On release from the depot, the testosterone ester undergoes hydrolysis into testosterone and the ester-specific fatty acid (35, 36). Indeed, this might explain the observation that IM injections are less painful in overweight and obese men (34). However, this device is expensive compared to administration of ester with conventional syringe and needles. More recently, newer formulations of testosterone replacement have become available, which include ultralong-acting testosterone undecanoate for IM injection, transdermal patches and gels, buccal tablets, intranasal sprays, and oral testosterone undecanoate (Table 1), thus providing a range of options to choose from. In addition, testosterone therapy is used for gender-affirming (hormone) therapy for transgender men to induce masculinization (and suppress endogenous estradiol concentrations in patients with intact ovaries) (2). Currently, testosterone therapy is indicated for men with unequivocal, organic, or pathologic androgen deficiency to alleviate symptoms and maintain secondary sexual characteristics by raising testosterone into the normal male range (1). Compounded ester combinations can offer multiple effects for more balanced levels. While each patient responds differently to medication, the starting dose is often 100 to 200 mg injected intramuscularly every 5-7 days. Studies show it can remain in the body in trace amounts for up to two weeks. Another commonly used ester, Testosterone Propionate is faster acting. 100 mg of Testosterone Cypionate typically yields around 68 mg of Testosterone, with the rest being the ester. As a result of the addition of an ester, the release into the bloodstream slowed. This improvement is significant because it slows the release of testosterone once it is injected into the body. These components are all testosterone and contain identical molecules. Data sharing is not applicable to this article because no data sets were generated or analyzed during the present study. A Luer-Lok syringe is preferred to prevent the needle from disengaging from the syringe during injection considering the viscosity of the solution. All patients should receive training from medical personnel on how to self-inject testosterone. Therefore, patient participation and engagement in the selection of testosterone formulation is likely to promote adherence (57). Following deep intramuscular injection, the drug provides a sustained release of testosterone into the bloodstream for up to 2 weeks. Testosterone enanthate and testosterone cypionate are slow-acting injectable forms. A slower release means fewer testosterone injections per year. The solubility in castor oil of hydroxyprogesterone caproate polymorphs was previously reported in the literature as being 278 mg/mL and 301 mg/mL, respectively, at a temperature of 20° , which are comparable to the prodrugs investigated. The solubilities of some short esters have been previously reported, averaging 110 mg/mL for the acetate ester, 175.5 mg/mL for the propionate, 139 mg/mL for the phenylpropionate and 447 mg/mL for the isocaproate . The analysis of structural features was accomplished by computational methods in terms of the type of intermolecular interactions, crystal energies and Hirshfeld surfaces analysis. Testosterone (17β-Hydroxyandrost-4-en-3-one) is the primary male anabolic-androgenic steroid. Ester weight reduces the proportion of active testosterone in each mg. This results in a wide range of half-lives, injection frequencies, and onset profiles that bodybuilders and clinicians leverage according to goals, side effect profiles, and lifestyle compatibility. LS-1727 is a nitrosocarbamate ester of nandrolone that was developed as a cytostatic antineoplastic agent but was never marketed. Sturamustine is a nitrosourea ester of dehydroepiandrosterone (DHEA) that was developed as a cytostatic antineoplastic agent but was never marketed. Moreover, the energies of the four testosterone esters were compared with those of the testosterone base deposited in CSD (denoted Tbas), which is not esterified. The crystal structure of propionate ester was previously reported but has slightly smaller unit cell parameters and lacks hydrogen atoms. The CSD database contains one entry reporting only the cell parameters for this particular testosterone ester and one entry reporting the unit cell parameters and atomic coordinates . The aim was to determine the absolute configurations for each of the testosterone esters investigated. This results in some of the esterified testosterone entering the lymphatics, thus prolonging the secondary absorption phase. The IM and SC routes present a defined phase of absorption, in which the serum concentration of the drug administered progressively increases to a maximum (Cmax) and then decreases according to its elimination half-life. Testosterone ester is also partly hydrolyzed within the interstitium, with free testosterone entering the circulation directly.
