Cytomel (liothyronine sodium) is a synthetically manufactured prescription thyroid hormone. It specially consists of the L-isomer of the natural thyroid hormone triiodothyronine (T3). Thyroid hormones stimulate basal metabolic rate and are involved with many cellular functions including protein, fat, and carbohydrate metabolism. Liothyronine sodium is used medically to treat hypothyroidism, a condition where the thyroid gland does not produce sufficient levels of thyroid hormone. Hypothyroidism is usually diagnosed with a serum hormone profile (T3, T4, & TSH), and may manifest itself with symptoms including loss of energy, lethargy, weight gain, hair loss, and changes in skin texture. T3 is the most active thyroid hormone in the body, and consequently, liothyronine sodium is considered to be a more potent thyroid medication than levothyroxine sodium (T4).
Bodybuilders and athletes are attracted to Cytomel for its ability to increase metabolism and support the breakdown of body fat. Most often utilized during contest preparation or periods of “cutting”, the drug is usually said to significantly aid in the loss of fat, often on higher levels of caloric intake than would normally be permissive of such fat loss. To this end, the drug is also commonly used in conjunction with other fat loss agents such as human growth hormone or beta-agonists. Some users also ascribe the ability of thyroid hormones like liothyronine sodium to increase the anabolic effect of steroids. While in theory, these drugs may support the greater utilization of protein and carbohydrates for muscle growth, they are not widely proven or accepted for this purpose.
The first medication that included T3 was technically a thyroid extract, first given to a patient with myxedema (a skin disorder associated with hypothyroidism) in 1891.1 Natural thyroid extracts contained therapeutically viable levels of the thyroid hormones T3 and T4, and were widely used in medical practice for more than 60 years. In the 1950s, however, these drugs slowly start giving way to new synthetic thyroid medications, namely liothyronine sodium and levothyroxine sodium, which were consistent in dosage and effect, and more desirable to consumers than prepared animal extracts. Although liothyronine sodium and levothyroxine sodium are both widely available in the U.S. and abroad to this day, liothyronine retains a significantly smaller portion of the global thyroid market. Given its more potent and fast-acting effect, however, liothyronine sodium remains a popular thyroid drug with bodybuilders and athletes. Cytomel® is the most recognized trade name for the drug in the U.S, where it is presently sold under the King Pharmaceuticals brand name.
Cytomel is most commonly supplied in oral tablets of 5 mcg, 25 mcg, and 50 mcg.
Liothyronine sodium is a synthetic form of T3 thyroid hormone. It has the chemical designation l-tyrosine,o-(4- hydroxy-3-iodophenyl)-3,5-diiodo-,monosodium salt.
FDA requires the following black box warning to accompany prescription liothyronine sodium products sold in the U.S.: “Drugs with thyroid hormone activity, alone or together with other therapeutic agents, have been 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.
Side effects of Cytomel 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 liothyronine sodium will produce symptoms normally associated with hyperthyroidism or the overproduction of natural thyroid hormones in the body. The occurrence of overexposure-linked side effects normally causes to immediately reduce or discontinue therapy with liothyronine sodium. Acute massive overdose may be life-threatening.
When used to treat mild hypothyroidism, the typical recommended starting dosage of Cytomel is 25 mcg daily. The daily dosage then may be increased by no more than 25 mcg every 1 to 2 weeks. The established maintenance dose is usually 25-75 mcg per day. Once a day administration of the full daily dose is usually recommended. Although liothyronine sodium is fast-acting, its effects may persist in the body for several days after discontinuance.
The usual protocol among bodybuilders and athletes taking Cytomel to accelerate fat loss involves initiating its use with a dosage of 25 mcg per day. This dosage may be increased by 25 mcg every 4 to 7 days, usually reaching a maximum of no more than 75 mcg per day. As in a medical setting, the intent of this slow buildup is to help the body become adjust to the increasing thyroid hormone levels and avoid sudden changes that may initiate side effects.
Cycles of Cytomel usually last no longer than 6 weeks, and the administration of the drug should not be halted abruptly. Instead, it is discontinued in the same slow manner in which it was initiated. This usually entails reducing the dosage by 25 mcg every 4 to 7 days. This tapering is done so that the body has time to readjust its endogenous hormone production at the conclusion of therapy and to avoid the onset of side effects.
Liothyronine is an old and widely prescribed medication. It can be found readily in most areas of the world and is sold in a variety of different brand and generic forms. Counterfeiting is not a large-scale problem. It is important to note than one should never purchase an injectable form of this drug. These are generally used as emergency room products only, with potentially very dangerous side effects if misused.