Typical Doses of Levonorgestrel and Ethinyl Estradiol in Oral Contraceptives
The typical doses of levonorgestrel in oral contraceptives range from 100-250 μg, while ethinyl estradiol doses typically range from 10-50 μg, with most modern formulations containing 20-30 μg of ethinyl estradiol to minimize side effects while maintaining efficacy.
Common Formulations
Standard Combined Oral Contraceptives
- Levonorgestrel 100 μg + Ethinyl estradiol 20 μg - Low-dose formulation 1, 2
- Levonorgestrel 150 μg + Ethinyl estradiol 30 μg - Common standard dose 3
- Levonorgestrel 250 μg + Ethinyl estradiol 20-30 μg - Higher progestin dose 4
Emergency Contraception
- Levonorgestrel 1.5 mg (single dose) or 0.75 mg (two doses 12 hours apart) 5
- Levonorgestrel 0.50 mg + Ethinyl estradiol 100 μg (two doses 12 hours apart) - Combined emergency contraceptive regimen 5
Dosing Patterns
Monophasic
- Consistent hormone doses throughout the active pill cycle (21-24 days)
- Followed by hormone-free interval (4-7 days) or low-dose estrogen pills
Extended-Cycle
- 84 active pills containing levonorgestrel 100 μg + ethinyl estradiol 20 μg
- Followed by 7 days of either placebo or low-dose estrogen pills 6
- Reduces number of menstrual cycles per year
Clinical Considerations
Efficacy
- Pearl Index (pregnancies per 100 woman-years) for low-dose formulations ranges from 0.13-4.45 1, 2, 3
- Laboratory-verified compliance significantly improves efficacy rates 2
Mechanism of Action
- Suppression of gonadotropins
- Inhibition of ovulation as primary mechanism
- Secondary mechanisms include changes in cervical mucus and endometrium 7
Dose Selection Factors
- Lower doses of ethinyl estradiol (≤30 μg) are preferred to minimize side effects while maintaining efficacy
- Higher doses of levonorgestrel may be associated with higher blood pressure, though differences are not always significant 5
- Drospirenone (a newer progestin) may have advantages over levonorgestrel for blood pressure management 5
Special Considerations
Blood Pressure Effects
- Ethinyl estradiol component is primarily responsible for blood pressure changes
- Blood pressure elevations have been observed with ethinyl estradiol doses ranging from <30 μg to >50 μg 5
- At low (≤30 μg) and moderate (>30-50 μg) doses, risk of hypertension may not be dose-dependent 5
Newer Formulations
- Formulations with natural estrogens (estradiol valerate, estetrol) and newer progestins may have fewer adverse effects on blood pressure 5
- Drospirenone-containing pills may actually decrease blood pressure in some users 5
Understanding these typical dosing ranges helps clinicians select appropriate oral contraceptive formulations based on individual patient needs and risk factors.