Comparison of ovarian follicular activity during treatment with a monthly injectable contraceptive and a low-dose oral contraceptive

Combination injectable contraceptives for contraception

BACKGROUND

Combination injectable contraceptives provide a highly effective, reversible method of preventing pregnancy, and they do not require daily administration or use at the time of coitus. Although they are used in many countries, their acceptability could be limited by method characteristics, such as the need to obtain a monthly injection or bleeding pattern changes.

OBJECTIVES

To assess the contraceptive efficacy, bleeding patterns, discontinuation, user preferences, and side effects of combination injectable contraceptives.

SEARCH STRATEGY

We searched computerized databases for randomized controlled trials of combination injectable contraceptives.

SELECTION CRITERIA

Randomized controlled trials were eligible if they compared a combination injectable with any other contraceptive method (e.g., a second combination injectable contraceptive, progestin-only injectable contraceptive, other hormonal contraceptive or barrier method) or placebo. We limited the review to currently marketed combination injectable contraceptives.

DATA COLLECTION AND ANALYSIS

One author evaluated all titles and abstracts from the literature searches to determine their eligibility. Two authors independently extracted data from the eligible trials. Data on contraceptive efficacy, bleeding patterns, continuation, and side effects were entered and analyzed with RevMan.

MAIN RESULTS

Combination injectable contraceptives include depot medroxyprogesterone acetate (DMPA) 25 mg plus estradiol cypionate (E(2)C) 5 mg, as well as norethisterone enanthate (NET-EN) 50 mg plus estradiol valerate (E(2)V) 5 mg. These contraceptives resulted in lower rates of early study discontinuation due to amenorrhea or other bleeding problems than progestin-only contraceptives. However, rates were higher for overall discontinuation and discontinuation due to other medical reasons. Acceptability results favored the combination injectable in one study and the progestin-only in another.Studies comparing two combination injectable contraceptives found that NET-EN 50 mg plus E(2)V 5 mg resulted in less overall discontinuation and less discontinuation due to amenorrhea or prolonged bleeding than DMPA 25 mg plus E(2)C 5 mg. However, these differences were not detected in all trials. The NET-EN plus E(2)V group also had more regular bleeding and fewer prolonged bleeding reference periods than the DMPA plus E(2)C group. The groups did not differ in their amenorrhea rates.

AUTHORS' CONCLUSIONS

While discontinuation rates can be viewed as a measure of method acceptability, the findings should be interpreted with caution since discontinuation depends on many factors. Future research should be directed toward interventions to improve the acceptability of combination injectable contraceptives, such as providing injections in settings more convenient than clinics, methods for women to administer their own injections, and counseling about possible bleeding pattern changes.

Feasibility study of Nestorone®–ethinylestradiol vaginal contraceptive ring for emergency contraception

OBJECTIVE

The Nestorone/ethinylestradiol (NES/EE) vaginal ring is being developed as a regular contraceptive method by the Population Council. This ring is designed to release NES 150 microg/day and EE 15 microg/day during 1 year. Here, we report a Phase I clinical trial to determine the usefulness of this ring for emergency contraception. To that end, we tested the ability of this ring to interfere with ovulation when it is inserted during the follicular phase.

METHOD

Forty-eight women protected from the risk of pregnancy by nonhormonal methods were divided into three groups, which differed by the size of the dominant follicle at the time of ring insertion: 12-14 mm (n = 16), 15-17 mm (n = 18) and >or=18 mm (n = 14) diameter. The NES/EE ring was left in the vagina for 7 consecutive days, after which it was removed. The growth of the leading follicle and plasma levels of estradiol, progesterone (P), luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the ensuing 5 days after ring insertion were determined. Afterwards, steroid hormones were measured twice a week, until menses took place. All women had a control cycle before the ring cycle, and the range of maximum follicular diameter assigned to each volunteer was the same for the control and the ring cycle at the time when placebo was ingested or the ring inserted.

RESULTS

During the 5-day period after ring insertion with follicles 12-17 mm, ovulation was absent in 25 of 34 cycles (p < .01 vs. control), and ovulatory dysfunction (absent, blunted or mistimed LH peak) occurred in 8 of the 9 remaining cycles (33/34 ovulatory processes altered; p < .005 vs. control). After ring insertion with follicles >or=18 mm in diameter, ovulation did not occur in 2 of 14 cycles or was dysfunctional in 7 of the 12 remaining cycles (9/14 ovulatory processes altered; p<.025 vs. control). Altogether, 87.5% of ring cycles (42/48) had either no ovulation or ovulatory dysfunction in the 5-day study period, in contrast to 39.6% (19/48 cycles) in control cycles (p < .001). Among follicles that failed to rupture within the 5-day study period, none ruptured later on in the ring-treated cycles, while 9 of 16 did so in control cycles. Sixty-two percent of ring-treated cycles were shorter than 24 days. Nausea, vaginal discharge and abdominal pain were the most frequently reported adverse events during ring use.

