What is the comparison between Levonorgestrel (a progestin) and Norethindrone (a progestin) for contraceptive use in adolescents?

From the Guidelines

Levonorgestrel is generally preferred over norethindrone for contraceptive use in adolescents due to its more favorable side effect profile and efficacy. According to the American Academy of Pediatrics 1, levonorgestrel is a preferred option for emergency contraception, and its use as a combined oral contraceptive has been shown to have a lower failure rate in real-world use among adolescents. The recommended dosage of levonorgestrel for emergency contraception is a single 1.5-mg dose 1. For menstrual suppression or contraception, levonorgestrel-containing combined oral contraceptives can be started at doses of 0.1-0.15mg daily, while norethindrone acetate is typically dosed at 5-10mg daily 1.

Key Considerations

• Levonorgestrel tends to cause fewer androgenic side effects (such as acne and hirsutism) compared to norethindrone, making it more suitable for adolescents who may be particularly concerned about these issues 1.
• Levonorgestrel has better cycle control and may be more effective at reducing heavy menstrual bleeding 1.
• Individual responses vary, and some adolescents may tolerate norethindrone better 1.
• When initiating either medication, start with the lowest effective dose and monitor for side effects including mood changes, headaches, and breakthrough bleeding 1.

Important Factors

• Both medications are effective for contraception when used correctly, but levonorgestrel-containing methods typically have lower failure rates in real-world use among adolescents due to ease of use and better adherence 1.
• The most serious adverse event associated with combined oral contraceptive use is the increased risk of blood clots, which increases from 1 per 10,000 to 3 to 4 per 10,000 woman-years during use 1.
• Patients should be informed that common transient adverse effects of combined oral contraceptives include irregular bleeding, headache, and nausea 1.

From the Research

Comparison of Levonorgestrel and Norethindrone for Contraceptive Use in Adolescents

• The efficacy and acceptability of levonorgestrel and norethindrone as contraceptive options for adolescents have been compared in several studies 2, 3.
• A study published in 2009 compared the performance of a combined injectable contraceptive containing norethisterone enanthate and estradiol valerate with a combined oral contraceptive containing levonorgestrel and ethinyl estradiol in adolescents, and found that the injectable contraceptive had significant differences in baseline social risk, confidence, psychiatric problems, consumption of alcohol, and number of sexual partners 2.
• Another study published in 1992 found that there was no significant difference in compliance or pill satisfaction between a levonorgestrel-containing triphasic pill and a monophasic norethindrone-containing pill in adolescent patients, but that socioeconomic factors were the overriding predictors of compliance 3.
• The use of levonorgestrel implants has also been studied in adolescents, with one study published in 1995 finding that levonorgestrel implants provided superior protection against unintended pregnancy, but caused more side effects than oral contraceptives in the early months after initiation 4.
• A study published in 1994 found that the levonorgestrel implant was a highly effective and desirable form of contraception for adolescents, with timely and reassuring counseling from nurse practitioners effective in allaying fears and dissatisfaction 5.

Side Effects and Satisfaction

• The studies found that levonorgestrel and norethindrone had different side effect profiles, with levonorgestrel implants causing more menstrual irregularity and cramping, amenorrhea, nervousness, abnormal hair growth or loss, rashes, and an increase in appetite than oral contraceptives 4.
• However, another study found that adolescents experienced fewer side effects with a triphasic levonorgestrel pill than with a monophasic norethindrone pill 3.
• Satisfaction with the contraceptive method was high among adolescents using levonorgestrel implants, with 93% of users expressing overall satisfaction despite experiencing side effects 4.

Continuation Rates and Effectiveness

• The studies found that the continuation rates and effectiveness of levonorgestrel and norethindrone varied, with one study finding that the final continuation rates at 12 months were 41.9% and 37.8% for the injectable contraceptive and oral contraceptive, respectively 2.
• Another study found that levonorgestrel implants provided superior protection against unintended pregnancy, with no pregnancies occurring among implant users, compared to six pregnancies among oral contraceptive users 4.
• The use of emergency contraception, including levonorgestrel, has also been discussed as a necessary option for adolescents seeking to prevent unintended pregnancy 6.