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Implanon 68mg implant for subdermal use

Last Updated on eMC 10-Sep-2009 View changes  | Merck Sharp & Dohme Limited Contact details

Discontinued Items

The preparations being discontinued are:

  • Implanon 68mg implant (Organon Laboratories Ltd)

The pharmaceutical company has decided to discontinue the product and so it may not be available in the future.  This document has been left on the eMC for information purposes.

1. Name of the medicinal product

Implanon®, 68 mg implant for subdermal use

2. Qualitative and quantitative composition

One implant contains 68 mg of etonogestrel; the release rate is approximately 60-70 µg/day in week 5-6 and has decreased to approximately 35-45 µg/day at the end of the first year, to approximately 30-40 µg/day at the end of the second year and to approximately 25-30 µg/day at the end of the third year.

For a full list of excipients, see section 6.1.

3. Pharmaceutical form

Implant for subdermal use

Non-biodegradable white to off-white flexible rod.

4. Clinical particulars
4.1 Therapeutic indications


Safety and efficacy have been established in women between 18 and 40 years of age.

4.2 Posology and method of administration

4.2.1 How to use Implanon

Pregnancy should be excluded before insertion of Implanon.

Prior to inserting Implanon it is strongly recommended to carefully read the instructions for insertion and removal of the implant in section 4.2.2 “How to insert Implanon” and section 4.2.4 “How to remove Implanon”.

Implanon is a long-acting contraceptive. One implant is inserted subdermally. The user should be informed that she can request the removal of Implanon at any time but the implant should not be left in place more than three years. Clinicians may consider earlier replacement of the implant in heavier women (see section 4.4.1). Only a physician who is familiar with the removal technique should perform, on request or at the end of the 3 years of use, the removal of Implanon. After the removal of the implant, immediate insertion of another implant will result in continued contraceptive protection.

To ensure uncomplicated removal it is necessary that Implanon is inserted correctly, directly under the skin. The risk of complications is small if the provided instructions are followed.

Some cases have been reported in which the implant was not inserted on the correct day, or was not properly inserted or not inserted at all. Incidentally, this has resulted in an unintended pregnancy. The occurrence of such incidents can be minimized when the instructions for insertion (section 4.2.2 “How to insert Implanon” and 4.2.3 “When to insert Implanon”) are strictly followed. The presence of the implant should be verified by palpation directly after insertion. In case the implant cannot be palpated or when the presence of the implant is doubtful, other methods must be applied to confirm its presence (see section 4.2.2 “How to insert Implanon”). Until the presence of Implanon has been verified a contraceptive barrier method must be used.

It is strongly recommended that physicians, prior to practicing the insertion of Implanon, participate in training sessions by the company supplying Implanon. Physicians who have little experience with subdermal insertion are advised to acquire the correct technique under supervision of a more experienced colleague. Additional information and more detailed instructions concerning the insertion and removal of Implanon will be sent on request free of charge (Organon Laboratories Ltd, Telephone +44 (0)1223 432700).

The Implanon package contains a USER CARD intended for the user, and an adhesive label intended for the physician's user record. Amongst others, the USER CARD records the batch number of the provided implant and helps to note the date of insertion, the arm of insertion, the name of the doctor and / or the hospital, and the intended day of removal. The adhesive label records the batch number and date of insertion.

4.2.2 How to insert Implanon

• Insertion of Implanon should be performed under aseptic conditions, and only by a physician who is familiar with the procedure.

• Insertion of Implanon is performed with the specially designed applicator. The use of this applicator differs substantially from that of a classical syringe. A drawing of a dismantled applicator and its individual components (e.g. cannula, obturator and needle with double-angled bevel) is shown in this leaflet to clarify their specific functions.

• The procedure used for insertion of Implanon is opposite to giving an injection . When inserting Implanon the obturator must remain fixed while the cannula (needle) is retracted from the arm. For normal injections the plunger is pushed and the body of the syringe remains fixed.

• Allow the subject to lie on her back with her non-dominant arm (the arm which the woman does not use for writing) turned outwards and bent at the elbow.

• To minimize the risk of neural or vascular damage, Implanon should be inserted at the inner side of the non-dominant upper arm about 8-10 cm above the medial epicondyle of the humerus.

Implanon should be inserted subdermally, i.e. just under the skin (subcutaneously).

