Testosterone Phenylpropionate API is a synthetic ester of testosterone belonging to the androgen class. It is formed by esterification of the 17β-hydroxyl group of testosterone with 3-phenylpropionic acid. The compound is also known as testosterone phenpropionate, testosterone 17-phenylpropionate, testosterone hydrocinnamate and testosterone phenylpropanoate. PubChem identifies its molecular formula as C₂₈H₃₆O₃, molecular weight 420.6 g/mol, CAS 1255-49-8, and FDA GSRS UNII 8GN84GWX51.
Testosterone Phenylpropionate has an established British Pharmacopoeia (BP) monograph, providing useful authoritative numerical quality requirements for API characterization, assay, loss on drying, sulfated ash, specific optical rotation and melting point. The current BP 2026 is the legally effective BP edition from 1 January 2026 and incorporates European Pharmacopoeia texts.
Testosterone Phenylpropionate is a lipophilic testosterone ester. After hydrolysis, the ester releases testosterone, which interacts with androgen receptors and contributes to androgenic and anabolic effects.
The BP description identifies the substance as 3-oxo-androst-4-en-17β-yl 3-phenylpropionate, with a molecular weight of 420.6 and CAS 1255-49-8. It is described as a white to almost white crystalline powder.
| Property | Value |
|---|---|
| Product Name | Testosterone Phenylpropionate |
| CAS Number | 1255-49-8 |
| UNII | 8GN84GWX51 |
| Molecular Formula | C₂₈H₃₆O₃ |
| Molecular Weight | 420.6 g/mol |
| Chemical Class | Testosterone Ester |
| Therapeutic Class | Androgen |
| Appearance | White to almost white crystalline powder |
| Pharmacopoeial Standard | BP |
Testosterone phenylpropionate functions as an esterified form of testosterone. Following enzymatic hydrolysis, testosterone becomes available to interact with androgen receptors. Androgen-receptor activation influences gene transcription involved in male reproductive development, maintenance of secondary sexual characteristics and other androgen-dependent physiological processes.
Testosterone esters have historically been used in androgen replacement and other testosterone-related pharmaceutical preparations. Testosterone phenylpropionate is particularly relevant as a pharmaceutical and analytical steroid substance and is included in pharmacopoeial/API reference systems.
Because testosterone phenylpropionate is a pharmacologically active androgen, its manufacture, distribution and use are subject to applicable regulatory requirements in the destination market.
The BP monograph provides strong support for the principal numerical specifications of Testosterone Phenylpropionate. The monograph specifies:
Importantly, the BP assay is UV spectrophotometric, not HPLC. The monograph dissolves the API in absolute ethanol and determines absorbance at the maximum at 240 nm, using 395 as the specific absorbance value A(1%, 1 cm). Therefore, your CMS field called “Assay (HPLC)” should not incorrectly describe this BP assay as HPLC.
Testosterone Phenylpropionate is a synthetic steroid ester manufactured through controlled chemical synthesis, purification, crystallization and drying. Manufacturing controls should address starting materials, reaction completion, purification efficiency, residual solvents and steroid-related impurities.
A qualified Testosterone Phenylpropionate API Manufacturer in India should operate an appropriate pharmaceutical quality system and provide batch-specific analytical documentation demonstrating compliance with the applicable BP or customer specification.
The BP monograph describes Testosterone Phenylpropionate as a white to almost white crystalline powder. It is practically insoluble in water and sparingly soluble in ethanol (96%).
The pharmacopoeial melting-point range is 114–117°C, while the specific optical rotation is +86 to +91° under the stated BP conditions.
The BP monograph specifies that Testosterone Phenylpropionate should be protected from light.
Bulk API packaging should provide adequate protection against light, moisture and contamination and should follow the validated stability and packaging requirements.
A professional Testosterone Phenylpropionate API supply package may include:
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 97.0–103.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Water Content | NMT 0.5% |
| Specific Rotation | +86° to +91° |
| Melting Point | 114–117°C |