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Synthroid vs Thyrolar
Introduction
For patients with hypothyroidism or other types of thyroid disorders, certain medications that alter the levels of hormones in the body can help in managing symptoms and maintaining a normal metabolic rate. Synthroid (levothyroxine) and Thyrolar (liotrix) are two such drugs that are prescribed for these conditions. They each impact different thyroid hormone levels in the body, but both aim to replace or provide more thyroid hormone which is normally produced by the thyroid gland.
Synthroid contains levothyroxine sodium, a synthetic version of thyroxine (T4), one type of thyroid hormone. It works by increasing levels of T4 when your body does not produce enough on its own.
On the other hand, Thyrolar offers a balanced combination of levothyroxine sodium (T4) and liothyronine sodium (T3). Unlike Synthroid, it affects both T3 and T4 levels as it attempts to closely mimic the natural production ratio from our bodies—approximately four parts T4 to one part T3.
Synthroid vs Thyrolar Side By Side
| Attribute | Synthroid | Thyrolar |
|---|---|---|
| Brand Name | Synthroid | Thyrolar |
| Contraindications | Should not be taken if using or have recently stopped using antithyroid agents. | Should not be taken if using or have recently stopped using antithyroid agents. |
| Cost | For the brand name, around $50 for 30 tablets (100 mcg). Generic levothyroxine costs between $0.10 to $0.40 per day. | Around $90 for 30 tablets (1/4 grain). Liotrix isn't typically found as a generic alternative. |
| Generic Name | Levothyroxine | Liotrix |
| Most Serious Side Effect | Signs of allergic reaction, chest pain, fast or pounding heartbeats, shortness of breath, swelling in hands and feet, changes in menstrual periods, weight changes, tremors, muscle weakness, headache with significant tiredness. | Severe allergic reactions, rapid heart rate, irregular heartbeat or palpitations, tremors or convulsions, changes in menstrual cycles, sudden weight loss, increased appetite, sweating, heat intolerance, feeling nervous. |
| Severe Drug Interactions | Antithyroid agents. | Antithyroid agents. |
| Typical Dose | 50-200 mcg/day for adults, starting at a lower dosage (25-50 mcg) and gradually increasing. Children's dosage is dependent on body weight, typically 2-3 mcg/kg/day. | Initiated at a dosage of 1/4 to 1 grain (15-60 mg) per day, gradually increased by half a grain (30 mg) every two weeks, until the desired therapeutic response is achieved. Often falls within the range of 1 to 2 grains (60-120 mg) daily. |
What is Synthroid?
Levothyroxine (the generic name for Synthroid) was the first synthetic thyroid hormone replacement drug, which marked a significant step forward from previously available natural dessicated thyroid extract. Levothyroxine was approved by the FDA in 1955. Synthroid provides supplemental T4, which is converted into the active hormone T3 in your body, effectively compensating for an underactive thyroid gland. It is prescribed as a lifelong therapy for those with hypothyroidism and to suppress thyroid-stimulating hormone (TSH) levels in those with certain types of thyroid cancer.
Thyrolar is another treatment option that contains both levothyroxine (T4) and liothyronine (T3), aiming to mimic the body's natural balance of these hormones more closely than levothyroxine alone does. Some patients report feeling better on combination therapy like Thyrolar, but it can be harder to manage and may carry a slightly higher risk of side effects than treatment with Synthroid alone due to its inclusion of direct T3.
What conditions is Synthroid approved to treat?
Synthroid is approved for the treatment of different thyroid conditions:
- Hypothyroidism, a condition where the thyroid gland does not produce enough hormones
- Treatment of goiter (enlarged thyroid gland), which can be caused by hormone imbalances, radiation therapy, surgery, or cancer
- Thyroid cancer (after surgical removal and as part of ongoing management)
How does Synthroid help with these illnesses?
Synthroid aids in managing hypothyroidism by supplementing the body with levothyroxine, a thyroid hormone that is produced naturally in the body. It does this by acting as a synthetic form of thyroxine (T4), which is converted to triiodothyronine (T3) in the cells and tissues of the body. Thyroid hormones play an essential role in our metabolism, growth, development, and temperature regulation amongst other things. In individuals with hypothyroidism, their bodies do not produce enough thyroid hormones leading to symptoms such as fatigue, slow heart rate, dry skin and constipation among others. Therefore, by supplying synthetic T4 hormone through Synthroid treatment can help patients manage their condition effectively.
On the other hand,Thyrolar provides both levothyroxine (T4) and liothyronine (T3). This gives it a more comprehensive approach since it directly supplies both T3 and T4 hormones for those whose bodies may struggle converting T4 into active T3.
