Map the solid-form landscape before a late-appearing polymorph becomes a CMC, formulation, manufacturing, regulatory, or IP problem. Triclinic designs phase-appropriate screens around development stage and available API, then ranks discovered forms using XRPD, thermal, moisture, solubility, stability, and orthogonal evidence.
The content of this page has been scientifically reviewed by Aeri Park, Ph.D., COO at Triclinic Labs · Updated 8/1/2026
A polymorph screen is not simply a search for crystalline forms. It is a risk-control experiment designed to determine whether the material used for PK, tox, formulation, stability, scale-up, or release is representative and controllable.
Energy differences between forms are usually small. Interconversion can occur during routine API manufacturing, formulation, milling, granulation, compression, storage, or use. A form that looked stable at small scale can be displaced by a more stable form when time, humidity, solvent history, mechanical stress, or seed exposure changes.
A decision-quality screen therefore keeps the material history attached to every sample: solvent, isolation method, drying condition, stress exposure, age, and analytical method. Without that context, a form list can be misleading because the same XRPD pattern may represent a stable target form, a kinetic form, a dehydrated hydrate, or a processing artifact.
Triclinic can design preliminary, extensive, or limited-material polymorph screens. A preliminary screen focuses on risk and likely stable forms. An extensive screen supports IP, regulatory confidence, and lifecycle coverage. A limited-material screen can be used when sample availability is below one gram.
The variety of sample-generation conditions is more important than the raw number of experiments. Solvent-based crystallization, slurry competition, thermal methods, grinding and solvent-drop experiments, sonication, vapor, pressure, hot-stage/Kofler methods, and novel nucleation conditions are selected according to the compound and the development question.
| Development point | Minimum solid-state action | Decision-quality output |
|---|---|---|
| Early discovery / lead optimization | Confirm crystallinity and form on key lots; compare lots with unusual solubility, dissolution, or exposure. | Risk flag: representative, metastable, amorphous, mixed, hydrated, solvated, or unknown. |
| Candidate selection | Run targeted polymorph, hydrate, solvate, salt/cocrystal, and ASD feasibility work; begin thermodynamic ranking. | Preferred developable form, fallback path, and known hydrate, solvate, salt, cocrystal, or ASD risks. |
| Preclinical tox / Phase I | Lock a form-control strategy; stress material against humidity, vehicle, slurry, milling, compression, and storage. | Reproducible cGMP form, process sensitivity statement, and method that confirms intended form. |
| Phase II/III / commercial | Complete broader screening; qualify release and stability methods; control process transfer, seeding, packaging, and lifecycle risks. | Control strategy linking form, process, specs, stability, packaging, site transfer, and lifecycle/IP decisions. |
Early discovery frequently samples kinetic products because rapid precipitation, evaporation, short aging, and limited material favor accessible forms. Development pressure changes the experiment: time, scale, humidity, thermal excursions, solvents, excipients, mechanical stress, and seeding can overcome kinetic barriers.
Monotropic systems have one thermodynamic winner across the relevant temperature range. Enantiotropic systems switch the thermodynamic winner at a transition temperature below melting. The relationship should not be inferred from melting point alone; DSC, slurry conversion, temperature-dependent solubility, van't Hoff analysis, or other thermodynamic evidence is needed.
The practical question is not just which form is lowest in free energy under one laboratory condition. It is whether the selected form will remain the controlled form under the program's process, packaging, storage, formulation, and analytical conditions.
Polymorph screening should be scoped to the decision gate. A candidate-selection screen, a cGMP form-control screen, a prior-art reproduction project, and a lifecycle/IP search should not be the same package.
Triclinic prioritizes diversity of sample-generation conditions, careful interpretation, retained-sample comparisons, and orthogonal confirmation over simple experiment count. The output should state what forms are known, how they interconvert, which form is preferred, what risks remain, and how the form should be monitored.
Use this decision tree to connect form selection, form control, formulation, process development, method development, release testing, stability, and lifecycle risk before the examples and publications section.
Polymorph work should deliberately sample both kinetic and thermodynamic space. Supersaturation, solvent functionality, polarity, hydrogen bonding, water mixtures, temperature, aging time, mechanical stress, and seed exposure can all influence which form appears.
High-throughput experiment count can create false confidence if the screen repeatedly samples the same accessible pathway. A useful polymorph screen is judged by whether it explores the pathways relevant to the molecule, process, dosage form, and IP objective, then scales and characterizes unique forms before property comparisons.
| Decision signal | What to test | Actionable output |
|---|---|---|
| Kinetic forms | Rapid precipitation, antisolvent addition, grinding, melt crystallization, and stress conditions can reveal forms that matter during processing. | Use the findings to flag process sensitivity and disappearing-form risk. |
| Thermodynamic ranking | Slurry aging, competitive experiments, temperature-dependent solubility, and water-activity boundaries identify stable forms and reversals. | Use ranking to support long-term form selection and control. |
| CSP support | Computational crystal structure prediction can guide the search, but energy gaps, solvent effects, flexibility, and kinetic accessibility limit it. | Treat CSP as a guide, not final evidence of accessible forms. |
Variable-temperature and variable-relative-humidity XRPD is useful when polymorph, hydrate, or phase-transition behavior depends on the temperature/RH space that the API will experience in storage or processing.
