Author: Carlos

Pit vipers, Gila monsters, cone snails and leeches produced real approved drugs. What made it to market, what the FDA labels actually say, and why almost none can be swallowed.

Mannitol, sucrose, buffers, polysorbate and preservatives: what the non-peptide ingredients in a vial are for, with real FDA label examples.

Why one inverted amino acid makes a different molecule that shares its formula and mass — racemization during synthesis, how it is detected, and the D-residues built into approved drugs on purpose.

Cell-penetrating peptides looked like they crossed membranes directly for fifteen years, until fixation was shown to be moving them. What they actually do, where the cargo gets stuck, and why none has become a drug.

Uroguanylin and guanylin were discovered by reverse-engineering a bacterial toxin. How the GC-C receptor works, and what linaclotide and plecanatide do.

Myostatin restrains muscle growth through a receptor it shares with activin A — which is why knockout mice are spectacular, human trials keep missing, and follistatin-344 is a gene name rather than a drug.

FGF21 binds heparan sulfate too weakly to stay put, which is exactly why it works as a hormone – and why every clinical analog had to be re-engineered.

Hepcidin is the 25-amino-acid liver peptide that controls how much iron reaches the blood — discovered twice as an antimicrobial peptide before anyone connected it to iron.

Peptide drug names follow a formal WHO specification. What -tide, -glutide, -relin, -relix and -pressin actually mean, and the four things a stem deliberately does not tell you.

Protease-activated receptors are switched on by being cut, not by a hormone arriving. How tethered-ligand activation works, why antagonists are so hard, and what vorapaxar showed.