When Implanon is inserted too deeply (intramuscular or in the fascia) this may cause neural or vascular damage.Too deep insertions have been associated with paraesthesia (due to neural damage) and migration of the implant (due to intramuscular or fascial insertion), and in rare cases with intravascular insertion. Moreover, when the implant is inserted too deeply, it may not be palpable and the localization and/or removal can be difficult later on.

• Mark the insertion site.

• Clean the insertion site with a disinfectant.

• Anaesthetize with an anaesthetic spray, or with 2 ml of lidocaine (1%) applied just under the skin along the 'insertion canal'.

• Remove the sterile disposable applicator carrying Implanon from its blister.

• While keeping the shield on the needle, visually verify the presence of the implant, seen as a white body inside the needle-tip. If the implant is not seen, tap the top of the needle shield against a firm surface to bring the implant into the needle tip. Following visual confirmation, the implant should be lowered back into the needle by tapping it back into the needle tip. The needle shield can now be removed.

• Please note that the implant can fall out of the needle prior to insertion. Therefore, always hold the applicator in the upward position (i.e. with the needle pointed upwards) until the time of insertion. This is to prevent the implant from dropping out. Keep the needle and the implant sterile. If contamination occurs, a new package with a new sterile applicator must be used.


• Stretch the skin around the insertion site with thumb and index finger (Figure 1).

• Insert first only the tip of the needle, slightly angled (~ 20°) (Figure 2).

• Release the skin.

• Lower the applicator to a horizontal position (Figure 3).

• While lifting the skin, gently insert the needle to its full length. Do not exert force. The needle should be inserted parallel to the skin to ensure that Implanon is inserted superficially just under the skin (Figure 4)

• Keep the applicator parallel to the surface of the skin.

When the implant is placed too deeply paresthesia and migration of the implant may occur. Moreover, removal can be difficult later on.


• Break the seal of the applicator (Figure 5).

• Turn the obturator 90° (Figure 6).

• Fix the obturator with one hand parallel to the arm and with the other hand slowly retract the canula (needle) out of the arm (Figure 7).

Never push against the obturator.

• Check the needle for the absence of the implant. After retraction of the canula, the grooved tip of the obturator should be visible (Figure 8).

Always verify the presence of the implant by palpation and also have the woman palpate it herself.

• In case the implant can not be palpated or when the presence of the implant is doubtful, other methods must be applied to confirm its presence. Suitable methods to locate the implant are first of all ultrasound (USS) and secondly magnetic resonance imaging (MRI). Prior to the application of USS or MRI for the localization of Implanon it is recommended to consult Organon for instructions. In case these imaging methods fail, it is advised to verify the presence of the implant by measuring the etonogestrel level in a blood sample of the subject. In this case Organon will also provide the appropriate procedure.

Until the presence of Implanon has been confirmed a contraceptive barrier method must be used.

• Apply sterile gauze with a pressure bandage to prevent bruising.

• Fill out the User Card and hand it over to the subject to facilitate removal of the implant later on.

• The applicator is for single use only and must be adequately disposed of, in accordance with local regulations for the handling of biohazardous waste.

4.2.3 When to insert Implanon

No preceding hormonal contraceptive use

Implanon should be inserted between Day 1-5, but at the latest on Day 5 of the woman's natural cycle (Day 1 is the first day of her menstrual bleeding).

Changing from a combined hormonal contraceptive (combined oral contraceptive (COC), vaginal ring, or transdermal patch)

Implanon should be inserted preferably on the day after the last active tablet (the last tablet containing the active substances) of her previous COC or on the day of removal of the vaginal ring or transdermal patch, but at the latest on the day following the usual tablet-free, ring-free, patch-free or placebo tablet interval of her previous combined hormonal contraceptive. All contraceptive methods (transdermal patch, vaginal ring) may not be marketed in all EU countries.

Changing from a progestagen-only-method (minipill, injectable, a different implant, or from a progestagen-releasing intrauterine system [IUS])

Implanon may be inserted any day when the woman is switching from a minipill, from another implant or an IUS on the day of its removal, from an injectable when the next injection would be due.

Following first-trimester abortion

Implanon should be inserted immediately.

Following childbirth or a second-trimester abortion

For breastfeeding women see section 4.6 'Pregnancy and lactation'

Implanon should be inserted on day 21-28 after delivery or second-trimester abortion. When the implant is inserted later, the woman should be advised to additionally use a barrier method on the first 7 days after the insertion. However, if intercourse has already occurred, pregnancy should be excluded or the woman's first natural period should be awaited before the actual insertion of the implant.

