Plasma levels of d-norgestrel after oral administration

The effect of deliberate non-adherence to a norgestrel progestin-only pill: A randomized, crossover study

OBJECTIVES

To estimate the effects on cervical mucus, ovarian activity and theoretical contraceptive protection of a 6-hour delay and of missing one norgestrel 0.075 mg progestogen-only pill.

STUDY DESIGN

In a prospective, two-site, randomized, crossover study, healthy women aged 18 to 35 with BMI <32.0 kg/m² and regular ovulatory cycles completed a baseline 28-day cycle with correct daily pill use followed by two intervention cycles in which, around mid-cycle, one pill was taken 6 hours late or missed completely. We undertook ovarian ultrasonography, estradiol and progesterone measurement, and cervical mucus assessments every 3 to 4 days (daily around the time of the incorrect use) and based the theoretical contraceptive protection score on ovarian activity status, cervical mucus and their temporal relationship.

RESULTS

Of 91 potential participants screened, 52 started the study and 46 provided complete data for each intervention cycle. Fourteen participants (30%) ovulated in each of the two intervention cycles, with four during the delayed pill cycle and two during the missed pill cycle having an abnormal luteal phase. Seven participants in the delayed pill cycle, and six with a missed pill had elevated cervical mucus scores temporally associated with the intervention. However only two women, one in the delayed pill cycle and one in the missed pill cycle, had cervical mucus scores in the range considered favorable for fertility.

CONCLUSIONS

Delayed or missed intake of a single norgestrel 0.075 mg progestogen-only pill appears to have little effect on theoretical contraceptive efficacy.

IMPLICATIONS

This biomedical study suggests that taking a norgestrel 0.075mg progestogen-only pill 6 hours late or missing one pill have little effect on ovarian activity or cervical mucus and may not jeopardize contraceptive efficacy. Correlation with typical use outcomes is necessary to confirm pregnancy risk with delayed or missed norgestrel intake.

Adherence among a cohort taking progestin-only pills prescribed by a healthcare provider: Results of the BENCHMARK study

OBJECTIVES

To measure adherence over 6 months of progestin-only pill (POP) use.

STUDY DESIGN

Prospective observational cohort study measuring adherence to daily dosing and timing of dose in patients prescribed a POP, with up to six months of follow-up, conducted from January to October 2020. A pharmacy benefit manager identified potential participants with a newly prescribed POP and extended an invitation to participate. We enrolled qualified respondents by telephone, trained them to use an electronic diary to report daily whether they had taken their POP and at what time. We followed participants for up to six months. We calculated adherence to daily pill taking as the proportion of evaluable days in which a participant took a POP, and the proportion of participants reporting ≥85% adherence. We calculated adherence to same time each day as the proportion of doses taken no later than three hours after the previous dose time of day.

RESULTS

The user population comprised 199 participants, 154 (77.4%) of whom completed six months of follow-up. The majority (n=170, 85.4%) were taking norethindrone. Norethindrone users reported POP intake on 22,327 (96.4%) of 23,156 evaluable days, with 155 (91.2%) participants reporting ≥85% adherence; less than half (n=73, 42.9%) reported 100% adherence. Participants reported adherence to same time each day on 21,698 of 22,157 (97.9%) evaluable days.

CONCLUSIONS

Among participants taking a prescribed POP, participants demonstrated high adherence for daily pill taking and the same time of day, though the majority were not 100% adherent.

IMPLICATIONS

This study reports data specific to adherence among those taking a progestin-only pill (POP) in the prescription setting. Clinicians who counsel patients about POP use should be aware that majority of patients were not 100% adherent, although most report ≥ 85% adherence.

Use of Dicloxacillin and Risk of Pregnancy among Users of Oral Contraceptives

The antibiotic dicloxacillin has been shown to induce drug-metabolizing CYP enzymes to a clinically relevant extent. In this study, we investigated whether the use of dicloxacillin confers an increased risk of unwanted pregnancy among oral contraceptive users. The study population comprised Danish women falling pregnant (1997-2015) during oral contraceptive use, defined as having filled a prescription for an oral contraceptive within 120 days both before and after the estimated date of conception. Data were analysed using a case-crossover approach. For each woman, we assessed the use of dicloxacillin preceding the date of conception and during 10 previous control periods and estimated the odds ratio for such unintended pregnancies associated with the use of dicloxacillin. Among 364 women using dicloxacillin prior to conception, 40 (11%) were exposed to dicloxacillin at the time of conception, yielding an odds ratio (OR) associating use of dicloxacillin to unintended pregnancy of 1.18 (95% CI 0.84-1.65). Supplementary and sensitivity analyses generally returned similar estimates, except for a slightly increased risk among users of progestogen-only oral contraceptives (OR 1.83, 95% CI 0.63-5.34). Analysis of other antibiotics as negative controls yielded results close to unity (ORs ranging from 0.83 to 1.13). In conclusion, our study found no evidence for an increased risk of oral contraceptive failure when using dicloxacillin. However, acknowledging study limitations, we suggest the use of supplementary barrier methods during treatment with dicloxacillin, until our findings are confirmed in further studies.

Levonorgestrel-releasing intrauterine system--the discontinuing story

Levonorgestrel-releasing Intrauterine System (LNG-IUS) is licensed for use as a contraceptive, for the treatment of heavy menstrual bleeding and during estrogen replacement therapy. It is publicized as a local source of progestogen with minimal systemic adverse effects. However, there is overwhelming evidence of elevated serum and tissue levels of levonorgestrel, and high discontinuation and dissatisfaction rates amongst users. The guidelines of The National Institute for Health and Clinical Excellence (NICE), United Kingdom recommended that the healthcare professionals should be aware that upto 60% of women discontinue using LNG-IUS within 5 years because of unscheduled bleeding, pain, and/or systemic progestogenic adverse effects. This article highlights these issues to healthcare professionals to ensure that the rates of adverse effects are not underestimated, and full information are made available to women to enable them making an informed choice.

Levonorgestrel intrauterine system: bleeding disorders and anticoagulant therapy

Hemostatic disorders in women are frequently associated with long-standing menorrhagia. This leads to significant morbidity and adversely affects quality of life. Management of these women poses a particular challenge; medical treatments may be contraindicated, and surgery carries additional risks. The levonorgestrel intrauterine system (LNG-IUS) has been shown to be highly efficacy in reducing menstrual blood loss in women with normal coagulation. It is also a reliable and reversible contraceptive. Data on the use of this system in women with bleeding disorders or those receiving anticoagulant therapy are limited. Analysis of data from four reported studies suggests that LNG-IUS is a viable and safe option for the management of menorrhagia in these women. Whether the underlying hemostatic disorders lead to a shorter duration of action or prolonged irregular bleeding/spotting post insertion is unknown and requires large prospective studies. Proper counselling remains crucial for patients' satisfaction.

