Testosterone phenylpropionate

Testosterone phenylpropionate is a synthetic ester of the naturally occurring male sex hormone testosterone. It is one of four testosterone esters contained in Sustanon 250, a solution for injection that is already authorised as a medicine.^[1] The product record for Sustanon 250 lists testosterone decanoate, testosterone isocaproate, testosterone phenylpropionate and testosterone propionate as its active ingredients.^[1]

Table of contents

• What is testosterone phenylpropionate?
• How does testosterone phenylpropionate work?
• Which conditions is it used or studied for?
• How is testosterone phenylpropionate given?
• What do the clinical trials show?
• What side effects are known?

What is testosterone phenylpropionate?

Testosterone phenylpropionate is a synthetic androgen, meaning it is a manufactured substance that acts like the male sex hormone testosterone in the body. Chemically, it is a small molecule with the molecular formula C₂₈H₃₆O₃.^[2] The substance is listed as investigational in one drug reference source, although it is also a component of an authorised medicine.^[2] In the European Union clinical trials registry, testosterone phenylpropionate appears as part of the fixed combination product Sustanon 250, which holds a marketing authorisation in Belgium.^[1] The authorisation holder for this product is Aspen Pharma Trading Limited.^[1]

How does testosterone phenylpropionate work?

Testosterone phenylpropionate belongs to a class of medicines called androgens. Androgens are hormones that bind to androgen receptors in various tissues of the body. When testosterone levels are low, supplementing with testosterone esters such as testosterone phenylpropionate can help restore normal hormone activity.^[2] The phenylpropionate ester is attached to the testosterone molecule to slow its release from the injection site, allowing the hormone to remain active in the body for a longer period than unmodified testosterone. In the Sustanon 250 formulation, four different esters with different release rates are combined to provide a more even supply of testosterone over time.^[3]

Which conditions is it used or studied for?

Testosterone phenylpropionate, as part of Sustanon 250, is used for testosterone replacement therapy in men who do not produce enough testosterone. According to one drug information source, testosterone phenylpropionate is indicated for testosterone replacement therapy in conditions including:

• Missing testicle — when one or both testicles are absent, the body cannot produce adequate testosterone.
• Hypopituitarism — a condition in which the pituitary gland does not produce enough hormones to stimulate testosterone production.
• Sterilization — a state in which the testicles no longer produce testosterone.
• Osteoporosis — a condition of weakened bones that can be related to low testosterone levels.

In the clinical trial listed in the EU registry, testosterone supplementation is being studied in male patients with androgen deficiency who are receiving best supportive care for advanced cancer and who do not wish to be resuscitated.^[1] The therapeutic area recorded for the trial is neoplasms, indicating that the study population consists of patients with cancer.^[1]

How is testosterone phenylpropionate given?

Testosterone phenylpropionate is given as a solution for injection. In the Sustanon 250 product, the solution contains 250 mg of testosterone esters per millilitre and is administered by injection.^[3] The clinical trial record lists the route of administration as intravenous use, although the product information for Sustanon 250 describes it as a solution for injection.^[1] The pharmaceutical form recorded in the trial registry is a solution for injection.^[1]

What do the clinical trials show?

One clinical trial involving testosterone phenylpropionate as part of Sustanon 250 is registered in the EU Clinical Trials Information System. The trial is a Phase 2 interventional study with a planned enrolment of 25 participants.^[1] Its status is authorised, meaning it has received regulatory approval but has not yet started recruiting.^[1]

The trial is designed to evaluate the impact of testosterone supplementation on the quality of life of male patients in best supportive care who have no therapeutic options left and who do not wish to be reanimated.^[1] The study measures two main outcomes. The first is the best improvement over time in independence, assessed using the ADL independence scale, which covers personal hygiene, dressing, going to the toilet, locomotion, continence and eating. The second is the best improvement over time in symptoms including pain, fatigue, sadness, anxiety, drowsiness, appetite, sense of well-being, shortness of breath, bowel movements and strength, measured with the Edmonton Symptom Assessment Scale.^[1]

Because the trial has not yet reported results, there are currently no published findings from this study. The registry record provides information about the planned design and outcomes but no efficacy or safety results.^[1]

What side effects are known?

The supplementary sources provided for this page do not contain a detailed list of side effects for testosterone phenylpropionate. The product information for Sustanon 250 is available through the electronic medicines compendium, where the Summary of Product Characteristics and Patient Information Leaflet can be consulted for full safety information.^[3] No specific side effect data from the registered clinical trial are yet available, as the study has not reported results.^[1]