What is Thyrolar?
Thyrolar, also known as liotrix, is a synthetic thyroid hormone replacement that provides both T3 (triiodothyronine) and T4 (thyroxine), the two primary hormones produced by your thyroid gland. Thyroid hormones are essential for regulating body metabolism, heart rate, and body temperature among other physiological functions. Just like bupropion does not inhibit serotonin reuptake which differentiates it from typical SSRI antidepressants such as Prozac, Thyrolar's action on both T3 and T4 distinguishes it from Synthroid which only contains synthetic thyroxine or T4.
Thyrolar was first approved by the FDA in 1956, making it one of the earliest available treatments for hypothyroidism. Its dual-action can be beneficial especially for patients who have difficulty converting T4 to its active form -T3- which could happen with some patients taking Synthroid alone.
Common side effects include rapid heartbeat, excessive sweating or feeling hot more often than usual but these usually indicate over-treatment rather than an adverse reaction per se. It's important to note that individual response varies widely; hence dosing should always be individualized based on clinical response and laboratory findings.
What conditions is Thyrolar approved to treat?
Thyrolar is recognized and approved for the treatment of the following conditions:
- Hypothyroidism, a condition where the thyroid doesn't produce enough hormones
- Thyroid cancer, to suppress thyrotropin (TSH) levels after surgery and radioiodine therapy.
Just like Synthroid, it replaces or provides more thyroid hormone that's normally produced by the thyroid gland. However, unlike Synthroid which only contains T4 (Levothyroxine), Thyrolar contains both T3 (Liothyronine) and T4 hormones, mimicking the body's natural ratio of thyroid hormones more closely. This can be especially beneficial for patients who struggle to convert T4 into active T3 in their bodies.
How does Thyrolar help with these illnesses?
Thyroid hormones are critical for many bodily processes, impacting metabolism, heart rate, and body temperature among others. Low levels of these hormones can lead to a condition known as hypothyroidism with symptoms like fatigue, weight gain, depression and memory issues. Thyrolar is a medication that works by supplementing both the thyroid hormones - T3 (triiodothyronine) and T4 (thyroxine), thereby helping restore normal hormone levels in the body and alleviating symptoms of hypothyroidism. Its dual-action approach contrasts with Synthroid which primarily supplements only T4 hormone. This makes Thyrolar particularly beneficial when a patient's body has difficulty converting T4 into active T3 or does not respond well to 'typical' single-hormone treatments such as Synthroid. In some cases, it may also be combined with other thyroid medications.
How effective are both Synthroid and Thyrolar?
Both levothyroxine (Synthroid) and liotrix (Thyrolar) have long established histories of success in treating hypothyroidism, with Synthroid approved by the FDA years before Thyrolar. Since they contain different forms of thyroid hormone, they may be prescribed under different circumstances.
Levothyroxine is a synthetic form of thyroxine (T4), the major hormone secreted by the thyroid gland. In contrast, liotrix is a combination product containing both T3 and T4 hormones in a fixed ratio. Due to its single-hormone content, levothyroxine's effect can be more easily monitored and adjusted through regular blood tests which measure serum TSH levels. A 2009 study confirmed that patients receiving levothyroxine had consistent control over their hypothyroid symptoms as well as promising safety profiles.
A review from 2012 demonstrated that levothyroxine remains effective in managing symptoms of hypothyroidism throughout life without causing adverse effects related to overdosage even if used for longer durations. The same report states that Synthroid has become one of the most commonly prescribed medications worldwide due to its efficacy and tolerability.
Liotrix offers an advantage for those who cannot convert T4 into its active form ,T3, efficiently due to certain medical conditions or genetic factors but it generally considered after trying monotherapy with Levothyroxin first because there are limited studies confirming its efficacy as stand-alone treatment compared to Levothyroixn . Nonetheless, due to its unique formulation combining both types of thyroid hormones naturally produced by body , Liotrix may provide optimal treatment for patients who do not respond well to standard therapy with Levohtyroxin alone.
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At what dose is Synthroid typically prescribed?
Oral dosages of Synthroid typically range from 50-200 mcg/day for treating hypothyroidism in adults, but studies have indicated that starting at a lower dosage (25-50 mcg) and gradually increasing may be more beneficial. Children's dosage is dependent on their body weight, typically 2-3 mcg/kg/day. Dosage can be increased after a few weeks if there is no response or if the TSH levels are not within the normal range. The maximum dosage varies greatly depending on individual needs and should only be determined by your doctor. With Thyrolar, it's important to remember that it contains both T4 and T3 thyroid hormones so the dose will look different; however, your healthcare provider will calculate an equivalent dose based upon your current Synthroid therapy.
