Classes
DEA Class; Rx
Common Brand Names; Synthroid, Levoxyl, Levo T, Tirosint, Tirosint-SOL, Unithroid, Thyquidity, Levolet
- Thyroid Products
Description
Oral and parenteral synthetic levo-isomer of the thyroid hormone thyroxine (T4); standardization of hormonal content in products provides consistent dosing
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
Indications
Indicted for the treatment of hypothyroidism of any etiology, except during the recovery phase of subacute thyroiditis; used as a replacement in primary (thyroidal), secondary (pituitary), tertiary (hypothalamic), congenital (cretinism), or acquired hypothyroidism.
Contraindications
Hypersensitivity to thyroid hormone or other ingredients
Uncorrected adrenal insufficiency
Adverse Effects
- Angina pectoris
- Arthralgia
- Congestive heart failure
- Flushing
- Increased pulse
- Myocardial infarction
- Palpitations
- Arrhythmias
- Cramps
- Diarrhea
- Nervousness
- Anxiety
- Choking sensation
- Emotional lability
- Headache
- Heat intolerance
- Insomnia
- Myasthenia
- Pseudotumor cerebri
- Alopecia
- Weight loss
- Infertility
- Dyspnea
- Fever
- Tachycardia
- Tremor
- Decreased bone mineral density
Warnings
Proper dose titration and careful monitoring is critical to prevent persistence of hypothyroidism or development of hyperthyroidism
Generally, do not use levothyroxine sodium preparations interchangeably, owing to narrow therapeutic index; check for bioequivalence if switching brands/generics; if formulations are changed, monitor TSH and adjust dose if needed
Synthroid and Unithroid tabs contain lactose
Pregnancy and Lactation
xperience with levothyroxine use in pregnant women, including data from post-marketing studies, in pregnant women treated with oral levothyroxine to maintain euthyroid state, have not reported increased rates of major birth defects or miscarriages
Limited published studies report that levothyroxine is present in human milk
Maximum Dosage
Narrow therapeutic index; dosage must be individualized.
Doses more than 200 mcg/day PO are rarely needed. However, rare patients may require up to 300 mcg/day PO for treating hypothyroidism or thyroid cancer. Inadequate response to 300 mcg/day or more may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors.
Doses more than 200 mcg/day PO are rarely needed. However, rare patients may require up to 300 mcg/day PO for treating hypothyroidism or thyroid cancer. Inadequate response to 300 mcg/day or more may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors.
Adolescents in whom growth and puberty are complete: Doses rarely exceed 200 mcg/day PO. However, rare patients may require up to 300 mcg/day PO for treating hypothyroidism or thyroid cancer. Inadequate response to 300 mcg/day or more may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors.
Dosage must be individualized to age, weight, growth, and clinical status; if more than 3 years of age, adult dosages may be required (usual adult Max: 200 mcg/day PO).
Individualize dosage.
Individualize dosage.
How supplied
Levothyroxine Sodium
tablet (Levo-T, Levoxyl, Unithroid, generic)
25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 112mcg
125mcg, 137mcg, 150mcg, 175mcg, 200mcg, 300mcg
capsule (Tirosint, generic)
13mcg, 25mcg, 50mcg, 75mcg, 88mcg
100mcg, 112 mcg, 125mcg, 137 mcg, 150mcg
oral solution
Tirosint-SOL
13mcg/mL, 25mcg/mL, 37.5mcg/mL, 44mcg/mL, 50mcg/mL, 62.5mcg/mL
75mcg/mL, 88mcg/mL, 100mcg/mL, 112mcg/mL, 125mcg/mL, 137mcg/mL
150mcg/mL, 175mcg/mL, 200mcg/mL
Thyquidity
20mcg/mL
injection, lyophilized powder for reconstitution
100mcg/vial
200mcg/vial
500mcg/vial
injection, solution
100mcg/mL
