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If you are someone who suffers from an underactive thyroid, then chances are your doctor has prescribed levothyroxine. Levothyroxine is the most commonly prescribed hypothyroidism medication. For decades, levothyroxine was only available in tablet form, but more recently, liquid levothyroxine has become available. In this article, explore the pros and cons of tablets versus liquid levothyroxine so that you can make the best choice for you.
Your thyroid is a small, butterfly-shaped gland in the neck, just below the Adam’s apple. This gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3), that regulate a person’s metabolism and energy levels. In hypothyroidism, the thyroid gland does not produce enough of these essential hormones, which leads to slowing bodily processes and symptoms such as fatigue, weight gain, depression, brain fog, hair loss, and constipation, among others. The diagnosis of hypothyroidism requires blood tests to measure the levels of Thyroid Stimulating Hormone (TSH) and free levels of T4 and T3. The treatment for hypothyroidism is thyroid hormone medication to replace the thyroid hormone your body cannot produce.
There are several types of thyroid hormone replacement medications, including:
- Levothyroxine – a synthetic version of the T4 hormone available in both tablet and liquid form. Popular brand names include Synthroid, Levoxyl, Unithroid, Euthyrox, Tirosint, and Tirosint-SOL. In addition, several manufacturers – including Mylan Pharmaceuticals and Sandoz AG – make generic levothyroxine tablets, and Thyquidity is a generic liquid levothyroxine.
- Liothyronine – a synthetic version of the T3 hormone. The brand name is Cytomel, and the drug is also available in generic form.
- Natural desiccated thyroid – a drug derived from the thyroid glands of pigs that includes both T4 and T3. Brand names are Armour Thyroid and NP Thyroid.
The most commonly prescribed medication for hypothyroidism is levothyroxine, the synthetic T4 drug. Levothyroxine is typically taken orally, and the dosage is adjusted based on the individual’s thyroid hormone levels and response to treatment.
Levothyroxine is usually taken once a day, ideally on an empty stomach, and at least 30 minutes to an hour before eating, drinking coffee, or taking calcium or iron supplements. The medication is then absorbed in the small intestine, where it is metabolized and converted into the active form of the hormone triiodothyronine (T3). T3 is the form of the hormone that affects metabolism and other body functions.
Levothyroxine is defined as a “narrow therapeutic range drug” because its safe and effective dose range is very small. This means that a slight increase or decrease in dosage can lead to significant changes in the patient’s thyroid hormone levels, resulting in adverse side effects or inadequate treatment.
Levothyroxine has a long half-life, which means it takes a long time for the drug to be metabolized and eliminated from the body. It can be challenging to adjust the dosage accurately and prolong the effects of underdosing or overdosing. Therefore, patients taking levothyroxine require close monitoring of their thyroid hormone levels and frequent dosage adjustments to ensure optimal treatment outcomes.
Because levothyroxine is a narrow therapeutic range drug, the FDA has established tight potency requirements. Brand name and generic drug manufacturers are expected to maintain a consistent level of potency within a narrow range to ensure efficacy and safety for patients.
Specifically, the potency requirements for levothyroxine are set at 95% to 105% of the labeled amount of the active ingredient. The drug needs to contain between 95% and 105% of the stated amount of levothyroxine indicated on the label. These requirements are regularly monitored through testing and inspection by the FDA to ensure that the medication meets the established standards.
Each manufacturer produces levothyroxine to its own consistent target potency within the 95 to 105% range.
The tablet form is the most commonly prescribed form of levothyroxine.
Levothyroxine tablets come in various dosages, and each brand or manufacturer uses a unique combination of fillers, binders, coatings, and dyes for their tablet formulations.
Levothyroxine tablets are somewhat unstable, and their potency can degrade when exposed to light, humidity, heat, and oxygen. As a result, experts recommend that levothyroxine be stored in a cool, dry place away from light and moisture and maintained at a temperature range between 20°C–25°C (68°F–77°F). Additionally, levothyroxine should not be stored in a bathroom, near a sink or heat source, or left on windowsills, cars, or mailboxes.
Most levothyroxine tablets are dispensed in bottles. Euthyrox tablets are dispensed in blister packs. Blister packs have been found to preserve the physicochemical properties and potency of tablets better than bulk packaging.
Levothyroxine tablets need to be swallowed whole with water.
Liquid levothyroxine is a newer formulation of the medication.
Liquid levothyroxine is subject to the same storage requirements as tablet forms.
Liquid levothyroxine can be conveniently taken by placing it under the tongue or mixed with water or juice.
Tirosint-SOL liquid levothyroxine is dispensed in single-dose ampules to help protect against moisture and light. The following dosages are available: 13, 25, 37.5, 44, 50, 62.5, 75, 88, 100, 112, 125, 137, 150, 175, and 200 mcg/mL. The inactive ingredients in Tirosint-SOL include glycerol and water.
