Testosterone replacement therapy (TRT) consists of a variety of compositions designed to complete or replace natural testosterone levels in people with deficiencies.The primary ingredient in TRT is synthetic or bioidentical testosterone, which mimics the naturally produced hormone in the body. The composition and composition depends on the delivery method to ensure the efficiency and safety of each patient.

Types of testosterone used in TRT

TRT utilizes different forms of testosterone, including:

  • Testosterone Cypionate – A long-acting injectable form commonly used in TRT.

  • Testosterone Enanthate – Another long-acting injectable with similar effects to cypionate.

  • Testosterone Propionate – A shorter-acting form requiring more frequent administration
  • Testosterone Undecanoate – Available in both oral and injectable forms, with longer-lasting effects.
  • Bioidentical Testosterone – Derived from plant sources like soy or yams and chemically modified to match human testosterone.

Each type has absorption rates and unique half-lives, affecting the frequency to which it should be administered.

Common ingredients in TRT formulations

Depending on the delivery method, TRT formulations may contain additional ingredients:

  • Injectable Testosterone: Typically suspended in an oil base (such as cottonseed or sesame oil) to aid in slow absorption.
  • Topical Gels & Creams: Contain testosterone mixed with carrier agents for skin absorption, often including ethanol or isopropyl alcohol.
  • Patches: Use adhesives and penetration enhancers to deliver testosterone steadily through the skin.
  • Pellets: Small, solid testosterone implants placed under the skin, dissolving over time.
  • Oral Testosterone: Often combined with fatty acids to improve bioavailability.

 

What Are Synthetic vs. Bioidentical Testosterone?

Synthetic testosterone is made in the laboratory and designed to function as natural testosterone.

  • Synthetic Testosterone is lab-made and designed to function like natural testosterone. It is widely used in prescription TRT options.
  • Bioidentical Testosterone is chemically identical to human testosterone and derived from plant-based sources. Some patients prefer it for its natural origins, though its effectiveness is comparable to synthetic versions.

Other important information about TRT: how it is administered. Read here more about TRT.