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Medical Correspondent John McKenzie provides answers about Implanon following a teleconference by Scott Monroe, M.D., acting director of the Division of Reproductive and Urologic Products at the Center for Drug Evaluation and Research in the Food and Drug Administration.

How is Implanon inserted?

It requires a small procedure for implant and removal. The company is planning on requiring training for all health providers who wish to prescribe the device. Only those who receive training will be allowed to order and prescribe the devices.

How was Implanon tested?

The primary clinical trials of Implanon included 942 healthy women of reproductive age. During the trial the device was found to be safe and effective. It is highly effective in that it doesn't depend on patient compliance.

How effective is Implanon?

During the trials with more than 900 women on the implanted contraceptive there were only six pregnancies. A rate of better than 99 percent.

Why did the pregnancies occur?

Whenever a pregnancy occurs close to removing a product it is conceivable that the pregnancy did not occur while device still implanted. Therefore it is possible that no one became pregnant while on the device. However the FDA records this as a pregnancy while on the device to be conservative in their rates of pregnancy while on the device. The device is not 100 percent effective but it is highly effective.

What are the warnings included with Implanon?

The patient and clinician are to ensure that the device is implanted by palpating the skin. This must be documented by the clinician. If the device cannot be located the patient should be warned that it may not have been inserted and therefore she may be at risk of becoming pregnant. The device will also come with an information brochure and consent form for the patient to sign. This will provide informed consent for the patient.

What are the side effects of Implanon?

Women will be informed that they will likely not have regular menstrual bleeding. They may have irregular menses or no periods at all.

How long does Implanon last?

Woman using the device will be provided with a small card to be reminded that she must have it removed in three years, and in which arm the device was implanted. The same information will be kept on a card in the patient's medical file. Also, the lot number for the particular product will be on the card and in the file. This will allow for women to be contacted if there is a problem with that lot.

How does it compare to other methods?

Implanon is a single rod, compared to Norplant which was six rods. Likely there will be fewer problems with the single rod with regards to insertion and removal compared to Norplant's six rods. (Although Norplant was effective for up to five years.)

What experience does the maker of Implanon have?

Organon has a lot of experience to look upon outside the U.S. Implanon was approved outside of the U.S. in 1997 and then was marketed in 1998. It has been used by about 2.5 million women worldwide. The post marketing database supports that it will be a safe and effective product.

Can the device be used in overweight women?

Women 30 percent over their ideal body weight were not included in the trials and the FDA does not know the effectiveness of the device in those women, though it may reduce the effectiveness somewhat.

Were the devices ever removed during the trials?

The devices were removed in 35 percent of patients in clinical trials. For some this was voluntary. The most common reason for removal was bleeding irregularities, which occurred in 11 percent of the women.

What happens when device cannot be located?

All devices were removed without problem in the clinical trial. However during the post marketing data there were a few instances where it was difficult to locate the device. When this happens it can be located by U/S or MRI.

When do women resume fertility after device is removed?

As early as 30 days. Rapid return to pretreatment fertility.

Is Implanon biodegradable?

It is not biodegradable. It contains progestin (Etonogestrel). It is made from a medical polymer. It is implanted subdermally. The progestin is slowly released over three years. It is effective for three years.