Insulin

Octreotide is a synthetic eight-amino-acid mimic of the natural hormone somatostatin, the body's main 'off switch' for hormone secretion. It shuts down excess growth hormone, so it is a frontline FDA-approved drug for acromegaly, and it also tames the flushing and diarrhea of hormone-secreting carcinoid and other neuroendocrine tumors. This is real, approved medicine with decades of clinical data behind it, sold as Sandostatin (injectable, since 1988), Sandostatin LAR (monthly depot), and Mycapssa (oral capsule, approved 2020).

Pasireotide (brand name Signifor) is a second-generation somatostatin analog, a cyclic six-amino-acid peptide engineered to hit more receptor subtypes than octreotide or lanreotide. Its standout use is Cushing's disease, where it was the first drug FDA-approved (2012) to directly target the pituitary tumor driving cortisol excess, and it is also approved for acromegaly that resists first-line analogs. The catch is real and well known: it raises blood sugar in most patients, so it is a powerful but high-maintenance option.

Glucagon is insulin's counterweight, a 29-amino-acid peptide hormone secreted by the alpha cells of the pancreas that raises blood sugar instead of lowering it. When glucose drops, glucagon tells the liver to break down stored glycogen and make new glucose, pushing blood sugar back up. Medically it is the emergency rescue treatment for severe hypoglycemia (the kind that knocks out a person with diabetes), available as injectable kits and a nasal-spray form, and it is also used in some diagnostic imaging to relax the gut.

HCG is a hormone produced in pregnancy that happens to be an almost perfect mimic of luteinizing hormone. That single fact is why it has two completely unrelated uses: it is an approved fertility medicine, and it is the standard tool for keeping the testicles working during testosterone therapy. It is also the basis of the discredited HCG diet, which is a separate story and not supported by evidence.

Oxytocin is a 9-amino-acid hormone made in the hypothalamus, famous as the chemistry behind labor contractions, breastfeeding, and social bonding. As an injectable drug it is FDA-approved to induce labor and control postpartum bleeding, but the intranasal 'love hormone' versions sold for trust, anxiety, and autism are experimental and the human results are genuinely mixed. The hype runs well ahead of the evidence.

Leuprolide (brand name Lupron) is a synthetic GnRH agonist, a modified peptide far more potent than natural GnRH, and it is FDA-approved for advanced prostate cancer, endometriosis, uterine fibroids, and central precocious puberty. The clever part is counterintuitive: it works by overstimulating the GnRH system so hard that the pituitary shuts down sex hormone production. It is a real, long-established prescription drug (first US approval 1985), not a research peptide, and it carries meaningful side effects from the low-hormone state it creates.