Usage
Desogestrel is primarily prescribed for oral contraception (birth control). It belongs to the progestogen class of medications, specifically a synthetic progestin. Desogestrel works by thickening cervical mucus, thinning the uterine lining (endometrium), and suppressing ovulation (release of an egg from the ovary) – all of which make pregnancy less likely. While it can be used alone, it is also commonly combined with ethinyl estradiol in combined oral contraceptives.
Alternate Names
Desogestrel is the generic name. Brand names include Cerazette, Lovima, and others. When combined with ethinyl estradiol, brand names vary widely (e.g., Apri, Desogen, Ortho-Cept, Mircette).
How It Works
Pharmacodynamics: Desogestrel is a prodrug, meaning it is inactive until converted into etonogestrel in the body. Etonogestrel is a potent progesterone receptor agonist. By binding to and activating progesterone receptors, it exerts its contraceptive effects primarily by:
- Thickening cervical mucus: This hinders sperm penetration and movement.
- Thinning the endometrium: This makes implantation of a fertilized egg less likely.
- Suppression of ovulation: At higher doses, desogestrel can inhibit the mid-cycle surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), preventing the release of an egg. The ovulation-inhibiting dose is around 60 µg/day.
Pharmacokinetics:
- Absorption: Desogestrel is rapidly and completely absorbed after oral administration.
- Metabolism: Primarily metabolized in the liver to etonogestrel, its active form. Some further metabolism via hydroxylation and conjugation occurs.
- Elimination: Excreted primarily in urine and feces, both as metabolites and unchanged drug.
Mode of action (cellular/molecular): Etonogestrel binds to progesterone receptors in target tissues, including the cervix, uterus, and hypothalamus/pituitary gland. This binding modulates gene expression, leading to the observed effects.
Receptor binding: Progesterone receptor agonist.
Enzyme involvement: Metabolized by CYP3A4 and CYP2X4.
Elimination pathways: Renal and hepatic excretion.
Dosage
Standard Dosage
Adults:
- Progestogen-only pill (Desogestrel alone): 75 mcg once daily, taken at approximately the same time each day, continuously, without regard to menstruation.
Children:
Not typically prescribed for contraceptive use before menarche. Postpubertal adolescents may use the same adult dose for combined oral contraceptives containing desogestrel and ethinyl estradiol.
Special Cases:
- Elderly Patients: Use with caution due to increased risk of thromboembolic events. Alternative methods may be preferred.
- Patients with Renal Impairment: No specific dosage adjustments are necessary for progestogen-only pills.
- Patients with Hepatic Dysfunction: Contraindicated in patients with severe liver disease. Use cautiously in mild to moderate hepatic impairment.
- Patients with Comorbid Conditions: Consult product-specific information as some comorbidities may influence choice of contraceptive method.
Clinical Use Cases
Desogestrel is not indicated for use in situations like intubation, surgical procedures, mechanical ventilation, or ICU use. It solely serves as a contraceptive. It is also not used for emergency contraception.
Dosage Adjustments
Dose modification may be necessary in cases of interacting medications. Some medications, such as enzyme inducers (e.g., rifampicin, certain anticonvulsants), can decrease the effectiveness of desogestrel. Alternative or additional contraception may be required.
Side Effects
Common Side Effects:
Menstrual irregularities (e.g., spotting, breakthrough bleeding, amenorrhea), headache, nausea, breast tenderness, mood changes, acne, weight changes.
Rare but Serious Side Effects:
Venous thromboembolism (VTE), arterial thromboembolism, hepatic adenomas, hypersensitivity reactions.
Long-Term Effects:
No significant long-term effects associated with desogestrel have been definitively established, but the possibility of long-term effects on bone mineral density warrants further investigation.
Adverse Drug Reactions (ADR):
Allergic reactions, jaundice, depression, significant changes in blood pressure or lipid levels.
Contraindications
Absolute contraindications include current or past breast cancer, severe liver disease, active thromboembolic disorders, unexplained vaginal bleeding, and hypersensitivity to desogestrel or any component of the formulation.
Drug Interactions
Enzyme-inducing drugs like rifampicin, rifabutin, some anticonvulsants (e.g., carbamazepine, phenytoin), and certain HIV medications can reduce the effectiveness of desogestrel. St. John’s Wort may also decrease effectiveness. Consult drug databases for a comprehensive list of interactions.
Pregnancy and Breastfeeding
Pregnancy: Contraindicated. Desogestrel should be discontinued if pregnancy occurs. FDA Pregnancy Category X.
Breastfeeding: Progestogen-only pills containing desogestrel are generally considered safe during breastfeeding. Small amounts of etonogestrel are excreted in breast milk, but no significant effects on the infant have been observed.
Drug Profile Summary
- Mechanism of Action: Progesterone receptor agonist; thickens cervical mucus, thins endometrium, suppresses ovulation.
- Side Effects: Menstrual irregularities, headache, nausea, breast tenderness. Serious but rare: VTE.
- Contraindications: Breast cancer, severe liver disease, thromboembolic disorders, unexplained vaginal bleeding.
- Drug Interactions: Enzyme-inducing drugs, St. John’s Wort.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy; generally safe during breastfeeding.
- Dosage: 75 mcg daily for progestogen-only pill.
- Monitoring Parameters: Blood pressure, weight, signs of VTE, liver function tests if indicated.
Popular Combinations
Combined with ethinyl estradiol in various formulations for oral contraception.
Precautions
- Assess for history of breast cancer, liver disease, and thromboembolic disorders before initiating therapy.
- Monitor blood pressure and be vigilant for signs of VTE.
FAQs
Q1: What is the recommended dosage for Desogestrel?
A: 75 mcg once daily for the progestogen-only pill. For combined oral contraceptives, dosing varies depending on the specific product.
Q2: How effective is Desogestrel as a contraceptive?
A: When taken correctly, Desogestrel is over 99% effective.
Q3: Can Desogestrel be used while breastfeeding?
A: Progestogen-only pills containing desogestrel are generally safe to use while breastfeeding.
Q4: What are the most common side effects of Desogestrel?
A: The most common side effects include menstrual irregularities, headache, nausea, and breast tenderness.
Q5: Who should not take Desogestrel?
A: Women with a history of breast cancer, severe liver disease, active thromboembolic disorders, or unexplained vaginal bleeding should not take Desogestrel.
Q6: Does Desogestrel interact with other medications?
A: Yes, certain medications like enzyme inducers can decrease the effectiveness of Desogestrel.
Q7: What should I do if I miss a dose of Desogestrel?
A: Take the missed pill as soon as possible and continue with the regular schedule. If more than 12 hours late, use additional contraception for 48 hours.
Q8: How does Desogestrel work at the cellular level?
A: Desogestrel is metabolized to etonogestrel, which binds to progesterone receptors, modulating gene expression and leading to thickened cervical mucus, thinned endometrium, and suppressed ovulation.
Q9: What is the difference between Desogestrel and combined oral contraceptives?
A: Desogestrel can be used alone as a progestogen-only pill. Combined oral contraceptives contain both Desogestrel (or another progestin) and an estrogen, like ethinyl estradiol.