Thyquidity is dispensed in larger 100 mL bottles, with a calibrated oral syringe for dosing. Inactive ingredients in Thyquidity include citric acid monohydrate, glycerin, methylparaben sodium, sodium hydroxide, and purified water.
Should you take the tablet form of levothyroxine, or would you have better results with liquid? There’s no definitive answer because it depends on your specific health situation. Let’s look at the various factors that differentiate tablet vs. liquid levothyroxine.
Tablets need to be taken with water. Liquid levothyroxine can be taken independently, without water, or mixed with water or juice.
Individuals with underlying medical conditions or difficulty swallowing pills may struggle with levothyroxine tablets. Liquid levothyroxine is an excellent alternative, making it easier to take the medication.
The 12 dosage sizes of levothyroxine tablets include 25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200, and 300 mcg/mL.
Tirosint-SOL liquid levothyroxine comes in 15 dosage sizes: 13, 25, 37.5, 44, 50, 62.5, 75, 88, 100, 112, 125, 137, 150, 175, and 200 mcg/mL.
Thyquidity liquid levothyroxine comes in a bottle, and an oral syringe is provided for customized dosing.
With more dosage options, liquid levothyroxine can make it easier for healthcare providers to adjust the medication according to a patient’s needs.
Speed and effectiveness of absorption
Levothyroxine tablets rely on the digestive system to absorb them, which means they may take longer to begin working. They are also subject to absorption problems due to gastrointestinal issues or insufficient stomach acid.
Compared to tablets, liquid levothyroxine is absorbed more quickly and more consistently in the body, thanks to its sublingual administration method (placing it under the tongue) or mixing it with liquid. This enhanced absorption leads to more stable thyroid hormone levels and can result in faster and more effective symptom relief in some patients. The speed of absorption with liquid levothyroxine can also benefit patients with severe hypothyroidism who require prompt relief from symptoms.
Many foods, drinks, medications, and supplements can impair the digestion and absorption of levothyroxine. The substances that can interfere with levothyroxine absorption include:
- Iron supplements and iron-fortified foods
- Calcium supplements and calcium-fortified foods
- Proton Pump Inhibitors (PPIs) - drugs that reduce the amount of stomach acid produced by glands in the stomach lining. Some common PPIs include omeprazole (Prilosec), esomeprazole (Nexium), and lansoprazole (Prevacid).
- Tyrosine kinase inhibitors, including the best-known, imatinib mesylate (Gleevec)
- Atrial fibrillation drugs including beta-blockers, digitalis drugs, anti-arrhythmia drugs, and blood thinners.
- Orlistat – an over-the-counter and prescription weight loss drug
- Bile acid sequestrant drugs – used to lower cholesterol, including cholestyramine (Questran), colesevelam (Welchol), and colestipol (Colestid)
- Antacids with aluminum and magnesium, including Gaviscon, Tums, Rolaids, Caltrate, Alka-Seltzer, and Bromo-Seltzer
- Coffee (including decaf)
- Calcium-fortified juice
- Food in general
- Soy foods, drinks, and supplements
- High-fiber foods and fiber supplements
The ability of these substances to interfere with levothyroxine absorption is far greater with levothyroxine tablets versus liquid. This has been demonstrated in several studies:
- Research has shown that levothyroxine liquid is absorbed better than tablets in hypothyroid patients, even when patients are under treatment with proton pump inhibitors
- A study found that liquid levothyroxine formulations can bypass factors such as proton pump inhibitors and other medications and supplements, allowing full absorption. Researchers concluded that liquid levothyroxine could be taken simultaneously with drugs that interfere with levothyroxine absorption.
- One study compared TSH levels with liquid formulation versus tablet formulation and found that liquid levothyroxine may be a better option for patients with persistent hypothyroidism despite adequate doses of tablet levothyroxine.
And here’s some good news for you morning people! Experts typically recommend waiting at least 60 minutes between breakfast, drinking coffee, and taking thyroid medication. However, a 2022 study found that drinking coffee is safe soon after taking liquid levothyroxine, as absorption is not impaired. And another study found that liquid levothyroxine can be taken with breakfast without absorption interference.
Tablets tend to have a longer shelf life than liquid levothyroxine. When stored properly in an original unopened bottle, levothyroxine tablets can have a shelf life of up to 24 months, which is especially susceptible to potency degradation if exposed to light and heat. Once the pouch containing Tirosint-SOL is opened, the ampules must be used within three months. The same timeframe applies to bottles of Thyquidity.
Dyes, fillers, excipients
Most drugs use fillers, dyes, coatings, and other inactive ingredients, known as excipients. Some patients can have allergies or sensitivities to particular excipients.