4.2.4 How to remove Implanon

• Removal of Implanon should only be performed by a physician who is familiar with the removal technique.


• The precise location of the implant is indicated on the USER CARD

• Locate the implant by palpation and mark the distal end (Figure a).

• A non-palpable implant should always first be localized by either ultrasound (USS) or magnetic resonance imaging (MRI) before removal is attempted and subsequently be removed under the guidance of USS. In case of doubt, the presence of Implanon can be verified by etonogestrel determination. Please contact Organon for further guidance. Exploratory surgery without knowledge of the exact localisation of the implant is strictly discouraged. Removal of deeply inserted implants should be conducted with caution in order to prevent damage to deeper neural or vascular structures in the arm and be performed by healthcare providers familiar with the anatomy of the arm.

• Wash the area and apply a disinfectant.


• Anaesthetize the arm with 0.5-1 ml lidocaine (1%) at the site of incision, which is just below the distal end of the implant. Note: Apply the anaesthetic under the implant. Application above the implant makes the skin swell, which may cause difficulties in locating the implant (Figure b).



• Push down the proximal tip to fix the implant; a bulge may appear indicating the distal end of the implant. Starting at the distal tip of the implant, make a longitudinal incision of 2 mm towards the elbow (Figure c)


• Gently push the implant towards the incision until the tip is visible. Grasp the implant with forceps (preferably 'mosquito' forceps) and remove it (Figure d).

• If the tip of the implant is not visible, there might be formation of fibrotic tissue around the implant. The fibrotic tissue can be split by continuing to cut towards the distal tip, until the tip is clearly visible. Remove the implant with a forceps (Figures e and f).






• If the tip of the implant is not visible, gently insert a forceps into the incision and grasp the implant (Figures g and h). With a second forceps carefully dissect the tissue around the implant. The implant can then be removed (Figure i).

• Close the incision with a butterfly closure.

• Apply sterile gauze with a pressure bandage to prevent bruising.

• There have been occasional reports of displacement of the implant (see also section 4.4.1 'Warnings'); usually this involves minor movement relative to the original position. This may complicate localisation of the implant by palpation, USS and/or MRI, and removal may require a larger incision and more time.

• If the woman would like to continue using Implanon, a new implant may be inserted immediately after the old implant is removed (see section 4.2.5 “How to replace Implanon”).

• If the woman does not wish to continue using Implanon and does not want to become pregnant, another contraceptive method should be recommended.

4.2.5 How to replace Implanon

• Replacement of Implanon should only be performed under aseptic conditions and only by a physician who is familiar with the insertion and removal procedure.

• Immediate replacement can be done after removal of the previous implant as described in section 4.2.4 'How to remove Implanon'.

• The procedure to replace Implanon is similar to the insertion procedure described in section 4.2.2 'How to insert Implanon'. The new implant can be inserted in the same arm, and often through the same incision from which the previous implant was removed. If the same incision is being used, the instructions below must also be taken into account.

• The small incision of the removal procedure can be used as the entrance for the needle of the new applicator.

• Anaesthetize the insertion site with 2 ml lidocaine (1%) applied just under the skin commencing at the removal incision along the 'insertion canal'.

• During replacement inserting the needle to its full length is crucial; failure to do so will result in a partly visible implant in the removal incision in the skin.

• Close the incision with a butterfly closure.

• Apply a sterile gauze with a pressure bandage to prevent bruising. Let the woman keep the bandage in place for at least 48 hours to allow the removal incision to heal.

4.3 Contraindications

• Active venous thromboembolic disorder.

• Known or suspected sex-steroid sensitive malignancies.

• Presence or history of severe hepatic disease as long as liver function values have not returned to normal.

• Undiagnosed vaginal bleeding.

• Hypersensitivity to the active substance or to any of the excipients of Implanon.

4.4 Special warnings and precautions for use

4.4.1 Warnings

If any of the conditions / risk factors mentioned below is present, the benefits of progestagen use should be weighed against the possible risks for each individual woman and discussed with the woman before she decides to start with Implanon. In the event of aggravation, exacerbation or first appearance of any of these conditions, the woman should contact her physician. The physician should then decide on whether the use of Implanon should be discontinued.