[Levonorgestrel-releasing intrauterine device (Mirena) and breast cancer: what do we learn from literature for clinical practice?]

Annual occurrence of breast cancer is constantly increasing in France. In 2000, the number of breast cancer cases for women of 30-49 years was estimated at 9,918, which represents 23.7% of all breast cancer cases diagnosed that year. The levonorgestrel-releasing intrauterine device (IUD LNG) is one of the most frequently used coils in France. Because contraception is an important matter for women whose ovarian function survived cancer treatments, the question of whether to use such device on a woman with breast cancer has become a frequent and controversial gynaecological issue. With the review of available literature as a basis, we have tried to answer the following questions. First, whether the use of IUD LNG increases the risk of breast cancer: there is at the moment no "A" level answer available. According to the only study published, which may be considered "C" level, there is no such increase. Second, whether the use of IUD LNG counterbalances the endometrial effects of Tamoxifene: based on a limited level of evidence via a single randomised controlled trial on a small number of patients for one year only, this device appears to be able to prevent benign endometrial modifications. However, there is no conclusive study regarding its effectiveness on the prevention of endometrium adenocarcinoma caused by Tamoxifene. In addition, there are numerous uncertainties as to whether levonorgestrel presence in the plasma would have a systemic prejudicial impact. Third, whether a woman with a personal antecedent of breast cancer can safely use DIU LNG: it is necessary to remove it promptly upon suspicion or diagnosis, to dissuade its use in case of current cancer, and, in the event of cancer remission for more than 5 years, to generally avoid this contraceptive method except on a case by case basis and with a regular medical follow-up. In the latter situation, the use of IUD LNG can be considered only after a multidisciplinary collective formal decision and after the woman gave her informed consent.

A comparative study of the levonorgestrel-releasing intrauterine system Mirena versus the Copper T380A intrauterine device during lactation: breast-feeding performance, infant growth and infant development

BACKGROUND

Mirena is a levonorgestrel-releasing intrauterine system (LNG-IUS) that provides highly effective and long-acting progestogen-only contraception.

OBJECTIVE

The objective of this study was to analyze the possible effects of using LNG-20 microg IUS on breast-feeding performance, infant growth and infant development during the first postpartum year as compared with the Copper T380A intrauterine device (Cu T380A IUD).

DESIGN

This study is a prospective, controlled and randomized trial.

SETTING

The study was conducted at the Department of Obstetrics and Gynecology, Assiut University Hospital, Egypt.

METHODS

Three hundred twenty lactating women asking for initiation of contraception during the early postpartum stage were assigned randomly into two groups, the LNG-20 microg IUS group (n=163) and the Cu T380A group (n=157). The insertions were done 6-8 weeks postpartum. Each participant was followed up at three monthly intervals after insertion and until the first birthday of her baby. During these visits, the breast-feeding pattern was assessed, certain infant physical growth parameters were measured and a set of infant development tests was performed.

RESULTS

No pregnancy occurred in both groups. There were no significant differences in the net continuation rates between the two groups (89.3 for LNG-IUS vs. 90.9 for Cu T380A). The LNG-20 microg IUS group had comparable rates of breast-feeding continuation, complete weaning, full breast-feeding and partial breast-feeding, with the Cu-IUD group. No statistically significant differences were found between groups with regard to all infant physical growth parameters and various infant development tests.

CONCLUSION

The findings of the current study confirm that the use of LNG-20 microg IUS during the first postpartum year in lactating women provides highly effective and acceptable contraception and does not negatively influence breast-feeding or the growth and development of breast-fed infants.

Benefit-Risk Assessment of the Levonorgestrel Intrauterine System in Contraception

The levonorgestrel-releasing intrauterine system (IUS) is a long-acting, fully reversible method of contraception. It is one of the most effective forms of contraception available, and combines the advantages of both hormonal and intrauterine contraception. The levonorgestrel-releasing IUS also gives the users many non-contraceptive benefits: the amount of menstrual bleeding and the number of days of menstrual bleeding are reduced, which makes it suitable for the treatment of menorrhagia (heavy menstrual blood loss). Dysmenorrhoea (painful menstruation) and premenstrual symptoms are also relieved. In addition, the levonorgestrel-releasing IUS provides protection for the endometrium during hormone replacement therapy. The local release of levonorgestrel into the uterine cavity results in a strong uniform suppression of the endometrial epithelium as the epithelium becomes insensitive to estradiol released from the ovaries. This accounts for the reduction in menstrual blood loss. All possible patterns of bleeding are seen among users of the levonorgestrel-releasing IUS; however, most of the women who experience total amenorrhoea continue to ovulate. The first months of use are often characterised by irregular, scanty bleeding, which in most cases resolves spontaneously. The menstrual pattern and fertility return to normal soon after the levonorgestrel-releasing IUS is removed. The contraceptive efficacy is high with 5-year failure rates of 0.5-1.1 per 100 users. The absolute number of ectopic pregnancies is low, as is the rate per 1000 users. The levonorgestrel-releasing IUS is equally effective in all age groups and the bodyweight of the user is not associated with failure of the method. In Western cultures continuance rates among users of the levonorgestrel-releasing IUS are comparable with those of other long-term methods of contraception. Premature removal of the device is most often associated with heavy menstrual bleeding and pain, as with other long-term methods of contraception, and is most common in the youngest age group. When adequately counselled about the benign nature of oligo- or amenorrhoea, most women are very willing to accept life without menstruation. The risk of premature removal can be markedly diminished with good pre-insertion counselling, which also markedly increases user satisfaction. User satisfaction is strongly associated with the information given at the time of the levonorgestrel-releasing IUS insertion. Thus, the benefits of the levonorgestrel-releasing IUS make it a very suitable method of contraception for most women.

