A Game-Changer for Diabetes: Polymer Delivers Insulin Painlessly Through Skin
November 25, 2025
Free CME credits
Both our subscription plans include Free CME/CPD AMA PRA Category 1 credits.
Brand Name :
Synthroid, Levoxyl, Unithroid, Thyquidity, Levolet, Levo T, Tirosint
Synonyms :
Class :
thyroid disease and t4 releasing hormone
Brand Name :
Synthroid, Levoxyl, Unithroid, Thyquidity, Levolet, Levo T, Tirosint
Synonyms :
Class :
thyroid disease and t4 releasing hormone
Capsule:
(175, 20, 13, 25, 50, 75, 88, 100, 112, 125, 137, 150) mcg
Solution, Intravenous:
100 mcg/5 ml (5 ml)
Solution, Intravenous [preservative free]:
(100, 200, 500) mcg/5 ml (5 ml)
Solution:
(37.5, 44, 62.5) mcg/ml (1 ml)
Solution, Oral:
Thyquidity: 100 mcg/5 ml
Tirosint: (13, 25, 50, 75, 88, 100, 112, 137, 150, 175, 200) mcg/ml (1 ml)
Tablet, Oral, as sodium:
(25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200) mcg
300 - 500
mcg
Intravenous (IV)
once a day
Or 50-100 mcg once a day until patient can tolerate
1.7
mcg
Orally
once a day
Age: >50 years old or less than 50 years with CV disease
25-50 mcg orally once a day
Or 12.5-25 mcg every 6-8Week
Age: >50 years with CV disease
12.5-25 mcg orally once a day
Or 12.5-25 mcg for every 4-6weeks until the patient becomes euthyroid
Severe Hypothyroidism
12.5-25 mcg orally once a day
Subclinical Hypothyroidism
1 mcg/kg orally once a day
Dosage Forms and Strengths
Capsule:
(175, 20, 13, 25, 50, 75, 88, 100, 112, 125, 137, 150) mcg
Solution, Intravenous:
100 mcg/5 ml (5 ml)
Solution, Intravenous [preservative free]:
(100, 200, 500) mcg/5 ml (5 ml)
Solution:
(37.5, 44, 62.5) mcg/ml (1 ml)
Solution, Oral:
Thyquidity: 100 mcg/5 ml
Tirosint: (13, 25, 50, 75, 88, 100, 112, 137, 150, 175, 200) mcg/ml (1 ml)
Tablet, Oral, as sodium:
(25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200) mcg
Age1-3 months
10-15 mcg/kg orally once a day
5-7.5 mcg/kg IV/IM once a day
For patients' risk of heart failure: 25 mcg/day
start a higher dose (50 mcg/day) as initial if serum T4 is lower than five mcg/dL
Age 3-6 months
8-10 mcg/kg orally OR 25-50 mcg orally once a day
4-7.5 mcg/kg IV/IM once a day
Age: 6-12 months
6-8 mcg/kg orally OR 50-75 mcg orally once a day
3-6 mcg/kg IV/IM once a day
Age: 1-5 years
5-6 mcg/kg orally, OR 75-100 mcg orally once a day
2.5-4.5 mcg/kg IV/IM once a day
Age: 6-12 years
4-5 mcg/kg orally OR 100-125 mcg orally once a day
2-3.75 mcg/kg IV/IM once a day
Age: >12 years
2-3 mcg/kg orally, OR 150 mcg orally once a day
1-2.25 mcg/kg IV/IM once a day
may diminish concentration of serum when combined with levothyroxine
may diminish concentration of serum when combined with levothyroxine
may diminish concentration of serum when combined with levothyroxine
may diminish concentration of serum when combined with levothyroxine
Sucralfate may diminish the serum concentration of levothyroxin
may diminish the serenum concentration of iron preparations
may diminish the serum concentration when combined with levothyroxine
may diminish the serum concentration of magnesium salts
may have a decreased serum concentration when combined with levothyroxine
may have a decreased serum concentration when combined with levothyroxine
may have a decreased serum concentration when combined with levothyroxine
may have a decreased serum concentration when combined with levothyroxine
may have a decreased serum concentration when combined with levothyroxine
aluminum hydroxide/magnesium hydroxide
may diminish the serum concentration of magnesium sulfate
may enhance the adverse/toxic effect of sympathomimetics
may enhance the adverse/toxic effect of sympathomimetics
may enhance the adverse/toxic effect of sympathomimetics
may enhance the adverse/toxic effect of sympathomimetics
may enhance the adverse/toxic effect of sympathomimetics
may have an increasingly adverse effect when combined with sympathomimetics
may have an increasingly adverse effect when combined with sympathomimetics
trimagnesium citrate anhydrous
The presence of trimagnesium citrate anhydrous inhibits the gastrointestinal absorption of levothyroxine, leading to decreased levels
It may diminish the levels when combined with sodium polystyrene sulfonate by inhibiting gastrointestinal absorption
It may enhance the serum concentration when combined with CYP3A4 Substrates
acetaminophen IV/ibuprofen IV (Pending FDA Approval)
It may enhance the serum concentration when combined with CYP3A4 Substrates
It may enhance the serum concentration when combined with CYP3A4 Substrates
It may enhance the serum concentration when combined with CYP3A4 Substrates
It may enhance the serum concentration when combined with CYP3A4 Substrates
levothyroxine: they may increase the CNS depressant effect of CNS Depressants
levothyroxine: they may increase the CNS depressant effect of CNS Depressants
levothyroxine: they may increase the CNS depressant effect of CNS Depressants