• The risk for breast cancer increases in general with increasing age. During the use of oral contraceptives (OCs) the risk of having breast cancer diagnosed is slightly increased. This increased risk disappears gradually within 10 years after discontinuation of OC use and is not related to the duration of use, but to the age of the woman when using the OC. The expected number of cases diagnosed per 10 000 women who use combined OCs (up to 10 years after stopping) relative to never users over the same period have been calculated for the respective age groups to be: 4.5/4 (16-19 years), 17.5/16 (20-24 years), 48.7/44 (25-29 years), 110/100 (30-34 years), 180/160 (35-39 years) and 260/230 (40-44 years). The risk in users of contraceptive methods, which only contain progestagens, is possibly of similar magnitude as that associated with combined OCs. However, for these methods, the evidence is less conclusive. Compared to the risk of getting breast cancer ever in life, the increased risk associated with OCs is low. The cases of breast cancer diagnosed in OC users tend to be less advanced than in those who have not used OCs. The increased risk observed in OC users may be due to an earlier diagnosis, biological effects of the OC or a combination of both.

• Epidemiological investigations have associated the use of combined OCs with an increased incidence of venous thromboembolism (VTE, deep venous thrombosis and pulmonary embolism). Although the clinical relevance of this finding for etonogestrel (the biologically active metabolite of desogestrel) used as a contraceptive in the absence of an estrogenic component is unknown, Implanon should be removed in the event of a thrombosis. Removal of Implanon should also be considered in case of long-term immobilization due to surgery or illness. Women with a history of thrombo-embolic disorders should be made aware of the possibility of a recurrence.

• If a sustained hypertension develops during the use of Implanon, or if a significant increase in blood pressure does not adequately respond to antihypertensive therapy, the use of Implanon should be discontinued.

• When acute or chronic disturbances of liver function occur the woman should be referred to a specialist for examination and advice.

• The use of progestagen-containing contraceptives may have an effect on peripheral insulin resistance and glucose tolerance. Therefore, diabetic women should be carefully monitored during the first months of Implanonuse.

• Chloasma may occasionally occur, especially in women with a history of chloasma gravidarum. Women with a tendency to chloasma should avoid exposure to the sun or ultraviolet radiation whilst using Implanon.

• The contraceptive effect of Implanon is related to the plasma levels of etonogestrel, which are inversely related to body weight, and decrease with time after insertion. The clinical experience with Implanon in heavier women in the third year of use is limited. Therefore it can not be excluded that the contraceptive effect in these women during the third year of use may be lower than for women of normal weight. Clinicians may therefore consider earlier replacement of the implant in heavier women.

• Expulsion may occur especially if the implant is inserted not according to the instructions given in section 4.2.2 “How to insert Implanon”, or as a consequence of a local inflammation.

• In rare cases, mostly related to either a too deep initial insertion (see also section 4.2.2 “How to insert Implanon”) and/or to external forces (e.g. manipulation of the implant or contact sports) the implant may migrate from the insertion site. In these cases localisation of the implant may be more difficult and removal may require a larger incision (see also section 4.2.4 “How to remove Implanon”). If Implanon cannot be found, contraception and the risk of progestogen-related undesirable effects may continue beyond the time desired by the woman.

• With all low-dose hormonal contraceptives, follicular development occurs and occasionally the follicle may continue to grow beyond the size it would attain in a normal cycle. Generally, these enlarged follicles disappear spontaneously. Often, they are asymptomatic; in some cases they are associated with mild abdominal pain. They rarely require surgical intervention.

• The protection with traditional progestagen-only contraceptives against ectopic pregnancies is not as good as with combined OCs, which has been associated with the frequent occurrence of ovulations during the use of these methods. Despite the fact that Implanon consistently inhibits ovulation, ectopic pregnancy should be taken into account in the differential diagnosis if the woman gets amenorrhea or abdominal pain.

• The following conditions have been reported both during pregnancy and during sex steroid use, but an association with the use of progestagens has not been established: jaundice and/or pruritus related to cholestasis; gallstone formation; porphyria; systemic lupus erythematosus; hemolytic uraemic syndrome; Sydenham's chorea; herpes gestationis; otosclerosis-related hearing loss.

4.4.2 Medical examination/consultation

Prior to the initiation or reinstitution of Implanon a complete medical history (including family medical history) should be taken and pregnancy should be excluded. Blood pressure should be measured and a physical examination should be performed, guided by the contraindications (Section 4.3) and warnings (Section 4.4.1). It is recommended that the woman returns for a medical check-up three months after insertion of Implanon. During this check-up, the blood pressure should be measured and an enquiry should be made after any questions, complaints or the occurrence of undesirable effects. The frequency and nature of further periodic checks should be adapted to the individual woman, guided by clinical judgment.