Optimisation of treatment by applying programmable rate-controlled drug delivery technology

A number of programmable rate-controlled drug delivery technologies have been developed during the last two decades with the aim of regulating the rate of drug delivery, sustaining the duration of therapeutic action and/or targeting the delivery of drug to a specific tissue. As a result, several therapeutically beneficial outcomes can be achieved, such as: (i) controlled delivery of a therapeutic dose at a desirable rate of delivery; (ii) maintenance of drug concentrations within an optimal therapeutic range for prolonged duration of treatment; (iii) maximisation of efficacy-dose relationship; (iv) reduction of adverse effects; (v) minimisation of the need for frequent dose intake; and (vi) enhancement of patient compliance. The treatment of illness can thus be optimised. To gain a better understanding of how to optimise the treatment of illnesses by applying programmable rate-controlled drug delivery technologies, this article reviews the scientific concepts and technical principles behind the development of various programmable rate-controlled drug delivery systems that have been marketed or are under active development. Finally, the roles of these technologies in optimising therapeutic outcomes in nine therapeutic areas are discussed.

Pharmacokinetic study of different dosing regimens of levonorgestrel for emergency contraception in healthy women

BACKGROUND

Levonorgestrel (LNG) is a commonly used progestin for emergency contraception; however, little is known about its pharmacokinetics and optimal dose for use.

METHODS

Serum levels of LNG and sex hormone-binding globulin (SHBG) were measured in five women who received three different regimens: A: 0.75 mg LNG twice with a 12 h interval; B: 0.75 mg twice with a 24 h interval; and C: 1.50 mg in a single dose, with a washout period of 28 days between each treatment. Blood samples were taken before pill intake and at 1, 2, 4, 8 and 12 h after each dose, every 12 h up to day 4 and every 24 h until day 10. LNG and SHBG were measured in all samples.

RESULTS

Maximum LNG concentrations were of approximately 27 nmol/l for treatments A and B, and close to 40 nmol/l for treatment C. The area under the curve was significantly higher for treatment C during the first 12 h, and significantly lower for treatment B during the first 24 h. After 48 h and up to 9 days from onset of treatment, serum LNG levels were similar in all three regimens. SHBG levels remained stable for 24 h, decreasing to 60% of the initial value from day 5 until day 10, with no difference between regimens.

CONCLUSIONS

The similarity of LNG serum levels obtained with one single dose of 1.5 mg or two doses of 0.75 mg with a 12 h interval justify a clinical comparison of these two regimes.

The roles of estrogen and progestin in producing deciduosarcoma and other lesions in the rabbit

The interactions of estrogens and progestins in producing decidualization, deciduosarcoma. and other lesions in the rabbit were explored. Steroids were delivered by silicone elastomer implants placed subdermally except for oral dosing in 1 experiment. Varying doses of levonorgestrel (LNG) were given with and without estradiol (E2) and varying doses of E2 with and without LNG. LNG alone delivered at an estimated mean dose of 233 microg/day did not result in endometrial decidualization or deciduosarcoma. Both conditions occurred when E2 was added to the regimen and increased as the dose of E2 was increased. Sixty microg of E2 per day produced endometrial decidualization in all test animals in a 2-month exposure, but deciduosarcoma occurred only when LNG was also supplied and increased as the LNG dose was increased. Progesterone given with E2 resulted in deciduosarcoma in most rabbits. Ethynylestradiol alone at 30 microg/day delivered by implants produced splenic and ovarian deciduosarcomas in 1 of 5 test animals. Adding LNG resulted in more numerous and widespread deciduosarcomas. These experiments indicate that exogenous estrogen is necessary for decidualization of the endometrium and to production of deciduosarcoma in the nonpregnant rabbit. Exogenous progestin promotes the process. Necrosis of the uterine wall tended to increase with increasing dose of estrogens.

Clinical performance of the levonorgestrel intra-uterine system in routine use by the UK Family Planning and Reproductive Health Research Network: 12-month report

Doctors working in general practice and at family planning clinics throughout the UK who collaborate in the UK Family Planning and Reproductive Health Research Network were responsible for the fitting of 692 Levonorgestrel Intra-uterine Systems (LNG IUS). This study was undertaken to determine the performance of the LNG IUS in British women in routine clinical use. The 12 months cumulative life-table event rates were: pregnancy 0.6, expulsion 4.5. The continuation rate was 70.6. Removals were also required for side effects, which may be due to absorbed levonorgestrel, the removal rate being 7.4. Positive effects include effective contraception and considerably reduced quantity of bleeding for most participants. A need was identified to counsel women about the early bleeding problems, including the possibility of oligomenorrhoea or amenorrhoea. This is considered to be very important as it will help women to persevere so that they can enjoy the longer-term benefits.

Use of a single implant of elcometrine (ST-1435), a nonorally active progestin, as a long acting contraceptive for postpartum nursing women

Because of its unique features, the contraceptive effectiveness and tolerance during breast-feeding of 16-methylene-17 alpha-acetoxy-19-nor-4-pregnene-3,20-dione (elcometrine), delivered within a single subdermal capsule of medical grade polydimethylsiloxane, was investigated. Unlike other progestational steroids, elcometrine has no affinity for androgen and estrogen receptors and is inactive by the oral route. A total of 66 breast-feeding women receiving elcometrine by the subdermal route were enrolled in the study, and 69 women who elected to use Copper-T380 intrauterine devices (IUD) served as control subjects. The women and their infants were observed until the end of the first postpartum year. There were no significant differences in growth and development measurements among the infants in the elcometrine and control groups. The percentage of infants continuing to breast-feed at 3 and 6 months was significantly higher in the elcometrine group. There were no significant differences between the concentration of elcometrine in the mother's blood and milk. At 75 days, blood levels of elcometrine in the infants were near the undetectable and were significantly lower than the levels in maternal blood or milk (p < 0.01). In 15 of 25 infants, blood levels of elcometrine were at the limit of assay sensitivity or undetectable. Two pregnancies occurred in women using IUD, whereas none occurred in those using implants. There were menstrual bleeding irregularities in both groups. A single elcometrine capsule placed subcutaneously at 6-monthly intervals appears to be an effective method of contraception for lactating women and results in blood concentrations of nursing infants at or near undetectable levels.

