It bears understanding that this type of peptide is not a treatment or cure for anything, nor should it be considered a preventative measure to skin cancer. While this tanning peptide is known to protect the skin through the natural tanning process, it is not in and of itself a foolproof UV shield, however it is an excellent way for those who don't tan otherwise to get rich golden tans without as much exposure to the sun.
It was under development as drug candidate for female sexual dysfunction and erectile dysfunction but clinical development ceased by 2003, and as of 2018, no product containing melanotan II was marketed and all commercial development had ceased.[1] Unlicensed, untested, or fraudulent products sold as "melanotan II" are found on the Internet, and purported to be effective as "tanning drugs", though side effects such as uneven pigmentation, new nevi (moles), and darkening or enlargement of existing moles are common and have led to medical authorities discouraging use.[2][3]

The uterine-contracting properties of the principle that would later be named oxytocin were discovered by British pharmacologist Sir Henry Hallett Dale in 1906,[125][46] and its milk ejection property was described by Ott and Scott in 1910[126] and by Schafer and Mackenzie in 1911.[127] In the 1920s, oxytocin and vasopressin were isolated from pituitary tissue and given their current names. The word oxytocin was coined from the term oxytocic, Greek ὀξύς, oxys, and τοκετός , toketos, meaning "quick birth".
5-HTP works in the brain and central nervous system by increasing the production of the chemical serotonin. Serotonin can affect sleep, appetite, temperature, sexual behavior, and pain sensation. Since 5-HTP increases the synthesis of serotonin, it is used for several diseases where serotonin is believed to play an important role including depression, insomnia, obesity, and many other conditions.
Tβ4 is the major monomeric actin-sequestering peptide in human tissues, and can bind globular actin (G-actin) in a 1:1 ratio and consequently involved in cytoskeletal regulation by inhibiting the polymerization of G-actin into fibrous actin (F-actin) [7]. In addition, Tβ4 is an ubiquitous naturally occurring molecule and is found at concentrations of 1 × 10−5 to 5.6 × 10−1 M in a variety of tissues and cell types, yet, no receptors for the protein have been identified [33]. A recent study suggests that internalization of exogenous Tβ4 is essential for its subsequent cellular functions [34]. Moreover, Tβ4 has been shown to be associated with, wound healing, hair growth, immunomodulation, and angiogenesis [7–9].
Exogenous Tβ4 can function like a hormone on cells in terms of its ability to modulate their biological behavior. Since one of the primary roles of Tβ4 in cells is the sequestration of actin monomers, and the protein is not secreted, previously indicated that it was unlikely that Tβ4 could have a hormonal function [42]. However, other studies have shown that the intracellular level of Tβ4 or its mRNA can be significantly and rapidly altered by external stimuli and that change in the level of Tβ4 often are correlated with cell differentiation [18, 43]. In the present study, exogenous Tβ4 peptide activate intracellular Tβ4, which results suggested that exogenous Tβ4 spontaneously enter the cytoplasm through rapid internalization, and acts their functions same as endogenous one [8, 18].
We had previously reported that successful hunters experienced a surge in testosterone that lasted from the moment they made a kill until their return home – a “winner effect,” rewarding them for their work. Testosterone reinforces the hunting activity and simultaneously helps with muscle regeneration afterwards - similar to the elated feeling we might have after doing sports or other exercise.
A user knowing their skin type in relation to the Fitzpatrick scale is important because it will dictate dosing needs. It should be noted that those who will benefit the most from this product are those in the upper spectrum of the Fitzpatrick scale (Types 1, 2 and 3 especially). Skin type 1 and 2 users will typically take longer to see any results from this product, however once beautiful tan is obtained maintenance is easy.
The short half-life (<2h)[16] of 5-HTP may inherently limit the therapeutic potential of 5-HTP,[17] as the systemic 5-HTP exposure levels will fluctuate substantially, even with relatively frequent dosing. Such exposure fluctuations are usually associated with increased adverse event burden, resulting from Cmax drug spikes, and decreased clinical efficacy resulting from sub-therapeutic exposure for large parts of the day. It has been proposed that 5-HTP dosage forms achieving prolonged delivery would be more effective,[17] as is generally the situation with short-acting active pharmaceutical ingredients.[18]