Women should be advised that Implanon does not protect against HIV (AIDS) and other sexually transmitted diseases.

4.4.3 Reduced efficacy

The efficacy of Implanon may be reduced when concomitant medication is used (See 'Interactions' (4.5.1)).

4.4.4 Changes in the vaginal bleeding pattern

During the use of Implanon, women are likely to have changes in their vaginal bleeding patterns which are often unpredictable. Amenorrhea was reported in about 1 of 5 women while another 1 of 5 women reported frequent and/or prolonged bleeding. Information, counseling and the use of a bleeding diary can improve the woman's acceptance of a bleeding pattern. Evaluation of vaginal bleeding should be done on an ad hoc basis and may include an examination to exclude gynaecological pathology or pregnancy.

4.5 Interaction with other medicinal products and other forms of interaction

4.5.1 Interactions

Interactions between hormonal contraceptives and other medicinal products may lead to breakthrough bleeding and / or contraceptive failure. No specific interaction studies have been performed with Implanon. The following interactions have been reported in the literature (mainly with combined contraceptives but occasionally also with progestogen-only contraceptives).

Hepatic metabolism: Interactions can occur with medicinal products that induce microsomal enzymes, specifically cytochrome P450 enzymes, which can result in increased clearance of sex hormones (e.g., phenytoin, phenobarbital, primidone, carbamazepine, rifampicin, and possibly also oxcarbazepine, topiramate, felbamate, ritonavir, nelfinavir, nevirapine, griseofulvin and the herbal remedy St. Johns wort).

Women on treatment with any of these drugs should temporarily use a barrier method in addition to Implanon. With microsomal enzyme-inducing drugs, the barrier method should be used during the time of concomitant drug administration and for 28 days after their discontinuation.

In women on long-term treatment with hepatic enzyme-inducing drugs, it is recommended to remove Implanon and to prescribe a non-hormonal method.

Hormonal contraceptives may interfere with the metabolism of other drugs. Accordingly, plasma and tissue concentrations may either increase (e.g., cyclosporin) or decrease (e.g. Iamotrigine).

Note: The prescribing information of concomitant medications should be consulted to identify potential interactions

4.5.2 Laboratory tests

Data obtained with combined OCs have shown that contraceptive steroids may influence the results of certain laboratory tests, including biochemical parameters of liver, thyroid, adrenal and renal function, serum levels of (carrier) proteins, e.g., corticosteroid binding globulin and lipid/lipoprotein fractions, parameters of carbohydrate metabolism and parameters of coagulation and fibrinolysis. The changes generally remain within the normal range. To what extent this also applies to progestagen-only contraceptives is not known.

4.6 Pregnancy and lactation

Implanon is not indicated during pregnancy. If pregnancy occurs during use of Implanon, the implant should be removed. Animal studies have shown that very high doses of progestagenic substances may cause masculinisation of female fetuses. Extensive epidemiological studies have revealed neither an increased risk of birth defects in children born to women who used OCs prior to pregnancy, nor of a teratogenic effect when OCs were inadvertently used during pregnancy. Although this probably applies to all OCs, it is not clear whether this is also the case for Implanon.

Pharmacovigilance data with various desogestrel-containing combined OCs (etonogestrel is a metabolite of desogestrel) also do not indicate an increased risk.

Implanon does not influence the production or the quality (protein, lactose or fat concentrations) of breast milk. However, small amounts of etonogestrel are excreted in breast milk. Based on daily milk ingestion of 150 ml/kg, the mean daily infant etonogestrel dose calculated after one month of etonogestrel release is approximately 27 ng/kg/day. This corresponds to approximately 2.2% of the weight-adjusted maternal daily dose and to approximately 0.2% of the estimated absolute maternal daily dose. Subsequently the milk etonogestrel concentration decreases with time during the lactation period.

Limited long-term data are available on 38 children, whose mothers started using Implanon during the 4th to 8th week postpartum. They were breast-fed for a mean duration of 14 months and followed-up to 36 months of age. Evaluation of growth, and physical and psychomotor development did not indicate any differences in comparison to nursing infants whose mothers used an IUD (n=33). Nevertheless, development and growth of the child should be carefully followed. Based on the available data, Implanon may be used during lactation.

