| cids | Yes | PubChem Compound IDs to fetch (1-100). Resolve from names/SMILES with pubchem_search_compounds. | |
| properties | No | Properties to retrieve. Defaults to a core set: MolecularFormula, MolecularWeight, IUPACName, CanonicalSMILES, IsomericSMILES, InChIKey, XLogP, TPSA, HBondDonorCount, HBondAcceptorCount, RotatableBondCount, HeavyAtomCount, Charge, Complexity. | |
| maxSynonyms | No | Max synonyms returned per compound per page (1-100). PubChem lists hundreds for common drugs; use synonymOffset to reach the ones past this page. Default: 20. | |
| synonymOffset | No | Zero-based index of the first synonym to return within each compound's synonym list. The same offset is applied to every compound in the batch. Pass the nextSynonymOffset from a previous call to read the following page. Default: 0. | |
| includeSynonyms | No | Fetch known names and synonyms (trade names, systematic names, registry numbers), paged via synonymOffset/maxSynonyms. Fetched for every found CID in the batch. Slower for large CID lists. | |
| maxDescriptions | No | Max number of distinct description entries per compound per page (1-20). PubChem returns near-duplicate summaries from many depositors; duplicates are collapsed before this cap applies. Default: 3. | |
| descriptionOffset | No | Zero-based index of the first description to return within each compound's description list. The same offset is applied to every compound in the batch. Pass the nextDescriptionOffset from a previous call to read the following page. Default: 0. | |
| includeDescription | No | Include textual descriptions (pharmacology, mechanism, therapeutic use) attributed by source. Well-studied compounds have many overlapping summaries — paged via descriptionOffset/maxDescriptions. Fetched only for the first 10 CIDs in the batch; remaining CIDs return without descriptions and are listed in the response's skippedCids. | |
| includeDrugLikeness | No | Compute drug-likeness assessment: Lipinski Rule of Five (MW, XLogP, HBD, HBA) and Veber rules (TPSA, rotatable bonds). Computed from the returned properties, so it adds no latency. | |
| includeClassification | No | Include pharmacological classification: FDA Established Pharmacologic Classes, mechanisms of action, MeSH classes, and ATC codes. Fetched only for the first 10 CIDs in the batch; remaining CIDs return without classification and are listed in the response's skippedCids. | |