Jump to content

Etonogestrel birth control implant

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 194.83.236.250 (talk) at 14:13, 13 March 2012. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Implanon
Implanon
Background
TypeHormonal
Progestin-ony implant
First use1998 (Indonesia)
Failure rates (first year)
Perfect use0.05%
Typical use0.05%
Usage
Duration effect3 years
ReversibilityYes
User remindersRequires removal after the 3 years
Advantages and disadvantages
STI protectionNo
WeightMay cause weight gain
Period disadvantagesMay cause irregular or prolonged bleeding
Period advantagesMinimizes pain. 20% of women will stop having their period.
BenefitsLong-term contraception.

Implanon, made by Organon International, is a single-rod long acting reversible hormonal contraceptive subdermal implant that is inserted just under the skin of a woman's upper arm. The 4 cm by 2 mm Implanon rod contains 68 milligrams of etonogestrel (a progestin) which is released over a three year period. Because of cases of incorrect insertion by medical personnel in the UK, Implanon will be replaced by Nexplanon , which is identical except that it is radiopaque so X-ray radiography can be used for location, and it has a pre-loaded applicator for easier insertion.[1]

Peak serum etonogestrel concentrations have been found to reach 781–894 pg/mL in the first few weeks, gradually decreasing to 192–261 pg/mL after 1 year, 154–194 pg/mL after 2 years, and 156–177 pg/mL after 3 years, maintaining ovulation suppression and contraceptive efficacy.[2] Implanon may be removed at any time, but must be removed after at most three years.

Implanon was first approved for use in Indonesia in 1998, was subsequently approved for use in over 30 other countries, and has been used by over 2.5 million women worldwide. Implanon was approved for use in the United States by the Food and Drug Administration (FDA) on July 17, 2006.

Mechanism of action

The mechanism of action of progestin only contraceptives depends on the progestin activity and dose.[3] Intermediate dose progestin-only contraceptives, like Implanon (and the progestin-only pill Cerazette) allow some follicular development but inhibit ovulation in almost all cycles as the primary mechanism of action. Ovulation was not observed in studies of Implanon in the first two years of use and only rarely in the third year with no pregnancies. A secondary mechanism of action is the progestogenic increase in cervical mucus viscosity which inhibits sperm penetration.[4] Hormonal contraceptives also have effects on the endometrium that theoretically could affect implantation, however no scientific evidence indicates that prevention of implantation actually results from their use.[5]

Insertion

Local anaesthetic is applied to the upper arm, and then a needle-like applicator is used to insert the implanon rod under the skin. The procedure can take less than a minute. An experienced clinician is required for proper insertion, to minimize the risk of nerve damage,[6] or misplacement which could result in unintended pregnancy. Implant site complications are experienced by 3.6% of patients, and include swelling, redness, hematoma and pain. [7]


Effectiveness in preventing pregnancy

In a comparison of birth control methods in terms of effectiveness in preventing pregnancy, Implanon is one of the most effective forms of birth control currently available, along with Jadelle.[8]

The failure rate for Implanon is about 0.0449%, as observed in the UK, where only 584 women have reported unwanted pregnancies, out of 1.3 million who have used Implanon since 1999.[1] Unlike other birth control methods, there is no differential for perfect use versus typical use, as no user action is required after insertion. Most cases of failure are due to incorrect insertion or insertion during pregnancy.

If a woman receives an Implant outside the first five days of her period, she should wait to have sex or use a back up method of contraception (such as a condom, female condom, diaphragm, sponge, or emergency contraception) for the following week after implantation to prevent fertilization of an egg.[9] However, if the Implant is inserted during the first five days of a woman's period, she is protected against pregnancy from that very moment.[9]

In comparison, surgical sterilization has a failure rate of 0.2%.[10] While these statistics suggest that Implanon is four times more effective in preventing pregnancy than surgical sterilization, it is important to remember that sterilization is permanent, whereas Implanon must be replaced every three years to continue to be effective. On the other hand, Implanon is completely reversible, while sterilization is permanent and cannot be reversed.

Fertility after Implanon

Within a few days of having Implanon removed the hormones released by Implanon will have left the body. The chances of becoming pregnant should be the same as they were before using Implanon (corrected for aging etc.).[citation needed]

Side effects and risks

Side effects caused by Implanon are similar to other hormonal birth control methods such as combined oral contraceptive pills, the Ring (Nuvaring), Depo-Provera, etc.

