When a molecule has no ionisable site, salt formation is not an option — but co-crystallization usually still is. We search for coformers that give your API the solubility, stability or processability it is missing.
Co-crystals are drug solids defined as multicomponent molecular crystals in which at least one of the compounds is an active pharmaceutical ingredient. Salts are considered different from co-crystals, provided they are crystals formed by ionic multicomponent.
The practical distinction matters. Salt formation requires the API to possess a suitable basic or acidic ionisable site; a large share of modern drug candidates does not. Co-crystallization places no such requirement on the molecule: the API is held in the lattice by hydrogen bonding and other non-ionic interactions with a neutral coformer, so in principle any API can be co-crystallized.
The result is a genuinely new solid with its own solubility, dissolution rate, hygroscopicity, melting point and mechanical behaviour — while the API itself remains chemically unchanged. For a poorly soluble, unstable or difficult-to-process candidate, that can be the difference between a formulation that works and one that does not. It is also, by definition, a new solid form, and therefore patentable.
The study is built around the property you need to change, and the coformer set is selected accordingly.
A coformer set chosen from pharmaceutically acceptable compounds, guided by hydrogen-bonding complementarity, acid–base considerations and precedent — not by screening everything on the shelf.
Solution crystallization, slurry conversion, liquid-assisted and neat grinding, melt and thermal methods. Co-crystals that refuse to form in solution often form readily by mechanochemistry.
Measurement of how much the co-crystal actually improves apparent solubility and dissolution, including whether the advantage survives contact with aqueous media.
Assessment of whether the co-crystal holds together under humidity, temperature and mechanical stress, or dissociates back to the parent components.
Diffraction, thermal analysis and spectroscopy to confirm that a true co-crystal has formed rather than a physical mixture, a salt or a eutectic.
Documentation sufficient to support a solid-form patent, including the evidence that distinguishes the co-crystal from its components.
Co-crystal work rewards breadth in the search and rigour in the confirmation, because false positives are easy to generate.
We examine the API for hydrogen-bond donors and acceptors, and confirm whether an ionisable site exists — which determines whether salt screening should run in parallel.
A coformer list is agreed with you, drawn from GRAS and pharmaceutically accepted compounds, and sized to the material available.
Neat and liquid-assisted grinding is used as a fast, material-efficient first screen: it identifies promising API–coformer pairs while consuming very little API.
Hits are reproduced by solution and slurry routes, which is what makes them scalable. This step separates laboratory artefacts from real, manufacturable co-crystals.
Diffraction, thermal analysis and vibrational spectroscopy together establish that a new crystalline phase has formed, and distinguish co-crystal from salt, mixture or eutectic.
Solubility, dissolution behaviour, hygroscopicity and physical stability of the confirmed co-crystals are measured and compared against the parent API.
Full technical-scientific report, with a recommendation on which co-crystal, if any, is worth taking forward.
Distinguishing a co-crystal from a salt or a physical mixture requires several independent lines of evidence, which is why the characterization set is deliberately broad.
As with every project, the deliverable is a detailed technical-scientific report documenting the whole study, not only the successful experiments.
In a salt, a proton has transferred between the API and the counter-ion, producing an ionic crystal. In a co-crystal, no proton transfer occurs and the components are held together by hydrogen bonding and other neutral interactions. The distinction has regulatory and patent consequences, so we confirm it experimentally rather than assume it.
It is usually the most promising one, alongside amorphous solid dispersion. Because co-crystallization does not depend on acid–base chemistry, it applies to molecules that are out of reach for salt formation.
That is precisely what the physical stability work is for. Some co-crystals dissociate on contact with water or under compression; others are robust. We test rather than predict, and report the result either way.
Timelines depend on the scope agreed with you — the number of crystallization conditions explored, the techniques required and the amount of characterization work on the forms found. We define the duration together with the study plan, before the project starts, and keep you updated as results come in rather than only at the end.
The quantity depends on the type of study and on how many conditions and techniques are involved. We tell you the exact amount when we scope the project, and we design the experimental plan to work with the material you have available — early-phase programmes often have very little API to spare.
Every project ends with a detailed technical-scientific report: experimental conditions, raw analytical data, interpretation and conclusions, written so that it can be used directly in your development documentation and regulatory filings.
Work starts only after a confidentiality agreement is in place. Samples, data and reports remain yours, and results are never shared or reused. We routinely handle undisclosed structures and early-phase candidates.
Tell us which property you need to improve — solubility, stability, processability — and we will propose a coformer set and a screening plan.