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Levothyroxine

    Brands

    DEA Class; Rx

    Common Brand Names; Synthroid, Levoxyl, Levo T, Tirosint, Tirosint-SOL, Unithroid, Thyquidity, Levolet

    • Thyroid Products

    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

    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.

    For the treatment of myxedema coma.
    As an adjunct to surgery and radioiodine (RAI) therapy in the management of well-differentiated thyroid cancer.
    For use as hormonal replacement therapy for organ preservation in brain dead donors before organ procurement.
    For the treatment of subclinical hypothyroidism.

    Hypersensitivity to thyroid hormone or other ingredients

    Uncorrected adrenal insufficiency

    • 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

    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

    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

    Narrow therapeutic index; dosage must be individualized.

    Adults

    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.

    Geriatric

    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

    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.

    Children

    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).

    Infants

    Individualize dosage.

    Neonates

    Individualize dosage.

    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