How much levothyroxine can you give a day?
Initially, 5 to 8 mcg/kg/day IV or IM in patients initiating levothyroxine who are unable to take oral doses. In patients already taking an oral dose of levothyroxine who require parenteral administration, give 50% to 75% of the oral dose IV or IM once daily. Use TSH measurements to ensure proper dose adjustments.
Can levothyroxine sodium for injection be given IV?
Levothyroxine Sodium for Injection can be used intravenously (IV) whenever a rapid onset of effect is critical, and either IV or intramuscularly (IM) in hypothyroid patients whenever the oral route is precluded for long periods of time. Levothyroxine Sodium for Injection by IM or IV routes can be substituted for the oral dosage form ...
What is the half life of levothyroxine sodium injection?
Levothyroxine Sodium for Injection produces a predictable increase in the reservoir level of hormone with a seven day half-life. This usually precludes the need for multiple injections but continued daily administration of lesser amounts parenterally should be maintained until the patient is fully capable of accepting a daily oral dose.
How much levothyroxine can you give a coma?
In myxedema coma or stupor, without concomitant severe heart disease, 200 to 500 mcg of Levothyroxine Sodium for Injection may be administered IV as a solution containing 100 mcg/mL. DO NOT ADD TO OTHER IV FLUIDS.
Is levothyroxine given IV push?
INDICATIONS AND USAGE Levothyroxine Sodium for Injection can be used intravenously (IV) whenever a rapid onset of effect is critical, and either IV or intramuscularly (IM) in hypothyroid patients whenever the oral route is precluded for long periods of time.
How can levothyroxine be administered?
Levothyroxine comes as a tablet and a capsule to take by mouth. It usually is taken once a day on an empty stomach, 30 minutes to 1 hour before breakfast. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand.
How fast can I take thyroid medication?
You should start to feel better a few days after you begin taking medicine. But it may take a few months for your thyroid hormone levels to get back to normal. If your levels get better, but you still have symptoms like fatigue and weight gain, your doctor may need to change your treatment.
Why do you have to wait 30 minutes after taking thyroid medication?
The absorption of levothyroxine in the gut is decreased when taking the hormone at the same time as calcium, iron and some foods and other drugs. Because of this, patients are usually instructed to take levothyroxine on an empty stomach 30-60 minutes before food intake to avoid erratic absorption of the hormone.
When do you give IV levothyroxine?
An initial intravenous loading dose of Levothyroxine Sodium for Injection between 300 to 500 mcg, followed by once daily intravenous maintenance doses between 50 and 100 mcg, should be administered, as clinically indicated, until the patient can tolerate oral therapy.
What should you assess before giving levothyroxine?
Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness. Assess episodes of angina pectoris at rest and during exercise.
Why does a patient starting on levothyroxine need to wait 4 6 weeks before repeating labs to check for therapeutic response to the drug?
Because of the half-life it takes about 3.5 weeks for serum T4 levels to reach a steady state, therefore repeat laboratory testing is usually done about 4 weeks after initial treatment and/or dosage adjustment.
What is the highest level of levothyroxine?
Levothyroxine comes in 12.5 microgram, 25 microgram, 50 microgram, 75 microgram and 100 microgram tablets.
How quickly does levothyroxine lower TSH?
Monitoring thyroid function during levothyroxine replacement TSH can take up to 4 months to normalize, even when starting on a full dose replacement regimen, due to thyrotroph hyperplasia. It is recommended that the TSH is measured 6–8 weeks after initiation of, or a change in levothyroxine dose.
Why do you have to drink a full glass of water with levothyroxine?
The Levoxyl-branded tablet may rapidly swell and disintegrate, and cause choking or gagging if it becomes stuck in your throat. Take with a full glass of water, but talk with your doctor should you have difficulty swallowing it.
What happens if your thyroid medication is too high?
Symptoms of overmedication can include anxiety, diarrhea, depression, elevated heartbeat, elevated blood pressure, fatigue, irritability, difficulty concentrating, difficulty sleeping, being overheated, and unprompted or unintentional weight loss.
What is the half life of levothyroxine?
Pharmacologic and Physiologic Considerations. Levothyroxine has a 7-day half-life. About 80% of the hormone is absorbed relatively slowly and equilibrates rapidly in its distribution volume, so large postabsorptive perturbations in fT4 levels are avoided.
Usual Adult Dose For Hypothyroidism
-HYPOTHYROIDISM IN ADULTS AND IN CHILDREN IN WHOM GROWTH AND PUBERTY ARE COMPLETE:Therapy may begin at full replacement doses in otherwise healthy...