4.7 Effects on ability to drive and use machines

On the basis of the pharmacodynamic profile, Implanon is expected to have no or negligible influence on the ability to drive or use machines.

4.8 Undesirable effects

During the use of Implanon, women are likely to have changes in their vaginal bleeding patterns which are often unpredictable. These may include changes in bleeding frequency (absent, less, more frequent or continuous), intensity (reduced or increased) or duration. Amenorrhoea was reported in about 1 of 5 women while another 1 of 5 women reported frequent and/or prolonged bleeding. Occasionally, heavy bleeding has been reported. In clinical trials, bleeding changes were the most common reason for stopping treatment with Implanon (about 11 %). The bleeding pattern experienced during the first three months is broadly predictive of future bleeding patterns for many women.

Possibly related undesirable effects reported in the clinical trials with Implanon have been listed in the Table below.

Body system

Adverse reaction in MedDRA Term1

Very common

> 1/10


< 1/10, ≥ 1/100


< 1/100, ≥ 1/1000

Infections and infestations

vaginal infection



pharyngitis, rhinitis, urinary tract infection

Immune system disorders






Metabolism and nutrition disorders



increased appetite



Psychiatric disorders




affect lability, depressed mood, nervousness, libido decreased

anxiety, insomnia

Nervous system disorders



migraine, somnolence

Vascular disorders



hot flush



Gastrointestinal disorders



abdominal pain, nausea, flatulence

vomiting, constipation, diarrhoea,

Skin and subcutaneous tissue disorders



hypertrichosis, rash, pruritus

Musculoskeletal and connective tissue disorders





back pain, arthralgia, myalgia, musculoskeletal pain

Renal and urinary disorders






Reproductive system and breast disorders


breast tenderness, breast pain, menstruation irregular

dysmenorrhoea, ovarian cyst

genital discharge, vulvovaginal discomfort, galactorrhoea, breast enlargement, prutitus genital

General disorders and administration site conditions




implant site pain, implant site reaction, fatigue, influenza like illness, pain

pyrexia, oedema


weight increased

weight decreased



1The most appropriate MedDRA term (version 10.1) to describe a certain adverse reaction is listed. Synonyms or related conditions are not listed, but should be taken into acount as well.

In rare cases, a clinically relevant rise in blood pressure has been observed during the use of Implanon. Urticaria and (aggravation of) angioedema and/or aggravation of hereditary angioedema may occur. Insertion or removal of Implanon may cause some bruising, slight local irritation, pain or itching. Fibrosis at the insertion site may occur, a scar may be formed or an abscess may develop. Paresthesia or paresthesia-like events may occur and expulsion or migration of Implanon may be possible (see also section 4.4.1 'Warnings'). Surgical intervention might be necessary when removing Implanon.

On rare occasions, ectopic pregnancies have been reported (see Section 4.4.1).

In women using (combined oral) contraceptives a number of (serious) undesirable effects have been reported. These include venous thromboembolic disorders, arterial thromboembolic disorders, hormone-dependent tumours (e.g. liver tumours, breast cancer) and chloasma, some of which are discussed in more detail in Section 4.4.'

4.9 Overdose

An implant should always be removed before inserting a new one. There are no data available on overdose with etonogestrel. There have been no reports of serious deleterious effects from an overdose of contraceptives in general.

5. Pharmacological properties
5.1 Pharmacodynamic properties


Implanon is a non-biodegradable, etonogestrel-containing implant for subdermal use. Etonogestrel is the biologically active metabolite of desogestrel, a progestagen widely used in OCs. It is structurally derived from 19-nortestosterone and binds with high affinity to progesterone receptors in the target organs. The contraceptive effect of Implanon is primarily achieved by inhibition of ovulation. Ovulations were not observed in the first two years of use and only rarely in the third year. Besides inhibition of ovulation, Implanon also causes changes in the cervical mucus, which hinders the passage of spermatozoa. Clinical trials were conducted in women between 18 and 40 years. Although no direct comparison was made, the contraceptive efficacy appeared to be at least comparable with that known for combined oral contraceptives. The high degree of protection against pregnancy is obtained among other reasons because, in contrast to OCs, the contraceptive action of Implanon is not dependent on the regular intake of tablets. The contraceptive action of Implanon is reversible, which is apparent from the rapid return of the normal menstrual cycle after removal of the implant. Although Implanon inhibits ovulation, ovarian activity is not completely suppressed. Mean estradiol concentrations remain above the level seen in the early-follicular phase. In a two-year study, in which the bone mineral density in 44 Implanon users has been compared with that in a control group of 29 IUD-users no adverse effects on bone mass have been observed. During the use of Implanon no clinically relevant effects on lipid metabolism have been observed. The use of progestagen-containing contraceptives may have an effect on insulin resistance and glucose tolerance. In clinical trials it has further been shown that Implanon users often have a less painful menstrual bleeding (dysmenorrhea).

