Solid Forms and Pharmacokinetics
In the world of pharmaceutics, a very close relationship exists between ADMET, pharmacokinetic parameters and the physicochemical properties of a drug. They are decisive factors dictating the therapeutic performance of the drug
Solid state modifications either by electrostatic interactions (such as in salts) or non-covalent interactions (such as in co-crystals) have evolved as an excellent alternative that can efficiently alter the dissolution rate and affect its pharmacokinetics. They can be custom designed, not only to alter the mode of administration, but can also optimize the release-action profiles of a drug for more patient-friendly dosages. In addition to the bountiful merits, solid state alterations can also prove to be life threatening. An altered form in a specific lot/generic batch can lead to varied concentrations of the drug in plasma which can potentially cross the therapeutic window leading to no efficacy or toxicity. Again, unanticipated co-crystallization amongst the formulation components during manufacture or storage can lead the formation of a form with unacceptable physicochemical and pharmacokinetic properties that is detrimental to the health of the patient. Therefore, detailed solid state screening during drug development is seminal in every discovery program.