ENOVA IUD

Indications

• Contraception in females of childbearing potential
• Long-term reversible contraception

Dosage

Children: Refer to the BNF for Children for guidance on contraceptive use in adolescents.

Adults: One subdermal implant (etonogestrel 68 mg) is inserted during the first five days of the menstrual cycle and can remain in place for up to three years.

Mechanism of action

Etonogestrel binds with high affinity to progesterone receptors in target organs such as the female reproductive tract, mammary gland, hypothalamus, and pituitary. This binding leads to changes in protein synthesis that result in decreased levels of gonadotropin-releasing hormone and luteinizing hormone, thereby inhibiting ovulation.

Pharmacodynamics

Etonogestrel inhibits fertility by impairing the release of luteinizing hormone, which is crucial for ovulation. It also increases the viscosity of cervical mucus, which hinders sperm passage, and alters the uterine lining to prevent implantation of fertilized eggs. Clinical trials have shown a failure rate of 0.1% over three years of use, with a rapid return to fertility upon removal of the implant.

Pharmacokinetics

After subdermal implantation, etonogestrel is released at a rate of 40 mcg daily, providing continuous contraception for up to three years. The pharmacokinetics involve high binding affinity to plasma proteins, and it is metabolized primarily in the liver. The mean elimination half-life is approximately 24 hours, and it reaches steady-state concentrations within a few days of implantation.

Contra-indications

• Acute porphyrias
• Current breast cancer

Adverse effects

• Headache
• Nausea
• Breast tenderness
• Irregular menstrual bleeding
• Mood changes

Interactions

• Etonogestrel + ulipristal may decrease efficacy
• Antiepileptics (e.g., carbamazepine, phenytoin) may decrease efficacy
• Modafinil may decrease efficacy
• Rifamycins may decrease efficacy
• St. John's Wort may decrease efficacy
• Ritonavir may decrease efficacy

Precautions

• Cardiac dysfunction
• Cervical cancer
• Diabetes
• History of stroke (including transient ischemic attack)
• Migraines with aura
• Multiple risk factors for cardiovascular disease

Pregnancy

Etonogestrel is contraindicated in pregnancy. It is a progestogen used for contraception.

Breast-feeding

Etonogestrel can be used during breastfeeding, typically advised after 6 weeks postpartum.

Storage

Store below 25°C. Protect from light and moisture.

Formulations

• Etonogestrel 68 mg subdermal implant

Indications

• Contraception
• Emergency contraception
• Menorrhagia management

Dosage

Children: For females of childbearing potential, the dosage for emergency contraception is the same as for adults, 1.5 mg as a single dose. For long-term contraception, consult the BNF

Adults: For emergency contraception, a single dose of 1.5 mg should be taken as soon as possible after unprotected intercourse, preferably within 12 hours but no later than 72 hours. For contraception, the recommended dose may vary based on the specific formulation and patient needs, refer to the BNF for specific guidelines.

Mechanism of action

Levonorgestrel suppresses gonadotropins, inhibiting ovulation by binding to progesterone and androgen receptors, and slowing the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. This leads to the suppression of the luteinizing hormone (LH) surge necessary for ovulation. Additionally, it increases the thickness of cervical mucus, hindering sperm movement and survival, and induces changes in the endometrium that prevent implantation of a fertilized egg.

Pharmacodynamics

Levonorgestrel effectively prevents pregnancy through multiple mechanisms: by interfering with ovulation, fertilization, and implantation. The emergency contraceptive tablet is approximately 89% effective when taken within 72 hours after unprotected intercourse, while IUDs releasing levonorgestrel demonstrate over 99% effectiveness. It also serves a therapeutic role in preventing endometrial carcinoma associated with unopposed estrogen therapy.

Pharmacokinetics

Levonorgestrel is rapidly absorbed after oral administration, with peak plasma concentrations typically achieved within 1 to 2 hours. It has a half-life of approximately 24 hours and is metabolized in the liver. The drug is primarily excreted via urine and feces, and its pharmacokinetic profile can be affected by certain enzyme-inducing medications.

Contra-indications

• Pregnancy
• Severe liver disease
• Known or suspected hormone-sensitive malignancies
• Undiagnosed vaginal bleeding

Adverse effects

• Nausea
• Vomiting
• Fatigue
• Headache
• Dizziness
• Breast tenderness
• Mood changes
• Abdominal pain
• Changes in menstrual bleeding

Interactions

• Antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin, oxcarbazepine, perampanel, phenobarbital, phenytoin, primidone, rufinamide, topiramate) may decrease efficacy
• Bosentan may decrease efficacy
• Ritonavir may decrease efficacy
• Lamotrigine may decrease effects
• Modafinil may decrease efficacy
• St. John's Wort may decrease efficacy
• Rifamycins may decrease efficacy
• Ulipristal may decrease efficacy

Precautions

• Monitor for ectopic pregnancy in women with a history of ectopic pregnancy or pelvic inflammatory disease
• Consider alternative contraceptive methods in cases of severe obesity
• Use caution in women with a history of thromboembolic disorders
• Regular follow-up is necessary to monitor for side effects and efficacy

Pregnancy

Levonorgestrel is contraindicated in pregnancy. It is not effective once implantation has occurred.

