Short esters break down quickly, requiring frequent administration, while long esters take longer to release, reducing injection frequency. Understanding the various aspects of testosterone and its treatments is crucial for those experiencing low levels of this vital hormone. Testosterone Enanthate is another long-acting ester commonly used in testosterone replacement therapy. Clinical outcomes improve dramatically when therapy is personalized when injection intervals are titrated to symptoms and trough levels, and when patients are educated to recognize the subtle differences between underreplacement and excess. Shorter esters like enanthate and cypionate provide flexibility and are ideal for men who can self-inject regularly or require dose adjustments based on symptoms. One of the most frequent clinical pitfalls is overextending injection intervals with short esters. Men undergoing testosterone therapy frequently describe emotional variability that parallels the rise and fall of serum testosterone. Many clinicians adjust dosing intervals rather than total dose to fine-tune therapy for instance, shifting cypionate injections from biweekly to weekly if mood swings emerge near the end of each cycle. For men who prefer to avoid frequent injections or self-administration, however, undecanoate can provide unmatched stability. While both short-acting and long-acting T have been shown to restore normal T levels, there are significant differences between the two modalities. Additionally, these societies suggest that free testosterone can be used if there is a low-normal total T measurement and/or sex hormone binding globulin (SHBG) levels are abnormal13. However, coinciding with an FDA communication about potential cardiovascular events following testosterone therapy, there was a decrease of 3.2% use of testosterone in men in 2013 to 1.67% in 2016, with new users decreasing from 1.26% to 0.48%5. In the latter case, the supraphysiologic dosing of testosterone exploits the androgenic effects on muscle, bone, and other tissues in men, especially in eugonadal patients1. Short-acting pharmacology mimics normal physiology more closely than long-acting TT but requires multiple doses per day, while long-acting TT has a higher rate of patient adherence but is more likely to create supraphysiologic serum testosterone and pathologic sequelae. Prescriptions for testosterone therapy (TT) to treat testosterone deficiency have increased in recent years. In a controlled study, Testavan provided higher bioavailable testosterone and delivering more testosterone in a smaller amount of gel when compared to Androgel. And as we all know HGH and IGF-1 are two very anabolic hormones. But did you know that the increase in these hormones are due to estrogen aromatization, ? The mechanism that tells the HPTA to cease testosterone production is estrogen biding in the hypothalamus. If something causes higher levels of nitrogen retention, and hangs around in your body longer, it's going to be more anabolic. In 1954, a scientist named Reifstein and his team conducted a study comparing Testosterone Enanthate with Testosterone Propionate. Something that is more fat soluble is going to take longer be released from the deposit or "depot" the injection creates. Specific to IM injections of TU, risks include immediate post-injection cough or syncope due to pulmonary oil microembolism (POME) and post-injection hematoma. Additional risks of which patients and providers should be aware are return of symptoms of testosterone deficiency related to subtherapeutic testosterone and hypertension7. Similarly, in a multicenter study of 271 men receiving 200 mg TE weekly by IM injection to assess the contraceptive efficacy of hormonally-induced azoospermia, 65% of men became azoospermic at 6 months51. Newer research shows that physiologic T in testosterone-deficient men may actually provide CVD benefit and may provide important symptomatic relief in patients with treated prostate cancer or low-risk prostate cancer on active surveillance without increasing cancer risk47,48. Many of these effects are considered mild and typically do not necessitate discontinuation of therapy. However, formulations such as TC can be taught to patients to be self-administered subcutaneously, which is thought to result in a lower risk of erythrocytosis and less variability in T levels35,41,42. There is also the risk of transference with the use of topical gels, which may cause alterations in hormonal levels and subsequent side effects in women or children who come in physical contact male users. Now you know just how significant esters are. Once injected, testosterone stays in its esterified form in the muscle tissue. For example, the cypionate ester consists of 8 carbon, 14 hydrogen, and two oxygen atoms, while the propionate ester is made up of 3 carbon, six hydrogen, and two oxygen atoms. The chief difference between the esters is the number of carbon and hydrogen atoms that make up the chain. As mentioned earlier, esters are a chain of carbon, hydrogen, and oxygen molecules.
