Testosterone Therapy with Subcutaneous Injections: A Safe, Practical and Reasonable Option.

CONTEXT Injections with intramuscular testosterone esters have been available for almost 8 decades and not only result in predictable serum testosterone levels but are also the most inexpensive modality. However, they are difficult to self-administer and associated with some discomfort. Recently, subcutaneous administration of testosterone esters has gained popularity, as self-administration is easier with this route. Available data, though limited, support the feasibility of this route. Here we review the pharmacokinetics and safety of subcutaneous testosterone therapy with both long- and ultralong-acting testosterone esters. In addition, we provide guidance for clinicians on how to counsel and manage their patients who opt for the subcutaneous route. EVIDENCE ACQUISITION Systematic review of available literature on subcutaneous testosterone administration including clinical trials, case series and case reports. We also review the pharmacology of testosterone absorption after subcutaneous administration. EVIDENCE SYNTHESIS Available evidence, though limited, suggests that subcutaneous testosterone therapy in doses similar to those given via intramuscular route results in comparable pharmacokinetics and mean serum testosterone levels. With appropriate training, patients should be able to safely self-administer testosterone esters subcutaneously with relative ease and less discomfort compared with the intramuscular route. CONCLUSION Although studies directly comparing the safety of subcutaneous vs intramuscular administration of testosterone esters are desirable, clinicians should consider discussing the subcutaneous route with their patients, as it is easier to self-administer and has the potential to improve patient adherence.