Usual Adult Dose For TSH Suppression
TSH SUPPRESSION IN WELL-DIFFERENTIATED THYROID CANCER AND THYROID NODULES:-The target level for TSH suppression in these conditions has not been es...
Usual Adult Dose For Myxedema Coma
Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism, and may result in unpredictable absorption of t...
Usual Geriatric Dose For Hypothyroidism
ELDERLY PATIENTS WITH CARDIAC DISEASE:-Initial dose: 12.5 to 25 mcg orally per day, with gradual dose increments at 4 to 6 week intervals-The dose...
Usual Pediatric Dose For Hypothyroidism
CONGENITAL OR ACQUIRED HYPOTHYROIDISM:-Neonatal: 10 to 15 mcg/kg/day; if patient is at risk for development of cardiac failure, begin with a lower...
How to administer levothyroxine?
Levothyroxine oral solution may be administered in water or directly into the mouth.#N#To administer in water, squeeze the contents of 1 single unit-dose ampule into a glass or cup containing water and stir . Do NOT dilute with any liquid other than water.#N#The preparation should be administered immediately and consumed in its entirety to ensure all of the dose is received. Rinse the glass or cup with additional water and drink the contents to ensure the entire dose is taken.#N#To administer directly (without water), either squeeze it into the mouth or onto a spoon and immediately consume.#N#Storage: Store unopened oral solution ampules in the original container (pouch) at 77 degrees F (25 degrees C); excursions are permitted to 59 to 86 degrees F (15 to 30 degrees C). Discard any unused ampules 15 days after opening the pouch.
What is the best treatment for hypothyroidism?
Guidelines recommend levothyroxine (T4) as the generally the preferred treatment for hypothyroidism in adults, adolescents, children, infants, and neonates. [22902] [60310] However, there are case reports of patients whose TSH values could only be normalized with a combination of both T4 and T3 (liothyronine). Therefore, treatment must be individualized. Closely monitor all patients to avoid undertreatment or overtreatment, which may produce hyperthyroidism or iatrogenic thyrotoxicosis. [60310] The management of hypothyroidism in pediatric patients is similar to adults, but there are unique differences based on the requirement of normal thyroid function for neurocognitive development as well as growth and development. There are increased weight-based requirements for thyroid hormone replacement in children and adolescents compared to adults. As the child advances through the pediatric age into adulthood, thyroid hormone replacement doses decrease, with a transition to the average adult dose once endocrine maturation is complete. [60310] Careful monitoring for growth, weight, epiphyseal closure and maturation, and clinical status are important in all pediatric patients. In patients with congenital hypothyroidism, closely monitor infants during the first 2 weeks of thyroid hormone therapy for cardiac overload, arrhythmias, and aspiration from avid suckling. [33700] [43942] [43943] [53562] [61764] Closely monitor all pediatric patients to avoid undertreatment or overtreatment. Undertreatment may have harmful effects on intellectual development and linear growth. Overtreatment is associated with craniosynostosis in infants, may adversely affect the tempo of brain maturation, and may accelerate the bone age and result in premature epiphyseal closure and compromised adult stature. In children with acquired hypothyroidism, undertreatment may result in poor school performance due to impaired concentration and slowed mentation and in reduced adult height. Overtreatment may accelerate the bone age and result in premature epiphyseal closure and compromised adult stature. Treated children may manifest a period of catch-up growth, which may be adequate in some cases to normalize adult height. In children with severe or prolonged hypothyroidism, catch-up growth may not be adequate to normalize adult height. [33700] [43942] [43943] [53562] [61764]
Is levothyroxine safe for breast feeding?
Levothyroxine is the preferential drug to treat hypothyroidism in most patients and is considered compatible with breast-feeding. [27500] [60310] Changes in thyroid status in the post-partum period may require careful monitoring and maternal dosage adjustment. In general, adequate thyroid status is needed to maintain normal lactation, and there is no reason maternal replacement should be halted due to lactation alone. Limited published studies report that levothyroxine is present in human milk. There is insufficient information to determine the effects of levothyroxine on the breastfed infant and no available information on the effects of levothyroxine on milk production. However, thyroid hormones do not have a known tumorigenic potential and are not associated with reports of serious adverse reactions in nursing infants. [27500] [33700] [43942] [43943] [43952] [53562] [61764]
Can thyroid hormone be used during pregnancy?