5.2 Pharmacokinetic properties


After the insertion of Implanon, etonogestrel is rapidly absorbed into the circulation. Ovulation-inhibiting concentrations are reached within 1 day. Maximum serum concentrations (between 472 and 1270 pg/ml) are reached within 1 to 13 days. The release rate of the implant decreases with time. As a result serum concentrations decline rapidly over the first few months. By the end of the first year a mean concentration of approximately 200 pg/ml (range 150-261 pg/ml) is measured, which slowly decreases to 156 pg/ml (range 111-202 pg/ml) by the end of the third year. The variations observed in serum concentrations can be partly attributed to differences in body weight.


Etonogestrel is for 95.5-99% bound to serum proteins, predominantly to albumin and to a lesser extent to sex hormone binding globulin. The central and total volume of distribution are 27 l and 220 l, respectively, and hardly change during the use of Implanon.


Etonogestrel undergoes hydroxylation and reduction. Metabolites are conjugated to sulfates and glucuronides. Animal studies show that enterohepatic circulation probably does not contribute to the progestagenic activity of etonogestrel.


After intravenous administration of etonogestrel, the mean elimination half-life is approximately 25 hours and the serum clearance is approximately 7.5 l/hour. Both clearance and elimination-half-life remain constant during the treatment period. The excretion of etonogestrel and its metabolites, either as free steroids or as conjugates, is with urine and feces (ratio 1.5:1). After oral intake of desogestrel by lactating women, the active metabolite etonogestrel is excreted in breast milk with a milk/serum ratio of 0.37-0.55. In lactating women using Implanon, the mean transfer of etonogestrel to the infant is approximately 2.2% of the maternal etonogestrel daily dose (values normalized per kg body weight). Concentrations show a gradual and statistically significant decrease over the time.

5.3 Preclinical safety data

Toxicological studies did not reveal any effects other than those, which can be explained on the basis of the hormonal properties of etonogestrel, regardless of the route of administration.

6. Pharmaceutical particulars
6.1 List of excipients


Core: Ethylene vinylacetate copolymer (28% vinyl acetate).

Skin: Ethylene vinylacetate copolymer (14% vinyl acetate).

6.2 Incompatibilities

Not applicable

6.3 Shelf life

5 years

Implanon should not be inserted after the expiry date as indicated on the primary package.

6.4 Special precautions for storage

Store in the original package in order to prevent damage.

6.5 Nature and contents of container

The pack contains one implant (4 cm in length and 2 mm in diameter) in the cannula of a disposable sterile applicator. The applicator consists of acrylonitrile‑butadiene‑styrene body with a stainless steel needle and a polypropylene shield. The applicator containing the implant is packed in a blister pack made of transparent polyethyleneterephtalate glycol sealed with coated paper.

6.6 Special precautions for disposal and other handling

See Section 4.2 (Posology and Method of Administration).

The applicator is for single use only.

7. Marketing authorisation holder

Organon Laboratories Limited, Cambridge Science Park, Milton Road, Cambridge CB4 0FL, UK

8. Marketing authorisation number(s)

PL 00065/0161

9. Date of first authorisation/renewal of the authorisation

9 June 1999 / 28 August 2008 (UK)

10. Date of revision of the text

August 2009

11. Legal category

Prescription Only Medicine

Applicator figure to form an integral part of the SmPC text


RA 0450 UK S8A (Ref 8.0)


Company contact details

Merck Sharp & Dohme Limited

Company image

Hertford Road, Hoddesdon, Hertfordshire, EN11 9BU


+44 (0)1992 479 292

Stock Availability

Call MSD customer services on 01992 452094


+44 (0)1992 467 272

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Before you contact this company: often several companies will market medicines with the same active ingredient. Please check that this is the correct company before contacting them. Why?

Active ingredients


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POM - Prescription Only Medicine

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