Androgen levels in women using a single implant of nomegestrol acetate

Contraceptive Implants: An Overview and Update

Contraceptive implants are safe, highly effective, and long-term methods of contraception that are widely applicable to any reproductive-aged woman. Implants require minimal user compliance and are cost-effective. The new single-rod system simplifies insertion and removal, making implants more accessible for both providers and patients. Specifically, progestin-only implants are safe options for various women including adolescents, postpartum, breast-feeding, those who are medically complicated, or those who have contraindications to or intolerance of estrogen-containing contraceptives.

Effects of a single Silastic® contraceptive implant containing nomegestrol acetate (Uniplant) on endometrial morphology and ovarian function for 1 year

PURPOSE

This study was undertaken to evaluate the effects of a subdermal implant containing nomegestrol acetate (Uniplant) on endometrial histology and ovarian function.

METHODS

Twenty healthy female volunteers of reproductive age were included and completed a menstrual diary throughout the study. Hysteroscopy, transvaginal sonography and blood sampling were performed prior to implant insertion (control cycle) and following 6 and 12 months of Uniplant use. Transvaginal sonography was performed every other day from Day 8 of the cycle up to the obtainment of sonographic evidence of a 12-mm follicle, then every day until the obtainment of sonographic evidence of follicular rupture and thereafter every other day until the next menstrual bleeding. Blood samples were taken for the measurement of estradiol, follicle-stimulating hormone, luteinizing hormone and progesterone on the same days on which transvaginal sonography was performed. The implants were removed after 1 year.

RESULTS

Twenty percent of cycles were ovulatory, and 80% were anovulatory. The development of persistent nonluteinized follicle occurred in 40% of all cycles studied, inadequate luteal phase occurred in 20% of cycles and no follicular development occurred in 40%. Endometrial thickness remained below 8 mm in all cycles studied. Alterations in endometrial vascularization were observed in all treated cycles.

CONCLUSION

Our results suggest that this long-acting contraceptive method affects follicular growth and endometrial vascularization, disrupts endometrial architecture and leads to inadequate luteal phase.

Newer progestogens

OBJECTIVE

To review the literature on the most recent progestogens to be developed, to provide clinical comparisons with older progestogens and to look at the potential of products not yet marketed.

DATA SOURCES

Searches of Medline and Popline together with requests for bibliographies from the Population Council, Wyeth-Ayerst Research and Schering Health Care.

STUDY SELECTION

Information from technical papers was used to ascertain the metabolic characteristics and receptor binding affinities of the compounds. Previous reviews were scrutinised in order to make comparisons with older compounds. Any available trials were examined to ascertain efficacy, bleeding patterns and tolerability, more weight being given to comparative trials.

DISCUSSION

Five progestogens have been developed in the last decade. They are all devoid of androgenic activity; some have antiandrogenic activity. Combined oral contraceptive (COC) pills containing dienogest and drospirenone are already marketed. Nomegestrol and nestorone have been extensively studied as subdermal implants.

CONCLUSIONS

Newer progestogens used in combination with oestrogen behave very similarly to existing products. Progestogen-only products using new progestogens have potential for significantly better tolerability due to their lack of androgenic activity.

Metabolic effects of implantable steroid contraceptives for women

The metabolic impact of progestin-only contraceptives is less than that of combined oral contraceptives. Subdermal contraceptive implant systems that provide a sustained release of low levels of progestins are now becoming widely available. This review evaluates the metabolic effects of currently available products that release the progestins levonorgestrel (Norplant, Jadelle, and their Chinese equivalents); etonogestrel (Implanon); nomegestrol acetate (Uniplant); and Nestorone, formally called ST-1435 (Nestorone implant/Elcometrine). Data on liver, kidney, and renal function; carbohydrates and insulin release; hemostasis; blood pressure; and lipids are considered. The metabolic effects reported for these methods as a whole were minimal. Any changes were generally within the normal range for the populations studied and, therefore, are unlikely to be of clinical significance. However, all published studies have been conducted in healthy populations of women. To inform clinical practice, the field would be well served to have additional empiric data from well-designed, well-implemented, and well-reported trials in women who are deemed to be at elevated risk for certain diseases including cardiovascular disease and diabetes.

Implantable contraception

Although levonorgestrel contraceptive implants have been available for over 15 years, innovations have only recently led to a wider choice. These new implants offer easier insertion and removal and other advantages depending on the type of progestin. Implants prevent pregnancy by several mechanisms, including inhibition of ovulation and luteal function and alteration of cervical mucus and the endometrium. The high efficacy and ease of maintenance make implants an ideal contraceptive for many women, including adolescents, a population that uses implants infrequently but reports high satisfaction. Implants are appropriate for women who are breastfeeding, who have contraindications to estrogen, or who have diseases such as diabetes, hypertension, sickle cell anemia, or an HIV infection because implants have few metabolic or hematologic effects. Long-term use has not been associated with a decrease in BMD and generally leads to increased blood levels and iron stores. Women who wish to space their pregnancies appreciate the nearly immediate onset of action with insertion and the rapid termination of all effects with removal. All types of implants lead to menstrual changes and other side effects in some women. Adverse effects that occur in implant users more than the general population include headaches and acne. Women must be thoroughly counseled regarding the potential for menstrual alteration, side effects, and sexually transmitted infections if they do not use condoms. Despite their initial high cost, implants are a cost-effective method over several years, even when discontinued before the life of the implant.

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.