Dosing and uses of Etonogestrel (Implanon, Nexplanon)
Adult dosage forms and strengths
implant
- 68mg
Contraception
Insert 1 implant subdermally
No preceding hormonal contraceptive use in past month: Insert between Days 1 through 5
Switch from combination other contraceptive
- OCP: Within 7 days after last active pill
- Vaginal ring: During 7-day ring-free period etonogestrel/ethinylestradiol
- Transdermal patch: During 7-day patch-free period of a transdermal contraceptive system
Switch from progestin-only contraceptive
- Any day of the month when switching from pill; do not skip any days between last pill and insertion
- On the same day as contraceptive implant removal
- On the same day as removal of a progestin-containing IUD
- On the day when next contraceptive injection would be due
Administration
For detailed info regarding use following delivery/abortion/miscarriage, see manufacturer's package insert
May be used for up to 3 years and then requires replacement
Insertion procedure and technique differs between brands
Nexplanon: Radiopaque; may use X-ray, CT, ultrasound, or MRI to locate once implanted
Implanon: Nonradiopaque; may use ultrasound or MRI to locate once implanted
Confirm that the entire implant, which is 4 cm long, has been removed by measuring its length
When an implant is broken or bent, in situ, the release rate of etonogestrel may be slightly increased; important to remove in its entirety
Pediatric dosage forms and strengths
Not recommended
Etonogestrel (Implanon, Nexplanon) adverse (side) effects
>10%
Oligomenorrhea (34%)
Headache (25%)
Vaginitis (24.5%)
Amenorrhea (22%)
Menorrhagia (18%)
Weight gain (14%)
Acne (13.5%)
Breast pain (13%)
Upper resp tract infection (13%)
Pharyngitis (11%)
Leucorrhea (10.5%)
1-10%
Back pain (7%)
Depression (6%)
Dizziness (7%)
Dysmenorrhea (7%)
Emotional lability (7%)
Flu-like symptoms (8%)
Insertion-site pain (9%)
Nausea (6%)
Nervousness (6%)
Pain (6%)
Postmarketing Reports
Gastrointestinal disorders: Constipation, diarrhea, flatulence, vomiting
General disorders and administration site conditions: Edema, fatigue, implant site reaction, pyrexia
Immune system disorders: Anaphylactic reactions
Infections and infestations: rhinitis, urinary tract infection
Investigations: Clinically relevant rise in blood pressure, weight decreased
Metabolism and nutrition disorders: Increased appetite
Musculoskeletal and connective tissue disorders: Arthralgia, musculoskeletal pain, myalgia
Nervous system disorders: Convulsions, migraine, somnolence
Pregnancy, puerperium and perinatal conditions: Ectopic pregnancy
Psychiatric disorders: Anxiety, insomnia, libido decreased
Renal and urinary disorders: Dysuria
Reproductive system and breast disorders: Breast discharge, breast enlargement, ovarian cyst, pruritus genital, vulvovaginal discomfort
Skin and subcutaneous tissue disorders: Angioedema, aggravation of angioedema and/or aggravation of hereditary angioedema, alopecia, chloasma, hypertrichosis, pruritus, rash, seborrhea, urticaria
Vascular disorders: Hot flush
Warnings
Contraindications
Documented hypersensitivity
Active or history of breast cancer
Arterial thromboembolic disease (stroke, MI), thrombophlebitis, DVT/PE, thrombogenic valvular disease
Estrogen-dependent neoplasia, liver disease, liver tumors
Undiagnosed abnormal vaginal bleeding
Uncontrolled hypertension
Diabetes mellitus with vascular involvement
Jaundice with prior oral contraceptive use
Hypersensitivity to etonogestrel or component of the formulation
Current/history of thrombophlebitis, thromboembolic disorders
Missed abortion
Cautions
Caution in family history of breast cancer and or DVT/PE, current/history of depression, endometriosis, DM, HTN, bone mineral density changes, renal/hepatic impairment, bone metabolic disease, SLE; conditions exacerbated by fluid retention (eg, migraine, asthma, epilepsy).
Discontinue if the following develop jaundice, visual problems (may cause contact lens intolerance), any signs of VTE, migraine with unusual severity, severe depression, increased risk of thromboembolic complications after surgery.
May cause retinal vascular thrombosis; discontinue if loss of vision, migraine proptosis, diplopia or other visual disturbances occur
Discontinue 4 week before major surgery or prolonged immobilization
Use caution in patients on warfarin, oral anticoagulants (increase in anticoagulant dose may be warranted)
Some studies link OCP use with increased risk of breast cancer, whereas other studies have not shown a change in risk; woman's risk depends on conditions where naturally high hormone levels persist for long periods of time including early onset menstruation before age 12, late onset menopause, after age 55, first child after age 30, nulliparity
Increased risk of cervical cancer with OCP use, however HPV remains as main risk factor for this cancer; evidence suggests long-term use of OCPs, 5 or more years, may be associated with increased risk
Increased risk of liver cancer with OCP use; risk increases with longer duration of OCP use
Be alert to the possibility of an ectopic pregnancy in women receiving therapy who become pregnant or complain of lower abdominal pain
Counsel women regarding changes in bleeding frequency, intensity, or duration
Implant should be removed in the event of a thrombosis
Implant should be removed if blood pressure rises significantly and becomes uncontrolled
When implant broken or bent, may increase release rate of etonogestrel; when implant removed, remove it in its entirety
Monitor prediabetic and diabetic women receiving therapy
Complications of Insertion
- Implant removal may be difficult or impossible if implant not inserted correctly, inserted too deeply, not palpable, encased in fibrous tissue, or has migrated
- Exploratory surgery without knowledge of exact location of implant is strongly discouraged
- Migration of implant within arm from insertion site, which may be related to deep insertion, reported; in cases where implant has migrated to pulmonary artery, endovascular or surgical procedures may be needed for removal
- If at any time implant cannot be palpated, it should be localized; removal is recommended
Pregnancy and lactation
Pregnancy category: X (pregnancy must be excluded before insertion)
Lactation: Small amounts excreted in breast milk; may nurse after the 4th postpartum week
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Etonogestrel (Implanon, Nexplanon)
Mechanism of action
Progestin; inhibits secretion of gonadotropins from pituitary gland; prevents follicular maturation and ovulation, increases viscosity of cervical mucous, and stimulates growth of mammary tissues
Absorption
Bioavailability: 100%
Release Rate
- Week 5-6: 60-70 mcg/day
- After 1 yr: 35-45 mcg/day
- After 2 yr: 30-40 mcg/day
- After 3 yr: 25-30 mcg/day
Distribution
Protein Bound: 98% (32% SHBG; 66% albumin)
Vd: 201 L
Metabolism
Hepatic CYP3A4
Elimination
Half-Life: 25 hr
Excretion: Urine (primarily), feces
