Progestin-Only Oral Contraceptive Pills
The progestin-only oral contraceptive pills (POPs) available in the United States include norethindrone (marketed as Micronor, Nor-QD, and others) and drospirenone-containing formulations. 1, 2, 3, 4
Traditional First-Generation POPs
Norethindrone-based pills represent the traditional progestin-only contraceptive option:
- Norethindrone 0.35 mg is the most commonly available traditional POP formulation in the US 2, 3, 4
- Brand names include Micronor and Ovrette (though Ovrette contains norgestrel) 4
- These require strict timing—must be taken at the same time each day, with backup contraception needed if taken more than 3 hours late 2
- Traditional POPs work by suppressing ovulation in approximately half of users, thickening cervical mucus, and altering the endometrium 3
Fourth-Generation POPs
Newer drospirenone-containing POPs offer improved efficacy:
- Drospirenone is a fourth-generation progestin with antiandrogenic and anti-mineralocorticoid properties 1
- Drospirenone POPs have a longer window for missed pills compared to norethindrone formulations 1
- These are associated with contraceptive effectiveness similar to combined oral contraceptives 5
Important Clinical Distinctions
Do not confuse progestin-only pills with combined oral contraceptives:
- Combined pills contain both estrogen and progestin (examples: norgestimate/ethinyl estradiol, drospirenone/ethinyl estradiol) and are NOT progestin-only formulations 1, 6
- Progestin-only formulations contain NO estrogen component 2, 7
Key Clinical Considerations
POPs are particularly useful for specific patient populations:
- Women with contraindications to estrogen (cardiovascular risk factors, hypertension, history of VTE, breastfeeding) 1, 2, 7
- Breastfeeding women, as POPs can be safely used during lactation 1, 2
- Women with systemic lupus erythematosus or positive antiphospholipid antibodies 2
Common side effects and counseling points:
- Irregular bleeding patterns are the most commonly reported complaint with all POPs 5, 4
- Traditional norethindrone POPs have higher typical-use failure rates than other hormonal methods due to strict timing requirements 2
- POPs do not protect against sexually transmitted infections; condoms should be recommended for STI protection 1, 2
- All POPs are completely reversible with no negative effect on long-term fertility 2