A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Unithroid Warnings, Precautions, Pregnancy, Nursing, Abuse - levothyroxine Sodium
Unithroid Warnings, Precautions, Pregnancy, Nursing, Abuse - levothyroxine Sodium
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WARNINGS
WARNING: Thyroid hormones, including UNITHROID, either
alone or with other therapeutic agents, should not be used for the treatment
of obesity. In euthyroid patients, doses within the range of daily hormonal
requirements are ineffective for weight reduction. Larger doses may produce
serious or even life threatening manifestations of toxicity, particularly
when given in association with sympathomimetic amines such as those used
for their anorectic effects.
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Levothyroxine sodium should not be used in the treatment of
male or female infertility unless this condition is associated with hypothyroidism.
PRECAUTIONS
General
Levothyroxine has a narrow therapeutic index. Regardless of
the indication for use, careful dosage titration is necessary to avoid the consequences
of over- or under-treatment. These consequences include, among others, effects
on growth and development, cardiovascular function, bone metabolism, reproductive
function, cognitive function, emotional state, gastrointestinal function, and
on glucose and lipid metabolism.
Effects on bone mineral density—In women, long-term
levothyroxine sodium therapy has been associated with decreased bone mineral
density, especially in postmenopausal women on greater than replacement doses
or in women who are receiving suppressive doses of levothyroxine sodium. Therefore,
it is recommended that patients receiving levothyroxine sodium be given the
minimum dose necessary to achieve the desired clinical and biochemical response.
Patients with underlying cardiovascular disease—Exercise
caution when administering levothyroxine to patients with cardiovascular disorders
and to the elderly in whom there is an increased risk of occult cardiac disease.
In these patients, levothyroxine therapy should be initiated at lower doses
than those recommended in younger individuals or in patients without cardiac
disease (see PRECAUTIONS
, Geriatric
Use and DOSAGE AND ADMINISTRATION).
If cardiac symptoms develop or worsen, the levothyroxine dose should be reduced
or withheld for one week and then cautiously restated at a lower dose. Overtreatment
with levothyroxine sodium may have adverse cardiovascular effects such as an
increase in heart rate, cardiac wall thickness, and cardiac contractility and
may precipitate angina or arrhythmias. Patients with coronary artery disease
who are receiving levothyroxine therapy should be monitored closely during surgical
procedures, since the possibility of precipitating cardiac arrhythmias may be
greater in those treated with levothyroxine. Concomitant administration of levothyroxine
and sympathomimetic agents to patients with coronary artery disease may precipitate
coronary insufficiency.
Patients with autonomous thyroid tissue—Exercise caution
when administering levothyroxine to patients with autonomous thyroid tissue
in order to prevent precipitation of thyrotoxicosis.
Associated endocrine disorders
Hypothalamic/pituitary hormone deficiencies—In patients with
secondary or tertiary hypothyroidism, additional hypothalamic/pituitary hormone
deficiencies should be considered, and, if diagnosed, treated (see PRECAUTIONS
,
Autoimmune polyglandular syndrome for adrenal insufficiency).
Autoimmune polyglandular syndrome—Occasionally, chronic autoimmune
thyroiditis may occur in association with other autoimmune disorders such as
adrenal insufficiency, pernicious anemia, and insulin-dependent diabetes mellitus.
Patients with concomitant adrenal insufficiency should be treated with replacement
glucocorticoids prior to initiation of treatment with levothyroxine sodium.
Failure to do so may precipitate an acute adrenal crisis when thyroid hormone
therapy is initiated, due to increased metabolic clearance of glucocorticoids
by thyroid hormone. Patients with diabetes mellitus may require upward adjustments
of their antidiabetic therapeutic regimens when treated with levothyroxine (see
PRECAUTIONS
, Drug
Interactions).
Other associated medical conditions
Infants with congenital hypothyroidism appear to be at increased
risk for other congenital anomalies, with cardiovascular anomalies (pulmonary
stenosis, atrial septal defect, and ventricular septal defect,) being the most
common association.
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