Levoxyl

Levothyroxine, a synthetic thyroid hormone, is a prescription medication used as a replacement or supplemental therapy in hypothyroidism, a condition in which the thyroid gland does not produce enough thyroid hormone. This medication is also used to treat nodules and goiters, as well as some types of thyroid cancer.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Levothyroxine is a tablet that is taken by mouth, usually once a day. It should be taken with a full glass of water. Take levothyroxine in the morning on an empty stomach, at least one-half hour to one hour before eating any food. Iron and calcium supplements and antacids can decrease the absorption of levothyroxine tablets. Take these products at least 4 hours before or 4 hours after you take levothyroxine.

If needed, levothyroxine tablets can be crushed and mixed in 1 to 2 teaspoons of plain water. This mixture must be taken right away.

If you forget a dose of levothyroxine, take the missed dose as soon as you remember it. If it is almost time for your next dose, skip the missed dose. Do not take a double dose of this medication.

Note: if you are prescribed levothyroxine in capsule form, you must swallow them whole. Never crush these capsules.

• Diabetes Prescription Insulin Medications
• Hypothyroidism

In the U.S.

• Levothroid
• Levoxyl
• Synthroid
• Tirosint
• Tirosint-Sol
• Unithroid

Available Dosage Forms:

• Capsule, Liquid Filled
• Tablet
• Solution

Therapeutic Class: Thyroid Supplement

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of levothyroxine in children.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of levothyroxine in the elderly. However, elderly patients are more likely to have age-related heart or blood vessel problems, which may require caution and an adjustment in the dose for patients receiving levothyroxine.

Pregnancy

Breast Feeding

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Amineptine
• Amitriptyline
• Amitriptylinoxide
• Amoxapine
• Clomipramine
• Desipramine
• Dibenzepin
• Doxepin
• Imipramine
• Ketamine
• Lofepramine
• Maprotiline
• Melitracen
• Midodrine
• Mirtazapine
• Nortriptyline
• Opipramol
• Protriptyline
• Tianeptine
• Trimipramine

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Aluminum Carbonate, Basic
• Aluminum Hydroxide
• Aluminum Phosphate
• Calcium Acetate
• Calcium Carbonate
• Calcium Citrate
• Cholestyramine
• Chromium
• Ciprofloxacin
• Colesevelam
• Conjugated Estrogens
• Dexlansoprazole
• Dihydroxyaluminum Aminoacetate
• Dihydroxyaluminum Sodium Carbonate
• Eltrombopag
• Esomeprazole
• Esterified Estrogens
• Estradiol
• Estriol
• Estrone
• Estropipate
• Fosphenytoin
• Imatinib
• Iron
• Kelp
• Lansoprazole
• Lanthanum Carbonate
• Lopinavir
• Magaldrate
• Magnesium Carbonate
• Magnesium Hydroxide
• Magnesium Oxide
• Magnesium Trisilicate
• Omeprazole
• Pantoprazole
• Patiromer
• Phenytoin
• Rabeprazole
• Rifampin
• Rifapentine
• Ritonavir
• Sevelamer
• Simvastatin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Enteral Nutrition
• Soybean

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Adrenal gland insufficiency (underactive adrenal gland), untreated or
• Heart attack, acute or recent or
• Thyrotoxicosis (overactive thyroid), untreated—Should not be used in patients with these conditions.

• Adrenal problems or
• Anemia, pernicious or
• Angina (severe chest pain), history of or
• Blood clotting problems, or history of or
• Diabetes or
• Heart or blood vessel disease (eg, coronary artery disease, heart failure), history of or
• Heart rhythm problems (eg, arrhythmia, atrial fibrillation), history of or
• Osteoporosis, history of or
• Pituitary gland problems—Use with caution. May make these conditions worse.

• Patients who have trouble swallowing capsules (including children younger than 6 years of age)—Tirosint® should not be given in these patients.

Levothyroxine sodium is used for the following indications:

Hypothyroidism

As replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis. Specific indications include: primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) hypothyroidism and subclinical hypothyroidism. Primary hypothyroidism may result from functional deficiency, primary atrophy, partial or total congenital absence of the thyroid gland, or from the effects of surgery, radiation, or drugs, with or without the presence of goiter.

