Usage
- Norgestrel is a progestin-only hormonal contraceptive indicated for the prevention of pregnancy in women and adolescent girls who have started menstruating.
- Pharmacological Classification: Progestin, Hormonal Contraceptive
- Mechanism of Action: Norgestrel primarily works by suppressing ovulation (the release of an egg from the ovary). It also thickens cervical mucus, creating a barrier that makes it difficult for sperm to reach the egg, and alters the uterine lining, making it less receptive to implantation of a fertilized egg.
Alternate Names
- d-Norgestrel
- levonorgestrel (the active enantiomer of norgestrel)
- Brand Name: Opill (progestin-only pill containing norgestrel)
How It Works
- Pharmacodynamics: Norgestrel exerts its contraceptive effect by binding to progesterone receptors in the hypothalamus, pituitary gland, and uterus. This binding leads to suppression of gonadotropin-releasing hormone (GnRH), which in turn reduces the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The reduced levels of FSH and LH prevent follicular development and ovulation. The thickening of cervical mucus and changes in the uterine lining are also mediated by progesterone receptor activation.
- Pharmacokinetics:
- Absorption: Norgestrel is rapidly absorbed after oral administration.
- Metabolism: It undergoes extensive hepatic metabolism, primarily by CYP3A4.
- Elimination: Metabolites are excreted primarily in urine and to a lesser extent in feces.
Dosage
Standard Dosage
Adults and Adolescents (Post-Menarche):
- 0.075 mg orally once daily, at the same time each day.
- Administration is continuous, with no hormone-free interval between packs.
Children (Pre-Menarche):
- Not indicated for use before the onset of menstruation.
Special Cases:
- Elderly Patients: Norgestrel is not typically indicated for use in postmenopausal women.
- Patients with Renal Impairment: Dosage adjustments are not specifically recommended but caution is advised in patients with severe renal impairment.
- Patients with Hepatic Dysfunction: Use with caution in patients with hepatic impairment due to potential alterations in metabolism. Close monitoring is recommended.
- Patients with Comorbid Conditions: Caution is advised in patients with certain conditions, including breast cancer (current or history), undiagnosed abnormal vaginal bleeding, active thromboembolic disorders, or liver tumors.
Clinical Use Cases
- Norgestrel is solely indicated for contraception and has no other clinical use cases. It is not indicated for use in intubation, surgical procedures, mechanical ventilation, intensive care settings, or emergency situations.
Dosage Adjustments
- No specific dosage adjustments are recommended based on patient-specific factors apart from the considerations mentioned for patients with renal or hepatic dysfunction.
Side Effects
Common Side Effects:
- Irregular vaginal bleeding (including spotting, prolonged bleeding, or amenorrhea)
- Headache
- Nausea
- Acne
- Breast tenderness
- Mood changes
Rare but Serious Side Effects:
- Ectopic pregnancy (pregnancy outside the uterus)
- Blood clots (deep vein thrombosis, pulmonary embolism)
- Allergic reactions (rash, hives, difficulty breathing, swelling of the face, lips, tongue, or throat)
- Liver problems (jaundice, dark urine)
- Mental health changes (new or worsening depression)
Long-Term Effects:
- The long-term effects of norgestrel use are generally related to the potential for ectopic pregnancy and blood clots with extended use.
Adverse Drug Reactions (ADR):
- Severe allergic reactions, thromboembolic events, and hepatic dysfunction require immediate medical attention.
Contraindications
- Current or past history of breast cancer
- Suspected or confirmed pregnancy
- Undiagnosed abnormal genital bleeding
- Liver disease, including tumors
- Hypersensitivity to norgestrel or any components of the formulation
Drug Interactions
- Medications that induce or inhibit hepatic enzymes, particularly CYP3A4, can affect norgestrel’s efficacy.
- Some medications, such as certain anticonvulsants (e.g., carbamazepine, phenytoin) and some antibiotics (e.g., rifampin) may reduce the effectiveness of norgestrel.
- St. John’s Wort may also decrease the efficacy of norgestrel.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: X (Contraindicated in pregnancy)
- Norgestrel is contraindicated during pregnancy. If pregnancy occurs while taking norgestrel, the drug should be discontinued immediately.
