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Liothyronine sodium
(T
3)
Liothyronine sodium (Cytomel)
T
3 (Cytomel)
Liothyronine sodium
(lye-oh-
THIGH-roh-neen)
Pregnancy Category: A
Cytomel
Sodium-L-Triiodothyronine
Triostat
(Rx)
Classification:
Thyroid preparation
See Also:
See also
Thyroid Drugs
[.
]
Action/Kinetics:
Synthetic sodium salt of levoisomer of T
3. Has more predictable effects due to standard hormone content. From 15 to 37.5 mcg is equivalent to about 60 mg of desiccated thyroid. May be preferred when a rapid effect or rapidly reversible effect is required. Has a rapid onset, which may result in difficulty in controlling the dosage as well as the possibility of cardiac side effects and changes in metabolic demands. However, its short duration allows quick adjustment of dosage and helps control overdosage.
t
1/2: 24 hr for euthyroid clients, approximately 34 hr in hypothyroid clients, and approximately 14 hr in hyperthyroid clients.
Duration: Up to 72 hr. Is 99% protein bound.
Additional Contraindications:
Use in children with cretinism because there is some question about whether the hormone crosses the blood-brain barrier.
How Supplied:
Injection: 10 mcg/mL;
Tablet: 5 mcg, 25 mcg, 50 mcg
Dosage
?Tablets
Mild hypothyroidism.
Adults, individualized, initial: 25 mcg/day. Increase by 12.5-25 mcg q 1-2 weeks until satisfactory response has been obtained.
Usual maintenance: 25-75 mcg/day (100 mcg may be required in some clients). Use lower initial dosage (5 mcg/day) for the elderly, children, and clients with CV disease. Increase only by 5-mcg increments.
Myxedema.
Adults, initial: 5 mcg/day increased by 5-10 mcg/day q 1-2 weeks until 25 mcg/day is reached;
then, increase q 1-2 weeks by 12.5-50 mcg.
Usual maintenance: 50-100 mcg/day.
Simple (nontoxic) goiter.
Adults, initial: 5 mcg/day;
then, increase q 1-2 weeks by 5-10 mcg until 25 mcg/day is reached;
then, dose can be increased by 12.5-25 mcg/week until the maintenance dose of 50-100 mcg/day is reached (usual is 75 mcg/day).
T
3 suppression test.
75-100 mcg/day for 7 days followed by a repeat of the I
131 thyroid uptake test (a 50% or greater suppression of uptake indicates a normal thyroid-pituitary axis).
Congenital hypothyroidism.
Adults and children, initial: 5 mcg/day;
then, increase by 5 mcg/day q 3-4 days until the desired effect is achieved. Approximately 20 mcg/day may be sufficient for infants a few months of age while children 1 year of age may require 50 mcg/day. Children above 3 years may require the full adult dose.
?IV Only
Myxedema coma, precoma.
Adults, initial: 25-50 mcg. Base subsequent doses on continuous monitoring of client's clinical status and response. Doses should be given at least 4 hr, and no more than 12 hr, apart. Total daily doses of 65 mcg in initial days of therapy are associated with a lower incidence of mortality. In cases of known CV disease, give an initial dose of 10-20 mcg. |
