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Indications and Dosage
Subdermal
Contraception Adult: As implant containing 68 mg etonogestrel: Insert 1 implant in the inner side of the upper non-dominant arm between day 1 and day 5 of the menstrual cycle for women with no preceding hormonal contraceptive use in the past month. Remove the implant not later than 3 years after the date of insertion. Refer to detailed product guideline for further instructions on the timing of insertion according to the patient’s recent contraceptive history.
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Hepatic Impairment
Contraindicated.
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Contraindications
Known, suspected or history of breast or progestin-sensitive cancers; current or history of thrombosis or thromboembolic disorders; undiagnosed abnormal vaginal bleeding. Hepatic impairment, active or history of hepatic tumour (benign or malignant), active hepatic disease. Pregnancy.
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Special Precautions
Patient with hypertension, diabetes or prediabetes, hypercholesterolaemia, hyperlipidaemia; diseases which aggravates fluid retention; gallbladder disease; history of depressed mood or chloasma gravidarum. Smokers and overweight patients. May consider removal of implant during prolonged immobilisation due to illness or surgery. Renal impairment. Lactation.
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Adverse Reactions
Significant: Ovarian cyst, increased risk of breast or cervical cancer; retinal vein thrombosis, thromboembolism (e.g. DVT), other vascular events (e.g. MI, stroke); changes in menstrual bleeding patterns, weight gain, increased risk of gall bladder disease, increased LDL concentration, sustained hypertension, fluid retention; depressed mood, depression; chloasma. Rarely, ectopic pregnancy, hepatic adenomas.
Gastrointestinal disorders: Abdominal pain, nausea, flatulence. General disorders and administration site conditions: Implant site pain and reactions, fatigue, pain, influenza-like illness. Immune system disorders: Hypersensitivity reactions. Investigations: Weight decreased. Metabolism and nutrition disorders: Increased appetite. Musculoskeletal and connective tissue disorders: Back pain. Nervous system disorders: Headache, dizziness. Psychiatric disorders: Nervousness, affect lability. Reproductive system and breast disorders: Vaginal infection, vaginitis, breast tenderness, breast pain, decreased libido, dysmenorrhoea, leucorrhoea, amenorrhoea. Respiratory, thoracic and mediastinal disorders: Pharyngitis. Skin and subcutaneous tissue disorders: Acne, alopecia. Vascular disorders: Hot flushes. Potentially Fatal: Pulmonary embolism. |
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Monitoring Parameters
Rule out pregnancy prior to implant insertion. Monitor blood pressure at baseline then yearly; weight at baseline and during therapy; signs and symptoms of thromboembolic disorders, visual changes, and depression. Perform diagnostic measures to rule out malignancy in all cases of undiagnosed abnormal vaginal bleeding. Instruct the patient to regularly palpate the implant.
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Drug Interactions
May decrease plasma concentration and efficacy with efavirenz, phenytoin, barbiturates, rifampicin, carbamazepine, nelfinavir, ritonavir, boceprevir, telaprevir, nevirapine, griseofulvin. May increase the plasma concentration with moderate to strong CYP3A4 inhibitors (e.g. fluconazole, diltiazem, erythromycin, itraconazole, clarithromycin), indinavir and atazanavir/ritonavir, etravirine. Plasma and tissue levels of ciclosporin may be increased, while lamotrigine may be decreased.
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Food Interaction
May decrease plasma concentration and efficacy with St. John’s wort. May increase the plasma concentration with grapefruit juice.
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Lab Interference
May interfere with the results of coagulation factor test, lipid test, glucose tolerance test, and binding protein test.
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Action
Description:
Mechanism of Action: Etonogestrel, an active metabolite of desogestrel, prevents pregnancy by inhibiting ovulation. It also increases the viscosity of cervical mucous which prevents the passage of sperms. Onset: Inhibition of ovulation: Within 1 day. Duration: Inhibition of ovulation: 3 years. Pharmacokinetics: Absorption: Rapidly absorbed into the circulation. Bioavailability: Approx 100%. Time to peak plasma concentration: Within 1-13 days. Distribution: Enters breast milk. Volume of distribution: Approx 201 L. Plasma protein binding: 66% to albumin; approx 32% to sex hormone-binding globulin. Metabolism: Metabolised in the liver by CYP3A4 isoenzyme via hydroxylation and reduction to sulfate and glucuronide conjugates. Excretion: Via urine and faeces (as unchanged drug and metabolites). Elimination half-life: Approx 25-30 hours. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 6917715, Etonogestrel. https://pubchem.ncbi.nlm.nih.gov/compound/Etonogestrel. Accessed Nov. 24, 2020. |
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Storage
Store between 15-30°C.
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MIMS Class
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ATC Classification
G03AC08 - etonogestrel ; Belongs to the class of progestogens. Used as systemic contraceptives.
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References
Anon. Etonogestrel. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/08/2020. Buckingham R (ed). Etonogestrel. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/08/2020. Implanon NXT 68 mg Implant for Subdermal Use (Merck Sharp & Dohme [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my/. Accessed 04/08/2020. Joint Formulary Committee. Etonogestrel. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/08/2020. Nexplanon 68 mg Implant for Subdermal Use (Merck Sharp & Dohme Limited). MHRA. https://products.mhra.gov.uk/. Accessed 04/08/2020. Nexplanon Implant (Organon USA Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 16/11/2020.
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