What is ulipristal acetate 5 mg used for?

Ulipristal Acetate 5mg: Indication and Use

Note: The question asks about ulipristal 5mg, but the standard emergency contraception dose is 30mg, not 5mg. There is also a 5mg formulation of ulipristal acetate that exists for a completely different indication—treatment of uterine fibroids (marketed as Esmya in Europe). However, the evidence provided focuses exclusively on the 30mg emergency contraception formulation. I will address the emergency contraception use, as this is what the available evidence supports.

Primary Indication: Emergency Contraception

Ulipristal acetate 30mg (not 5mg) is used as emergency contraception to prevent pregnancy when taken within 5 days (120 hours) after unprotected sexual intercourse or contraceptive failure. 1, 2

Mechanism of Action

• Ulipristal acetate is a selective progesterone receptor modulator that works primarily by inhibiting or delaying ovulation 2, 3
• It can delay the onset of luteinizing hormone (LH) surge or postpone LH peak even if LH surge has already started 3
• It may also have a direct inhibitory effect on follicular rupture when administered just before ovulation 3

Timing and Effectiveness Window

• Effective throughout the entire 120-hour (5-day) window after unprotected intercourse, unlike levonorgestrel which loses effectiveness after 72 hours 2
• Should be taken as soon as possible within this 5-day period for maximum effectiveness 2
• Maintains sustained efficacy even when taken 72-120 hours after intercourse, whereas levonorgestrel shows significantly reduced effectiveness in this later window 1, 4

Comparative Effectiveness

• More effective than levonorgestrel (Plan B), particularly in the 72-120 hour window after intercourse 1, 4
• Meta-analysis shows ulipristal acetate has a pregnancy risk 42% lower than levonorgestrel up to 72 hours and 65% lower in the first 24 hours 5, 6
• May be more effective than levonorgestrel in women who are overweight or obese 1, 2
• Levonorgestrel loses effectiveness in women weighing more than 165 pounds and is ineffective in women weighing more than 176 pounds 1
• Among emergency contraception options, copper IUDs are most effective, followed by ulipristal acetate, then levonorgestrel 2

Administration and Follow-up

• Single oral dose of 30mg (again, not 5mg as asked in the question) 3, 4
• After taking ulipristal acetate, women can start regular contraception immediately but must use barrier contraception or abstain for 14 days or until next menstrual period 2
• A pregnancy test is recommended if withdrawal bleeding does not occur within 3 weeks 2

Safety Profile

• Generally well tolerated with similar side effects to levonorgestrel 3, 6
• Most common adverse event is headache (19.3% of users) 4
• Typically delays onset of menses by 2-3 days 3
• Pregnancy category X: unlike levonorgestrel, a pregnancy test may be considered before prescribing 1

Drug Interactions

• Predominantly metabolized by CYP3A4, so interactions with antiretroviral agents (particularly efavirenz) can be expected 1
• Limited evidence suggests levonorgestrel levels are significantly reduced with efavirenz use 1

Important Clinical Caveat

The 5mg formulation mentioned in your question is NOT the emergency contraception dose. The emergency contraception formulation is 30mg (marketed as ella® in the US or ellaOne® in Europe). If you are asking about the 5mg daily formulation, this is used for treatment of uterine fibroids, which is an entirely different indication not covered by the provided evidence.