Nebido: A long-acting injectable testosterone for the treatment of male hypogonadism

Over the last six decades, tremendous strides have been made in the development of safe, efficacious and 'patient-friendly' modalities of testosterone replacement therapy in men. The most recent forms of androgen replacement that are in widespread use include testosterone patch and gel. These preparations are convenient in their use and deliver a physiological amount of testosterone. Although these transdermal preparations are gaining popularity, many hypogonadal men still receive treatment with intramuscular esters. Testosterone enanthate remains the most commonly prescribed ester. Although testosterone esters are efficacious in terms of improving bone and muscle mass, they possess unfavourable pharmacokinetics that result in fluctuations in the mood, energy and sexual function of patients. Furthermore, these esters need to be injected every 2 - 4 weeks. Hence, there has been a need to develop long-acting esters that can be administered infrequently and deliver a physiological amount of testosterone without major fluctuations. Recently, injectable testosterone undecanoate (Nebido®) has become available in Europe and will soon be marketed in south America, Asia and Australia. In this paper, the structure, pharmacokinetics, efficacy and side-effect profile of testosterone undecanoate will be reviewed and also compared with other existing testosterone esters.