With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.
25 mcg
orange
50 mcg
white
75 mcg
violet
88 mcg
olive
100 mcg
yellow
112 mcg
rose
125 mcg
brown
137 mcg
turquoise
150 mcg
orange
175 mcg
lilac
200 mcg
pink
300 mcg
green
Tablets shown not actual size and may not represent actual color.
With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.
25 mcg
orange
50 mcg
white
75 mcg
violet
88 mcg
olive
100 mcg
yellow
112 mcg
rose
125 mcg
brown
137 mcg
turquoise
150 mcg
blue
175 mcg
lilac
200 mcg
pink
300 mcg
green
Tablets shown not actual size and may not represent actual color.
25 mcg
orange
50 mcg
white
75 mcg
violet
88 mcg
olive
100 mcg
yellow
112 mcg
rose
125 mcg
brown
137 mcg
turquoise
150 mcg
blue
175 mcg
lilac
200 mcg
pink
300 mcg
green
Tablets shown not actual size and may not represent actual color.
With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.
Thyroid disease spectrum
Abbreviations: AACE, American Association of Clinical Endocrinologists; NACB, National Academy of Clinical Biochemistry
TSH levels alone may not be diagnostic of a thyroid disorder. Additional laboratory testing and clinical findings may be necessary.
The goal is to achieve steady TSH levels within the appropriate therapeutic range.
*In adolescents in whom growth and puberty are complete.
| Patient Type | Starting Dose | Dose Adjustment and TSH Measurement |
|---|---|---|
| Non-elderly, otherwise healthy individuals with hypothyroidism for a short time | Begin at full replacement dose: 1.6 mcg/kg/day | By 12.5 to 25 mcg every 4 to 6 weeks until clinically euthyroid and TSH normalized |
| Elderly patients or those with underlying cardiac disease | 12.5-25 mcg/day (In the elderly, full replacement dose may be <1 mcg/kg/day) | Every 6-8 weeks as needed until clinically euthyroid and TSH normalized NOTE: If cardiac symptoms develop/worsen, reduce dose OR withhold for 1 week and restart at lower dose |
| Severe long-standing hypothyroidism | 12.5-25 mcg/day | Adjust the dose in 12.5 to 25 mcg increments every 2-4 weeks until clinically euthyroid and TSH normalized |
| Pregnant patients with new onset hypothyroidism: Moderate to severe signs and symptoms | Begin at full replacement dose: 1.6 mcg/kg/day | Evaluate TSH every 4 weeks and adjust dosage until a TSH is within the normal trimester specific range |
| Pregnant patients with new onset hypothyroidism: Mild hypothyroidism | Begin at 1.0 mcg/kg/day | Evaluate TSH every 4 weeks and adjust dosage until a TSH is within the normal trimester specific range |
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
Select pill below to enlarge and see dosage
The FDA has determined that certain levothyroxine products are therapeutically equivalent, and can be substituted at the pharmacy with the full expectation that the substituted product will produce the same clinical effect and safety profile as the reference product.15
Tablets shown not actual size and may not represent exact color.
Select pill below to enlarge and see dosage
The FDA has determined that certain levothyroxine products are therapeutically equivalent, and can be substituted at the pharmacy with the full expectation that the substituted product will produce the same clinical effect and safety profile as the reference product.15
Tablets shown not actual size and may not represent exact color.
