Synthroid Uses, Dosage & Side Effects

Because some preparations of the drug may contain iodine or lactose, patients should tell their doctors about such allergies or reactions to these components. Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness, and wheezing. 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.

Warnings and Precautions

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

• This is not an all-inclusive list of possible drug interactions, adverse effects, precautions, nursing considerations, or patient instructions.
• Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone.
• You may be more likely to have a broken bone while using levothyroxine.
• 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.

Drugs That May Decrease T4 Absorption (Hypothyroidism)

• HypothyroidismSYNTHROID® (levothyroxine sodium) tablets, for oral use is indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.
• Some brands of levothyroxine have different dosage instructions and/or recommendations of how soon you need to take them before eating food.
• Note that this list is not all-inclusive and includes only common medications that may interact with Synthroid.
• Careful titration of medication and monitoring is required in that setting.

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. 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. Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response. Synthroid (levothyroxine) treats hypothyroidism (low thyroid hormone) and different types of … Following a 25-mcg dose change of levothyroxine, most patients had changes in TSH levels. Personally, I have had experiences where I have written for brand-name SYNTHROID and the patients have been dispensed generic levothyroxine or even another branded levothyroxine product.

T4 absorption is increased by fasting, and decreased in malabsorption syndromes and by certain foods such as soybeans. In addition, many drugs and foods affect T4 absorption see Drug Interactions (7). 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. 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). In addition, many drugs and foods affect T4 absorption see DRUG INTERACTIONS. Titrate the dosage (every 2 weeks) as needed based on serum TSH or free- T4 until the patient is euthyroid see Important Considerations For Dosing.

This is important as 32% of patients who think they are on SYNTHROID are actually not given this because substitutions are made at the pharmacy. 54% of prescriptions for SYNTHROID were not protected with a DAW or state-specific language in one study. A levothyroxine product that is not therapeutically equivalent with SYNTHROID might not have the exact same effect on the patient’s TSH as SYNTHROID. I go over with them the fact that they should check the label at the pharmacy, on the bottle, to make sure synthroid menorrhagia it says brand-name SYNTHROID and not generic levothyroxine.

Grapefruit juice may delay the absorption of levothyroxine and reduce its bioavailability. Titrate the dose of SYNTHROID carefully and monitor response to titration to avoid these effects see Dosage and Administration (2.4). Consider the potential for food or drug interactions and adjust the administration or dosage of SYNTHROID as needed see Dosage and Administration (2.1), Drug Interactions (7.1), and Clinical Pharmacology (12.3).

Steve is a 50-year-old man with hypothyroidism.

In the elderly and in patients with cardiovascular disease, SYNTHROID should be initiated at lower doses than those recommended in younger individuals or in patients without cardiac disease. Patients with coronary artery disease who are receiving SYNTHROID should be closely monitored for cardiac arrhythmias during surgical procedures. Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of Synthroid. Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take this medicine if you have certain medical conditions.

• Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see Drug Interactions (7.2).
• Synthroid works best if you take it on an empty stomach, 30 to 60 minutes before breakfast.
• The major pathway of thyroid hormone metabolism is through sequential deiodination.
• Levothyroxine is given when your thyroid does not produce enough of this hormone on its own.
• The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance, and longer half-life of T4 compared to T3.

Get medical help right away, if you have any of the symptoms listed above. Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Note that this list is not all-inclusive and includes only common medications that may interact with Synthroid. You should refer to the prescribing information for Synthroid for a complete list of interactions.

Stop biotin and biotin-containing supplements for at least 2 days before assessing TSH and/or T4 levels see DRUG INTERACTIONS. Patients The SYNTHROID dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer. Concurrent use of tyrosine-kinase inhibitors such as imatinib may cause hypothyroidism. Monitor serum free-T4 levels and maintain in the upper half of the normal range in these patients. The SYNTHROID dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer. Take levothyroxine tablets and capsules on an empty stomach, at least 30 to 60 minutes before breakfast with a full glass of water.

I review with the patients the important issues about how to take the medication, as consistency is really the key message. I talk about the fact that it’s important to take the medication in the same timing and pattern each day, take it on an empty stomach minutes before they eat. I also review the safety and risks of taking thyroid medication.