TB-500 has been used extensively for race horses to prevent adhesions from forming, although it is not a prescription veterinary drug. It’s an injectable peptide with limited human use. Mostly, it’s limited to humans who like to experiment, although reports of human use of thymosin dates back as far as 1974 – when a young girl became the first person to receive injections of thymosin because she was diagnosed without a functioning thymus gland.

To pursue the sexual dysfunction agent, melanotan-II was licensed by Competitive Technologies to Palatin Technologies.[9] Palatin ceased development of melanotan-II in 2000 and synthesized, patented, and began to develop bremelanotide, a likely metabolite of melanotan-II that differs from melanotan-II in that it has a hydroxyl group where melanotan-II has an amide.[6][13] Competitive Technologies sued Palatin for breach of contract and to try to claim ownership of bremelanotide;[13] the parties settled in 2008 with Palatin retaining rights to bremelanotide, returning rights to melanotan-II to Competitive Technologies, and paying $800,000.[14]
In humans, the Tβ4 gene TMSB4X is localized to the X chromosome at Xq21.3–q22 (). The Tβ4 cDNA open reading frame contains an initial methionine codon followed by a codon for the N-terminal serine and, although cells secrete a certain amount of Tβ4, there is no hydrophobic signal sequence. The initial methionine residue of the nascent Tβ4 polypeptide is removed and the N-terminal serine residue is often acetylated in the cells.

The idea that oxytocin is central to social cognition made it an attractive candidate for treating psychiatric disorders, especially autism spectrum disorder. People with this condition, who often have problems with social interaction and communication, may not process social stimuli appropriately — and scientists theorized that oxytocin might reverse some of the symptoms. Beginning in 2010, results emerged that seemed to support this theory: researchers found that single puffs of oxytocin could temporarily improve measures of empathy and social cooperation in people with autism spectrum disorder.

There have been some side effects reported while using Melanotan 2, typically these effects appear during the first few days of dosing and will become increasingly less obvious as the body adjusts to the peptide. These effects include: nausea, appetite loss, drowsiness and increased sex drive. In order to combat nausea, an anti-histamine can be taken when injecting until the body gets used to it. But most common way to deal with this is to inject Melanotan before bed, this is also beneficial to combat any drowsiness.
Down syndrome. Some research shows that giving 5-HTP to infants with Down syndrome might improve muscle and activity. Other research shows that it does not improve muscle or development when taken from infancy until 3-4 years of age. Research also shows that taking 5-HTP along with conventional prescription drugs does improve development, social skills, or language skills.

Melanotan II has reported toxicity effects from therapeutic and overdose exposures including: renal dysfunction, rhabdomyolysis, sympathomimetic overdrive, change in size and pigmentation of pre-existing moles, rapid increase in the number of new moles associated with causing melanomas, posterior reversible encephalopathy syndrome, refractory priapism, stretching and yawning syndrome, shortness of breath, chest pain, abdominal cramping and pain, dizziness and lethargy. XXXXXX alone has received 28 calls about melanotan II since 2006.

Potential side effects of 5-HTP include heartburn, stomach pain, nausea, vomiting, diarrhea, drowsiness, sexual problems, vivid dreams or nightmares, and muscle problems.[19] Because 5-HTP has not been thoroughly studied in a clinical setting, possible side effects and interactions with other drugs are not well known. According to the US National Institute of Health TOXNET, 5-HTP has not been associated with serotonin syndrome or any serious adverse events in humans.[20] Across multiple studies, 5-HTP also been reported to not cause any noticeable hematological or cardiovascular changes.[21] 5-HTP also has not been associated with eosinophilia.[22]