Hypothyroidism that is diagnosed during pregnancy should be promptly treated. During pregnancy, thyroxine (T4) is thought to be crucial for fetal brain development, and guidelines recommend that levothyroxine be the preferred drug for treatment of hypothyroidism in the pregnant patient. [60310] The clinical experience to date does not indicate any adverse fetal effect when thyroid hormones such as levothyroxine are administered during pregnancy. Thyroid replacement therapy to hypothyroid women should not be discontinued during pregnancy. Thyroid hormones undergo minimal placental transfer. Measure TSH and free-T4 as soon as pregnancy is confirmed and, at a minimum, during each trimester to gauge the adequacy of thyroid replacement dosage since during pregnancy as thyroid requirements may increase. For patients with serum TSH above the normal trimester-specific range, increase the dose of thyroid hormone and measure TSH every 4 weeks until a stable dose is reached and serum TSH is within the normal trimester-specific range. Immediately after obstetric delivery, dosage should return to the pre-pregnancy dose, monitor thyroid function tests TSH at 4 to 8 weeks postpartum to assess for needed adjustments. [33700] [43942] [43943] [53562] [61764]
Is levothyroxine a cardiostimulator?
All levothyroxine dosage formulations are cardiostimulatory and should be used with great caution in patients with angina pectoris, uncontrolled hypertension, cardiac arrhythmias, CAD, a previous history of acute myocardial infarction, or current acute myocardial infarction.
Is levothyroxine excreted by the kidney?
Levothyroxine is known to be substantially excreted by the kidney, and the risk of toxic reactions may be increased in patients with renal impairment. Care should be used during initial dose selection. Dosing is individualized to achieve therapeutic goals.
Is levothyroxine a T4?
Used orally for hypothyroidism of most etiologies in adult and pediatric patients; used intravenously as a preferred treatment for myxedema coma. Replacement with T4 is alone sufficient in most individuals; levothyroxine is, therefore, the preferred replacement in all ages.
How much TSH should be suppressed?
TSH levels should generally be suppressed to below 0.1 IU/L#N#-A dose greater than 2 mcg/kg orally once a day is usually required to achieve this degree of suppression#N#Comments:#N#-Patients with high-risk tumors may target a greater level of TSH suppression, however, this is not well defined.#N#-This drug 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 may induce hyperthyroidism.#N#Use: As an adjunct to surgery and radioiodine therapy in the management of thyrotropin-#N#dependent well-differentiated thyroid cancer.
How much mcg/kg is needed for a newborn?
0 to 3 months: 10 to 15 mcg/kg orally once a day#N#3 to 6 months: 8 to 10 mcg/kg orally once a day#N#6 to 12 months: 6 to 8 mcg/kg orally once a day#N#1 to 5 years: 5 to 6 mcg/kg orally once a day#N#6 to 12 years: 4 to 5 mcg/kg orally once a day#N#12 years or older and incomplete growth and puberty: 2 to 3 mcg/kg orally once a day#N#12 years or older with growth and puberty complete: 1.6 mcg/kg orally once a day#N#Newborns (0 to 3 months) at Risk for Cardiac Failure: Consider a lower initial dose; increase dose every 4 to 6 weeks as needed based on clinical and laboratory response#N#Pediatric Patients at Risk for Hyperactivity: Initial dose should be one-fourth the recommended full replacement dose; increase weekly by one-fourth to the full recommended replacement dose#N#Comments:#N#-Dose should be individualized with regular monitoring of clinical status and laboratory parameters; peak effect may not be attained for 4 to 6 weeks.#N#-Not indicated for the treatment of hypothyroidism during the recovery phase of subacute thyroiditis.#N#-Co-administered food and concomitant medications may significantly affect absorption; take on an empty stomach and at least 4 hours before or after drugs known to interfere with levothyroxine absorption.#N#-The capsule formulation is indicated for patients 6 years or older as the capsule should be swallowed whole; see Other Comment/Administration Advice for specific administration instructions including instructions for those unable to swallow intact tablets.#N#Use: For the treatment of congenital or acquired hypothyroidism.
How much mcg/kg for 12 year olds?
12 years or older and incomplete growth and puberty: 2 to 3 mcg/kg orally once a day. 12 years or older with growth and puberty complete: 1.6 mcg/kg orally once a day. Newborns (0 to 3 months) at Risk for Cardiac Failure: Consider a lower initial dose; increase dose every 4 to 6 weeks as needed based on clinical and laboratory response.
Is thyroxine overdosage?
