Switching levothyroxine brands frequently results in abnormal thyroid function tests

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. By Mary ShomonMary Shomon is a writer and hormonal health and thyroid advocate. These standards must be documented and approved by the FDA before a generic manufacturer can produce and sell the drug.

Symptoms of overdose may include the following:

Closely monitor coagulation tests to permit appropriate and timely dosage adjustments. Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy. For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal see Recommended Dosage And Titration.

• Familial hyper- or hypo-thyroxine binding globulinemias have been described, with the incidence of TBG deficiency approximating 1 in 9000.
• Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy.
• Regardless of the number of switches, switchers were also more likely to have TSH levels outside the recommended target range.
• You are more likely to experience ill effects by changing to a brand-name product.

If you are pregnant, talk with your health care provider about how much iodine you need. It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies. It may take several weeks before you notice a synthroid rp change in your symptoms. The dose of this medicine will be different for different patients.

levothyroxine (Rx)

You may wish to ask your healthcare provider what they make of these reports. From batch to batch, brand-name levothyroxine productsare consistent in terms of potency. This article explains how the potency can vary between brand-name and generic versions of levothyroxine. It also explains the possible consequences of switching, as well as when a brand-name product is the best choice.

Consider the potential for food or drug interactions and adjust the administration or dosage of SYNTHROID as needed see DOSAGE AND ADMINISTRATION, DRUG INTERACTIONS and CLINICAL PHARMACOLOGY. For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. During their follow-up, the final TSH lab outcomes were “out of range” for 22.6% of patients who took the generic levothyroxine and 20.9% for those who took Synthroid. If you are certain that you need to stick with a particular brand of levothyroxine, make sure your healthcare provider writes “DAW” (dispense as written) or “no generic substitution” on your prescription. Levothyroxine is a synthetic (man-made) version of thyroxine, or T4, the main hormone that is made and released by your thyroid gland.

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• In general, however, studies comparing generic and brand name formulations of levothyroxine fail to definitively show advantages of one preparation over another.
• The amount of medicine that you take depends on the strength of the medicine.
• Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss.
• Closely monitor infants during the first 2 weeks of SYNTHROID therapy for cardiac overload and arrhythmias.

Hypothyroidism can be clinically overlooked as it may present with nonspecific complaints or symptoms that may be attributed to other conditions 3. Known associations between hypothyroidism and other serious comorbidities include depression 4, 5, obesity 6, 7, fatigue 8, 9, hyperlipidemia 3, 10, 11, hypertension 12, 13, chronic kidney disease (CKD) 14, and heart failure 3. The recommended starting daily dosage of SYNTHROID in pediatric patients with primary, secondary, or tertiary hypothyroidism is based on body weight and changes with age as described in Table 2.

Introduction to Levothyroxine and Synthroid

• Once you find the right dose, you will probably get a blood test in 6 months.
• What the researchers found was that people who switched were 15% more likely to have their thyroid hormones fall out of the “normal” range than those who stuck with Synthroid.
• Given the retrospective nature of the study design and the de-identified data, the study was exempt from ethics board approval.
• Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of SYNTHROID see WARNINGS AND PRECAUTIONS and Use In Specific Populations.

Whether they take a brand name or a generic form of levothyroxine, some people continue to experience symptoms of hypothyroidism even when their TSH is normal. Levothyroxine typically causes no side effects when used in the correct dose. If you change brands of the medicine, tell your health care provider, as the dosage may need to change. You’ll likely start to feel better one or two weeks after you begin treatment. Because the dosage you need may change, your health care provider may check your TSH level every year. TSH tests also play an important role in managing hypothyroidism over time.

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Familial hyper- or hypo-thyroxine binding globulinemias have been described, with the incidence of TBG deficiency approximating 1 in 9000. Consumption of certain foods may affect SYNTHROID absorption thereby necessitating adjustments in dosing see DOSAGE AND ADMINISTRATION. Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of SYNTHROID from the gastrointestinal tract.

Use of oral thyroid hormone drug products is not recommended to treat myxedema coma. Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma. Treatment for hypothyroidism usually includes taking the thyroid hormone medicine levothyroxine (Levo-T, Synthroid, others) every day. It returns hormone levels to a healthy range, eliminating symptoms of hypothyroidism. 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.

In children with severe congenital hypothyroidism, Synthroid and a generic levothyroxine formulation were not found to be bioequivalent. The study showed that children treated with Synthroid had significantly lower TSH levels compared to those treated with the generic formulation, indicating that Synthroid may be more effective in this population. Levothyroxine is a synthetic form of the thyroid hormone used to treat hypothyroidism, a condition where the thyroid gland does not produce enough hormones. While both are used to manage hypothyroidism, there is ongoing debate about whether they are truly interchangeable. Propensity score matching resulted in a sample of 9925 continuous users and 9925 switchers. Switchers were significantly more likely than continuers to have a TSH laboratory value out-of-range in the post-period odds ratio (OR) 1.15; 95% confidence interval (CI) (1.08–1.23).