Dextrothyroxine

Dextrothyroxine (D-thyroxine) is a synthetic form of the thyroid hormone thyroxine (T4), designed as the right-handed (dextro) isomer of the naturally occurring hormone, which is the left-handed (levo) isomer. Unlike the naturally occurring form, dextrothyroxine has been found to have different effects on the body, which has led to its investigation for various clinical uses. However, it is not commonly used in current medical practice.

Medical Uses

Dextrothyroxine was primarily investigated for its potential in treating hypercholesterolemia due to its ability to lower cholesterol levels. In the past, it was also explored as a treatment for hypothyroidism, but it was found to be less effective and less desirable compared to levothyroxine, the standard treatment for hypothyroidism.

Mechanism of Action

The mechanism of action of dextrothyroxine is similar to that of the natural thyroid hormones. Thyroid hormones are crucial for the regulation of metabolism, and they exert their effects by entering cells and affecting the transcription of genes, thereby modulating the synthesis of various proteins. However, the exact mechanism by which dextrothyroxine lowers cholesterol levels is not fully understood. It is believed to involve modulation of lipid metabolism in the liver.

Side Effects

The use of dextrothyroxine can lead to several side effects, particularly when used in high doses. These may include symptoms of hyperthyroidism such as weight loss, increased heart rate, anxiety, and insomnia. Due to its effects on cholesterol and lipid metabolism, there may also be impacts on cardiovascular health.

History

Dextrothyroxine's potential for treating hypercholesterolemia was explored in the mid-20th century. However, subsequent studies revealed that the benefits might not outweigh the risks, particularly concerning cardiovascular health. Its use has significantly declined since then, with more effective and safer treatments for cholesterol management, such as statins, becoming available.

Current Status

As of now, dextrothyroxine is not widely used in clinical practice. Its role in modern medicine is limited, with research into its use being largely historical. The focus has shifted towards other treatments that offer better efficacy and safety profiles for the conditions dextrothyroxine was once considered for.

See Also

• Thyroid hormone
• Hypercholesterolemia
• Hypothyroidism
• Levothyroxine