Pituitary TSH Suppression

In the treatment or prevention of various types of euthyroid goiters (see WARNINGS and PRECAUTIONS ), including thyroid nodules (see WARNINGS and PRECAUTIONS ), subacute or chronic lymphocytic thyroiditis (Hashimoto's thyroiditis), multinodular goiter (see WARNINGS and PRECAUTIONS ) and, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

General Principles

The goal of replacement therapy is to achieve and maintain a clinical and biochemical euthyroid state. The goal of suppressive therapy is to inhibit growth and/or function of abnormal thyroid tissue. The dose of Levoxyl that is adequate to achieve these goals depends on a variety of factors including the patient's age, body weight, cardiovascular status, concomitant medical conditions, including pregnancy, concomitant medications, and the specific nature of the condition being treated (see WARNINGS and PRECAUTIONS ). Hence, the following recommendations serve only as dosing guidelines. Dosing must be individualized and adjustments made based on periodic assessment of the patient's clinical response and laboratory parameters (see PRECAUTIONS , Laboratory Tests ).

The Levoxyl should be taken in the morning on an empty stomach, at least one-half hour before any food is eaten. Levoxyl should be taken at least 4 hours apart from drugs that are known to interfere with its absorption (see PRECAUTIONS , Drug Interactions ).

Levoxyl should be taken with water (see Information for Patients and ADVERSE REACTIONS ).

Due to the long half-life of levothyroxine, the peak therapeutic effect at a given dose of levothyroxine sodium may not be attained for 46 weeks.

Caution should be exercised when administering Levoxyl to patients with underlying cardiovascular disease, to the elderly, and to those with concomitant adrenal insufficiency (see PRECAUTIONS ).

Specific Patient Populations

(see WARNINGS and PRECAUTIONS ,Laboratory Tests )

Therapy may begin at full replacement doses in otherwise healthy individuals less than 50 years old and in those older than 50 years who have been recently treated for hyperthyroidism or who have been hypothyroid for only a short time (such as a few months). The average full replacement dose of levothyroxine sodium is approximately 1.7 mcg/kg/day (e.g., 100125 mcg/day for a 70 kg adult). Older patients may require less than 1 mcg/kg/day. Levothyroxine sodium doses greater than 200 mcg/day are seldom required. An inadequate response to daily doses ≥300 mcg/day is rare and may indicate poor compliance, malabsorption, and/or drug interactions.

For most patients older than 50 years or for patients under 50 years of age with underlying cardiac disease, an initial starting dose of 2550 mcg/day of levothyroxine sodium is recommended, with gradual increments in dose at 68 week intervals, as needed. The recommended starting dose of levothyroxine sodium in elderly patients with cardiac disease is 12.525 mcg/day, with gradual dose increments at 46 week intervals. The levothyroxine sodium dose is generally adjusted in 12.525 mcg increments until the patient with primary hypothyroidism is clinically euthyroid and the serum TSH has normalized.

In patients with severe hypothyroidism, the recommended initial levothyroxine sodium dose is 12.525 mcg/day with increases of 25 mcg/day every 24 weeks, accompanied by clinical and laboratory assessment, until the TSH level is normalized.

In patients with secondary (pituitary) or tertiary (hypothalamic) hypothyroidism, the levothyroxine sodium dose should be titrated until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range.

(see PRECAUTIONS , Laboratory Tests )

General Principles

In general, levothyroxine therapy should be instituted at full replacement doses as soon as possible. Delays in diagnosis and institution of therapy may have deleterious effects on the child's intellectual and physical growth and development.

Undertreatment and overtreatment should be avoided (see PRECAUTIONS ,Pediatric Use ).

Levoxyl may be administered to infants and children who cannot swallow intact tablets by crushing the tablet and suspending the freshly crushed tablet in a small amount (510 mL or 12 teaspoons) of water. This suspension can be administered by spoon or dropper. DO NOT STORE THE SUSPENSION. Foods that decrease absorption of levothyroxine, such as soybean infant formula, should not be used for administering levothyroxine sodium tablets. (see PRECAUTIONS , Drug-Food Interactions ).

