Testosterone replacement therapy is a standard treatment for low testosterone levels in men. The estimated prevalence of testosterone deficiency in the United States ranges from 5.6% to 6.5%. Current therapies are applied either transdermally, via intra-muscular injection (IM), or intra-nasally using an oil-based gel. According to Harvard Medical School, transdermal administration of testosterone can take up to two to three weeks for the majority of men to show measurable increases in testosterone levels. IM administration offers faster uptake but requires painful injections that can induce adverse reactions, including cellulitis, tissue necrosis, and abscesses. A more elegant solution is intra-nasal delivery, which allows for simple and painless administration as well as fast uptake (producing measurable changes in 20 to 40 minutes). However, the current nasal dosage suffers from the potential for adverse reactions to the carrier gel and the risk of inadvertent transfer beyond the patient as the gel remains in the nasal passages for an extended period of time.
Researchers at The University of Texas at Austin have developed a saline-based testosterone nasal spray that offers both fast absorption and minimized risk for adverse reaction to the carrier and transfer beyond the patient. In vivo rat studies indicate that intranasal testosterone administration is able to induce brain levels of testosterone that are 2× higher than IV-injected testosterone, offering a significant efficiency advantage. Additional studies undertaken by the researchers indicate that this fast-acting intra-nasal testosterone may have potential as a treatment for anxiety disorders in both men and women.