Breast-feeding

Levonorgestrel is excreted in breast milk, but it is considered safe for use during breastfeeding. However, it is advisable to take the medication just after breastfeeding to minimize exposure to the infant.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Levonorgestrel 1.5 mg oral tablet for emergency contraception
• Levonorgestrel intrauterine device (IUD) releasing 20 micrograms per day

Mechanism of action

Etonogestrel binds with high affinity to the progesterone receptors in the target organs. From the target organs, they include the female reproductive tract, mammary gland, hypothalamus, and pituitary. Once bound, this drug changes the synthesis of different proteins which in order decreases the level of gonadotropin-releasing hormone and the luteinizing hormone. There is no evidence that etonogestrel has affinity for estrogen receptors.

Pharmacodynamics

Etonogestrel attains its therapeutic effect inhibiting fertility by impairing the release of the luteinizing hormone which is one of the most important reproductive hormones for ovulation. As well, etonogestrel is known to increase the viscosity of the cervical mucus hindering the passage of the spermatozoa and altering the lining in the uterus to prevent the implantation of the fertilized eggs in the endometrium. In clinical trials, etonogestrel was implanted and reported to avoid 100% of pregnancies over a three year period. When the implant was removed, normal periods were reinstalled within 90 days in 91% of the individuals. Fertility was established quickly with 20 reported pregnancies within 3 months of implant removal. The implants of etonogestrel release 40 mcg of etonogestrel daily and they usually provide a continuous contraception effect for 3 years. When the implant is administered, the failure rate is reported to be 0.1%. Some non-contraceptive effects are improved dysmenorrhea. All data of etonogestrel comes from patients between 80-130% of the body mass.

Mechanism of action

**Mechanism of action on ovulation** Oral contraceptives containing levonorgestrel suppress gonadotropins, inhibiting ovulation. Specifically, levonorgestrel binds to progesterone and androgen receptors and slows the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. This process results in the suppression of the normal physiological luteinizing hormone (LH) surge that precedes ovulation. It inhibits the rupture of follicles and viable egg release from the ovaries. Levonorgestrel has been proven to be more effective when administered before ovulation. **Mechanism of action in cervical mucus changes** Similar to other levonorgestrel-containing contraceptives, the intrauterine (IUD) forms of levonorgestrel likely prevent pregnancy by increasing the thickness of cervical mucus, interfering with the movement and survival of sperm, and inducing changes in the endometrium, where a fertilized ovum is usually implanted. Levonorgestrel is reported to alter the consistency of mucus in the cervix, which interferes with sperm migration into the uterus for fertilization. Levonorgestrel is not effective after implantation has occurred. Interestingly, recent evidence has refuted the commonly believed notion that levonorgestrel changes the consistency of cervical mucus when it is taken over a short-term period, as in emergency contraception. Over a long-term period, however, levonorgestrel has been proven to thicken cervical mucus. The exact mechanism of action of levonorgestrel is not completely understood and remains a topic of controversy and ongoing investigation. *Effects on implantation** The effects of levonorgestrel on endometrial receptivity are unclear, and the relevance of this mechanism to the therapeutic efficacy of levonorgestrel is contentious. Prescribing information for levonorgestrel IUDs state that they exert local morphological changes to the endometrium (e.g. stromal pseudodecidualization, glandular atrophy) that may play a role in their contraceptive activity. **Mechanism of action in hormone therapy** When combined with estrogens for the treatment of menopausal symptoms and prevention of osteoporosis, levonorgestrel serves to lower the carcinogenic risk of unopposed estrogen therapy via the inhibition of endometrial proliferation. Unregulated endometrial proliferation sometimes leads to endometrial cancer after estrogen use. Norgestrel (and more specifically the active stereoisomer levonorgestrel) binds to the progesterone and estrogen receptors within the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like levonorgestrel will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge. Loss of the LH surge inhibits ovulation and thereby prevents pregnancy. Combination oral contraceptives act by suppression of gonadotrophins. Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cer-vical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which may reduce the likelihood of implantation). Progestins enter target cells by passive diffusion and bind to cytosolic (soluble) receptors that are loosely bound in the nucleus. The steroid receptor complex initiates transcription, resulting in an increase in protein synthesis. /Progestins/ Progestins are capable of affecting serum concentrations of other hormones, particularly estrogen. Estrogenic effects are modified by the progestins, either by reducing the availability or stability of the hormone receptor complex or by turning off specific hormone-responsive genes by direct interaction with the progestin receptor in the nucleus. In addition, estrogen priming is necessary to increase progestin effects by upregulating the number of progestin receptors and/or increasing progesterone product

Pharmacodynamics

Levonorgestrel prevents pregnancy by interfering with ovulation, fertilization, and implantation. The levonorgestrel-only containing emergency contraceptive tablet is 89% effective if it is used according to prescribing information within 72 hours after intercourse. The intrauterine and implantable devices releasing levonorgestrel are more than 99% in preventing pregnancy. Levonorgestrel utilized as a component of hormonal therapy helps to prevent endometrial carcinoma associated with unopposed estrogen administration.