levothyroxine: they may increase the CNS depressant effect of CNS Depressants
levothyroxine: they may increase the CNS depressant effect of CNS Depressants
When levothyroxine is used together with adenine, this leads to a reduction in the levothyroxine’s metabolism
may increase GI absorption of levothyroxine and decrease serum levels
may increase the toxic effect of sympathomimetics
may increase the toxic effect of sympathomimetics
may diminish the serum concentration when combined with levothyroxine
the vasoconstricting activity of felypressin may be increased
Levothyroxine (T4) is a synthetic form of the endogenous hormone thyroxine that is used in the management of hypothyroidism. Under normal circumstances, the hypothalamus initiates the release of the thyroid-stimulating hormone TSH which in turn stimulates the thyroid gland to produce the T4 and T3 hormones. T4 is then converted to the active hormone T3 which then will bind to nuclear receptors to affect metabolism. Levothyroxine can be used to replenish the absent T4 in hypothyroidism to help the body regain normal metabolism.
Adverse drug reactions:
Frequency Not Defined
Choking sensation
Cramps
Diarrhea
Nervousness
Emotional lability
Headache
Heat intolerance
Insomnia
Myasthenia
Pseudotumor cerebri
Fever
Myocardial infarction
Palpitations
Arrhythmias
Tachycardia
Tremor
Alopecia
Weight loss
Infertility
Dyspnea
Decreased bone mineral density
Angina pectoris
Arthralgia
Congestive heart failure
Flushing
Increased pulse
None
Thyrotoxicosis
Hypersensitivity
Acute myocardial infarction
Adrenal insufficiency
Caution
Diabetes
Osteoporosis
Pregnancy consideration: AU TGA pregnancy category: A
US FDA pregnancy category: Not Assigned
Lactation: Excretion of the drug in human breast milk is known
Pregnancy category:
Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.
Category B: there was no evidence of risk to the fetus in animal studies and there were not enough studies on pregnant women.
Category C: there was evidence of risk of adverse effects in animal reproduction studies and no adequate evidence in human studies must take care of potential risks in pregnant women.
Category D: data with sufficient evidence of human fetal risk from various platforms but despite the potential risk and used only in emergency cases for potential benefits.
Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.
Category N: There is no data available for the drug under this category
It is a synthetic form of natural thyroid hormones thyroxine with minor activity of triiodothyronine and used in hypothyroidism. Once absorbed in the small intestine, it is converted to the active hormone, triiodothyronine (T3), which combines with nuclear receptors to control metabolism, growth, and development. Levothyroxine has a prolonged half-life of 6-7 days and can thus be given as a single daily dose; its metabolism occurs mainly in the liver.
IV Preparation with Reconstitution lyophilized powder:
Until a clear solution is achieved, add 5 mL of a 0.9% NaCl vial containing 200 or 500 mcg and shake.
Reconstituted solutions should be used right away, and any leftovers should be thrown away.
A solution containing approximately 100 mcg/mL can be made by adding 2 mL of 0.9% NaCl to a vial containing 200 mcg.
Avoid mixing with intravenous infusion solutions.
For oral administration
Take the tablets with a full glass of water, ideally 30 to 1 hour before breakfast, on an empty stomach to prevent gagging or choking.
When frequently delivering within an hour of specific foods that may impair absorption, assess the need for dose modifications.
Levothyroxine should not be administered with meals that reduce absorption.
Levothyroxine should be taken orally at least four hours apart from medications that may affect absorption.
Patient information leaflet
Generic Name: levothyroxin
Why do we use levothyroxin?
Levothyroxine is a synthetic levo-isomer of the thyroid hormone thyroxine that is used to treat hypothyroidism and other deficient conditions.
For primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism, levothyroxine is recommended as a replacement treatment.
It is also recommended as a treatment for thyrotropin-dependent well-differentiated thyroid carcinoma in addition to surgery and radioiodine therapy.
Both our subscription plans include Free CME/CPD AMA PRA Category 1 credits.
On course completion, you will receive a full-sized presentation quality digital certificate.
A dynamic medical simulation platform designed to train healthcare professionals and students to effectively run code situations through an immersive hands-on experience in a live, interactive 3D environment.
When you have your licenses, certificates and CMEs in one place, it's easier to track your career growth. You can easily share these with hospitals as well, using your medtigo app.
