Contraception Technology Reports: The Vaginal Contraceptive Ring — Efficacy, Caution, and Instructions
Contraception Technology Reports: The Vaginal Contraceptive Ring — Efficacy, Caution, and Instructions
Author: Felicia H. Stewart, MD, Adjunct Professor, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco. Peer Reviewer: Kurt T. Barnhart, MD, MSCE, Assistant Professor of Obstetrics and Gynecology and Epidemiology, University of Pennsylvania, Philadelphia.
Introduction
NuvaRing, approved by the Food and Drug Administration (FDA) in November 2001, provides a low-dose, steady release of estrogen (ethinyl estradiol) and progestin (etonogestrel, the active form of desogestrel) for three weeks of continuous wear. Women using the new contraceptive vaginal ring have a hormonal pattern and contraceptive effectiveness similar to women using low-dose birth control pills, but with much less to remember. The regimen is very simple: A new ring is inserted any time during the first five days of a normal menstrual cycle, and the woman removes it at the end of three weeks of wear. After one ring-free week, the woman inserts a new ring. The woman’s menstrual period occurs during the off week, just as it would with oral contraceptives. Instead of 21 pills to remember each cycle, however, there are only two tasks for ring users: insertion and removal.
A hormone-releasing vaginal ring has been available for postmenopausal estrogen treatment, but this is the first contraceptive device based on vaginal absorption to be approved for marketing. Contraceptive vaginal rings that release only progestin also have been studied. Like progestin-only oral contraceptives, however, they have a slightly lower effectiveness and significantly higher rates for spotting and bleeding between menses.1 A progestin-only option nevertheless may prove in the future to be a good option for women who are postpartum or breast-feeding.
Rings will be available in the United States in spring 2002, with cost anticipated to be similar to that of oral contraceptives.
Ring Design and Mechanism of Action
Each NuvaRing is a soft, flexible transparent circular tube, 54 mm (2 inches) in diameter and 4-mm (¼ inch) thick. (See Figure 1, below.) The ring is made of ethylene vinylacetate polymer and contains a hormone reservoir that releases 0.120 mg (120 mcg) of etonogestrel and 0.015 mg (15 micrograms) of ethinyl estradiol each day over a three-week period.2 Hormone content in the ring is sufficient to provide a "grace period" of at least 14 additional days2 in the event that the woman does not remember to remove the ring at the correct time. The hormone release rate was designed to ensure that the hormone level maintained in the woman’s bloodstream is similar to that of the average level in a low-dose oral contraceptive user. With oral hormones, however, there is a daily spike in hormone levels after the woman swallows each dose, followed by a gradual drop through the rest of the day. The vaginal ring maintains a steady low release rate throughout wear. (See Figure 2, below) The overall systemic exposure for etonogestrel is identical for ring users and for women taking oral contraceptives containing 0.150 mg of desogestrel. The systemic exposure to ethinyl estradiol for ring users is lower than that of the oral contraceptive pills.2
Ethinyl estradiol is the familiar synthetic estrogen used for oral contraceptives. Etonogestrel, also called 3-ketodesogestrel, is also a synthetic hormone. It is the active metabolite of desogestrel, the progestin component of commonly used oral contraceptives including Apri (Duramed, Cincinnati), Cyclessa (Organon, West Orange, NJ), Desogen (Organon), Mircette (Organon), and Ortho-Cept (Ortho-McNeil, Raritan, NJ). Etonogestrel also is the hormone used in Implanon, a subdermal contraceptive implant for which final FDA approval is expected soon.
The contraceptive effect of hormones absorbed from the vaginal ring is parallel to the effect with hormones taken orally. The hormone levels in the woman’s bloodstream are high enough to prevent ovulation, so no egg is released and pregnancy is prevented.3 In addition, cervical mucus is sticky and thick because of the progestin effect, and endometrial development also may be altered. Initiating ring use during the first five days of a normal cycle ensures that ovulation in that cycle is suppressed. Similarly, allowing no more than seven ring-free days each month is important. Also, making sure that the ring is continuously in place, with no more than three hours out in one day, is also important for efficacy. Ring removal is not necessary and is not recommended. Women who want to remove the ring during intercourse, however, may do so as long as the three-hour limit is not exceeded.
No special accuracy is required for ring placement; absorption is fine anywhere in the vagina, and the ring is small enough that it can rest comfortably without worrying about its positioning. Because it is small and flexible, most women do not notice any pressure or discomfort and it is unlikely to be uncomfortable for the woman’s partner during intercourse.