Newborns

The recommended starting dose of levothyroxine sodium in newborn infants is 1015 mcg/kg/day. A lower starting dose (e.g., 25 mcg/day) should be considered in infants at risk for cardiac failure, and the dose should be increased in 46 weeks as needed based on clinical and laboratory response to treatment. In infants with very low (< 5 mcg/dL) or undetectable serum T4 concentrations, the recommended initial starting dose is 50 mcg/day of levothyroxine sodium.

Infants and Children

Levothyroxine therapy is usually initiated at full replacement doses, with the recommended dose per body weight decreasing with age (see TABLE 3). However, in children with chronic or severe hypothyroidism, an initial dose of 25 mcg/day of levothyroxine sodium is recommended with increments of 25 mcg every 24 weeks until the desired effect is achieved.

Hyperactivity in an older child can be minimized if the starting dose is one-fourth of the recommended full replacement dose, and the dose is then increased on a weekly basis by an amount equal to one-fourth the full recommended replacement dose until the full recommended replacement dose is reached.

Pregnancy may increase levothyroxine requirements (see PREGNANCY).

If this condition is treated, a lower levothyroxine sodium dose (e.g., 1 mcg/kg/day) than that used for full replacement may be adequate to normalize the serum TSH level. Patients who are not treated should be monitored yearly for changes in clinical status and thyroid laboratory parameters.

The target level for TSH suppression in these conditions has not been established with controlled studies. In addition, the efficacy of TSH suppression for benign nodular disease is controversial. Therefore, the dose of Levoxyl used for TSH suppression should be individualized based on the specific disease and the patient being treated.

In the treatment of well differentiated (papillary and follicular) thyroid cancer, levothyroxine is used as an adjunct to surgery and radioiodine therapy. Generally, TSH is suppressed to <0.1 mU/L, and this usually requires a levothyroxine sodium dose of greater than 2 mcg/kg/day. However, in patients with high-risk tumors, the target level for TSH suppression may be <0.01 mU/L.

In the treatment of benign nodules and nontoxic multinodular goiter, TSH is generally suppressed to a higher target (e.g., 0.10.5 mU/L for nodules and 0.51.0 mU/L for multinodular goiter) than that used for the treatment of thyroid cancer. Levothyroxine sodium is contraindicated if the serum TSH is already suppressed due to the risk of precipitating overt thyrotoxicosis (see CONTRAINDICATIONS , WARNINGS and PRECAUTIONS ).

Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism, and may result in unpredictable absorption of levothyroxine sodium from the gastrointestinal tract. Therefore, oral thyroid hormone drug products are not recommended to treat this condition. Thyroid hormone products formulated for intravenous administration should be administered.

NDC 60793-850-01

Pfizer

Levoxyl®
(levothyroxine
sodium tablets, USP)
tablets

25 mcg

100 Tablets
Rx only

NDC 60793-857-01

Pfizer

Levoxyl®
(levothyroxine
sodium tablets, USP)
tablets

137 mcg

100 Tablets
Rx only

NDC 60793-859-01

Pfizer

Levoxyl®
(levothyroxine
sodium tablets, USP)
tablets

175 mcg

100 Tablets
Rx only

Get emergency medical help if you have signs of an allergic reaction to Levoxyl: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• fast or irregular heart rate;

• chest pain, feeling short breath;

• fever, hot flashes, sweating;

• feeling unusually cold;

• weakness, tiredness, sleep problems (insomnia);

• memory problems, feeling depressed or irritable;

• muscle aches;

• dryness of your skin or hair, hair loss;

• changes in your menstrual periods; or

• vomiting, diarrhea, appetite changes, weight changes.

Certain side effects may be more likely in older adults.

Common Levoxyl side effects may include:

• leg cramps, muscle weakness;

• headache;

• feeling nervous or irritable;

• diarrhea; or

• skin rash, mild hair loss.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Many other medicines can be affected by your thyroid hormone levels. Other medicine may also increase or decrease the effects of Levoxyl.

Many drugs can interact with levothyroxine and not all possible interactions are listed in this medication guide.

Tell your doctor about all medications you use, start using, or stop using during your treatment with Levoxyl. This includes prescription, over-the-counter, vitamin, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.