At what dose is Thyrolar typically prescribed?
Thyrolar treatment is typically initiated at a dosage of 1/4 to 1 grain (15-60 mg) per day. The dose can then be gradually increased by half a grain (30 mg) every two weeks, until the desired therapeutic response is achieved. Often, this falls within the range of 1 to 2 grains (60-120 mg) daily, taken in a single morning dose or divided into two doses: one in the morning and one in late afternoon. The maximum dose varies widely according to individual patient requirements for thyroid replacement therapy. If there's no sufficient response after several weeks of reaching what should usually be an effective dosage level, your doctor might need to reassess your situation.
What are the most common side effects for Synthroid?
Common side effects of Synthroid and Thyrolar, two medications used to treat thyroid hormone deficiency, can include:
- Nervousness or anxiety
- Difficulty falling asleep (insomnia)
- Excessive sweating
- Increased appetite
- Sensitivity to heat
- Weight loss despite increased food intake
- More frequent bowel movements or diarrhea
- Tremors (shaking)
- Rapid or irregular heartbeat
- Chest pain Note that these potential side effects are often a sign of excessive dosage; if you experience any of these symptoms after starting one of these medications, it's important to consult with your healthcare provider right away. It may be necessary to adjust your dose in order to achieve the desired effect without causing adverse reactions.
Are there any potential serious side effects for Synthroid?
Using either Synthroid or Thyrolar, you should be aware of certain potentially serious side effects. They include:
- Signs of allergic reaction like hives, difficulty breathing, swelling in your face or throat
- Chest pain, fast or pounding heartbeats
- Shortness of breath during regular activity or experiencing difficulty to catch breath after mild exertion
- Swelling in your hands and feet due to fluid retention
- Changes in menstrual periods
- Weight changes (either weight gain or loss)
- Tremors, muscle weakness or limp feeling
- Headache with significant tiredness; if these symptoms are accompanied by low fever, hot flashes, sweating it could indicate a hormonal imbalance.
In rare cases affected individuals may experience the following symptoms:
- Feverish feeling coupled with vomiting and severe headache
- Skin reactions including blistering skin rash
- Extreme fatigue leading to fainting spells
If any such adverse conditions occur while on these medications seek immediate medical attention.
What are the most common side effects for Thyrolar?
Thyrolar, while effective in treating hypothyroidism, can potentially cause a number of side effects including:
- Swelling of the face, lips or throat
- Chest pain or irregular heartbeat
- Shortness of breath
- Fever and hot flashes
- Weight loss
- Tremors and nervousness
- Headache, nausea and vomiting
- Diarrhea
-Increased appetite or changes in menstrual periods -Skin rash
Are there any potential serious side effects for Thyrolar?
While Thyrolar is regularly prescribed for hypothyroidism, it's important to be aware of potential serious side effects. These may include:
- Severe allergic reactions such as hives, difficulty breathing, or swelling in your face or throat
- Rapid heart rate, irregular heartbeat or palpitations
- Tremors or convulsions
- Changes in menstrual cycles
- Sudden weight loss and increased appetite
- Sweating more than usual
- Heat intolerance and feeling nervous
If you notice any of these symptoms while taking Thyrolar, seek immediate medical attention. Remember that some side effects might not appear right away but could develop over time.
Contraindications for Synthroid and Thyrolar?
Like many other hormone replacement medications, both Synthroid and Thyrolar can cause symptoms of hyperthyroidism in some individuals. These may include increased heart rate, nervousness, irritability, excessive sweating or feelings of overheating. If you notice these signs worsening after taking either medication, it is crucial to seek immediate medical attention.
Neither Synthroid nor Thyrolar should be taken if you are currently using or have recently stopped using a type of medication known as an antithyroid agent. Always inform your healthcare provider about all the medicines you are taking; antithyroids may need a period of two weeks to clear from your system before starting treatment with Synthroid or Thyrolar to avoid potential harmful interactions.
How much do Synthroid and Thyrolar cost?
For the brand name versions of these drugs:
- The price for 30 tablets of Synthroid (100 mcg) averages around $50, which works out to approximately $1.67 per day.
- The price for 30 tablets of Thyrolar (1/4 grain) averages about $90, working out to approximately $3/day.
