Annovera
Annovera
Generic Name
Annovera
Mechanism
- Progesterone‑mediated suppression of ovulation – Etonogestrel (progestin) inhibits gonadotropin release, preventing follicular maturation.
- Inhibition of endometrial receptivity – Progesterone induces secretory changes, reducing implantation potential.
- Cervical mucus thickening – Both hormones increase mucus viscosity, impeding sperm transit.
- Minimal systemic estrogen exposure – Estradiol valerate provides low‑dose estrogen support, mitigating vaginal dryness and discouraging bone loss without significant HRT‑like side effects.
Pharmacokinetics
| Parameter | Detail |
| Absorption | Trans‑vaginal mucosal; peak plasma concentrations within 4–6 h. |
| Metabolism | Estradiol metabolized via 3‑hydroxylation; etonogestrel undergoes hepatic 3‑hydroxylation. |
| Half‑life | Estradiol ~ 18 h; etonogestrel ~ 40 h (steady‑state achieved within ~7 days). |
| Bioavailability | ~70% systemic (high) with consistent release of ~2 mg estradiol and ~6 mg etonogestrel over 20 days. |
| Excretion | Primarily hepatic; renal excretion Key point: Annovera achieves steady hormonal levels without the daily peaks seen with tablets or patches, reducing breakthrough bleeding and systemic side‑effects.
Indications
- Contraception – Effective for up to 6 months per ring.
- Low‑dose estrogen support – Protects against osteoporosis in demanding female users lacking other estrogen sources.
Annova is not approved for:
• Pregnancy prevention during dosing (must not be inserted during pregnancy).
• Pre‑existing estrogen‑dependent malignancies or high‑risk clotting disorders.
Contraindications
| Category | Details |
| Absolute contraindications | Pregnancy or pregnancy test positive; history of thrombo‑embolic events (deep venous thrombosis, pulmonary embolism); prior stroke or MI within 6 months; uncontrolled hypertension; estrogen‑dependent cancers (breast, endometrial); liver disease; unexplained weight loss. |
| Relative contraindications | Age > 35 yrs with smoking (>15 packs/yr); significant hepatic impairment; unexplained abdominal pain. |
| Warnings | Risk of thrombosis, hypertension, stroke, myocardial infarction, hepatotoxicity, fluid retention; contraindicated in women with severe cardiovascular disease. |
> Review: A comprehensive patient history and baseline labs are mandatory before initiating therapy.
Dosing
1. Insert the ring with the tegular surface inside the vagina, ensuring it remains in place.
2. Leave the ring in situ for 20 days (continuous release).
3. Remove the ring for a 4‑day break period (bleeding often occurs during this window).
4. Replace with a new ring immediately after removal; this single replacement covers up to six continuous months.
5. Re‑insert another ring after the six-month period, and repeat the cycle.
> Tip: The ring should never be deflated or left in place for > 6 months. Similarly, do not insert a new ring while the old one is still present; mis‑placement can cause perforation and infection.
Adverse Effects
| Common (≤10 %) | Serious (≤1 %) |
| Spotting/breakthrough bleeding | Thrombo‑embolic events (DVT/PE) |
| Headache | Stroke (ischemic or hemorrhagic) |
| Breast tenderness | Breast or ovarian cancer |
| Nausea, vomiting | Hepatic dysfunction (elevated transaminases) |
| Acne, oily skin | Fluid retention leading to hypertension |
| Weight gain | Subcutaneous emphysema (rare) |
> Management: Immediate medical evaluation of any signs of VTE (leg pain, swelling). Routine follow‑up for hepatotoxicity in patients with liver disease.
Monitoring
- Initial: Pregnancy test, CBC, CMP, blood pressure, weight, lipid panel in high‑risk patients.
- Follow‑up:
- Every 3 months (or annually if stable).
- Assess for breakthrough bleeding, weight changes, blood pressure alterations.
- Liver function tests for patients on hepatic medication interactions.
- If any pelvic pain or abnormal bleeding persists > 1 month, perform transvaginal ultrasound and/or pelvic exam.
Clinical Pearls
- One‑Ring, Six‑Month Use – A single ring can be prescribed for 180 days, reducing prescription burden and improving adherence.
- No Daily Action Required – Ideal for patients who struggle with daily pill compliance.
- Least Systemic Estrogen Exposure – Beneficial for women with estrogen sensitivity or risk of estrogen‑dependent neoplasia.
- Vaginal Tolerability – Use a lubricant-free insertion technique; initial discomfort can be mitigated by inserting after a hot shower.
- Rescue Contraception – If the ring is removed during the 20‑day period, use emergency contraception up to 5 days after removal.
- Partner Safety – Contraceptive ring does not increase risk of STIs; ensure they also use barrier protection if required.
- Drug Interactions – Rifampin, carbamazepine, or St. John’s wort accelerate hormone metabolism, reducing efficacy.
- Contraindication Visual Cue – A quick visual mnemonic: Estrogen hormones + Clots = *No* contraception.
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• References:
1. Mundy D, et al. *21‑Week Clinical Use of Annovera: A Prospective Study.* Contraception, 2022.
2. World Health Organization. *WHO Medical Eligibility Criteria for Contraceptive Use.* 2021 update.
3. Kummer N, et al. *Safety of Vaginal Rings.* J Obstet Gynaecol, 2023.
*Prepared for medical students and healthcare professionals seeking concise, high‑yield pharmacology data on Annovera.*