Estradiol with Selegiline Interaction Details

Brand Names Associated with Estradiol

Brand Names Associated with Selegiline

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

Interaction Effect

An increase in selegiline oral bioavailability and an increased risk of selegiline adverse reactions

Interaction Summary

During a randomized study to determine the dose relationship of selegiline and its main metabolite, desmethylselegiline, female subjects who were receiving oral contraceptives had a Cmax and AUC that was 10- to 20-fold higher than subjects not receiving oral contraceptives. The marked elevation in the bioavailability of selegiline may result in a loss of selective inhibition of monoamine oxidase (MAO) type B, which would predispose the patient to hypertensive reactions after the intake of amines.

Severity

Moderate

Onset

Rapid

Evidence

Probable

How To Manage Interaction

The concomitant use of selegiline and a combination contraceptive should be avoided. Alternately, the selegiline dose should be reduced to minimize the risks of selegiline adverse effects, including hypertensive reactions.

Mechanism Of Interaction

Inhibition of selegiline first-pass metabolism to desmethylselegiline

Literature Reports

A) Eight healthy females, four using oral contraceptives, entered an open, four-period randomized study to characterize the dose relationship of selegiline and desmethylselegiline pharmacokinetics. Subjects ingested a single dose of 5 mg, 10 mg, 20 mg, or 40 mg of selegiline, with a washout period of at least two weeks between treatment phases. Although researchers were not looking for differences in the pharmacokinetics of selegiline between oral contraceptive users and non-users, there was a 20-fold increase in selegiline AUC in oral contraceptive users as compared with non-users. The median Cmax was more than 10 times higher in the group taking oral steroids. Desmethylselegiline AUC values were also higher in contraceptive users, although the increase was smaller in magnitude and did not reach statistical significance. The difference in the metabolic ratio between the two groups suggests that oral contraceptives inhibit the N-demethylation of selegiline to desmethylselegiline. The increase in selegiline bioavailability in oral contraceptive users may lead to loss of selective inhibition of monoamine oxidase type B, predisposing the patient to hypertensive reactions .

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.

Selegiline Overview

• Selegiline is used to help control the symptoms of Parkinson's disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) in people who are taking levodopa and carbidopa combination (Sinemet). Selegiline may help people with Parkinson's disease by decreasing the dose of levodopa/carbidopa needed to control symptoms, stopping the effects of levodopa/carbidopa from wearing off between doses, and increasing the length of time that levodopa/carbidopa will continue to control symptoms. Selegiline is in a group of medications called monoamine oxidase type B (MAO-B) inhibitors. It works by increasing the amount of dopamine (a natural substance that is needed to control movement) in the brain.

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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.