Drug · EGFR TKI · EGFR TKI · Sourced compound
Erlotinib structure · mechanism
PubChem CID 176870. Molecular formula C22H23N3O4. Independently assigned structure; reviewed 2026-10-08. Family grouping is editorial and does not establish shared activity.
Erlotinib 2D structure
- Role
- Drug
- Mechanism class
- EGFR TKI
- Aliases
- tarceva
- InChIKey
AAKJLRGGTJKAMG-UHFFFAOYSA-N
- Structure checked
- 2026-10-08
- Molecular formula
- C22H23N3O4
- Structure source
- PubChem
- PubChem CID
- 176870
- InChI Key
- AAKJLRGGTJKAMG-UHFFFAOYSA-N
Read the two structures
Follow the bonds from erlotinib’s rings into its substituents and terminal groups, and inspect whether gefitinib has the same connections. Drawings can rotate or arrange the same motif differently; compare atoms and bond sequence rather than screen position.
| Observation | Erlotinib | Gefitinib |
|---|---|---|
| Carbon triple bond C≡C | 1 | 0 |
| Fluorine atoms | 0 | 1 |
| Chlorine atoms | 0 | 1 |
Connect the structural observations with the fingerprint result
Gefitinib has one highlighted fluorine and one chlorine. Erlotinib has neither of these query matches and instead has one carbon triple-bond C≡C match. Read the coloured regions with the counts to distinguish the selected substituents concretely. [Erlotinib] · [Gefitinib]
There are 31 shared set bits across a union of 76, giving 0.408. The selected substituents differ while other encoded environments overlap. This is a whole-structure fingerprint calculation, not a score comparing only halogens and the triple bond.
Visual resemblance is a useful observation, but this calculation neither computes a maximum common substructure nor establishes an identical scaffold. Fingerprint overlap and a shared-scaffold claim require different evidence.
Calculated structural similarity: 0.408 · Morgan radius 2 / 2048 bits · Tanimoto
Calculation: 31 / (47 + 60 − 31) = 31 / 76 ≈ 0.408. Set-bit counts are not counts of unique atoms or functional groups.
Query definitions and reproducibility
- Carbon triple bond C≡C:
C#C - Fluorine atoms:
[F] - Chlorine atoms:
[Cl]
RDKit 2025.03.4 · Matches with identical atom sets are counted once. Colours mark atoms and bonds matching selected queries, not a proven shared scaffold or synthesis route.
- Read elemental composition from the formulas.
- Trace ring and substituent connections in each drawing.
- Compare your observations with the fingerprint score calculated under identical settings.
- Check stereochemistry and the complete InChIKey in the source records.
The score is fingerprint overlap, not a percentage of efficacy or safety. RDKit
Structure-source check: 2026-10-08 / 2026-10-08 · Editorial update and calculation check: 2026-10-16
Download source structures, queries and bit counts for this comparison (JSON)
StructureMoa editorial · source review 2026-10-08
Molecular identity
Erlotinib: independently retrieved PubChem CID 176870, formula C22H23N3O4.
How to compare
Follow the bonds from erlotinib’s rings into its substituents and terminal groups, and inspect whether gefitinib has the same connections. Drawings can rotate or arrange the same motif differently; compare atoms and bond sequence rather than screen position.
Interpretation limits
The Morgan/Tanimoto score measures fingerprint overlap. It does not establish efficacy, safety, clinical superiority or full stereochemical identity.
SMILES
COCCOC1=C(C=C2C(=C1)C(=NC=N2)NC3=CC=CC(=C3)C#C)OCCOCTags
Related compounds
Comparisons · briefs
External IDs · BioMoa
StructureMoa is a chemical-structure exploration tool. Structural similarity, clustering, and SAR relationships are intended for research exploration and do not establish shared potency, selectivity, safety, efficacy, or clinical performance.
Editorial responsibility and corrections
Operated and edited by the independent StructureMoa project. Explanations use AI assistance; structural identity and similarity are checked against source records and calculation tests. Molecular data and clinical or regulatory evidence have separate review scopes.
- Source structures
- PubChem · CID / SMILES / InChIKey
- Calculations and automated checks
- RDKit · Morgan / SMARTS
- Disclosed specialist review
- No separate external specialist review is disclosed. Passing automated tests is not specialist review of clinical claims.
For a correction, include the page URL, molecule name or CID, the field in question and a supporting source. Corrections are checked against sources, and the affected editorial update date is changed when a correction is published. [email protected]