Estradiol with Tizanidine Interaction Details

Brand Names Associated with Estradiol

Brand Names Associated with Tizanidine

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

Interaction Effect

Increased tizanidine plasma concentrations resulting in increased hypotensive and sedative effects

Interaction Summary

The concomitant use of tizanidine and oral contraceptives is not recommended. In a retrospective analysis of population pharmacokinetic data, 50% lower clearance of tizanidine was reported in women taking oral contraceptives than in women not on oral contraceptives following single and multiple 4-mg doses of tizanidine. If coadministration is clinically necessary, initiate tizanidine at a dose of 2 mg and increase daily by 2 to 4 mg based on therapeutic response. Reduce the dose or discontinue tizanidine therapy if hypotension, bradycardia, or excessive drowsiness occurs.

Severity

Major

Onset

Rapid

Evidence

Probable

How To Manage Interaction

Concomitant use of tizanidine and oral contraceptives is not recommended. If coadministration is required, initiate tizanidine at a dose of 2 mg and increase daily by 2 to 4 mg based on response to therapy. Reduce the dose or discontinue tizanidine therapy if hypotension, bradycardia, or excessive drowsiness occurs.

Mechanism Of Interaction

Inhibition of CYP1A2-mediated tizanidine metabolism by the contraceptive

Literature Reports

A) One study reported higher serum levels of tizanidine in women taking oral contraceptives than in men . In a retrospective analysis of population pharmacokinetic data, 50% lower clearance of tizanidine was reported in women taking oral contraceptives than in women not on oral contraceptives. Patients were given single and multiple 4-mg doses of tizanidine .

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.

Tizanidine Overview

• Tizanidine is used to relieve the spasms and increased muscle tone caused by multiple sclerosis (MS, a disease in which the nerves do not function properly and patients may experience weakness, numbness, loss of muscle coordination and problems with vision, speech, and bladder control), stroke, or brain or spinal injury. Tizanidine is in a class of medications called skeletal muscle relaxants. It works by slowing action in the brain and nervous system to allow the muscles to relax.

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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.