CONCLUSION

Interference with 87.5% of ovulatory processes, without ovulation occurring later in the cycle and shortening of cycle length, suggests the NES/EE ring may be used as an emergency contraceptive method, with the potential advantage of providing continuing contraception after it has performed its emergency function.

[Update on contraception]

Since the introduction of hormonal contraceptives in the 1960s, great advances have been achieved in contraception. Biological effects of sexual steroids as well as risks and benefits of oral contraception are better estimated. After the development of a new hormone-containing intra-uterine system, new hormone delivery systems offer women safe and effective contraceptive options. These new options that combine high efficacy and ease of use should allow better acceptance and compliance than daily pill ingestion and should then reduce the high rate of unintended pregnancies terminated by elective abortion. Transdermal contraceptive system and vaginal ring offer a promising innovative approach in pregnancy prevention. Subdermal implants give women the choice of a highly effective contraceptive system in spite of significant side effects. New hormonal delivery systems such as injectables are under development. Hysteroscopic tubal sterilization is now also available and is a very effective procedure. This wide variety of new contraceptive methods offers a marked improvement from previous medications for users by providing better efficacy and tolerability.

Combination injectable contraceptives for contraception

BACKGROUND

Combination injectable contraceptives provide a highly effective, reversible method of preventing pregnancy, and they do not require daily administration or use at the time of coitus. Although they are used in many countries, their acceptability could be limited by method characteristics, such as the need to obtain a monthly injection or bleeding pattern changes.

OBJECTIVES

To assess the contraceptive efficacy, bleeding patterns, discontinuation, user preferences, and side effects of combination injectable contraceptives.

SEARCH STRATEGY

We searched computerized databases for randomized controlled trials of combination injectable contraceptives.

SELECTION CRITERIA

Randomized controlled trials reported in any language were eligible if they compared a combination injectable with any other contraceptive method (e.g., a second combination injectable contraceptive, progestin-only injectable contraceptive, other hormonal contraceptive or barrier method) or placebo. We limited the review to currently marketed combination injectable contraceptives.

DATA COLLECTION AND ANALYSIS

The primary reviewer evaluated all titles and abstracts from the literature searches to determine their eligibility. Two reviewers independently extracted data from the eligible trials. Data on contraceptive efficacy, bleeding patterns, continuation, and side effects were entered and analyzed with RevMan 4.2.

MAIN RESULTS

Combination injectable contraceptives include depot medroxyprogesterone acetate (DMPA) 25 mg plus estradiol cypionate (E(2)C) 5 mg, as well as norethisterone enanthate (NET-EN) 50 mg plus estradiol valerate (E(2)V) 5 mg. These combination injectable contraceptives resulted in lower rates of early study discontinuation due to amenorrhea or other bleeding problems, but had higher rates of discontinuation due to other reasons than the progestin-only comparison contraceptives. Studies comparing two combination injectable contraceptives found that NET-EN 50 mg plus E(2)V 5 mg resulted in less overall early discontinuation and less discontinuation due to amenorrhea or prolonged bleeding than DMPA 25 mg plus E(2)C 5 mg. However, these differences were not detected in all trials making this comparison. The NET-EN plus E(2)V group also had more cyclical (regular) bleeding and fewer prolonged bleeding reference periods than the DMPA plus E(2)C group. The groups did not differ in their amenorrhea rates.

AUTHORS' CONCLUSIONS

While discontinuation rates can be viewed as a measure of method acceptability, the findings should be interpreted with caution since discontinuation rates are dependent on many other factors. Future research should be directed toward interventions to improve the acceptability of combination injectable contraceptives, such as providing injections in settings more convenient than clinical sites, methods for women to administer their own injections, and counseling about possible bleeding pattern changes.

New contraceptive methods: update 2003

The decline in adolescent pregnancy rates noted in the 1990s has been attributed to more teenagers choosing abstinence, the availability of long-acting contraceptive options, and the increased use of condoms. Many adolescents remain at risk of unplanned pregnancy, however, because of method failure, inconsistent or incorrect use, or discontinuation of a method without choosing another method. Practitioners who care for adolescents and young women have access to several new methods in 2003. Recent additions include a contraceptive transdermal patch, a hormone-releasing intravaginal ring, new formulations of pills, and a new intrauterine device. Additionally, the World Health Organization has updated its guidelines to provide the practitioner with evidence-based recommendations to assist in selecting the most appropriate contraceptive method for each patient.