For secondary or tertiary hypothyroidism, TSH is not a reliable measure of Synthroid dose adequacy and should NOT be used to monitor therapy. Use free-T4 to monitor and titrate Synthroid dosing until clinically euthyroid and free-T4 is restored to upper half of normal range.1
Certain foods may decrease absorption and require dosing adjustments, including1:
Grapefruit juice delays the absorption of Synthroid and reduces its bioavailability.1
Iron, calcium supplements, and antacids can also decrease absorption.1
Many drugs can exert effects on thyroid hormone pharmacokinetics and metabolism (eg, absorption, synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to Synthroid.1
| Drugs That May Decrease T4 Absorption (Hypothyroidism) | |
|---|---|
| Potential impact: Concurrent use may reduce the efficacy of Synthroid by binding and delaying or preventing absorption, potentially resulting in hypothyroidism. | |
| Drug or Drug Class | Effect |
| Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) |
Phosphate binders may bind to levothyroxine. Administer SYNTHROID at least 4 hours apart from these agents. |
| Orlistat | Monitor patients treated concomitantly with orlistat and Synthroid for changes in thyroid function. |
| Bile Acid Sequestrants: (e.g., colesevelam, cholestyramine, colestipol) |
Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer Synthroid at least 4 hours prior to these drugs or monitor TSH levels. |
| Ion Exchange Resins: (e.g., Kayexalate) |
|
| Proton Pump Inhibitors Sucralfate Antacids (e.g., aluminum & magnesium hydroxides, simethicone)
|
Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids, and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately. |
| Drugs That May Alter T4 and Triiodothyronine (T3) Serum Transport Without Affecting Free Thyroxine (FT4) Concentration (Euthyroidism) | |
|---|---|
| Drug or Drug Class | Effect |
| Clofibrate Estrogen-containing Oral Contraceptives Estrogens (oral) Heroin/Methadone 5-Fluorouracil Mitotane Tamoxifen |
These drugs may increase serum thyroxine-binding globulin (TBG) concentration. |
| Androgens/Anabolic Steroids Asparaginase Glucocorticoids Slow-release Nicotinic Acid |
These drugs may decrease serum TBG concentration. |
| Potential impact (below): Administration of these agents with Synthroid results in an initial transient increase in FT4. Continued administration results in a decrease in serum T4 and normal FT4 and TSH concentrations. | |
| Salicylates (>2 g/day) | Salicylates inhibit binding of T4 and T3 to TBG and transthyretin. An initial increase in serum FT4 is followed by return of FT4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T4 levels may decrease by as much as 30%. |
| Other Drugs: Carbamazepine Furosemide (>80 mg IV) Heparin Hydantoins NSAIDS - Fenamates |
These drugs may cause protein-binding site displacement. Furosemide has been shown to inhibit the protein binding of T4 to TBG and albumin, causing an increase free T4 fraction in serum. Furosemide competes for T4-binding sites on TBG, prealbumin, and albumin, so that a single high dose can acutely lower the total T4 level. Phenytoin and carbamazepine reduce serum protein binding of levothyroxine, and total and free T4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. Closely monitor thyroid hormone parameters. |
| Drugs That May Alter Hepatic Metabolism of T4 (Hypothyroidism) | |
|---|---|
| Potential impact: Stimulation of hepatic microsomal drug-metabolizing enzyme activity may cause increased hepatic degradation of levothyroxine, resulting in increased Synthroid requirements. | |
| Drug or Drug Class | Effect |
| Phenobarbital Rifampin |
Phenobarbital has been shown to reduce the response to thyroxine. Phenobarbital increases L-thyroxine metabolism by inducing uridine 5’-diphospho-glucuronosyltransferase (UGT) and leads to lower T4 serum levels. Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. Rifampin has been shown to accelerate the metabolism of levothyroxine. |
| Drugs That May Decrease Conversion of T4 to T3 | |
|---|---|
| Potential impact: Administration of these enzyme inhibitors decreases the peripheral conversion of T4 to T3, leading to decreased T3 levels. However, serum T4 levels are usually normal but may occasionally be slightly increased. | |
| Drug or Drug Class | Effect |
| Beta-adrenergic antagonists (eg, Propranolol >160 mg/day) |
In patients treated with large doses of propranolol (>160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid. Actions of particular beta-adrenergic antagonists may be impaired when a hypothyroid patient is converted to the euthyroid state. |
| Glucocorticoids (eg, Dexamethasone ≥4 mg/day) |
Short-term administration of large doses of glucocorticoids may decrease serum T3 concentrations by 30% with minimal change in serum T4 levels. However, long-term glucocorticoid therapy may result in slightly decreased T3 and T4 levels due to decreased TBG production (see above). |
| Other Drugs: Amiodarone | Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients. |
Hypothyroidism
SYNTHROID® (levothyroxine sodium) tablets for oral use is an L-thyroxine (T4) indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.
Pituitary Thyrotropin (Thyroid Stimulating Hormone, TSH) Suppression
SYNTHROID is indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.
SYNTHROID is not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients, as there are no clinical benefits and overtreatment with SYNTHROID may induce hyperthyroidism.
SYNTHROID is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
US-SYNT-220356
