IMPLANON

What it is

IMPLANON NXT is an etonogestrel 68 mg subcutaneous implant. Etonogestrel is the biologically active metabolite of desogestrel, a progestagen widely used in oral contraceptives. It binds with high affinity to progesterone receptors in the target organs.

Approved indications

— Contraception.

Key safety warnings

The use of combined hormonal contraceptives has been associated with venous thrombosis (deep vein thrombosis and pulmonary embolism) and arterial thrombosis (such as myocardial infarction and stroke) and associated complications, sometimes with fatal consequences. An increased risk of thromboembolic and thrombotic disease associated with their use is well-established. The frequency of venous thromboembolism in women using combined hormonal contraceptives has been estimated to be 3 to 12 cases per 10,000 women-years. Etonogestrel is associated with a higher risk of venous thromboembolism than certain second generation oral contraceptives, with studies indicating an approximate two-fold increased risk, which corresponds to an additional one to two cases of venous thromboembolism per 10,000 women-years of use. Hypersensitivity reactions of angioedema and anaphylaxis have been reported during use of etonogestrel-containing products. If angioedema and/or anaphylaxis is suspected, the product should be discontinued and appropriate treatment administered. A meta-analysis from 54 epidemiological studies reported that there is a slightly increased relative risk of having breast cancer diagnosed in women who are currently using combined oral contraceptives. The excess risk gradually disappears during the course of the 10 years after cessation of use. In rare cases, benign liver tumours, and even more rarely, malignant liver tumours have been reported in users of combined oral contraceptives. In isolated cases, these tumours have led to life-threatening intra-abdominal haemorrhages.

Contraindications

IMPLANON should not be used in the presence of venous or arterial thrombosis, history of such conditions, or known hereditary or acquired predisposition for venous or arterial thromboembolism such as Activated Protein C resistance (including Factor V Leiden), antithrombin-III deficiency, protein C deficiency, protein S deficiency, hyperhomocysteinaemia and antiphospholipid antibodies. History of migraine with focal neurological symptoms is a contraindication. Diabetes mellitus with vascular involvement is a contraindication. IMPLANON is contraindicated in the presence or history of severe hepatic disease (as long as liver function values have not returned to normal), liver tumours (benign or malignant), and known or suspected sex steroid-influenced malignancies. Undiagnosed vaginal bleeding and known or suspected pregnancy are contraindications. IMPLANON is contraindicated in patients with hypersensitivity to etonogestrel or to any of the excipients.

PBS listing

The subcutaneous implant 68 mg formulation is listed on the PBS with one item. The listing is unrestricted. The ex-manufacturer price is A$144.67.

Regulatory history

IMPLANON NXT was first registered on the ARTG on 11 May 2021. In November 2017, the PBAC recommended an amendment to the PBS listing to allow the etonogestrel implant to be used for contraception.