Contraceptive Efficacy
Results for the European sites in a multicenter study of ring efficacy, side effects, and acceptability have been published;4 publication of results for the U.S. sites is expected soon. The European sites included 1,145 ring users followed for one year, and documented an overall pregnancy rate of 0.65 (0.24-1.41, 95% confidence interval) per 100 woman-years (all first-year users). This level of effectiveness is similar to that found for women using combined oral contraceptives. The European sites found that adherence to rules for ring use was very high, with consistent and correct use reported in 90.8% of all cycles. Women using the ring also reported good cycle control, with expected withdrawal bleeding in 98% of cycles, and bleeding at other times in only 6.4% of cycles.4
Side Effects and Cautions
Risks and adverse reactions possible with use of combined hormonal oral contraceptives also are likely to apply to the vaginal contraceptive ring. In addition, some women using the ring experienced side effects related to the device itself, including vaginal discomfort or problems during intercourse; vaginal discharge, or vaginitis. These device-related problems were reported by 2-5% of women of European ring study sites.4 Other side effects reported by 1% or more of subjects are shown in Figure 3, below.
Cautions that apply to combined hormonal oral contraceptives recently were updated by the World Health Organization,5 and were summarized along with recommendations for history and physical examination steps needed prior to providing hormonal methods in a review article on this subject.6 Use of combined hormonal contraceptives, including the vaginal ring, is not recommended, or requires caution or special monitoring for women whose medical history includes serious medical conditions. (See Table 1 enclosed in this issue.) All women who smoke, regardless of contraceptive method, should be strongly encouraged to stop. For women who are light smokers (< 15 cigarettes daily) and are age 34 or younger, however, the advantages of effective combined hormonal contraception generally outweigh the disadvantages.
Instructions for Users
To begin ring use for the first time, the user should count the first day of a normal period as Day One and insert the first ring on or before Day Five, even if menstrual bleeding has not finished. She should use an additional backup method of contraception, such as condoms, along with the ring for the first seven days of ring use. A woman switching from oral contraceptives to the ring can insert the first ring any time during the first seven days after her last active pill. No backup method is needed in this situation.
To insert the ring, a woman should remove it from the foil pouch and compress the ring between two fingers. Standing with one leg up, squatting or lying down, she should slide the ring into the vagina. The exact position is not critical as long as it remains comfortably inside.
The ring should be left in place for three weeks before removing it by hooking an index finger over the ring or grasping it between two fingers to pull it out. The used ring should placed in the foil pouch and discarded. The device must be kept out of the reach of children or pets and not flushed down the toilet.
The user should allow one week with no ring in place; a menstrual period usually starts within two or three days. On the seventh day, a new ring should be inserted, even if bleeding has not completely finished.
Removing the ring during the three "ring-in-place" weeks is not recommended. (Editor’s note: Dr. Stewart discourages removal of the ring at the time of intercourse during the "ring-in-place" weeks. If the user does this and forgets to put it back in, the method’s effectiveness is reduced.) If a woman needs to remove it or wants to do so during intercourse, she should be sure it is reinserted within three hours. No special cleaning or rinsing is recommended.
The ring can be used along with vaginal lubricants (water-based or oil-based) or spermicide. Vaginal medication, including oil-based yeast medication, also can be used during ring wear and does not interfere with proper hormone release or absorption.
Ring use also does not interfere with having a routine pelvic examination, or with Pap or STI (sexually transmitted infection) testing. The clinician simply can remove the ring just before inserting a speculum and replace it when the exam is finished.
References
- Hatcher R, Trussell J, Stewart F, et al. Contraceptive Technology, 17th Revised Edition. New York City: Ardent Media; 1998.
- Timmer CJ, Mulders TMT. Pharmacokinetics of etonogestrel and ethinylestradiol released from a combined contraceptive vaginal ring. Clin Pharmacokinet 2000; 39:233-242.
- Mulders TMT, Dieben, TOM. Use of the novel combined contraceptive vaginal ring NuvaRing for ovulation inhibition. Fertil Steril 2001; 75:865-870.
- Roumen FJME, Apter D, Mulders TMT, et al. Efficacy, tolerability, and acceptability of a novel contraceptive vaginal ring releasing etonogestrel and ethiny oestradiol. Hum Reprod 2001; 16:469-475.
- World Health Organization. Medical eligibility criteria for initiating and continuing use of contraceptive methods. Geneva: WHO; 2001.
- Stewart FH, Harper CC, Ellertson CE, et al. Clinical breast and pelvic examination requirements for hormonal contraception: Current practice vs. evidence. JAMA 2001; 285: 2,232-2,239.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.