INDICATIONS
Thyroid hormone drugs are indicated:
1. As replacement or supplemental therapy in patients
with hypothyroidism of any etiology, except transient
hypothyrodism during the recovery phase of subacute thyroiditis.
This category includes cretinism, myxedema and ordinary
hypothyroidism in patients of any age (pediatric patients,
adults, the elderly) or state (including pregnancy); primary
hypothyroidism resulting from functional deficiency, primary
atrophy, partial or total absence of thyroid gland, or
the effects of surgery, radiation, or drugs, with or without
the presence of goiter and secondary (pituitary) or tertiary
(hypothalamic) hypothyroidism (see WARNINGS).
2. As pituitary thyroid-stimulating hormone (TSH) suppressants,
in the treatment or prevention of various types of euthyroid
goiters, including thyroid nodules subacute or chronic
lymphocytic thyroiditis (Hashimoto's) and multinodular
goiter.
3. As diagnostic agents in suppression tests to differentiate
suspected mild hyperthyroidism or thyroid gland autonomy.
Cytomel (liothyronine sodium) Tablets can be used in
patients allergic to desiccated thyroid or thyroid extract
derived from pork or beef.
DOSAGE AND ADMINISTRATION
The dosage of thyroid hormones is determined by the indication
and must in every case be individualized according to
patient response and laboratory findings.
Cytomel (liothyronine sodium) Tablets are intended for
oral administration once-a-day dosage is recommended.
Although liothyronine sodium has a rapid cutoff, its metabolic
effects persist for a few days following discontinuance.
Mild Hypothyroidism: Recommended standing
dosage is 25 mcg daily. Daily dosage then may be increased
by up to 25 mcg every 1 or 2 weeks. Usual maintenance
dose is 25 to 75 mcg daily.
The rapid onset and dissipation of action of liothyronine
sodium (T3) as compared with levothyroxine sodium (T4),
has led some clinicians to prefer its use in patients
who might be more susceptible to the untoward effects
of thyroid medication. However, the wide swings in serum
T3 levels that follow its administration and the possibility
of more pronounced cardiovascular side effects tend to
counterbalance the stated advantages.
Cytomel (liothyronine sodium) Tablets may be used in
preference to levothyroxine (T4) during radioisotope scanning
procedures, since induction of hypothyroidism in those
cases is more abrupt and can be of shorter duration. It
may also be preferred when impairment of peripheral conversion
of T4 to T3 is suspected.
Myxedema: Recommended starting dosage
is 5 mcg daily. This may be increased by 5 to 10 mcg daily
every 1 or 2 weeks. When 25 mcg daily is reached dosage
may be increased by 5 to 25 mcg every 1 or 2 weeks until
a satisfactory therapeutic response is attained. Usual
maintenance dose is 50 to 100 mcg daily.
Myxedema Coma: Myxedema coma is usually
precipitated in the hypothyroid patient of long standing
by intercurrent illness or drugs such as sedatives and
anesthetics and should be considered a medical emergency.
An intravenous preparation of liothyronine sodium is
marketed by Jones Medical Industries under the trade name
Triostat™ for use in myxedema coma/precoma.
Congenital Hypothyroidism: Recommended
starting dosage is 5 mcg daily, with a 5 mcg increment
every 3 to 4 days until the desired response is achieved.
Infants a few months old may require only 20 mcg daily
for maintenance. At 1 year 50 mcg daily may be required.
Above 3 years, full adult dosage may be necessary (see
PRECAUTIONS: Pediatric Use).
Simple (non-toxic) Goiter: Recommended
starting dosage is 5 mcg daily. This dosage may be increased
by 5 to 10 mcg daily every 1 or 2 weeks. When 25 mcg daily
is reached dosage may be increased every week or two by
12.5 or 25 mcg. Usual maintenance dosage is 75 mcg daily.
In the elderly or in pediatric patients, therapy should
be started with 5 mcg daily and increased only by 5 mcg
increments at the recommended intervals.
When switching a patient to Cytomel (liothyronine sodium)
Tablets from thyroid L-thyroxine or thyroglobulin, discontinue
the other medication, initiate Cytomel at a low dosage,
and increase gradually according to the patient's response.
When selecting a starting dosage, bear in mind that this
drug has a rapid onset of action, and that residual effects
of the other thyroid preparation may persist for the first
several weeks of therapy.
Thyroid Suppression Therapy: Administration
of thyroid hormone in doses higher than those produced
physiologically by the gland results in suppression of
the production of endogenous hormone. This is the basis
for the thyroid suppression test and is used as an aid
in the diagnosis of patients with signs of mild hyperthyroidism
in whom baseline laboratory tests appear normal or to
demonstrate thyroid gland autonomy in patients with Graves'
ophthalmopathy 131I uptake is determined before and after
the administration of the exogenous hormone. A 50% or
greater suppression of uptake indicates a normal thyroid-pituitary
axis and thus rules out thyroid gland autonomy.
Cytomel (liothyronine sodium) Tablets are given in doses
of 75 to 100 mcg/day for 7 days and radioactive iodine
uptake is determined before and after administration of
the hormone. If thyroid function is under normal control,
the radioiodine uptake will drop significantly after treatment.
Cytomel (liothyronine sodium) Tablets should be administered
cautiously to patients in whom there is a strong suspicion
of thyroid gland autonomy, in view of the fact that the
exogenous hormone effects will be additive to the endogenous
source.
HOW SUPPLIED
Cytomel (liothyronine sodium) Tablets:
5 mcg in bottles of 100;
25 mcg in bottles of 100; and
50 mcg in bottles of 100.
5 mcg 100's: NDC 52604-3414-1
25 mcg 100's: NDC 52604-3416-1
50 mcg 100's: NDC 52604-3417-1
Store between 15° and 30°C (59° and 86°F).
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