Endocrine Abstracts

The interest in replacing testosterone, the most important male hormone, dates to back to antiquity. Ancient Roman and later in the Middle Ages European, Arabic and Chinese physicians prescribed the ingestion of animal testes to restore male virility. Fast forward through an interesting and questionable history of organotherapy that includes various concoctions of questionable sources for xenotransplantation of testes to modern attempts to replace testosterone. Modern testosterone therapy includes formulations administered by various means. Injectable testosterone therapy has been available for decades and has historically been given IM. A 2022 trial suggests that similar pharmacokinetics and mean serum testosterone levels can be achieved using subcutaneous injections, making self-administration easier. Buccal patches placed on the gums also delivers controlled release testosterone directly into the systemic circulation, bypassing first-pass hepatic metabolism and increasing bioavailability. Nasal testosterone has been available in the US since 2014 and EU since 2020 for treatment of low testosterone. Transdermal administration includes gels, liquids and patches. The first patch became available in the 1980s and was placed on shaved scrotum. A 2020 Dutch study followed 12 men for 4 years and found 7 of 12 men found this an acceptable therapy. A more acceptable patch is placed in any of several locations, but not the scrotum. Gels are applied to specified areas defined by the manufacturer. Subdermal pellets were first developed in the 1940s and surgically placed in the hip area or other fatty tissue. Oral replacement has met with difficulties of poor absorption and liver toxicity. Testosterone undecanoate became available in oral formulation in the EU in the 1970s and the US in 2014. The future of testosterone deficiency treatment may include novel therapies such as androgen receptor modulators and other methods to increase endogenous testosterone production.