Pha 2022 Tute 4

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Implanon Nxt (subdermal implant)

SUSMP Classification

S4

TGA approved indications

Contraception

PBS listed?

Yes – Medical practitioners, midwives and nurse practitioners can prescribe

Mechanism of action (provide a brief summary of the mechanism of action)

Progesterones thicken cervical mucus. This inhibits the passage of sperm and changes endometrium, which reduces the chances of implantation. They also act on the hypothalamus and supress the pituitary LH surge and may also inhibit ovulation.

Major adverse effects (either serious or common)

Menstrual irregularity, prolonged bleeding, spotting, amenorrhea, breast tenderness, depression and acne

Contraindications & why (if any)

There are many contraindications including known or suspected carcinoma of the breasts. This is because it was found that the use of progesterone-only contraceptives slightly increased the risk of breast cancer

Potential drug interactions & why (if any)

No specific studies have been performed with etonogestrel however other hormonal contraceptives have been found to interact with products that induce microsomal enzymes which leads to the contraceptive having a reduced effect. This is due to the interaction causing increased clearance of sex hormones.

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COMPARISON

Etonogestrel and Levonorgestrel are both Progesterone only contraceptive that inhibits ovulation. Both these drugs belong to the Progestin class of drugs. The implant is administrated by using subcutaneous approach and Etonogestrel itself is released in the blood stream in minute amounts over 3 years. On the other hand, Levonorgestrel is administered orally via tablets.

Both these drugs have similar mode of action where the two drugs act on the hypothalamus to reduce the amount of Luteinizing hormone (LH), which in turn inhibits ovulation. These drugs also thicken cervical mucus which can reduce the sperm follow through the endometrium.

When comparing costs of these two drugs, Levonorgestrel is a cheaper option as it costs significantly less than Etonogestrel. However, both these drugs are readily available but a Medical Practitioner has the authorize the purchase.