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Services / Solid form screening / Salt Screening

Salt Screening

Usually, the first decision in early stage drug development, is whether it is more desirable to develop the uncharged molecule or, if possible, a salt thereof. Salts are multi-component solid forms involving the API and pharmaceutically acceptable counter-ions, linked by ionic interactions. Since making a salt will normally involve an additional step in the synthesis and since the molecular weight of a salt will always be higher than that of the neutral molecule, salts will only be chosen if they promise to have clear advantages compared with the API. As a rule, a salt is chosen if the free acid/base has at least one of the following undesirable properties:

  • very low solubility in water;
  • apparently not crystallizable;
  • low melting point;
  • high hygroscopicity;
  • low chemical stability.

Our salt screening studies enable us to rationally select suitable counter-ions for salt formation and are restricted to acids/bases and solvents suitable for pharmaceutical manufacturing. Such studies are designed to explore a range of stoichiometries and to optimize crystallisation conditions for a particular crystalline form.

Contact us: tel/fax: +4(0)364.439.995