preformulation

Before anyone designs a tablet or an injection, the drug substance has to be interviewed like a new hire — what does it look like, how does it behave under heat and humidity, will it dissolve, will it crack? Preformulation is that interview: a systematic early characterization of a drug's physical and chemical properties, run on tiny amounts of material before the real formulation work begins.

Typical preformulation work measures solubility across pH, the ionization constant (pKa), the partition coefficient (log P), melting point, crystal forms and their stability, hygroscopicity, particle size and powder flow, and how the drug reacts with common excipients. The goal is not to make a product but to build a fact sheet that tells the formulator which dosage form is feasible and which problems must be designed around.

Preformulation is done with very limited drug supply, so methods are deliberately small-scale and information-dense (a single differential scanning calorimetry run, a few milligrams for X-ray powder diffraction). The honest caveat is that early data can mislead: a salt or polymorph chosen on milligram-scale solubility may behave differently at manufacturing scale, so key findings are reconfirmed as more material becomes available.