In general, levothyroxine tablets have more excipients than the liquid forms. The different brands and generic forms of levothyroxine have different ingredients, which can include the following:
- Butylated hydroxyanisole
- Microcrystalline cellulose
- Sodium starch glycolate
- Crospovidone/Povidone (a form of iodine)
- Colloidal silicon dioxide
- Magnesium stearate
- Calcium phosphate dibasic
- Lactose monohydrate
- Modified wheat starch (gluten)
- Croscarmellose sodium
- Acacia (a derivative of tree bark that can be an allergen for people with seasonal allergies)
- Sodium lauryl sulfate
Liquid levothyroxine is considered hypoallergic and includes no dyes or coatings. The inactive ingredients in Tirosint-SOL include glycerol and water. The inactive ingredients in Thyquidity include citric acid monohydrate, glycerin, methylparaben sodium, sodium hydroxide, and purified water.
Levothyroxine tablets are generally inexpensive and almost always covered by health insurance. Some patients have copays as low as $0 to $5 monthly for their prescriptions. According to GoodRx, cash prices for levothyroxine tablets for patients without insurance range from around $1 to 10 for generics and up to $60 for popular brand names.
The liquid forms of levothyroxine are typically more expensive than tablets and may not be covered by insurance plans. The retail cash price for Tirosint-SOL and Thyquidity ranges from $120 to $150 a month. However, the manufacturers have coupons and discount programs that can significantly reduce the cost for cash-pay and insured patients.
Some patients may experience gastrointestinal side effects such as nausea and constipation when taking levothyroxine tablets. These side effects are typically due to a patient’s sensitivity to the excipients. Liquid levothyroxine has fewer side effects with few excipients and no common allergens like gluten, lactose, cornstarch, acacia, or dyes.
Many gastrointestinal conditions can impair the absorption of levothyroxine. These include celiac disease, atrophic gastritis, helicobacter pylori infection, gastroesophageal reflux disease (GERD), Crohn’s disease, irritable bowel disease, irritable bowel syndrome, and ulcers.
Liquid levothyroxine was initially formulated to maximize absorption in patients with gastrointestinal diseases and malabsorption issues, and numerous studies have shown that patients with these issues have better absorption when taking liquid levothyroxine.
Accuracy of Dosing
The liquid form of levothyroxine allows for more precise dosing and more effortless adjustment of medication levels. This characteristic is particularly important for thyroid patients who require precise hormone levels, such as pregnant women with hypothyroidism or thyroid cancer survivors.
Liquid levothyroxine is absorbed more quickly than tablets, which can increase the risk of overdosing. Overdosing can cause symptoms like chest pain, rapid heartbeat, shaking, and sweating. It’s essential to take the medication as directed and ensure proper dosing with the help of a healthcare provider.
When it comes to treating hypothyroidism, the best medication to treat your hypothyroidism is the one that safely works best for you. While both tablet and liquid forms of levothyroxine aim to improve thyroid hormone levels in the body, each has advantages and disadvantages.
That said, one recent observational study revealed that, compared to tablets, liquid levothyroxine is more effective and improves the quality of life and thyroid levels.
Another recent article published in 2022 in the journal Thyroid presented the results of a two-year study of almost 1,000 hypothyroid patients taking liquid and tablet forms of levothyroxine who had no preexisting malabsorption problems and were not taking any medications or supplements known to affect the absorption of levothyroxine negatively.
The researcher found:
- After one year, 85% of the patients taking liquid levothyroxine had thyroid levels in the reference range, compared to only 79% of patients treated with tablets
- After two years, 83% of patients receiving liquid levothyroxine had thyroid levels in the reference range, compared to only 72% of those taking tablets tablet.
The researchers concluded that liquid levothyroxine maintains thyroid levels more effectively in hypothyroid patients in the long term compared to tablets.
Levothyroxine is one of the thyroid hormone replacement medications your doctor may prescribe to treat your hypothyroidism. Whether in tablet or liquid form, the medication works by replacing missing or deficient thyroid hormone levels.
Liquid levothyroxine and tablets are both effective treatment options for hypothyroidism. Liquid levothyroxine has faster absorption rates and may be more appropriate for patients with gastrointestinal issues or those who can’t swallow tablets. However, it has a shorter shelf life and is usually more expensive.
Tablets have a longer shelf life and are a more common treatment option for hypothyroidism. However, they may be less effective in patients with absorption issues or those requiring high medication doses.
Ultimately, the decision to use liquid levothyroxine versus tablets should be made in consultation with your healthcare provider. Your provider can evaluate your medical history, conduct necessary tests, and provide personalized recommendations based on the findings.
By consulting with Paloma’s knowledgeable thyroid care providers, you can ensure that you receive hypothyroidism treatment that meets your unique healthcare needs. Paloma’s team of thyroid experts will work with you to assess your hypothyroidism treatment and recommend the best form of thyroid hormone replacement to safely and effectively relieve your symptoms and restore optimal thyroid function.