How to use NCT identifiers, PubMed and sponsor websites to locate trials listed under alternate compound names?
Executive summary
Finding clinical trials when a drug is listed under alternate chemical or code names is tractable by chaining the stable NCT identifier on ClinicalTrials.gov to PubMed records and sponsor pages; the NCT number is the single most reliable bridge because it is unique and present in registry XML and often in PubMed metadata when authors follow reporting guidance [1] [2] [3]. When the published paper omits the NCT in the abstract or metadata, full‑text searches of PubMed Central and ML/linking tools—plus direct queries of sponsor websites and the ClinicalTrials.gov XML API—are the practical workarounds, though none are foolproof because not all trials generate PubMed‑indexed articles and some publications lack any NCT mention [4] [1] [5].
1. Start with the canonical anchor: ClinicalTrials.gov and the NCT ID
Every registered interventional trial on ClinicalTrials.gov has a unique NCT identifier (format NCT + 8 digits) and a structured registry record that names sponsors, start dates, phase, and often compound synonyms in the protocol or title; that NCT record is queryable directly via the web UI or programmatically through the ClinicalTrials.gov XML URL interface (for example: http://clinicaltrials.gov/show/NCTxxxxxxx?resultsxml=true) [6] [2] [7]. Use the registry entry to collect all text strings associated with the compound—protocol code names, chemical designations, and trade names—because sponsor pages and publications sometimes use only a subset of those variants [2].
2. Use PubMed’s NCT linkage and MEDLINE fields to find publications
PubMed/MEDLINE captures trial identifiers when they appear in the article (NCT‑links) and exposes them as a searchable attribute in MEDLINE and via the PubMed e‑Utilities; querying PubMed for the explicit NCT number is the fastest way to retrieve any indexed article that follows ICMJE guidance and reports the NCT in the abstract [8] [2] [3]. Be aware that ClinicalTrials.gov can also host “result references” manually supplied by investigators linking PMIDs back to the trial record; those bidirectional links are high value but depend on author or sponsor action [8].
3. When the NCT is missing in abstracts, search full text and PMC bulk data
A minority of trial‑derived articles either omit the NCT in abstract metadata or never get linked; PubMed Central full‑text searches and bulk PMC XML mining detect NCT mentions appearing in Methods or elsewhere and reliably link those papers to their trials when present [9] [5]. Natural‑language and ML systems—such as NCT Link or other trials‑to‑publications models—index MEDLINE metadata and can rank candidate PubMed articles for a given NCT even when the identifier isn’t explicit in abstracts, but they rely on article metadata and are imperfect [10] [4] [1].
4. Cross‑check sponsor websites and publication practices for alternate names
Sponsors routinely list trials on corporate pipeline or press pages using internal code names, generic names, or commerce‑focused labels that differ from registry titles; cross‑referencing the NCT, start dates, inclusion criteria and investigator names from ClinicalTrials.gov against sponsor trial pages can reveal the mapping between a compound’s alternate name and its registered NCT [2]. Note that automatic indexing works best when the NCT appears in the article abstract—studies of industry‑sponsored manuscripts show high but not perfect compliance with that convention, so lack of an abstract NCT does not prove absence of a trial record [11].
5. Practical cautions and a checklist for reliable linking
Always validate extracted NCTs because a small fraction of PubMed‑extracted registry numbers are invalid or mistyped, which can mislead searches [12]; prefer matching NCTs back to ClinicalTrials.gov to confirm legitimacy [9]. If a direct NCT→PMID link is absent, combine: ClinicalTrials.gov XML pulls for sponsor/PI names and study dates [2], PubMed SI/MEDLINE NCT fields and e‑utils searches [8], PMC full‑text searches [5], and ML ranking tools for candidate articles [10] [4]. Reporters and researchers should document each mapping step; the public registry remains the authoritative anchor, but supplementary methods are often required to locate trials reported under alternate compound names [7] [1].