akn
Musclechemistry Member
Description:
Levothyroxine sodium is a synthetically ~anufactured
form of the natural thyroid hormone tetraiodothyronine
(T-4). Thyroid hormones are primarily responsible for
regulating the body's metabolic rate, and playa vital role in
the body's utilization of protein, fat, and carbohydrates.
Levothyroxine sodium is used medically to treat cases of
hypothyroidism, which is characterized by insufficient
natural production of thyroid hormones.This may manifest
itself with a number of symptoms including loss of energy,
lethargy, weight gain, hair loss, and changes in skin texture.
Levothyroxine sodium is considered a slow-acting
medication, and may take up to 4 to 6 weeks before full
therapeutic levels are reached in the blood. It is also the
most commonly prescribed thyroid medication in the
world, and is considered to be the standard form of
treatment for most cases of hypothyroidism.
The action of levothyroxine sodium is very similar to that of
the popular thyroid preparation Cytomel® (liothyronine
sodium). Cytomel® is slightly different in structure,
however, being a synthetic form of the thyroid hormone
triiodothyronine (T-3). A healthy individual with have
sufficient levels of both T-3 and T-4 thyroid hormones
present in their body. T-3 is considered the primary active
form of thyroid hormone, while T4 serves mainly as a
reserve for T3, exerting most of its metabolic activity via
conversion to T3 in peripheral tissues. T3 is regarded as
having an effect that is roughly four times stronger than
that of T-4 on a milligram-for-milligram basis. Likewise,
Cytomel® is considered to be a more potent form of
thyroid medication, both with regard to activity and side
effect potentiaI.
Levothyroxine sodium is valued by many drug-using
athletes and bodybuilders for its ability to stimulate the
metabolic rate and support the breakdown of body fat
stores. It is usually taken during a period of calorie
restriction ("cutting"), when the individual is focused on fat
loss or increasing muscle definition. It is often thought that
the use of thyroid drugs can support fat loss at a higher
level of caloric intake than would otherwise be possible
without the drugs, adding to their perceived value among
the communities. Anabolic steroids are generally used in
conjunction with these hormones, and many believe that
the metabolism boosting effect of these drugs may
produce faster gains in muscle mass. The drugs, however,
have yet to be widely proven or accepted for this purpose.
History:
Levothyroxine sodium was the first synthetic thyroid
medication to be sold in the U.S., and was first introduced
to market in 1955 by Flint Laboratories as Synthroid. The
drug has a long history of therapeutic use in the U.S. and
internationally, and for decades has been the most widely
prescribed medication for the treatment of hypothyroid.
The Synthroid brand has historically been the most
successful, with figures estimating that it retained 850/0 of
total levothyroxine sales and $600 million in annual
revenues (1990 estimates). In the bodybuilding and
athletic communities, however, the faster acting and more
powerful drug Cytomel (Iiothyronine sodium) is most
popular. Since Synthroid is weaker and slower acting,
athletes need to take the drug for a longer duration to
achieve similar results.
The Synthroid brand itself has a long and at times
controversial history.876 For many years after its inception
by Flint Laboratories, Synthroid enjoyed a virtual
monopoly on the levothyroxine sodium market. Generic
medications finally began taking a large share of
levothyroxine sodium sales going in to the 1980s. In
response, Flint Laboratories funded a study at the
University of California in 1986 which attempted to
demonstrate that Synthroid had a higher therapeutic value
than its generic counterparts. The study was completed in
1990, and, in fact, proved that the generic drugs had equal
efficacy to Synthroid.877 Flint exercised a clause in its
contract requiring company approval before the university
could publish its study. A legal battle over its publication
ensued. Even after Flint Laboratories was sold to Boots, and
thereafter Boots sold to Knoll, publication of the study was
vigorously opposed. It was eventually ordered into
publication in 1997. A class action lawsuit followed,
alleging that misconduct over the publication and
marketing claims forced consumers to pay 2 to 3 times
more for a brand name drug than an equivalent generic
counterpart. Knoll eventually settled for $135 million.
How Supplied:
Levothyroxine sodium is most commonly supplied in oral
tablets of 25 mcg, 50 mcg, 75 mcg, 100 mch, 125 mcg, 150
meg, 200 meg, and 300 meg.
Structural Characteristics:
Levothyroxine sodium is a synthetic form of T4 thyroid
hormone. It has the chemical designation L-3,3',5,5'tetraiodothyronine
sodium salt.
Warnings:
FDA requires that the following black box warning
accompany prescription liothyronine sodium products
sold in the U.S. "Thyroid hormones, including
levothyroxine sodium, either alone or with other
therapeutic agents, should not be used for the treatment
of obesity or for weight loss. 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."
