Levothyroxine with Sodium Polystyrene Sulfonate Interaction Details

Brand Names Associated with Levothyroxine

Brand Names Associated with Sodium Polystyrene Sulfonate

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 05, 2023

Interaction Effect

Reduced levothyroxine efficacy

Interaction Summary

Coadministration of levothyroxine and a cation exchange resin may decrease the efficacy of levothyroxine by binding and delaying or preventing absorption of T(4), potentially leading to hypothyroidism. Administer other oral medications, including prescription and over-the-counter drugs, at least 3 hours before or 3 hours after orally administered cation exchange resins. For patients with gastroparesis or other conditions that delay emptying of food from the stomach into the small intestine, increase this to 6 hours . Monitor blood levels or clinical response where appropriate. Alternatively, administer cation exchange resin rectally.

Severity

Moderate

Onset

Unspecified

Evidence

Theoretical

How To Manage Interaction

Use caution with coadministration of levothyroxine and a cation exchange resin, as it may decrease the therapeutic effect of levothyroxine and potentially lead to hypothyroidism. Administer other oral medications, including prescription and over-the-counter drugs, at least 6 hours before or 6 hours after orally administered cation exchange resins. For patients with gastroparesis or other conditions that delay emptying of food from the stomach into the small intestine, increase this to 6 hours . Monitor blood levels or clinical response where appropriate. Alternatively, administer cation exchange resin rectally.

Mechanism Of Interaction

Binding and delaying or preventing absorption of T(4) by a cation exchange resin

Literature Reports

A) In a case report, a woman who was coadministered levothyroxine 150 mcg/d after a thyroidectomy and sodium polystyrene sulfonate (SPS) 15 g orally for hyperkalemia developed symptoms of hypothyroidism. Other medications included digoxin, clofibrate, nicotinic acid, calcium carbonate, ferrous sulfate, folic acid, and magnesium trisilicate. Six months after institution of SPS, symptoms of hypothyroidism (lethargy, hoarse voice, facial fullness, weight gain) were evident, free levothyroxine levels were low (3.5 pmol/L), and TSH levels were high (139.5 milliunits/L). Because of speculation that SPS was preventing absorption of levothyroxine, the dose of levothyroxine was increased to 200 mcg/day and was administered 10 hours after SPS. After 6 weeks her symptoms had disappeared, free levothyroxine levels were in the normal range (10 to 25 pmol/L), and TSH levels (5.9 milliunits/L) were only slightly above normal (0.2 to 3 milliunits/L) .

Levothyroxine Overview

• Levothyroxine is used to treat hypothyroidism (condition where the thyroid gland does not produce enough thyroid hormone). It is also used with surgery and radioactive iodine therapy to treat thyroid cancer. Levothyroxine is in a class of medications called hormones. It works by replacing thyroid hormone that is normally produced by the body.

• Without thyroid hormone, your body cannot function properly, which may result in poor growth, slow speech, lack of energy, excessive tiredness, constipation, weight gain, hair loss, dry, thick skin, increased sensitivity to cold, joint and muscle pain, heavy or irregular menstrual periods, and depression. When taken correctly, levothyroxine reverses these symptoms.

Sodium Polystyrene Sulfonate Overview

• Sodium polystyrene sulfonate is used to treat hyperkalemia (increased amounts of potassium in the body). Sodium polystyrene sulfonate is in a class of medications called potassium-removing agents. It works by removing excess potassium from the body.

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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.