FDA Approves Implanon
Implanon, a single rod contraceptive implant that is highly effective for 3 years, has been approved in the United States, with a training and marketing plan designed to avoid some of the problems that plagued Norplant, the last implantable contraceptive available in this country.
About the size of a matchstick, Implanon is made of a soft polymer containing 68 mg of etonogestrel [a progestin] that is slowly released over 3 years at a rate of about 30 mcg/day. In a simple office-based procedure, the rod is inserted subdermally on the inner side of the upper arm and is 99% effective in preventing pregnancy, according to Organon, the manufacturer. Implanon works primarily by suppressing ovulation, but it also thickens cervical mucus, a secondary mechanism, according to Organon, which also markets NuvaRing, the vaginal ring that contains etonogestrel and estrogen.
Approved by the Food and Drug Administration in July, Implanon is the first long-term implantable contraceptive to become available in the United States since 2000 when Wyeth stopped marketing Norplant, the six-rod levonorgestrel implant. Since 1998, Implanon has been approved in more than 30 other countries, where it has been used by about 2.5 million women.
"We have been waiting for this for quite some time," Dr. Anita Nelson, professor of obstetrics and gynecology at the University of California, Los Angeles, said in an interview. The availability of a contraceptive with this degree of effectiveness and convenience, which takes about 1 minute to insert in a simple, office-based procedure and lasts for 3 years, should meet some of the unmet needs of women who find compliance a challenge even with monthly options such as vaginal rings.
Dr. Nelson expects that the product's gradual dissemination and the requirement that physicians be trained before they receive Implanon should avoid some of the problems that were associated with Norplant. When Norplant became available, there was "a fair amount of enthusiasm [for an implantable contraceptive] pent up for years" so it was widely prescribed soon after approval, and while training was available, it was not required to obtain the product, she said.
Dr. Andrew M. Kaunitz, professor and assistant chairman of the department of obstetrics and gynecology at the University of Florida Health Science Center, Jacksonville, said that the company's training requirements will lead to greater acceptance of the method by women and physicians, "because the clinicians providing the method will have the knowledge to appropriately counsel women and the skills to appropriately perform insertions."
The Implanon implant is longer, thicker, and slightly more rigid than the Norplant rods, and "because it's a single rod system, it's easier and quicker to insert, but more importantly, it's easy and quick to remove," Dr. Kaunitz said in an interview.
And note this, too:
They [Drs. Kaunitz and Nelson] both emphasized the importance of making sure women considering Implanon understand its impact on menstrual bleeding, as with other progestin-only methods. It is "almost unpredictably unpredictable," Dr. Nelson said, noting that in studies, no patterns of irregular bleeding were identified.
Bleeding irregularities were frequent and were the most common reason for choosing to discontinue the contraceptive, in 11% of women. About 4% of patients had implant site complications that included swelling, redness, hematoma, and pain. Nearly 2% had removal complications, which included implants that could not be palpated, a broken or damaged implant, slight migration, difficult localization, and formation of fibrosis, according to Organon.
Among heavier women, the failure rate of Norplant increased during the fifth year of use. Women weighing more than 30% above their ideal body weight were not included in Implanon trials, but Dr. Monroe said postmarketing data provided no clear evidence that failure was higher in overweight women. The label states that health care providers and patients should be aware that it is unknown whether effectiveness is lower in women over 30% above their ideal body weight.