Screen ionizable APIs for counterions that improve crystallinity, solubility, dissolution, stability, manufacturability, or developability while controlling disproportionation risk.
View serviceUse coformer selection, phase-diagram logic, crystallization methods, and formulation strategy to improve properties and expand solid-form options.
View serviceCharacterize non-crystalline materials, local order, recrystallization risk, spray drying feasibility, polymer selection, drug loading, and solid-dispersion stability.
View serviceBuild reproducible crystallization processes that control the chosen solid form, particle attributes, purity, and scale-up behavior.
View serviceResolve form conversion, failed crystallizations, process sensitivity, stability drift, unexplained PK/dissolution changes, and batch-to-batch material differences.
View serviceA phase-appropriate screen should begin before an Investigational New Drug (IND) submission whenever possible, so the selected form, known alternatives, conversion risks, and analytical controls can inform toxicology, formulation, stability, and early clinical supply. Additional screening may be appropriate as the process, formulation, and development stage change.
Quality depends on the diversity and relevance of the conditions, not the raw experiment count. A strong screen explores solvent history, water activity, temperature, slurry competition, mechanical stress, seeding, isolation, and storage conditions that matter to the molecule and development stage, then follows unexpected behavior with scientist-directed experiments.
Triclinic scopes the screen around available active pharmaceutical ingredient (API), purity, salt or free-form state, prior solid-form data, solubility, stability, and the next development decision. Early screens can be designed around limited material; broader secondary and characterization work generally requires more API and representative process material.
A primary screen surveys diverse solvents and crystallization conditions to identify likely forms and early risk. A secondary screen uses what was learned to challenge the landscape more deeply, investigate thermodynamic relationships and interconversion, and support form selection and control.
Experiments vary water activity, solvent composition, temperature, humidity, isolation, drying, and storage conditions. XRPD, thermal analysis, dynamic vapor sorption, Karl Fischer titration, spectroscopy, and other evidence distinguish true hydrates or solvates from surface moisture, residual solvent, mixtures, and transformation products.
No. A screen defines the forms found under the conditions studied and reduces uncertainty; it cannot prove that an undiscovered form will never appear. The output should state residual risk and the control strategy appropriate to the development stage.
Polymorphism can affect solubility, dissolution, bioavailability, stability, filtration, drying, milling, flow, compaction, and manufacturability because each polymorph has a different crystal structure. Development teams must identify relevant forms, select a suitable form, understand conversion risks, and maintain the selected form during manufacturing, storage, and use.
Common challenges include generating meaningful experimental diversity, reproducing discovered forms, detecting low-level phases, and distinguishing polymorphs from hydrates, solvates, amorphous material, degradation products, or mixtures. Studies must also establish form relationships and determine whether manufacturing, formulation, or storage conditions can cause conversion. Limited active pharmaceutical ingredient availability can further constrain early-development studies.
Polymorphs can differ in crystal packing, free energy, moisture response, and chemical reactivity. A selected form may convert to another form when exposed to heat, humidity, solvents, pressure, milling, formulation ingredients, or long-term storage. Identifying relevant forms and their conversion conditions helps teams select a robust form, interpret stability results, and establish appropriate manufacturing and storage controls.
Confidence requires a reproducible, distinct crystalline phase and exclusion of hydrates, solvates, salts, cocrystals, amorphous material, degradation products, and mixtures. XRPD is primary because it directly probes long-range crystalline order, but thermal analysis, spectroscopy, microscopy, water or solvent measurements, and structural methods may be needed for complete classification.
The preferred form is selected by balancing thermodynamic and physical stability, solubility and dissolution, manufacturability, process sensitivity, formulation performance, analytical control, and intellectual property considerations. The recommendation also identifies known alternative forms and residual risks.
The form should be confirmed, classified, and assessed in proportion to risk. The critical questions are whether it is reproducible, whether it can occur in the proposed manufacturing process or drug product, and whether it affects stability, manufacturability, dissolution, exposure, analytical control, or intellectual property. Discovery does not automatically require reformulation or routine specification.
Solvent exposure, water activity, temperature, drying, pressure, shear, milling, granulation, compression, excipients, and seeding can favor another phase. Conversion may occur through solid-state rearrangement, solution-mediated recrystallization, dehydration, desolvation, or an amorphous intermediate. Risk should be evaluated at relevant unit operations, not only in the incoming API and final product.
Send the polymorph question, material history, screening data, known forms, process and storage stresses, formulation context, and decision timeline. Triclinic can help determine which solid-form evidence is relevant to the project, whether additional screening or thermodynamic ranking is needed, and how the selected form should be monitored through development. For a connected program from candidate nomination through IND, explore the candidate-to-IND solid-form development pathway.