- Breastfeeding: Norgestrel can be excreted in breast milk, although levels are generally low. The decision to use norgestrel while breastfeeding should be made after careful consideration of the risks and benefits for both the mother and the infant.
Drug Profile Summary
- Mechanism of Action: Progestin-only contraceptive, primarily suppressing ovulation, thickening cervical mucus, and altering the uterine lining.
- Side Effects: Irregular bleeding, headache, nausea, acne, breast tenderness, mood changes. Serious side effects include ectopic pregnancy, blood clots, and hepatic dysfunction.
- Contraindications: Breast cancer, pregnancy, undiagnosed abnormal vaginal bleeding, liver disease.
- Drug Interactions: Primarily with CYP3A4 inducers and inhibitors.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy; use with caution during breastfeeding.
- Dosage: 0.075 mg orally once daily.
- Monitoring Parameters: Menstrual cycles, signs of thromboembolic events, hepatic function.
Popular Combinations
- Norgestrel is used as a single-agent progestin-only contraceptive. It is not typically combined with other medications for contraceptive purposes.
Precautions
- Patients should be screened for contraindications and risk factors before starting norgestrel.
- Patients should be advised to report any signs of thromboembolic events or hepatic dysfunction.
- Patients with a history of depression should be monitored closely for mood changes.
- Norgestrel does not protect against sexually transmitted infections (STIs), including HIV.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Norgestrel?
A: The recommended dosage for adult and adolescent females (post-menarche) is 0.075 mg orally once daily, taken at the same time each day.
Q2: How effective is Norgestrel as a contraceptive?
A: Norgestrel is highly effective when taken consistently as directed. Typical use effectiveness is around 91-95%, meaning that about 5-9 out of 100 women using norgestrel may become pregnant within the first year of use.
Q3: Can Norgestrel be used as emergency contraception?
A: No, Norgestrel (Opill) is not indicated for emergency contraception. It is designed for daily continuous use to prevent pregnancy. Other progestin-only or combined hormonal methods are available for emergency contraception.
Q4: What should a patient do if she misses a dose of Norgestrel?
A: If a dose is missed by less than 3 hours, the patient should take the missed pill as soon as possible and resume her regular dosing schedule. If a dose is missed by more than 3 hours, the patient should take the missed pill as soon as possible and use a backup contraceptive method (e.g., condoms) for the next 48 hours.
Q5: What are the most common side effects of Norgestrel?
A: The most common side effects are irregular bleeding (including spotting, prolonged bleeding, and changes in menstrual flow), headaches, nausea, acne, and breast tenderness.
Q6: Are there any serious side effects associated with Norgestrel?
A: Yes, although rare, serious side effects can include ectopic pregnancy, blood clots (deep vein thrombosis, pulmonary embolism), and liver problems. Patients should be advised to seek immediate medical attention if they experience symptoms such as severe abdominal pain, chest pain, shortness of breath, or jaundice.
Q7: Can Norgestrel be used while breastfeeding?
A: Norgestrel can be used while breastfeeding, but it can be excreted in breast milk. The decision to use norgestrel while breastfeeding should be made in consultation with a healthcare professional, considering the potential risks and benefits for both the mother and the infant.
Q8: Does Norgestrel protect against sexually transmitted infections (STIs)?
A: No, Norgestrel does not protect against STIs, including HIV. Patients should be counseled on the importance of using barrier methods (e.g., condoms) for STI prevention.
Q9: Who should not take Norgestrel?
A: Norgestrel is contraindicated in women with a current or past history of breast cancer, known or suspected pregnancy, undiagnosed abnormal vaginal bleeding, or liver disease, including tumors.
Q10: What are the drug interactions associated with Norgestrel?
A: Norgestrel can interact with medications that induce or inhibit hepatic enzymes, particularly CYP3A4, affecting its effectiveness. Certain anticonvulsants, antibiotics, and St. John’s Wort are known to potentially reduce the efficacy of norgestrel. Patients should disclose all medications and supplements they are taking to their healthcare provider.
