites was 0.5-10(-9) mol/mg protein. Norgestrel-binding protein in the plasma appeared to be a protein different from human serum albumin, corticosteroid-binding globulin and sex-steroid-binding protein. This binding protein showed some similarities to alpha1-acid glycoprotein.

The effect of daily norethisterone (0.35 mg) on cervical mucus and on urinary LH, pregnanediol and oestrogen levels

The effect of 0.35 mg of norethisterone daily on cervical mucus and on urinary LH, pregnanediol and oestrogen levels was studied during two treatment cycles in five subjects who had been observed during a control cycle. Variable changes in hormone excretion patterns were found and are discussed.