“Barbie Peptide.” Why “Barbie” and why “peptide?” Barbie, the iconic little polyvinyl chloride (PVC) doll with the bronzed skin, svelte waistline and sexy figure first appeared in toy stores in 1959. Little surprise that social media influencers have now named a drug that is supposed to produce a tan, curb the appetite and enhance sexual performance after her.
But why “peptide?” That term was coined in the early 20th century by German Nobel Prize winning chemist Emil Fischer who was studying the products formed when proteins are digested. Proteins are composed of long chains of amino acids and during digestion they are broken down into much smaller fragments that Fischer named “peptides” from the Greek “peptos” for “digested.” The stomach enzyme that is responsible for breaking down proteins was accordingly named “pepsin.”
In general, peptides are short chains of amino acids, while proteins are longer chains, consisting of more than 50 amino acids, although that is not a hard cut off. Since nature has provided 20 commonly occurring amino acids, it is clear that there are a virtually infinite number of ways in which these can be assembled into peptides. So “peptide” is a general term for a large class of molecules and questions about peptides being useful or harmful make no sense unless a specific peptide is identified. “Melittin” in bee venom disrupts cell membranes and causes inflammation so it can be termed to be a toxic peptide that we would rather not encounter. “Insulin” is a peptide hormone that we cannot live without because it regulates blood glucose and is definitely useful. So are the GLP-1 agonists like semaglutide that can result in impressive weight loss when medically indicated.
The scientific name for “Barbie peptide” is “melanotan II.” It is made synthetically in the lab using chemical reactions that join amino acids together via “peptide bonds” and is composed of seven amino acids in a specific sequence. That sequence of amino acids is also found as part of “alpha-melanocyte-stimulating hormone (alpha-MSH),” a 13 amino acid chain that is produced by cells in the brain as well as in the skin. MSH acts as a chemical messenger, fitting into “melanocortin” receptors found in skin, adrenal glands and brain cells. In the brain, MSH can affect appetite, energy expenditure and hence body weight. In the adrenal glands it can stimulate the production of various steroids such as cortisol while in the skin it can fire up melanocytes, the cells that produce the pigment melanin responsible for tanning.
Around 1980, researchers at the University of Arizona became interested in investigating the effects of MSH but found that the natural peptide breaks down very quickly when injected into the body. They then found that replacing two of the amino acids in the hormone not only allowed it to resist breakdown by enzymes but also increased its potency. The novel compound, termed melanotan II, was alluring because of the possibility of pigmenting the skin without exposure to ultraviolet light. This raised the prospect of protecting fair-skinned people from sun damage by producing a “sunless tan.”
Unfortunately, melanotan II did not pan out as hoped due to side effects that include flushing, nausea, sweating, headaches and spontaneous erections. Changes in mole pigmentation have raised concern about an enhanced risk of melanoma. Since no clinical trials have shown an acceptable risk-benefit ratio, neither Canada nor the U.S. has approved melanotan II for any purpose. However, that has not stopped “wellness influencers” on Tik Tok, Instagram and Facebook from recommending it for a sunless tan, sexual arousal or weight loss. There have been a few small placebo-controlled studies that have shown benefits for erectile dysfunction and an increase in sexual desire, but there are also recorded cases of priapism, which is a prolonged, painful erection requiring emergency treatment. Social media posts also claim that Barbie peptide reduces appetite and leads to weight loss. This is based on some animal studies but there is no corroborating evidence in humans.
Since melanotan II is not an approved medication, it cannot be prescribed by physicians. But it is available on the “grey market” from peptide producers in China. This really makes for a buyer beware situation since there is no telling what impurities the product may contain or even if it actually is melanotan II. It is not a good idea to play Chinese roulette.
