Dosage and Duration of Micronor (Norethindrone)
The recommended dose for Micronor (norethindrone) is one 0.35 mg tablet taken orally every day at the same time with continuous administration (no interruption between pill packs). 1
Dosing Regimen
- Micronor must be taken exactly as directed to achieve maximum contraceptive effectiveness 1
- Administration is one tablet (0.35 mg) daily at the same time every day 1
- The medication should be taken continuously without breaks between pill packs 1
- Continuous daily administration is essential for maintaining contraceptive efficacy 2
Duration of Use
- Micronor can be used long-term as a contraceptive method 2
- Studies have demonstrated effective use over periods of up to 5 years 2
- There is no specified maximum duration of use in the FDA labeling 1
- Continuous use without interruption is the standard administration pattern 1
Efficacy and Considerations
- When taken regularly as prescribed, Micronor has a drug-effectiveness rate of 1.9 pregnancies per 100 woman-years 2
- With typical use (including missed doses), the use-effectiveness rate is 2.5 pregnancies per 100 woman-years 2
- Cycle length may be variable while using Micronor 2
- Taking the pill at the same time each day is crucial for maintaining contraceptive effectiveness 1
Important Clinical Considerations
- If a dose is missed, contraceptive effectiveness may be reduced 1
- Patients should be advised to refer to the patient labeling for detailed instructions on missed doses 1
- Unlike combined hormonal contraceptives, there are no placebo pills or pill-free intervals with Micronor 1
- Long-term studies have not shown significant trends in blood pressure changes, though there may be a tendency toward weight gain 2
Micronor is a progestin-only pill (mini-pill) that works primarily by thickening cervical mucus, inhibiting sperm penetration, and in some cases suppressing ovulation. The continuous daily dosing schedule is essential for maintaining these effects and providing reliable contraception.