Thus, if you are on a typical dosage range for thyroid replacement therapy (i.e., one tablet daily), then branded Synthroid is less expensive on a per-day treatment basis. However, cost should not be your primary consideration in determining which medication is most suitable for you.
For the generic versions of Synthroid and Thyrolar - levothyroxine and liotrix respectively - costs can be significantly lower:
- Levothyroxine (100 mcg tablets) is available in packs from 15 up to 500 capsules with approximate costs between $0.10 to $0.40 per day depending on where it's purchased.
- Liotrix isn't typically found as a generic alternative due its complex formulation; thus no significant decrease in pricing occurs when compared to its brand-name equivalent, Thyrolar.
Popularity of Synthroid and Thyrolar
Levothyroxine, which is available as a generic medication and under the brand name Synthroid, was prescribed to about 122 million people in the US in 2020. This made it one of the most commonly prescribed medications in the country. Levothyroxine is a synthetic form of thyroxine (T4), an essential hormone produced by your thyroid gland.
On the other hand, Liotrix, sold under brand names such as Thyrolar, combines both levothyroxine (T4) and liothyronine (T3) - another important thyroid hormone. This combination therapy might be beneficial for certain patients who do not respond well to T4 alone. However, it's generally less frequently used due to higher cost and lack of clear evidence showing superiority over T4 monotherapy. In fact, prescriptions for Thyrolar have been decreasing over recent years with its use being somewhat controversial among endocrinologists.
Both drugs are crucial for managing hypothyroidism but their use should be guided by individual patient response rather than population-based guidelines.
Conclusion
Both Synthroid (levothyroxine) and Thyrolar (liotrix) have a long-standing record of usage in patients with hypothyroidism, which is an underactive thyroid. Both medications are supported by numerous clinical studies indicating that they are effective treatments for this condition. They work by replacing or providing more thyroid hormone, which is normally produced by the thyroid gland.
The main difference between these two drugs lies in their composition; Synthroid contains only T4 (Levothyroxine), whereas Thyrolar contains a combination of both T3 (Liothyronine) and T4 hormones. This means that they may be prescribed under different circumstances; for instance, Synthroid is usually considered as the first-line treatment option due to its stable effect on thyroid hormone levels and fewer side effects.
Thyrolar might be considered if there's a particular need to increase both T3 and T4 levels quickly, such as when other treatments haven't worked well enough. These considerations would rely heavily on careful physician supervision due to potential contraindications between them.
Both drugs require some time for adjustments meaning results may not be evident right away. In terms of cost-effectiveness, generic versions of levothyroxine represent significant savings especially for those who must pay out-of-pocket.
Side-effects profiles are similar between the two drugs - common ones include weight changes, heat intolerance, hair loss - but Thyrolar might have slightly higher chances of causing heart palpitations because it has direct active T3 component. As always with hormonal therapies like these, close monitoring by healthcare providers during initiation or change in therapy is crucial to avoid over- or under-treatment complications.
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Refrences
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- Escobar-Morreale, H. F., Botella-Carretero, J. I., & Morreale de Escobar, G. (2015, January). Treatment of hypothyroidism with levothyroxine or a combination of levothyroxine plus L-triiodothyronine. Best Practice & Research Clinical Endocrinology & Metabolism. Elsevier BV.http://doi.org/10.1016/j.beem.2014.10.004
- Fish, L. H., Schwartz, H. L., Cavanaugh, J., Steffes, M. W., Bantle, J. P., & Oppenheimer, J. H. (1987, March 26). Replacement Dose, Metabolism, and Bioavailability of Levothyroxine in the Treatment of Hypothyroidism. New England Journal of Medicine. Massachusetts Medical Society.http://doi.org/10.1056/nejm198703263161302
- JOFFE, R. T., SAWKA, A. M., MARRIOTT, M. J., MACQUEEN, G. M., & GERNSTEIN, H. C. (2004, December). Does Substitution of T4 with T3 Plus T4 for T4 Replacement Improve Depressive Symptoms in Patients with Hypothyroidism?. Annals of the New York Academy of Sciences. Wiley.http://doi.org/10.1196/annals.1314.040
- Concepción-Zavaleta, M. J., Ildefonso-Najarro, S. P., Paz-Ibarra, J. L., Valdivia Fernández-Dávila, F. R., Deutz Gómez-Condori, D. C., Rivera-Fabián, K. E., … Concepción-Urteaga, L. A. (2021, December 30). Liothyronine use in primary hypothyroidism — current concepts. Endokrynologia Polska. VM Media SP. zo.o VM Group SK.http://doi.org/10.5603/ep.a2021.0093