Side Effects:
Side effects are generally associated with overdosage,and
may include headache, irritability, nervousness, sweating,
irregular heartbeat, increased bowel motility, or menstrual
irregularities. Overdosage may also induce shock, and may
aggravate or trigger angina or congestive heart failure.
Chronic overexposure to levothyroxine sodium will
produce symptoms normally associated with
hyperthyroidism, or the overproduction of natural thyroid
hormones in the body. The occurrence of overexposurelinked
side effects is normally cause to immediately
reduce or discontinue therapy with levothyroxine sodium.
Acute massive overdose may be life threatening.
Administration:
When used to treat mild to moderate hypothyroidism, the
average replacement dose of levothyroxine sodium is
approximately 1.7 meg/kg/day. This equates to 100-125
meg/day per day for a 1541b adult. The full therapeutic
dose may be given from the onset of therapy in otherwise
healthy adult patients. Note that due to the long half-life
of levothyroxine, the peak therapeutic effect at a given
dose may not be achieved for 4 to 6 weeks.
When used (off-label) to accelerate fat loss by
bodybuilders and athletes, the typical protocol involves
slow buildup of the dosage so that the body has ample
time to adjust to the changing thyroid hormone levels. An
individual will generally start with a low dosage of 25-50
meg, and will slowly increase the amount 25-50 meg each
day or two. The final dosage will usually be in the range of
100-150 meg, and will rarely exceed 250 meg. It is
important to remember that thyroid drugs are strong
medications with significant side effect potential.
Cautious individuals will be sure not to use excessive
amounts of levothyroxine sodium, nor continue treatment
for longer than eight weeks. It is also generally advised to
also reduce the Synthroid dosage gradually at the
conclusion of each cycle. This is usually accomplished by
dropping the dosage by 25 meg every second or third day.
The focus here, again, is to help avoid any sudden change
in hormone levels that. might otherwise trigger side
effects. Note that due to the slow acting nature of
levothyroxine sodium, it may take several weeks or longer
for the active drug to be fully eliminated from the body.
Availability:
Although levothyroxine sodium is a widely manufactured
drug, it is not as common on the black market as the
stronger thyroid drug Cytomel®. Large scale
counterfeiting does not appear to be a problem.
Levothyroxine sodium is a synthetically ~anufactured
form of the natural thyroid hormone tetraiodothyronine
(T-4). Thyroid hormones are primarily responsible for
regulating the body's metabolic rate, and playa vital role in
the body's utilization of protein, fat, and carbohydrates.
Levothyroxine sodium is used medically to treat cases of
hypothyroidism, which is characterized by insufficient
natural production of thyroid hormones.This may manifest
itself with a number of symptoms including loss of energy,
lethargy, weight gain, hair loss, and changes in skin texture.
Levothyroxine sodium is considered a slow-acting
medication, and may take up to 4 to 6 weeks before full
therapeutic levels are reached in the blood. It is also the
most commonly prescribed thyroid medication in the
world, and is considered to be the standard form of
treatment for most cases of hypothyroidism.
The action of levothyroxine sodium is very similar to that of
the popular thyroid preparation Cytomel® (liothyronine
sodium). Cytomel® is slightly different in structure,
however, being a synthetic form of the thyroid hormone
triiodothyronine (T-3). A healthy individual with have
sufficient levels of both T-3 and T-4 thyroid hormones
present in their body. T-3 is considered the primary active
form of thyroid hormone, while T4 serves mainly as a
reserve for T3, exerting most of its metabolic activity via
conversion to T3 in peripheral tissues. T3 is regarded as
having an effect that is roughly four times stronger than
that of T-4 on a milligram-for-milligram basis. Likewise,
Cytomel® is considered to be a more potent form of
thyroid medication, both with regard to activity and side
effect potentiaI.
Levothyroxine sodium is valued by many drug-using
athletes and bodybuilders for its ability to stimulate the
metabolic rate and support the breakdown of body fat
stores. It is usually taken during a period of calorie
restriction ("cutting"), when the individual is focused on fat
loss or increasing muscle definition. It is often thought that
the use of thyroid drugs can support fat loss at a higher
level of caloric intake than would otherwise be possible
without the drugs, adding to their perceived value among
the communities. Anabolic steroids are generally used in
conjunction with these hormones, and many believe that
the metabolism boosting effect of these drugs may
produce faster gains in muscle mass. The drugs, however,
have yet to be widely proven or accepted for this purpose.
