What is the difference between Estarylla (drospirenone and ethinyl estradiol) and another contraceptive, such as Micronor (norethindrone)?

Differences Between Estarylla (Drospirenone/Ethinyl Estradiol) and Micronor (Norethindrone)

Estarylla and Micronor are fundamentally different types of contraceptives with distinct hormonal compositions, mechanisms of action, and risk profiles - Estarylla is a combined hormonal contraceptive while Micronor is a progestin-only pill, making Micronor the safer option for women with cardiovascular risk factors.

Key Differences in Composition

Estarylla (Combined Hormonal Contraceptive)

• Contains two hormones: ethinyl estradiol (estrogen) and drospirenone (progestin)
• Drospirenone is a fourth-generation progestin with unique properties:
  • Antimineralocorticoid activity (similar to spironolactone)
  • Antiandrogenic effects (beneficial for acne and PMDD)
  • Derived from 17α-spirolactone, not testosterone 1

Micronor (Progestin-Only Pill)

• Contains only norethindrone (a progestin)
• No estrogen component
• Norethindrone is a first-generation progestin 2, 3

Mechanism of Action

Estarylla

• Primary mechanism: Inhibits ovulation through suppression of gonadotropin-releasing hormone
• Secondary mechanisms:
  • Increases sex hormone-binding globulin
  • Reduces free testosterone
  • Blocks androgen receptors
  • Reduces 5-alpha-reductase activity 2
  • Thickens cervical mucus
  • Thins endometrial lining

Micronor

• Primary mechanisms:
  • Thickens cervical mucus (preventing sperm penetration)
  • Thins endometrial lining (preventing implantation)
• May inhibit ovulation in some women, but less consistently than combined pills 3

Effectiveness

Estarylla

• Perfect use: 99% effective
• Typical use: 93-97% effective 2

Micronor

• Perfect use: 99.5% effective
• Typical use: approximately 90-94% effective 3

Safety Profile and Cardiovascular Risk

Estarylla

• Higher cardiovascular risks due to estrogen component:
  • Increased risk of venous thromboembolism (VTE)
  • Risk of VTE: 9-10 per 10,000 woman-years (higher with drospirenone) 2
  • Increased risk of stroke, especially with:
    • Higher estrogen doses
    • Smoking
    • Hypertension
    • Age over 35 years 2

Micronor

• No increased risk of thromboembolism or stroke 2, 3
• Safe for women with:
  • Hypertension
  • History of VTE
  • Migraine with aura
  • Smokers over age 35 3

Administration Requirements

Estarylla

• Traditional 21/7 or 24/4 regimen (24 active pills, 4 placebo)
• Can be taken within 24 hours of usual time

Micronor

• Must be taken at the same time every day (within 3 hours)
• No placebo pills - continuous active pills 3

Non-Contraceptive Benefits

Estarylla

• FDA-approved for:
  • Acne treatment
  • PMDD (Premenstrual Dysphoric Disorder) 4, 5
• Additional benefits:
  • Reduced menstrual pain
  • Lighter, more regular periods
  • Protection against endometrial and ovarian cancers 2

Micronor

• Safe during breastfeeding
• Fewer metabolic effects than combined pills
• May reduce menstrual pain 3

Side Effects

Estarylla

• Water retention (though less than other combined pills due to drospirenone's antimineralocorticoid effect)
• Breast tenderness
• Nausea
• Mood changes
• Breakthrough bleeding 6, 4

Micronor

• Irregular bleeding patterns (most common)
• Spotting
• Amenorrhea
• Fewer systemic side effects than combined pills 3

Contraindications

Estarylla

• Multiple contraindications due to estrogen component:
  • History of VTE or arterial thrombosis
  • Migraine with aura
  • Smoking in women over 35
  • Uncontrolled hypertension
  • Active liver disease
  • Breast cancer 2

Micronor

• Fewer contraindications:
  • Current breast cancer
  • Severe cirrhosis
  • Unexplained vaginal bleeding 3

Clinical Decision Algorithm

1. Assess cardiovascular risk factors:

   • If patient has history of VTE, stroke, hypertension, migraine with aura, or is a smoker >35 → Choose Micronor
   • If no cardiovascular risk factors → Proceed to step 2

2. Consider non-contraceptive benefits needed:

   • If acne treatment or PMDD management is desired → Consider Estarylla
   • If breastfeeding → Choose Micronor

3. Evaluate medication adherence capability:

   • If patient can take medication at exact same time daily → Either option suitable
   • If timing adherence is challenging → Estarylla provides more flexibility

4. Consider side effect tolerance:

   • If concerned about mood effects or fluid retention → Consider individual factors
     • Estarylla's drospirenone may help with water retention but has higher VTE risk
     • Micronor has fewer systemic effects but more irregular bleeding

Common Pitfalls to Avoid

1. Assuming all birth control pills are the same - Combined pills and progestin-only pills have fundamentally different risk profiles and mechanisms.

2. Overlooking cardiovascular risk factors - Always screen for VTE risk, hypertension, migraine with aura, and smoking status before prescribing Estarylla.

3. Not counseling about timing requirements - Micronor's 3-hour window is much stricter than Estarylla's 24-hour window.

4. Failing to consider drug interactions - Certain medications (rifampin, some anticonvulsants, St. John's wort) can reduce effectiveness, particularly with progestin-only pills 3.