What is the efficacy of Ulipristal acetate (UPA) for emergency contraception and treatment of uterine fibroids?

Efficacy of Ulipristal Acetate (UPA) for Emergency Contraception and Uterine Fibroids

Ulipristal acetate is highly effective for emergency contraception with a pregnancy rate reduction from 5.5% to 2.2% when taken 48-120 hours after unprotected intercourse, and for uterine fibroids it can achieve amenorrhea rates of 70-90% with fibroid volume reduction of 54-72% after repeated treatment courses. 1, 2

Emergency Contraception Efficacy

Mechanism of Action

• Primary mechanism: Inhibition or delay of ovulation 1
• UPA can delay follicular rupture even when taken close to ovulation (when LH has started to rise) 1
• UPA is effective in delaying ovulation even 24-48 hours before expected ovulation, when levonorgestrel is no longer effective 3

Clinical Efficacy Data

• Effective when taken within 120 hours (5 days) after unprotected intercourse 2
• Pregnancy rate reduction from expected 5.5% to observed 2.2% when taken 48-120 hours after unprotected intercourse 1
• Pregnancy rate reduction from expected 5.6% to observed 1.9% when taken within 72 hours 1
• No pregnancies observed when administered more than 72 hours after unprotected intercourse in clinical trials 1

Comparative Efficacy

• Similar effectiveness to levonorgestrel when taken within 3 days after unprotected intercourse 2
• More effective than levonorgestrel when taken 3-5 days after unprotected intercourse 2, 3
• May be more effective than levonorgestrel among women who are overweight or obese 2
• Meta-analysis suggests UPA may be more effective than levonorgestrel throughout the entire 5-day period following unprotected intercourse 4, 3

Important Clinical Considerations

• Should be taken as soon as possible within 5 days of unprotected intercourse 2
• Regular hormonal contraception should not be started until 5 days after UPA use due to potential interactions 2, 1
• UPA has a larger window of effectiveness (up to 120 hours) compared to levonorgestrel (up to 72 hours) 4, 3

Uterine Fibroids Treatment Efficacy

Clinical Efficacy Data

• Amenorrhea rates: 70-90% of patients across treatment courses 2, 5
• Fibroid volume reduction:
  • After 1 course: 30-45% reduction
  • After 2 courses: 63% reduction
  • After 4 courses: 67-72% reduction 2
• Controlled bleeding achieved in >80% of patients during treatment courses 5
• Significant improvements in quality of life and pain reduction 2, 5

Treatment Regimen for Uterine Fibroids

• Typically administered in 3-month courses (5 or 10 mg daily) 2
• Can be used for up to 4 treatment courses with maintained efficacy 2
• Median time to amenorrhea: 2-4 days after starting treatment 2
• Effects on fibroid volume reduction maintained through 3-month post-treatment follow-up 2

Clinical Applications for Uterine Fibroids

• Effective for controlling bleeding symptoms and shrinking fibroids before surgery 2
• Can be used as a bridge to surgery to improve quality of life 2
• May help facilitate minimally invasive surgical approaches by reducing fibroid size 2
• Can be used in repeated intermittent courses for long-term management in selected patients 2

Safety Considerations

• Generally well tolerated with similar adverse event profile to levonorgestrel for emergency contraception 4
• Most common side effects for fibroid treatment: headaches and hot flashes 2
• Less than 5% of patients discontinue fibroid treatment due to adverse events 5
• Onset of menses typically delayed by 2-3 days following emergency contraception use 4
• Progesterone receptor modulator-associated endometrial changes (PAEC) can occur with repeated use for fibroids but return to baseline within 3 months after treatment cessation 2

Clinical Pitfalls to Avoid

1. For emergency contraception:

   • Do not start hormonal contraception immediately after UPA use; wait at least 5 days to avoid reducing UPA effectiveness 2, 1
   • Do not delay administration; efficacy decreases with time after unprotected intercourse 2
   • Consider potential reduced efficacy in overweight/obese women when choosing between UPA and levonorgestrel 2

2. For uterine fibroid treatment:

   • Monitor for endometrial changes with repeated courses 2
   • Be aware that clinical benefits can persist up to 6 months following treatment cessation 2
   • Counsel patients about the need for non-hormonal contraception during treatment as ovulation may still occur in up to 20% of cycles 2

UPA represents an important option both for emergency contraception with extended effectiveness window and for medical management of uterine fibroids with significant symptom control and quality of life improvements.