History:
Levothyroxine sodium was the first synthetic thyroid
medication to be sold in the U.S., and was first introduced
to market in 1955 by Flint Laboratories as Synthroid. The
drug has a long history of therapeutic use in the U.S. and
internationally, and for decades has been the most widely
prescribed medication for the treatment of hypothyroid.
The Synthroid brand has historically been the most
successful, with figures estimating that it retained 850/0 of
total levothyroxine sales and $600 million in annual
revenues (1990 estimates). In the bodybuilding and
athletic communities, however, the faster acting and more
powerful drug Cytomel (Iiothyronine sodium) is most
popular. Since Synthroid is weaker and slower acting,
athletes need to take the drug for a longer duration to
achieve similar results.
The Synthroid brand itself has a long and at times
controversial history.876 For many years after its inception
by Flint Laboratories, Synthroid enjoyed a virtual
monopoly on the levothyroxine sodium market. Generic
medications finally began taking a large share of
levothyroxine sodium sales going in to the 1980s. In
response, Flint Laboratories funded a study at the
University of California in 1986 which attempted to
demonstrate that Synthroid had a higher therapeutic value
than its generic counterparts. The study was completed in
1990, and, in fact, proved that the generic drugs had equal
efficacy to Synthroid.877 Flint exercised a clause in its
contract requiring company approval before the university
could publish its study. A legal battle over its publication
ensued. Even after Flint Laboratories was sold to Boots, and
thereafter Boots sold to Knoll, publication of the study was
vigorously opposed. It was eventually ordered into
publication in 1997. A class action lawsuit followed,
alleging that misconduct over the publication and
marketing claims forced consumers to pay 2 to 3 times
more for a brand name drug than an equivalent generic
counterpart. Knoll eventually settled for $135 million.
How Supplied:
Levothyroxine sodium is most commonly supplied in oral
tablets of 25 mcg, 50 mcg, 75 mcg, 100 mch, 125 mcg, 150
meg, 200 meg, and 300 meg.
Structural Characteristics:
Levothyroxine sodium is a synthetic form of T4 thyroid
hormone. It has the chemical designation L-3,3',5,5'tetraiodothyronine
sodium salt.
Warnings:
FDA requires that the following black box warning
accompany prescription liothyronine sodium products
sold in the U.S. "Thyroid hormones, including
levothyroxine sodium, either alone or with other
therapeutic agents, should not be used for the treatment
of obesity or for weight loss. 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."
Side Effects:
Side effects are generally associated with overdosage,and
may include headache, irritability, nervousness, sweating,
irregular heartbeat, increased bowel motility, or menstrual
irregularities. Overdosage may also induce shock, and may
aggravate or trigger angina or congestive heart failure.
Chronic overexposure to levothyroxine sodium will
produce symptoms normally associated with
hyperthyroidism, or the overproduction of natural thyroid
hormones in the body. The occurrence of overexposurelinked
side effects is normally cause to immediately
reduce or discontinue therapy with levothyroxine sodium.
Acute massive overdose may be life threatening.
Administration:
When used to treat mild to moderate hypothyroidism, the
average replacement dose of levothyroxine sodium is
approximately 1.7 meg/kg/day. This equates to 100-125
meg/day per day for a 1541b adult. The full therapeutic
dose may be given from the onset of therapy in otherwise
healthy adult patients. Note that due to the long half-life
of levothyroxine, the peak therapeutic effect at a given
dose may not be achieved for 4 to 6 weeks.
When used (off-label) to accelerate fat loss by
bodybuilders and athletes, the typical protocol involves
slow buildup of the dosage so that the body has ample
time to adjust to the changing thyroid hormone levels. An
individual will generally start with a low dosage of 25-50
meg, and will slowly increase the amount 25-50 meg each
day or two. The final dosage will usually be in the range of
100-150 meg, and will rarely exceed 250 meg. It is
important to remember that thyroid drugs are strong
medications with significant side effect potential.
Cautious individuals will be sure not to use excessive
amounts of levothyroxine sodium, nor continue treatment
for longer than eight weeks. It is also generally advised to
also reduce the Synthroid dosage gradually at the
conclusion of each cycle. This is usually accomplished by
dropping the dosage by 25 meg every second or third day.
The focus here, again, is to help avoid any sudden change
in hormone levels that. might otherwise trigger side
effects. Note that due to the slow acting nature of
levothyroxine sodium, it may take several weeks or longer
for the active drug to be fully eliminated from the body.
Availability:
Although levothyroxine sodium is a widely manufactured
drug, it is not as common on the black market as the
stronger thyroid drug Cytomel®. Large scale
counterfeiting does not appear to be a problem.