According to the manufacturer, irregular periods or prolonged bleeding, headaches, acne, weight gain and abdominal pain were among the most commonly reported side effects in clinical trials. 10% of women had Implanon removed because of irregular menstrual bleeding, which can include excessive menstrual bleeding. 20% of women may have no menstrual period at all while using Implanon. The manufacturer advises "Expect your menstrual periods to be irregular and unpredictable throughout the time you are using IMPLANON™". It is not known whether Implanon changes a woman's risk for breast cancer. As with other hormonal contraceptives, women who are older than 35 or who smoke are at higher risk of serious cardiovascular side effects.[2][11]

In a 2-year study of 330 sexually active American women, 14% discontinued Implanon because of bleeding pattern changes. Other adverse experiences included emotional lability (6.1%), weight increase (3.3%), depression (2.4%) and acne (1.5%).[12]

Implanon has also been shown to induce mild insulin resistance though the effects are not clinically relevant for healthy women.[13]

Complications

Complications which can occur include:

  • impalpability of implant
  • broken or damaged implant
  • slight migration
  • fibrosis

An implant that cannot be found through palpation may be caused by damage, migration or fibrosis, requiring an ultrasound assessment or removal.

See also

References

  1. ^ a b Ormsby, Avril (5 Jan 2011). "Contraceptive alert after women fall pregnant". Reuters. Archived from the original on 10 May 2011. Retrieved 10 May 2011.
  2. ^ a b "Implanon label" (PDF). FDA. 2010-10-26. Retrieved 2010-10-26.
  3. ^ Glasier, Anna (2006). "Contraception". In DeGroot, Leslie J.; Jameson, J. Larry (eds.) (ed.). Endocrinology (5th ed.). Philadelphia: Elsevier Saunders. pp. 3000–1. ISBN 0-7216-0376-9. {{cite book}}: |editor= has generic name (help)CS1 maint: multiple names: editors list (link)
  4. ^ Organon (2006). "Implanon SPC (Summary of Product Characteristics)". Retrieved 2007-04-15. {{cite web}}: Unknown parameter |month= ignored (help)
  5. ^ Rivera R, Yacobson I, Grimes D (1999). "The mechanism of action of hormonal contraceptives and intrauterine contraceptive devices". Am J Obstet Gynecol. 181 (5 Pt 1): 1263–9. doi:10.1016/S0002-9378(99)70120-1. PMID 10561657.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ Wechselberger G, Wolfram D, Pulzl P, Soelder E, Schoeller T (2006). "Nerve injury caused by removal of an implantable hormonal contraceptive". Am J Obstet Gynecol. 195 (1): 323–6. doi:10.1016/j.ajog.2005.09.016. PMID 16813761. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  7. ^ The Mayo Clinic (2010). "Implanon (Contraceptive Implant)." Retrieved from http://www.mayoclinic.com/health/implanon/MY01007/DSECTION=what-you-can-expect
  8. ^ Raymond, Elizabeth (2008). "8". In 19 (ed.). Contraceptive Technology. Ardent Media. p. 146. ISBN 9781597080019. Retrieved 10 May 2011. Implants are the most effective of all the available contraceptive methods {{cite book}}: |editor= has numeric name (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  9. ^ a b Bedsider (2010). "Implant." Retrieved from http://bedsider.org/methods/implant#how_to_tab on March 17, 2011.
  10. ^ "Implanon effectiveness".
  11. ^ "Implanon patient information" (PDF). Organon USA Inc. 2006. Retrieved 2006-08-23. {{cite web}}: Unknown parameter |month= ignored (help)
  12. ^ Funk, Sidney (2005). "Safety and efficacy of Implanon, a single-rod implantable contraceptive containing etonogestrel". Contraception. 71 (5): 319–26. doi:10.1016/j.contraception.2004.11.007. PMID 15854630. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  13. ^ Biswas A, Viegas OA, Coeling Bennink HJ, Korver T, Ratnam SS (2001). "Implanon contraceptive implants: effects on carbohydrate metabolism". Contraception. 63 (3): 137–41. doi:10.1016/S0010-7824(01)00182-2. PMID 11368985. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
Retrieved from "https://en.wikipedia.org/w/index.php?title=Etonogestrel_birth_control_implant&oldid=481683896"