Testosterone is a hormone produced in the testes in men, playing a broad role in male development and overall well-being. It influences the development of male sex organs, muscle mass, bone density, and sperm production. Beyond these physical aspects, testosterone also affects mood, cognition, and energy levels. While often associated with men, it is also present in women and contributes to various bodily functions. Historically, the administration of oral testosterone faced significant hurdles, but recent advancements have made effective oral forms available for specific medical uses.
Why Oral Testosterone Was Historically Challenging
Traditional oral testosterone formulations encountered significant barriers to effectiveness and safety due to how the body processes orally ingested substances. A major issue was “first-pass metabolism,” where orally absorbed drugs travel directly to the liver via the portal vein before reaching general circulation. The liver extensively metabolizes natural testosterone, leading to very low bioavailability.
To circumvent this, older oral testosterone derivatives, such as methyltestosterone, were chemically modified. These modifications allowed them to bypass immediate liver breakdown, but they introduced liver toxicity. Such formulations could cause severe liver damage, including jaundice, liver tumors, and a rare condition called peliosis hepatis. Consequently, these older oral forms fell out of favor due to their safety profile.
Currently Available Oral Testosterone Medications
Recent advancements have led to new oral testosterone formulations that address historical challenges. The primary oral form now available is testosterone undecanoate. This medication is marketed under brand names such as Jatenzo, Tlando, and Kyzatrex.
Testosterone undecanoate is designed to bypass the liver’s first-pass metabolism. Instead of being absorbed directly into the portal circulation, it is primarily absorbed through the lymphatic system. This allows active testosterone to enter the bloodstream more effectively, reducing liver strain. Once in systemic circulation, it is converted into testosterone by enzymes, exerting its effects. These newer oral forms have received regulatory approval from the U.S. Food and Drug Administration (FDA) for men with diagnosed hypogonadism.
Unique Characteristics of Oral Testosterone Delivery
Oral testosterone undecanoate offers distinct characteristics compared to other testosterone delivery methods. Its lymphatic absorption pathway helps it avoid the rapid breakdown that occurs with direct liver processing.
Oral testosterone typically requires twice-daily dosing to maintain stable hormone levels and manage natural peak and trough levels. In contrast, daily gels provide more stable levels, while injections, administered less frequently, can result in higher peaks and lower troughs. Specific monitoring requirements for oral testosterone include regular checks of blood pressure and lipid profiles. Some oral testosterone medications carry warnings about potential blood pressure increases, necessitating careful monitoring.
Considerations for Oral Testosterone Therapy
Oral testosterone is prescribed for adult men with clinically diagnosed hypogonadism, aiming to restore testosterone levels and alleviate deficiency symptoms. Regardless of the chosen delivery method, testosterone therapy necessitates strict medical supervision, including a thorough diagnosis and ongoing monitoring.
Patients undergoing oral testosterone therapy may experience side effects. These can include gastrointestinal issues such as nausea, burping, and diarrhea. Other general side effects include increased red blood cell counts, an enlarged prostate, headache, and swelling in the lower legs. The suitability of oral testosterone therapy depends on individual patient factors, lifestyle considerations, and a comprehensive assessment by a healthcare provider. Regular blood tests for testosterone levels, prostate-specific antigen (PSA), and hematocrit are also part of the general monitoring for all testosterone replacement therapies.