Sex hormone binding globulin and free levonorgestrel index in the first week after insertion of Norplant implants

Levonorgestrel has an inhibitory effect on sex hormone binding globulin (SHBG). This decrease in SHBG leads to an increase in the free levonorgestrel index (FLI), which has a stronger biological effect. The interaction between serum levels of levonorgestrel and SHBG in long-term users of Norplant implants has been described. This study was designed to understand the same interaction immediately after the insertion of the implants, in a group of 16 women, sampled at 0 and 6 h and at 1, 3, and 7 days after Norplant implant insertion. Peak serum levonorgestrel levels were achieved at 24 h after insertion, remaining stable on day 3 and decreasing by > 10% by day 7. SHBG did not change during the first 24 h, but decreased by 19% and 60% on days 3 and 7, respectively. FLI more than doubled from day 1 to day 7 after insertion. The large decrease in SHBG and doubling of FLI is not followed by a similar reduction in levonorgestrel, which is hard to explain without an increase in the release rate of the steroid from the capsule.

Timing of onset of contraceptive effectiveness in Depo-Provera users: Part I. Changes in cervical mucus

OBJECTIVE

To evaluate the changes in cervical mucus within the first hours or days after depot medroxyprogesterone acetate (MPA) injection so as to estimate the time at which cervical mucus becomes hostile enough to prevent pregnancy.

DESIGN

Multicenter, clinical descriptive study.

SETTING

Family planning clinic.

PATIENT(S)

Thirty women who were between days 8 and 13 of their menstrual cycle and who had requested Depo-Provera were enrolled in the study.

INTERVENTION(S)

Cervical mucus and blood samples were obtained; transvaginal ultrasonography was performed.

MAIN OUTCOME MEASURE(S)

Cervical mucus scores, sperm penetration distances, ovarian follicular size, and serum levels of progesterone and estradiol.

RESULT(S)

From 6 to 24 hours after injection, there was a sharp decline in the cervical mucus score for most of the subjects. All subjects exhibited poor mucus on day 3 after injection, and by day 7, all subjects had zero scores, with the exception of two outliers on each day. Sperm penetration, as measured by the vanguard sperm distance, was already poor (< 1 cm) in 7 of the 30 subjects at the time of injection and was reduced progressively up to 24 hours after injection, when only four subjects had a sperm penetration of > 1 cm. A rapid decline in the estimated number of sperm was observed at 12 hours and more so at 24 hours in the majority of subjects.

CONCLUSION(S)

The data presented in this report confirmed that depot MPA causes profound changes in cervical mucus after injection. Although very little change was seen at 6 hours, alterations were observed subsequently, with 90% of the subjects showing a poor cervical mucus score 24 hours after administration of the progestin. No reliable clinical marker is available to identify in which women depot MPA might exert its effect on cervical mucus within 3 days. Thus, we believe that at present, women should be informed of this uncertainty and should use a backup method of contraception for 7 days when the first injection of depot MPA is provided after the seventh day of the menstrual cycle.

An enzyme immunoassay for serum and urinary levonorgestrel in human and non-human primates

A microtiter plate enzyme immunoassay (EIA) is reported for the measurement of levonorgestrel (LNG) in serum and urine samples of human and non-human primates, and the results are compared to data obtained by radioimmunoassay (RIA). Rabbit polyclonal antibodies were raised against the bovine serum albumin conjugate of the 3-O-carboxymethyl oxime (CMO) derivative of LNG. The enzyme label was produced by the conjugation of horseradish peroxidase to LNG at the 3-position by the same CMO bridge used for the immunogen. The assay requires 2.5 hours to perform using 2.2-azino-di-(3-ethylbenzthiazoline sulfonic acid) diammonium salt as the chromogenic substrate. Serum (100 microliters) is extracted with petroleum ether prior to assay, whereas urine samples (25 microliters) are diluted and measured directly. The sensitivity of the assay is 0.25 pg/well with a 50% displacement of label at 7.5-9.5 pg and a linear response through 250 pg/well. Minimum levels of 8.7 and 10.0 pg/ml can be detected in serum and urine samples, respectively. Changes in serum LNG concentrations were measured in women and non-human primates following LNG implantation or injection. In the non-human primate study, serum LNG concentrations began to rise rapidly following i.m. injection of LNG, with peak levels occurring on days 3 to 5, then decreasing to approximately 25-35% of peak levels for the duration of the study. Circulating concentrations of 1.86 +/- 0.18 ng/ml LNG were reached in women the first week post-insertion of Norplant implants and decreased by 50% at 7-10 days, 75% after 14-21 days, followed by a steady decrease during the next 60-70 days to constant low levels that exhibited a high individual variation. Correlation coefficients of EIA and RIA results were 0.988 for human serum, 0.926 for human urine, and 0.972 for non-human primate serum.

Interrelationship of serum levonorgestrel and sex hormone-binding globulin levels following vaginal and oral administration of combined steroid contraceptive tablets

Ten women were treated daily with a standard dose contraceptive tablet containing 0.25 mg levonorgestrel (LNG) in combination with 0.05 mg ethinylestradiol. Five women used the tablet vaginally, while the other five used it orally. Blood samples were taken at frequent intervals on the first day of treatment and after 1 and 2 hours on treatment days 7 and 14. Serum LNG levels were measured by radioimmunoassay, and sex hormone-binding globulin (SHBG) was quantitated by charcoal assay. On day 1, peak concentrations of LNG (5.1 ng/ml) occurred within 2 hours in the oral group, whereas in the vaginal group a peak of 2.2 ng/ml was reached after 4 hours. After 24 hours, mean serum concentrations of LNG were 1.1 and 0.69 ng/ml in the oral and vaginal groups, respectively. In both groups, mean LNG concentrations increased dramatically on days 7 and 14 compared to day 1. There was no significant difference between the two groups in LNG concentrations, except after 2 hours on day 1. SHBG levels were increased after one day of treatment. By day 14 of treatment, there was a 3.5- to 4.5-fold rise in SHBG levels from pretreatment values in both groups. However, there was no significant difference in SHBG levels between the two groups throughout the study. A high correlation was found between serum levels of SHBG and LNG in both the vaginal and oral groups. The results suggest that the increase in serum LNG levels in women receiving combined contraceptive tablets either vaginally or orally is due to increased levels of SHBG. Also, the measured concentrations of LNG in the vaginal group are consistent with the previously reported clinical contraceptive efficacy of combined contraceptive tablets administered vaginally.