Although measurements of normal blood levels of thyroxine in patients on oral replacement regimens frequently coincide with clinical impressions of normal thyroid status, higher than normal levels occur occasionally and should not be considered evidence of overdosage per se.
Can levothyroxine sodium be used for oral ingestion?
Levothyroxine Sodium for Injection by IM or IV routes can be substituted for the oral dosage form when ingestion of tablets is precluded for long periods of time. Important: The initial parenteral dosage should be approximately one half of the previously established oral dosage of levothyroxine sodium tablets.
Can you take IV levothyroxine without weighing the risks?
Under such circumstances, IV therapy should not be undertaken without weighing the alternative risks of the myxedema coma and the cardiovascular disease. clinical judgment in this situation may dictate smaller IV doses of Levothyroxine Sodium for Injection.
Why do I take L-T 4?
This may be due to taking L-T 4 at the same time as food, calcium, iron or certain drugs that decrease the absorption of the thyroid hormone or due to GI problems that prevent the usual absorption of the hormone. However, varying dose requirements may also be due to missing doses on an intermittent or regular basis.
What is the best test to determine if your thyroid is functioning properly?
TSH: thyroid stimulating hormone – produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally. Hypothyroidism is a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone.
Indications and Usage For Levothyroxine Injection
Dosage Forms and Strengths
- Levothyroxine Sodium Injection is clear, colorless solution supplied as: 1. 100 mcg per 5 mL (20 mcg per mL) single-dose vial
Warnings and Precautions
- Cardiac Adverse Reactions in the Elderly and in Patients with Underlying Cardiovascular Disease
Overtreatment with Levothyroxine Sodium Injection may cause arrhythmias, tachycardia, myocardial ischemia and infarction, or worsening of congestive heart failure and death, particularly in patients with cardiovascular disease and in elderly patients. Start with lower dose… - Acute Adrenal Crisis in Patients with Concomitant Adrenal Insufficiency
Chronic autoimmune thyroiditis, which can lead to myxedema coma, may occur in association with other autoimmune disorders such as adrenal insufficiency. Thyroid hormone increases metabolic clearance of glucocorticoids. Initiation of thyroid hormone therapy prior to initiating gl…
Adverse Reactions
- Adverse reactions associated with levothyroxine are primarily those of hyperthyroidism due to therapeutic overdosage [see Warnings and Precautions (5), Overdosage (10)]. They include the following: 1. General:fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating 2. Central nervous system:headache, hyperactivity, nervousness, anxiety, irritability, em…
Drug Interactions
- Drugs Known to Affect Thyroid Hormone Pharmacokinetics
Many drugs affect thyroid hormone pharmacokinetics and metabolism (e.g., synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to Levothyroxine Sodium Injection (see Tables 1-3). - Antidiabetic Therapy
Addition of levothyroxine to antidiabetic or insulin therapy may result in increased antidiabetic agent or insulin requirements. Careful monitoring of glycemic control is recommended.
Use in Specific Populations
- Pregnancy
Risk Summary There is no available data with use of Levothyroxine Sodium Injection in pregnant women. The clinical data in pregnant women treated with oral levothyroxine to maintain a euthyroid state have not reported increased rates of major birth defects, miscarriages, or advers… - Lactation
Risk Summary Published studies report that levothyroxine is present in human milk following the administration of oral levothyroxine. However, there is insufficient information to determine the effects of levothyroxine on the breastfed infant and no available information on the effects of le…
Overdosage
- The signs and symptoms of overdosage are those of hyperthyroidism [see Warnings and Precautions (5) and Adverse Reactions (6)].In addition, confusion and disorientation may occur. Cerebral embolism, shock, coma, and death have been reported. Reduce the Levothyroxine Sodium Injection dose or temporarily discontinue if signs or symptoms of overdosage occur. Init…
Levothyroxine Injection Description
- Levothyroxine Sodium Injection contains synthetic crystalline levothyroxine (T4) in sodium salt form. Levothyroxine sodium has an empirical formula of C15H10I4NNaO4, a molecular weight of 798.85 g/mol (anhydrous), and the following structural formula: Levothyroxine Sodium Injection is a sterile, preservative free, clear, colorless, sterile solution for intravenous administration availab…
Levothyroxine Injection - Clinical Pharmacology
- Mechanism of Action
Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. Triiodothyronine (T3) and levothyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. This hormone nuclear receptor complex activates ge… - Pharmacodynamics
Levothyroxine sodium is a synthetic T4 hormone that exerts the same physiologic effect as endogenous T4, thereby maintaining normal T4 levels when a deficiency is present.