From the FDA Drug Label
Testosterone cypionate is a white or creamy white crystalline powder, odorless or nearly so and stable in air It is insoluble in water, freely soluble in alcohol, chloroform, dioxane, ether, and soluble in vegetable oils.
Testosterone esters are less polar than free testosterone.
Testosterone is fat soluble. It is freely soluble in alcohol, chloroform, dioxane, ether, and soluble in vegetable oils 1. This indicates that testosterone has lipophilic properties, allowing it to dissolve in fats and oils.
From the Research
Yes, testosterone is fat soluble, as evidenced by its chemical structure derived from cholesterol, making it hydrophobic and lipophilic, allowing it to easily cross cell membranes and bind to androgen receptors. This property is crucial in understanding how testosterone is distributed, metabolized, and eliminated from the body 2. The fat solubility of testosterone explains why it is stored in adipose tissue and why many testosterone medications are formulated in oil-based solutions or patches that allow the hormone to be absorbed through the skin.
Key Points
- Testosterone's fat solubility allows it to penetrate the skin's lipid barriers, making transdermal patches and gels effective delivery methods 3.
- The hormone's lipophilic nature also explains why it is often formulated in oil-based solutions for injections, such as testosterone undecanoate in castor oil 4.
- Understanding testosterone's fat solubility is essential for appreciating its effects on the body, including its distribution, metabolism, and elimination, as well as its role in various physiological processes, such as carbohydrate, fat, and protein metabolism 5.
- Recent studies have focused on developing new oral formulations of testosterone, such as JATENZO and TLANDO, which utilize unique chemistry to address limitations of other dosing routes while providing a safe option without evidence of liver dysfunction 2.
Administration and Formulations
The fat solubility of testosterone influences how the hormone is administered therapeutically, with options including:
- Injections in oil
- Transdermal patches
- Gels that can penetrate the skin's lipid barriers
- New oral formulations, such as JATENZO and TLANDO, which utilize self-emulsifying drug delivery systems and lymphatic absorption to provide a safe and effective option for testosterone replacement therapy 2.