Synthroid Levothyroxine Sodium: Side Effects, Uses, Dosage, Interactions, Warnings

Toxic effects may include increased risk of cardiac arrhythmias and central nervous system stimulation. Administration of sertraline in patients stabilized on SYNTHROID may result in increased SYNTHROID requirements. Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy. Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see Drug Interactions (7.2). Over-treatment with levothyroxine may cause an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients. Initiate SYNTHROID therapy in this population at lower doses than those recommended in younger individuals or in patients without cardiac disease see Dosage and Administration (2.3) and Use in Specific Populations (8.5).

Many drugs can inhibit Synthroid’s adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed. Providing a complete list of medications to the doctor will help with getting the correct dose established for each individual patient. Throughout your lifetime, your doctor may have to adjust your dose of Synthroid. That’s because the amount of thyroid hormone your body needs may change. Some of the reasons for this may include major life events like pregnancy or menopause, or aging. Many other medicines can be affected by your thyroid hormone levels.

• The major pathway of thyroid hormone metabolism is through sequential deiodination.
• 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.
• Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination.

SYNTHROID- levothyroxine sodium tablet

Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins see DRUG INTERACTIONS. Thyroid hormones do not readily cross the placental barrier see Use In Specific Populations. Synthroid is prescribed in tablets that range from 25 to 300 mcg in strength and is usually taken once a day with a full glass of water (about 8 ounces) 30 to 60 minutes before breakfast for best adsorption into the body.

CLINICAL PHARMACOLOGY

The peak therapeutic effect of a given dose of SYNTHROID may not be attained for 4 to 6 weeks. Administer SYNTHROID at least 4 hours before or after drugs known to synthroid reduction interfere with SYNTHROID absorption see Drug Interactions (7.1). Costs at follow-up were also compared using a GLM regression with gamma distribution and log link function and several baseline variables as covariates (refer to Supplemental Material Table 3 for a list of included variables). We anticipate reposting the images once we are able identify and filter out images that do not match the information provided in the drug labels. Pregnant and lactating females need to discuss the dose and use of this medication with their caregivers.

Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants. Synthroid is also used in patients who need surgery and radioiodine therapy to manage a type of thyroid cancer called well-differentiated thyroid cancer. Synthroid is a prescription medicine used to treat hypothyroidism (low thyroid hormone). Levothyroxine is given when your thyroid does not produce enough of this hormone on its own. The major pathway of thyroid hormone metabolism is through sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination.

• These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness, and wheezing.
• Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins see Drug Interactions (7).
• Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on cognitive development as well as on overall physical growth and maturation.
• Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma.
• The statistical analyses were performed using SAS Enterprise Guide 7.1 (SAS Institute Inc., Cary, NC, USA, 2014).

You are encouraged to report negative side effects of prescription drugs to the FDA. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using. Levothroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … Eltroxin is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … Unithroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma …

The liver is the major site of degradation for both T4 and T3, with T4 deiodination also occurring at a number of additional sites, including the kidney and other tissues. Approximately 80% of the daily dose of T4 is deiodinated to yield equal amounts of T3 and reverse T3 (rT3). Thyroid hormones are also metabolized via conjugation with glucuronides and sulfates and excreted directly into the bile and gut where they undergo enterohepatic recirculation. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

1 Drugs Known to Affect Thyroid Hormone Pharmacokinetics

Symptoms may not necessarily be evident or may not appear until several days after ingestion of levothyroxine sodium. Serum TSH levels should be monitored and the SYNTHROID dosage adjusted during pregnancy. Since postpartum TSH levels are similar to preconception values, the SYNTHROID dosage should return to the pre-pregnancy dose immediately after delivery see DOSAGE AND ADMINISTRATION. Administer SYNTHROID to pediatric patients who cannot swallow intact tablets by crushing the tablet, suspending the freshly crushed tablet in a small amount (5 to 10 mL) of water and immediately administering the suspension by spoon or dropper.

Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid see Dosage and Administration (2.2). All patients were ≥ 18 years old on the index date, and all had at least 6 months of pre-index (baseline) and 12 months of post-index (follow-up) health plan enrollment. Patients were required to have at least 1 TSH laboratory result during the 12-month follow-up period and be persistent in their index therapy through follow-up. In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status. Absorption of orally administered T4 from the gastrointestinal tract ranges from 40% to 80%.

To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached. At baseline, hospitalizations and ED visits were rare (6–8% all-cause), while most patients in both cohorts had outpatient visits and pharmacy fills (94–99% all-cause), with mean number of all-cause pharmacy fills per patient of 9.2–9.3. Total all-cause costs were approximately $5800–6000 per patient in 2017 USD (Table 2). Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. This hormone nuclear receptor complex activates gene transcription and synthesis of messenger RNA and cytoplasmic proteins.