The effect of follicular growth and luteal function of "missing the pill". A comparison between a monophasic and a triphasic combined oral contraceptive

The effects of follicular growth and hormonal indices of the deliberate omission of two low-dose combined oral contraceptives, a monophasic 130 micrograms ethinylestradiol + 150 micrograms desorgestrel) and a triphasic (30 micrograms ethinylestradiol + 50 micrograms levonorgestrel for 6 days, followed by 40 micrograms ethinylestradiol + 75 micrograms levonorgestrel for 5 days and 30 micrograms ethinylestradiol + 125 micrograms levonorgestrel for 10 days) combination during the first three days of one contraceptive pill cycle was studied in two groups of 10 women each. Follicular growth was followed by ultrasound scanning and plasma levels of estradiol, and progesterone were measured every other day until day 19 of the contraceptive pill cycle. In each group, ovulation occurred in one subject and 4 women reacted with follicular activity only, while 5 women on the monophasic and 3 on the triphasic formulation exhibited complete ovarian suppression. Two subjects on the triphasic preparation showed follicular growth followed by insufficient luteal function. Thus, the risk of escape ovulation when the pill-free interval is prolonged to 10 days in women taking low-dose combined oral contraceptive pills, is low (1/10).

Pharmacokinetics and biotransformation of orally administered oestrone sulphate and oestradiol valerate in post-menopausal women

The pharmacokinetic properties and biotransformation of two orally active oestrogens, piperazine oestrone sulphate (PE1S, 2.5 mg/day) and oestradiol valerate (E2V, 2.0 mg/day), given alone or in combination with levonorgestrel (LNG, 250 micrograms/day) were compared in 8 post-menopausal women, using a randomized cross-over design. The end points measured in peripheral plasma included oestrone (E1), oestradiol (E2), oestriol (E3), oestrone sulphate (E1S), oestradiol sulphate (E2S) and oestriol sulphate (E3S). In addition, LNG and sex-hormone-binding globulin SHBG concentrations were also assessed. The plasma levels of E3 were invariably below the detection limit (220 pmol/l). The levels of all the other oestrogens analyzed were consistently higher and the area under the curve significantly greater (except in the case of E3S) following PE1S administration than those recorded after E2V ingestion. The terminal half-lives of the circulating oestrogens measured after PE1S administration did not differ from those found after E2V administration. After 21 days of PE1S administration (in combination with LNG for the last 10 days), the maximum levels of all the oestrogens (except those of E2) were significantly higher than those seen after the first dose. No such difference was observed after E2V administration. There was no difference between the effects of the two treatment regimens with regard to the E1/E2 ratios, but the E1/E1S ratios were significantly lower after PE1S treatment than after E2V administration. It is concluded that, compared with an equivalent dose of PE1S, daily repeated oral administration of E2V yields consistently lower peripheral plasma levels of E2 and its principal metabolites. However, in contrast to PE1S therapy, prolonged administration of E2V does not result in an accumulation of the circulating oestrogens measured.

Pharmacokinetics of gestagens: some problems

Various approaches to studying the pharmacokinetics of gestagens and the factors that influence derivation of the parameters are described with levonorgestrel used as an example. Published studies of the pharmacokinetics of levonorgestrel are reviewed, and new information is presented regarding intra- and intersubject variation. Differences between various formulations of levonorgestrel are apparent when the formulations are compared in the same subjects. There is also a marked difference in the parameters when derived under single-dose or steady-state conditions. The role of sex hormone-binding globulin in the metabolism of levonorgestrel is questioned. Large intra- and inter-subject variations in the parameters exist, and a subject may show a large month-to-month variation when one levonorgestrel formulation is used and smaller variations when another formulation is used. This wide variability in the pharmacokinetic parameters, problems that arise in the derivation and interpretation of the parameters, the biologic significance of most of these parameters, and their lack of correlation with pharmacodynamic responses severely limit the usefulness of pharmacokinetic studies of the gestagens.

Potency and pharmacokinetics of gestagens

Serum concentrations of gestagens were compared after single doses and after multiple doses (steady-state conditions) of four widely used oral contraceptives containing norethisterone (NET), levonorgestrel (LNG), desogestrel (DSG) and gestodene (GSD). There were marked differences among the gestagens with respect to the serum concentrations. Under steady-state conditions 12 h after dosing, the relative concentrations were approximately GSD, 4.5:DSG, 1:LNG, 1:NET, 2 compared to ratios of 1:2:2:13.3, respectively, for dose. Thus, there was no correlation between serum concentration and dose. These differences in serum concentrations are determined by the different pharmacokinetic behaviour of the gestagens, which in turn is largely determined by their binding to serum proteins. Calculations suggest that the concentrations of unbound gestagen in serum, and hence probably also at the target organ, are similar (about 35 pg/ml) for LNG, DSG and GSD but may be higher (up to 60 pg/ml) for NET whose half-life of elimination is about half that of the other three gestagens. Measurement of the serum total concentration is unlikely to correlate with their pharmacological activity. A further complication is the multiplicity of pharmacological effects elicited by the gestagens and each of these effects is likely to have its own dose-response relationship.

Clinical and hormonal effects of two contraceptives: correlation to serum concentrations of levonorgestrel and gestodene

Two triphasic oral contraceptives containing gestodene (GES) (a new progestogen) and levonorgestrel (LNG) were compared with respect to contraceptive effect, cycle control, acceptability and side effects. The serum concentrations of ingested hormones were measured together with ovarian, pituitary, and some adrenal hormones, as well as sex hormone binding globulin (SHBG). The contraceptive effect and cycle control were good with both preparations, and there were only a few minor side effects. SHBG was elevated 2-fold in the LNG group and 3-fold in the GES group. The GES concentration in serum varied more than the LNG concentration, but with correction for variations in SHBG binding, less variability in actual GES and LNG concentrations was seen. Serum levels of FSH, LH, estradiol and progesterone were all depressed with both preparations. The depression was more marked in the GES group, despite lower progestogen ingestion and similar serum concentrations. Equal decreases were found in testosterone, androstenedione and dehydroepiandrosterone sulfate (DHEA-S) with both preparations.

Effect of some oral contraceptives on serum concentrations of sex hormone binding globulin and ceruloplasmin

Serum SHBG and ceruloplasmin (CP) concentrations were measured in women throughout a cycle of treatment with four oral contraceptives. In women receiving 150 micrograms levonorgestrel (LNG) daily both SHBG and CP decreased. SHBG also decreased, but CP increased, in women receiving ethynyloestradiol (EE) 30 micrograms with LNG 150 micrograms. In women taking 35 micrograms EE with either 600 micrograms or 1000 micrograms norethisterone, increases in CP were similar but SHBG increased more with the lower dose. Serum concentrations had not returned to pretreatment levels by eight days after cessation of dosing. The findings are compared with similar results for women taking 30 micrograms or 50 micrograms EE or an EE,LNG triphasic formulation. Serum concentrations of the gestagens were also measured. Increases in these concentrations when the gestagen was administered with EE to levels higher than expected from administration of the gestagen alone cannot be explained by increased binding to SHBG but are more likely to be due to changes in their metabolism. Differences in the responses of ostensibly closely related proteins of hepatic origin such as SHBG and CP to the oral contraceptives demonstrate that neither can be extrapolated to other pharmacodynamic responses.

