The development of injectable anabolic steroids by pharmaceutical companies represented a significant advancement in enhancing the pharmacokinetics of these compounds. This development focused on modifying the steroid molecule to alter its solubility, absorption rate, and the duration of its action in the body. A key innovation in this area has been the attachment of ester chains to the steroid molecule.

Note: Before the development of esterified steroids, testosterone suspension, a water-based form, was used to deliver the steroid. However, its rapid clearance required frequent injections to maintain levels for medical or enhancement purposes, making it impractical for long-term use. The introduction of esterified testosterone allowed for slower release, reducing injection frequency and stabilizing hormone levels, significantly improving treatment and performance strategies.

Esterification is a chemical reaction that attaches an ester chain to the steroid molecule. This process alters the steroid’s solubility in oil, making it more suitable for injection. The length of the ester chain can significantly impact the steroid’s release rate and half-life, allowing for less frequent injections and a more stable blood concentration. For example, Testosterone Enanthate and testosterone Cypionate are esterified forms of testosterone with longer half-lives than base testosterone, providing a sustained release of the hormone.