progestogen only implant (contraceptive)

Last edited 03/2021 and last reviewed 03/2021

Nexplanon is a highly effective, long-acting contraceptive implant containing etonogestrel, a synthetic progestogen (1,2,3,4,5)

• Nexplanon acts by preventing ovulation and is usually effective for 3 years. Safety and efficacy have been established in women between 18 and 40 years of age. For maximum effectiveness and safety, Nexplanon needs to be correctly implanted by someone who is trained to fit it.

There have been reports of neurovascular injury and migration of the contraceptive implant from the insertion site and in rare cases into the pulmonary artery. Some cases have reported haematoma and excessive bruising at the insertion site and dyspnoea (5):

General points re: long-acting contraceptive progestogen implant include:

• single etonogestrel capsule (a progestogen in a slow - release carrier)
  • in 2010 (Europe) and 2011 (US), the original implant, Implanon (Merck),was replaced by the second-generation Nexplanon, in some countries named Implanon NXT
    • these devices contain the same dose of etonogestrel but come with an improved pre-loaded inserter, which makes correct subdermal placement easy (1)
    • correct placement is essential for easy removal
      • core contains barium sulphate detectable by x-ray - this allows an additional option to check for correct positioning if palpation fails
        
        
• contraceptive effect via inhibition of ovulation, supplemented by effects on mucus and endometrium
  
  
• while the etonogestrel levels reduce to their low constant levels for the following 2.5 years, menstrual irregularities are likely (varying from amenorrhoea to frequent vaginal bleeding); in more than 50% of women amenorrhoea or an acceptable pattern of menstrual loss is achieved
  
  
• side effects that occur during the first 6 months provide no indication of the woman's possible response to use of the Implanon in the subsequent 2.5 years
  
  
• NICE state that the failure rate for this method of contraception is fewer than 0.1 in 100 over 3 years (2)


• the implant is an anovulant - special indications may include intractable Mittelschmerz and history of ectopic pregnancy (4)
  
  
• after removal of the implant serum levels of etonogestrel have been shown to be undetectable within one week. Further data has revealed that over 90% of women were ovulating normally within 3 weeks following removal of the implant
(4)

Dose and frequency of administration (6):

• Insert once every three years. 
• Insert between day 1-5 of the menstrual cycle with no need for additional precautions
• The implant may be inserted or reinserted at any time as quick start if it is reasonably certain that the individual is not pregnant. Additional contraception is then required for 7 days after insertion
• If the individual has an implant in situ which has been in place for over 3 but less than 4 years the implant can be removed and replaced.  A pregnancy test should be performed and if negative replace the implant and advise additional contraception is then required for 7 days after insertion with a repeat pregnancy test after 3 weeks.
• If inserting the implant after levonorgestrel emergency contraception, a barrier contraception is required for 7 days.
• After the use of ulipristal acetate emergency contraception the implant should not be inserted for five days. A barrier contraceptive should then be used for a further 7 days.
• A pregnancy test is advised three weeks after any oral emergency contraception - see FSRH guidance

Notes:

• if there is prolonged bleeding during the first 6 months after insertion of the progestogen implant then this can be treated with either one or two packets of combined oral contraceptive pill, progesterone alone, oestrogen alone, or tranexamic acid (1)
• extrapolation to the possible effects of Implanon cannot be made with respect to previous use of progestogen - only pills and injectables
• up to 43% of women stop using Implanon within 3 years; 33% because of irregular bleeding, and less than 10% for other reasons including hormonal (non bleeding) problems (2)
• acne may occur secondary to implanon use
• there is no evidence of effect on weight, mood, libido, headaches or bone mineral density (2)
• treat irregular bleeding with mefenamic acid, ethinylestradiol or mifepristone (2)
• remove the implant if a woman becomes pregnant and continues with the pregnancy, although there is no evidence of a teratogenic effect (2)
• vaginal bleeding patterns are likely to change while using an etonogestrel implant. Vaginal bleeding may stop, become more or less frequent, or be prolonged during implant use (3)
• dysmenorrhoea may reduce during etonogestrel implant use (3)
• no evidence showing a delay in return to fertility after an etonogestrel implant is removed (3)
• complications with etonogestrel implant insertion and removal are uncommon. (Possible complications are listed in the summary of product characteristics.) (3)

The respective Summary of Product Characteristics (SPC) must be consulted before prescribing this drug.

Reference:

1. Mansour D, Mommers E, Teede H, Sollie-Eriksen B, Graesslin O, Ahrendt H, Gemzell-Danielsson K: Clinician satisfaction and insertion characteristics of a new applicator to insert radiopaque Implanon: an open-label, noncontrolled, multicenter trial. Contraception 2010, 82:243-9.
2. NICE (October 2005). Long-acting reversible contraception
3. NICE (September 2014). Long-acting reversible contraception (update)
4. Prescriber 2001; 12 (5): 83-95.
5. MHRA (February 18th 2020). Drug Safety Update - Nexplanon (etonogestrel) contraceptive implants: new insertion site to reduce rare risk of neurovascular injury and implant migration
6. Patient Group Direction (PGD) (NHS Specialist Pharmacy Service). Insertion of etonogestrel (e.g. Nexplanon®) 68mg subdermal implant for contraception . (Accessed 17th March 2021)