The effect of levonorgestrel administered in large doses at different stages of the cycle on ovarian function and endometrial morphology

In a pharmacokinetic study, levonorgestrel (L-NOG) 0.75 mg was administered orally to 10 swedish women in the early follicular phase of the menstrual cycle. L-NOG levels were measured after L-NOG administration. A peak level of 16 nmol/l was reached after 2 hours, T 1/2 was estimated to be 14.5 hours (8.5-18.5) in the 24-48-hour interval after dosing. Seventy-two women (in Stockholm, Bombay and Shanghai) were assigned to 4 treatment groups and studied during a control cycle, a treatment cycle and a posttreatment cycle when 0.75 mg L-NOG was administered orally for 4 days in the follicular phase, periovulatory period or luteal phase. Peripheral blood was drawn 3 times weekly during the entire study for the assay of estradiol and progesterone. In 22 women in Stockholm, an endometrial biopsy was obtained on cycle day 20-22 in all 3 cycles studied. When L-NOG was administered on periovulatory days 9, 11, 13, and 15, 3 women showed follicular activity only, 7 exhibited follicular activity followed by insufficient luteal function and 7 women ovulated normally. When L-NOG was administered on periovulatory days 11, 12, 16 and 19, 7 women ovulated during treatment, 6 women exhibited follicular activity followed by insufficient luteal function and 5 exhibited follicular activity only. When L-NOG was administered in the follicular or luteal phase, no effect on ovarian function was seen. No significant prolongation of the cycle lengths was seen when L-NOG was taken during the follicular phase. Only minor effects in the endometrium were observed during treatment.

Clearance of levonorgestrel from the circulation following removal of NORPLANT subdermal implants

The disappearance of levonorgestrel from plasma after the removal of NORPLANT subdermal implants was studied in 12 women who had been treated from 5.5 to 78 months. The existence of one or two half-lives for the rate of disappearance was assessed. The influence of body weight, body fat and length of treatment upon levonorgestrel clearance was studied through stepwise regression analysis. It was found that the levonorgestrel decay rate after implant removal can be entirely accounted assuming one half-life of 42 +/- 16 h (mean +/- SD; range 13 to 62 h). Stepwise regression analysis showed that levonorgestrel half-life is positively correlated with body weight and not significantly correlated with the length of treatment or body fat. It is concluded that, after long-term administration of levonorgestrel via subdermal implants, the major part of the steroid is cleared from plasma within 96 h and that only trace amounts are detected in the following days.

Norplant-2 rods: one year experience in Singapore

Norplant-2 contraceptive implants consist of two silastic rods in which levonorgestrel has been incorporated with the polymer. This study describes our experience with 100 acceptors of the Norplant-2 rods in Singapore. No pregnancies occurred during the first year of use. Menstrual irregularities was the main complaint associated with the use of Norplant-2. However, the incidence of menstrual irregularities appeared to diminish with time and the continuation rate at the end of one year was 95.0 per cent. Thus, it appears that the Norplant-2 rod systems offer a highly effective, convenient means of contraception which should be well accepted in future.

Serum levels of 3-keto-desogestrel and SHBG during 12 cycles of treatment with 30 micrograms ethinylestradiol and 150 micrograms desogestrel

The serum concentrations of 3-keto-desogestrel (KDG) have been determined radioimmunologically in 11 female volunteers on Day 1, 10, and 21 of the 1st, 3rd, 6th, and 12th cycle of treatment with 30 micrograms ethinylestradiol and 150 micrograms desogestrel during the first 4 hours and 24 hours after intake. On the first day of each cycle the KDG levels were low, but increased thereafter until Day 21. Highest serum concentrations were measured on Day 21 of the 3rd and 6th cycle with peak levels between 1.5 and 6.2 ng/ml. Contrary to this, the KDG levels were significantly reduced during the 12th treatment cycle. The serum concentrations of SHBG rose significantly between Day 1 and Day 21 of each cycle reaching values which were 3-fold of those at the beginning of treatment. During the pill-free intervals, SHBG levels decreased but remained elevated as compared to controls. There was a significant correlation between the SHBG levels and the area under the KDG-concentration-versus-time curves (AUC) indicating a pronounced influence of the serum steroid-binding protein upon the pharmacokinetics of KDG. There were great interindividual differences in the KDG levels. The serum levels of the individual woman remain, however, in a relatively constant range throughout the treatment period of 12 months, possibly due to genetic factors.

A sensitive direct radioimmunoassay for assessing D-norgestrel levels in human plasma

A direct radioimmunoassay was developed for assessing the levonorgestrel levels in human plasma without the need for heat, chromatographic or extraction pretreatment. D-norgestrel-3 (0-carboxymethyl)-oximino-BSA conjugate was used to raise antibodies having a low binding affinity towards other endogenous steroids. The rivanol-purified antiserum after dilution was used as the binding protein. The direct assay of levonorgestrel in human plasma was then compared to an extraction procedure. Lower intra-assay variability was shown by the direct assay when compared to the extraction method used at a sensitivity level of 0.15 nmol/L. The performance of the direct assay in quality control tests was more than favourable when compared with the extraction procedure. An examination of the effects of protein concentration on extraction efficiency was carried out together with an assessment of levonorgestrel levels in plasma in eight normal healthy women currently taking oral contraceptives and eight women who were not, at 0-24 h after the ingestion of 150 micrograms of D-NG and 30 micrograms of ethynyl oestradiol.

Pharmacokinetic study of levonorgestrel used as a postcoital agent

The pharmacokinetics and pharmacodynamics of levonorgestrel (LNG) were studied in six women given 0.75 mg LNG orally for seven days during the periovulatory phase of the menstrual cycle. Steady-state concentrations of LNG were reached within three days and serum LNG concentrations at various times on day 7 were generally lower than on day 1, presumably due to a reduced serum level of SHBG. On day 7 the volume of distribution was significantly increased and Co significantly decreased and both the clearance and elimination half-life were higher on day 7 than on day 1. Half-lives varied from 5.6 to 25.1 hours. The day-to-day intra-subject variations in serum LNG concentrations ranged from 23% to 80%. Serum concentrations of pituitary and ovarian hormones suggested that ovulation was not inhibited in four of the six subjects and was delayed in the remaining two. No significant changes in serum prolactin levels were observed.

