Estradiol with Ulipristal Interaction Details

Brand Names Associated with Estradiol

Brand Names Associated with Ulipristal

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 13, 2023

Interaction Effect

Reduced efficacy of ulipristal or progestin-based hormonal contraceptives

Interaction Summary

Progestin-containing contraceptives may reduce the effectiveness of ulipristal in delaying ovulation. Conversely, ulipristal may reduce hormonal contraceptive effects. Combined oral contraceptive use within 1 day of ulipristal administration did not affect ovulation rates; however, use within 2 days impaired the ability of ulipristal to delay ovulation. Progestin-only contraceptive use within 1 day of ulipristal administration increased the ovulation rate within 6 days of ulipristal administration. Additionally, progestin-only contraceptive use within 2 days of ulipristal administration was associated with a reduction in the ability of the progestin to inhibit cervical mucus permeability. Start hormonal contraception no sooner than 5 days after ulipristal use. A reliable barrier method should also be used until the patient's next menstrual period. Follow instructions on the initiation or resumption of specific hormonal contraceptives after ulipristal intake.

Severity

Major

Onset

Rapid

Evidence

Established

How To Manage Interaction

Progestin-containing contraceptives may reduce the effectiveness of ulipristal in delaying ovulation. Conversely, ulipristal may reduce hormonal contraceptive effects. Start hormonal contraception no sooner than 5 days after ulipristal use. A reliable barrier method should also be used until the patient's next menstrual period. Follow instructions on the initiation or resumption of specific hormonal contraceptives after ulipristal intake.

Mechanism Of Interaction

Competition for progesterone receptor binding

Literature Reports

A) In clinical trials, ovulation rates were similar among women who started ethinyl estradiol 30 mcg/levonorgestrel 150 mcg (COC) within 1 day of ulipristal use during the follicular phase of the menstrual cycle vs women using placebo plus COC. Ovulation occurred in 33.3% of subjects who received ulipristal plus COC vs 32.4% of subjects who received placebo plus COC .

B) When a combined oral contraceptive containing ethinyl estradiol 30 mcg/levonorgestrel 150 mcg was started 2 days after ulipristal intake, the ability of ulipristal to delay ovulation, as assessed by transvaginal ultrasound, was reduced; follicular rupture occurred in 27% of subjects in less than 5 days, compared to 3% of subjects after ulipristal alone .

C) The effects on ovarian activity of delaying versus immediately resuming combination oral contraceptives (COCs) after ulipristal intake were investigated in women who had been using contraceptives containing ethinyl estradiol 30 mcg/levonorgestrel 150 mcg once daily for 21 days followed by 7 days of placebo pills for at least one cycle (N=49). All subjects missed 3 consecutive pills (Days 5 to 7) during the first week of pills in the subsequent cycle and took ulipristal on the following day (Day 8). These subjects were randomized to resume their COCs either on the same day as ulipristal intake vs 5 days later. No ovulations with potential risk of pregnancy occurred in either group in the 5 days following ulipristal. However, in the group that waited 5 days to resume taking COCs, 17.4% of women did ovulate later in the cycle (Days 18 to 26) whereas no ovulations occurred in the group that resumed COC intake on the same day as ulipristal .

D) Compared with women who used ulipristal alone, more women in the follicular phase of their menstrual cycle ovulated within 6 days of ulipristal use when they started desogestrel 75 mcg within a day of ulipristal intake. Conversely, ulipristal was associated with a reduction in the ability of desogestrel to inhibit cervical mucus permeability; thickening of cervical mucus was slowed by 3 to 4 days among patients who used ulipristal 2 days before desogestrel initiation compared with those who used desogestrel alone .

Estradiol Overview

• Estrogen is used to treat hot flushes ('hot flashes'; sudden strong feelings of heat and sweating) in women who are experiencing menopause ('change of life', the end of monthly menstrual periods). Some brands of estrogen are also used to treat vaginal dryness, itching, or burning, or to prevent osteoporosis (a condition in which the bones become thin and weak and break easily) in women who are experiencing or have experienced menopause. However, women who need a medication only to treat vaginal dryness or only to prevent osteoporosis should consider a different treatment. Some brands of estrogen are also to relieve symptoms of low estrogen in young women who do not produce enough estrogen naturally. Some brands of estrogen are also used to relieve the symptoms of certain types of breast and prostate (a male reproductive gland) cancer. Estrogen is in a class of medications called hormones. It works by replacing estrogen that is normally produced by the body.

Ulipristal Overview

• Ulipristal is used to prevent pregnancy after unprotected sexual intercourse (sex without any method of birth control or with a birth control method that failed or was not used properly [e.g., a condom that slipped or broke or birth control pills that were not taken as scheduled]). Ulipristal should not be used to prevent pregnancy on a regular basis. This medication is to be used as an emergency contraceptive or backup in case regular birth control fails or is used incorrectly. Ulipristal is in a class of medications called progestins. It works by preventing or delaying the release of an egg from the ovary. It also may work by changing the lining of the uterus (womb) to prevent development of a pregnancy. Ulipristal may prevent pregnancy, but it will not prevent the spread of human immunodeficiency virus (HIV, the virus that causes acquired immunodeficiency syndrome [AIDS]) and other sexually transmitted diseases.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.