Cytomel is the most common synthetic version of the T3 or triiodothyronine. T3 is not produced directly by the thyroid gland but by the thyroid-stimulating hormone or THS. THS is also responsible for the production of T4 or thyroxine.

Drugs with thyroid hormone activity, such as Cytomel, are used for the treatment of obesity since they are effective fat-burning agents.
Cytomel exerts its fat-burning ability via the following metabolic pathways and processes.

Cytomel up-regulates the beta-2 adrenergic receptors in fat tissues. In lipolysis, or the breakdown of fat in fat tissues, the enzyme HSL (hormone sensitive lipase) plays a significant part. HSL controls the rate of lipolysis. For HSL to be activated, epinephrine and nonepinephrine (catecholomines) are necessary. These catecholomines bind to the beta-2 receptors, and thus when Cytomel up-regulates the beta-receptors, there is a corresponding increase in the ability of catecholomines to activate HSL, resulting to increased lipolysis.

This drug is likewise known to increase the UCP-3 or uncoupling protein-3. This process significantly increases lipolysis. Further, Cytomel also stimulates growth hormone (GH) production, as substantiated by several studies. And since GH is a thermogenic, it contributes to this drug’s fat-burning action. This is why when athletes are using Cytomel they find no need to use HGH.

Advantages of Cytomel therapy

With AAS use, the suppression occurs even after the therapy is stopped, sometimes in periods of weeks or months (especially in cases of long-term use). The same thing is observed during insulin intake, whereby the pancreas (the organ responsible for insulin production) ceases its production of insulin. Such is not the case with exogenous T3 hormone therapy. Several studies have concluded that thyroid therapy does not cause prolonged suppression of thyroid normal production. Thyroid function is normalized just days after medication is discontinued. In other words, there is no thyroid shutdown due to T3 supplementation; there is only a down-regulation of thyroid output during therapy.

Drawbacks of Cytomel therapy

Side effects of this class of drug include tachycardia and atrial arryhtmias, bone resorption, and loss of lean muscle tissue. Secondary side effects include insomnia, diarrhea, and nausea. These adverse reactions are highly possible if the user takes high dosages.

Notice that some of its major side effects relate to the cardiovascular system. This is because thyroid hormones have significant effects on cardiac structures (including cardiac muscles) and systems that alter cardiovascular hemodynamics.

Hyperthyroidism increases virtually all cardiac functions including heart rate and contractility, diastolic relaxation, and rate of ventricular pressure development. This results to an increased cardiac output by as much as 250 percent. These physiological changes are (most likely) the consequences of an increase in the expression of ATP and a decrease in the expression of ATP’s inhibitor, phospholamban.

Another drawback of Cytomel is its catabolic ability. When Cytomel exerts this ability on stored fats, this is an asset. However, this becomes a liability when it exerts this on bones and muscles. The negative result is bone resorption and muscle wasting (mentioned above). Moreover, this drug also diminishes GH’s nitrogen retention ability (although it stimulates GH’s production, as mentioned earlier).

Dosage

There is consensus among Cytomel users that the dosage protocol with this drug is to ramp it up, which means you start at the lowest dosage then gradually move upward. However, there are divergent opinions on how long the ‘gradually’ part should be. There are those who say it should be every three days, and then some pharmacological studies endorse it from 1 to 2 weeks. However, the user’s tolerance level ultimately determines the timeframe; that is, if the user reacts really well with Cytomel, then the dosage can gradually increase every three days.

Users are advised not to ramp up and down the dosage during therapy as this causes fluctuations in hormone levels, which further results to hormonal imbalance. The more prudent practice is to taper off the dosage. The minimum daily dosage of T3 is 5mcg and the maximum is 100mcg.

Cytomel intake is not dependent on bodyweight or gender, but rather on the individual’s blood level. This means that females can take the same dosage volume and schedule as males.

【中文名称】： 三碘甲状腺原氨酸钠

【简写拼音】： SDJZXYASN

【英文名称】： Liothyronine Sodium

【所属类别】： 甲状腺用药

药物说明：

【别名】 碘噻罗宁;甲碘安;甲碘氨;三碘甲状腺素钠;三碘甲状腺原氨酸钠 ,碘甲腺氨酸钠 ,三碘甲状腺氨酸钠

【外文名】Liothyronine Sodium

【适应症】 常用于粘液性水肿及其它严重甲状腺功能不足状态，还可用作甲状腺功能的诊断药。

【用量用法】 口服：成人开始时，１日１０～２０μｇ，分２～３次口服，以后逐渐增加至１日８０～１００μｇ为止。体重在７ｋｇ以下的儿童开始时１日２．５μｇ，７ｋｇ以上１日５μｇ。以后每隔１周，用量增加１日５μｇ，维持量为１日１５～２０μｇ，分２～３次口服。三碘甲状腺原氨酸抑制试验：用于对摄碘率高的病人作鉴别诊断。方法是：１日口服６０～１００μｇ，分３次服用，共６日，重复作放射性同位素碘摄碘试验，正常人及单纯性甲状腺肿者摄碘率受抑制数值超过服本品前基数的５０％以上，而甲状腺功能亢进者受抑制的数值低于５０％。

【注意事项】 同甲状腺素。 1.剂量过大可出现甲状腺功能亢进症状、多汗、体重减轻等。 2.神经兴奋性增高、失眠、呕吐、腹泻、发热。 3.糖尿病、高血压、冠心病及快速型心律失常病人禁用。

【规格】 片剂：每片２０μｇ。

CYTOMEL TAB 25MCG 100
(LIOTHYRONINE SODIUM)

CYTOMEL TAB 5MCG 100
(LIOTHYRONINE SODIUM)

CYTOMEL TAB 50MCG 100
(LIOTHYRONINE SODIUM)

LIOTHYRON INJ 10MCG/ML X-G 1ML
(LIOTHYRONINE SODIUM)