Reduced incidence of rabbit endometrial neoplasia with levonorgestrel implant

To test the hypothesis that progestogens protect against the development of endometrial neoplasia, we placed polydimethylsiloxane implants (levonorgestrel or inert) into the right uterine horn at random in 114 old female rabbits. Cross-sectional uterine biopsy specimens were taken from both horns at the time of implantation and at 6, 12, and 24 months thereafter. Twenty-nine levonorgestrel-treated and 33 controls survived to the completion of the study. The incidence of endometrial neoplasia of 17.2% in the group treated with levonorgestrel was significantly less (p less than 0.05) than the 42.4% incidence observed in the control does. Before the completion of the study, one levonorgestrel-treated doe died and was found to have an endometrial tumor. When the findings of this doe are included in the report, the statistical significance is marginally lost. No endometrial neoplasia was found in the eight does with serum levonorgestrel concentrations greater than 0.12 ng/ml. Only one of the five tumors in the levonorgestrel-treated group occurred in the horn containing the levonorgestrel implant, which suggests that a dose effect is likely. Treatment with levonorgestrel decreases the incidence of endometrial neoplasia in rabbits. This finding gives further credence to the use of progestogen supplementation in women at risk for developing endometrial neoplasia.

New progestogens in oral contraceptives

The aim of using new synthetic progestogens (gestodene and norgestimate) in oral hormonal contraceptives is to find a combination that has a more beneficial effect on metabolism and endometrium than presently available formulations. Our studies with low-dose pills containing 30 micrograms ethinyl estradiol/150 micrograms levonorgestrel or 30 micrograms ethinyl estradiol/150 micrograms desogestrel compared with the new pills with 35 micrograms ethinyl estradiol/250 micrograms norgestimate or 30 micrograms ethinyl estradiol/75 micrograms gestodene revealed no significant alterations of serum glucose after glucose loading. With all four combination pills, insulin levels were slightly elevated when compared with controls. Studies of the lipid metabolism showed that depending on the type and estrogen combination, progestogens have different effects on lipid metabolism. The new progestogens seem to have a more pronounced effect on triglycerides, whereas total cholesterol and high-density lipoprotein cholesterol remain almost unchanged. In general, it could be shown that low-dose oral contraceptives have little impact on lipid metabolism. Studies with low-dose monophasic preparations, including the new formulations, reveal only a low effect on blood coagulation. According to our and other data on the new progestogens in oral contraceptives available so far, it can be expected that such low-dose monophasic and triphasic combination pills will be beneficial during longtime use with respect to side effects on the cardiovascular system and control of the menstrual cycle.

Norplant contraceptive implants: rods versus capsules

Norplant contraceptive implants are silastic implants containing levonorgestrel. When placed subcutaneously in the medial aspect of the upper arm, they release low levels of levonorgestrel in a constant manner over an extended period of time. Comparative studies of two silastic rods versus six capsules containing levonorgestrel were studied in 250 subjects for 4,464 months of use. Only one pregnancy occurred during the study. Side effect patterns were similar in both groups; the major side effect being irregular uterine bleeding. The bleeding, however, was well tolerated by subjects in both groups and discontinuation rate was very low. The two-rod system offers the advantages of easier insertion technique and shorter insertion time as well as ease of removal as compared to the six-capsule system. Norplant contraceptive implants offer a highly effective means of contraception which is particularly suited for women who are concerned about failure and compliance with oral contraceptives. This type of contraception should become well accepted, not only in underdeveloped countries, but in developed countries as well.

ICMR Task Force Study on hormonal contraception. Transfer of norethisterone (NET) and levonorgestrel (LNG) from a single tablet into the infant's circulation through the mother's milk

A single tablet of either of the three different types of oral contraceptive preparations, viz. "Gynovlar" containing 3000 micrograms norethisterone (NET) and 50 micrograms ethinyl estradiol (EE2) or "Ovral" containing 250 micrograms levonorgestrel (LNG) and 50 micrograms EE2, or a daily progestogen only type--"Minipill" containing 30 micrograms of LNG only, were administered to 40 normal lactating women on a random basis. The sampling schedule in all the three body fluids, i.e. the maternal sera, breast milk and the infant's sera, was kept in such a manner that the peak levels of the contraceptive steroids would be expected to be present in these fluids. The results of this study indicate that the transfer ratio of LNG or NET from the maternal sera to her breast milk was approximately 10% (6-34%) for Gynovlar, 9% (5-18%) for Ovral and 6% (2-34%) for Minipill. However, it was interesting to observe that whereas the transfer ratio of NET or LNG from breast milk to infant's sera was similar for combination pills--8% (3-23%) for Gynovlar and 12% (3-42%) for Ovral, it was significantly higher for progestogen only Minipills--38% (13-92%) for LNG. The precise reason for the higher transfer ratio of LNG from breast milk to infant's serum in Minipill users cannot be explained.

Fluctuations in quantitative features of intermediate cells in normal cervical smears during the menstrual cycle of ovulating women and contraceptive users

In this study we report on the variation in nuclear and cytoplasmic size of intermediate cells in normal cervical smears, in relationship to the week of the menstrual cycle and in relationship to the mode of contraception. A total of 18000 cells from 360 different women was studied. A significant difference in nuclear size of intermediate cells in smears from ovulating women not using contraception was found in comparison with intermediate cells in smears from women using contraceptive pills (ANOVA: F(1.312) = 4.98, p less than 0.02). Also a significant difference in the nuclear size of intermediate cells in smears from women using norgestrel- (or levonorgestrel)-containing formulas compared with lynestrenol-containing formulas was found (ANOVA: F(1.232) = 5.82, p less than 0.01). The influence of exogenous and endogenous hormones on cell populations in cervical smears is discussed. It is concluded that in studies on intermediate cells in cervical smears the contraceptive status of the women has to be taken into account.

Absorption of an oral contraceptive gestagen in ulcerative colitis before and after proctocolectomy and construction of a continent ileostomy

Plasma 1-norgestrel (1-Ng) levels after administration of a common oral contraceptive in fertile women (mean age 29 +/- 5 yrs) with mild ulcerative colitis before or after proctocolectomy with a conventional ileostomy or a continent ileostomy reservoir were determined and compared to those of a group of healthy volunteers serving as controls. Before operation, peak and 10-hour levels of 1-Ng were not statistically different from control. Levels in patients with either type of ileostomy were slightly lower than controls, but were only statistically significantly lower in patients with continent ileostomy (p less than 0.05). In a subgroup of patients studied both before and after proctocolectomy with construction of a continent ileostomy, there was a slight reduction in peak and 10-hour levels compared to control. After administration of the pill directly into the reservoir, significant levels of 1-Ng in plasma were found with peak and 10-hour levels approximately one-half of those achieved after oral administration. Although the material is small, it suggests that patients with mild ulcerative colitis and with small ileal resections (8.8 +/- 8 cm) can use combined contraceptive pills containing 1-norgestrel with confidence. Caution should be exercised, however, in prescribing "mini-pills" to patients after proctocolectomy and ileal resection.

Levonorgestrel plasma levels during continuous administration with different models of subdermal implants

Plasma concentrations of levonorgestrel were determined in women using subdermal levonorgestrel implants. One group had 6 Silastic capsules (NORPLANT), one group had 4 and one group had 6 covered Silastic rods for variable lengths of time. Levonorgestrel concentrations remained constant around 0.4 ng/ml up until 6 years of use in the Norplant group. The observation period was shorter for the covered rods; plasma concentrations were, however, constant around 0.55 ng/ml and 0.70 ng/ml for 3.5 years with the 4 rods and 6 covered rods, respectively. The difference in mean levonorgestrel concentrations between the three groups were statistically significant (p less than 0.0005). Plasma levels of levonorgestrel were twice to three times higher in blood obtained from the arm with the implants compared to the levels found in the other arm. The application of a tourniquet for variable periods before blood sampling did not influence the plasma concentrations of levonorgestrel.

Pharmacokinetics of levonorgestrel in Indian women

A low dose combination pill containing levonorgestrel 150 micrograms and ethynylestradiol 50 micrograms was administered orally to 13 women. Based on their anthropometric index they were classed as well-nourished (Group A) or undernourished (Group B). Plasma levels of levonorgestrel at various intervals after dosing were analysed by a specific radioimmunoassay and its pharmacokinetic parameters were computed. Peak plasma levels in both groups occurred within 2 h and the absorption half-lives were also similar. The decline in plasma levonorgestrel showed a tri-exponential decline in all Group A women, whereas it was biphasic in most of Group B. The pi t1/2 was lower in Group A women and the alpha-phase was found to be negligible in Group B. A significant positive correlation between elimination half-life (beta t1/2) and some of the anthropometric indices suggests a possible role of nutritional status in the metabolic handling of levonorgestrel.

Serum levels and pharmacokinetics of norethisterone after ingestion of lynestrenol: its relation to dose and stage of the menstrual cycle

The peak concentration, peak time, the area under the serum concentration time curve (AUC) and half-life of serum norethisterone (NET) after a single application of lynestrenol (LYN) to female volunteers demonstrated that 0.7 mg NET is bioequivalent to 1 mg LYN which is rapidly converted to NET. There was a decrease of the peak values and an increase of half-life of NET during the periovulatory and luteal phase which was, however, not significant due to the great individual differences. The shift of the peak time to longer intervals and the increase of half-life of NET after ingestion of higher LYN doses indicate a certain limitation of the metabolic capacity of the liver. One of the volunteers who complained of nausea and vertigo after the administration of 5 mg LYN, showed the highest serum values of NET. The large interindividual variations of the serum levels of synthetic steroids demonstrate a possible risk of contraceptive safety in women with low steroid levels and possibly a coherence between extremely high serum levels of synthetic steroids and side effects.

Danazol and gestagen displacement of testosterone and influence on sex-hormone-binding globulin capacity

The mechanism of action of danazol is poorly understood, but this testosterone (T) derivate is frequently used in the clinical treatment of endometriosis, and its tendency to androgenic/anabolic side effects is well known. The interaction of danazol with T binding to sex-hormone-binding globulin (SHBG) was studied with the use of an aqueous two-phase system with polyethylene glycol (PEG) and dextran for equilibrium partition. Competitive binding studies were also performed with norethisterone (NET), d-norgestrel (d-Ng), medroxyprogesterone acetate (MPA), and tamoxifen (TMX). Danazol, d-Ng, and NET were found to exert a marked T displacing activity, while MPA and TMX had no significant effect. The low values for SHBG binding capacity that were found during danazol therapy mainly reflect occupation of binding sites by danazol and to a lesser degree a real decrease in protein concentration. It was calculated that during treatment the total SHBG capacity in serum is approximately 20 times exceeded. Therapeutic danazol serum levels are 1000 times those of normal female total T levels; and since the affinity to SHBG for danazol was found to be 1/20 that to T one should conclude an almost total occupation of binding sites. The endocrine effects of danazol might be interpreted in terms of T displacement and as a consequence of increased levels of free T during therapy.

Effects on sex hormone binding globulin of different oral contraceptives containing norethisterone and lynestrenol

Six combined oral contraceptive drugs containing ethinyloestradiol or mestranol and norethisterone or lynestrenol were studied throughout six 21-day cycles in healthy female volunteers. There was always one menstrual cycle without treatment between every treatment cycle. Plasma levels of norethisterone were determined throughout treatment by use of a specific radioimmunoassay. Sex hormone binding globulin (SHBG) was measured by an ammonium sulphate precipitation method at the beginning and at the end of each treatment cycle. The results indicated an accumulation of norethisterone in plasma when 1 to 3 mg of norethisterone or lynestrenol was given. There was no obvious accumulation during treatment with 0.5 mg norethisterone. SHBG increased during treatment with all combinations studied. However, this increase was most pronounced with the 50 microgram ethinyloestradiol/l mg lynestrenol, 50 microgram mestranol/l mg norethisterone and 35 microgram ethinyloestradiol/0.5 mg norethisterone combinations. There was no statistically significant increase in SHBG with 50 microgram ethinyloestradiol/2.5 mg lynestrenol or 50 microgram ethinyloestradiol/3 mg norethisterone acetate combinations. The results indicated that the induction of SHBG by the synthetic oestrogens was antagonized by the progestogens in a dose-dependent manner. The effect on SHBG by a combind preparation could be one assessment of the oestrogenicity or androgenicity of the preparation.