Adverse Drug Reaction Classification System

Pharmaceutical Information
Drug Name Letrozole
Drug ID BADD_D01257
Description Letrozole, or CGS 20267, is an oral non-steroidal type II aromatase inhibitor first described in the literature in 1990.[A190543,A1559,L11623,L11626] It is a third generation aromatase inhibitor like [exemestane] and [anastrozole], meaning it does not significantly affect cortisol, aldosterone, and thyroxine.[A190546] Letrozole was granted FDA approval on 25 July 1997.[L11623]
Indications and Usage Letrozole is indicated to treat postmenopausal women with hormone receptor (HR) positive early breast cancer, postmenopausal women with early breast cancer who have periviously been treated with tamoxifen, and postmenopausal women with HR+ or unknown advanced breast cancer.[L11623] Letrozole, given with ribociclib, is indicated to treat pre, peri, and postmenopausal women with HR+ and human epidermal growth factor 2 (HER2) negative advanced or metastatic breast cancer.[L11626]
Marketing Status approved; investigational
ATC Code L02BG04
DrugBank ID DB01006
KEGG ID D00964
MeSH ID D000077289
PubChem ID 3902
TTD Drug ID D0C1WH
NDC Product Code 58623-0099; 62135-491; 63629-7819; 71205-587; 69988-0014; 50268-476; 68554-0039; 16729-034; 51991-759; 59651-180; 63850-0025; 57884-0011; 65096-0116; 13808-514; 63592-3376; 65129-1130; 0078-0249; 55111-809; 63850-7723; 0093-7620; 42291-374; 71335-1526; 63850-7701; 55111-646
UNII 7LKK855W8I
Synonyms Letrozole | 4,4'-(1H-1,2,4-triazol-1-yl-methylene)-bis(benzonitrile) | CGS 20267 | CGS-20267 | CGS20267 | Femara | Fémara
Chemical Information
Molecular Formula C17H11N5
CAS Registry Number 112809-51-5
SMILES C1=CC(=CC=C1C#N)C(C2=CC=C(C=C2)C#N)N3C=NC=N3
Chemical Structure
ADRs Induced by Drug
*The priority for ADR severity classification is based on FAERS assessment, followed by the most severe level in CTCAE rating. If neither is available, it will be displayed as 'Not available'.
**The 'Not Available' level is hidden by default and can be restored by clicking on the legend twice..
ADR Term ADReCS ID ADR Frequency (FAERS) ADR Severity Grade (FAERS) ADR Severity Grade (CTCAE)
Intervertebral disc protrusion15.10.01.0040.000263%Not Available
Subileus07.13.01.0040.000263%Not Available
Musculoskeletal chest pain22.09.01.001; 15.03.04.0120.001897%
Macular hole06.09.03.0090.000790%Not Available
Cardiopulmonary failure22.02.06.004; 02.05.01.0040.000263%Not Available
Foreign body sensation in eyes06.01.01.0060.000263%Not Available
Central nervous system lesion17.02.10.0110.001054%Not Available
Malignant neoplasm progression16.16.01.0050.024498%Not Available
Acute coronary syndrome24.04.04.011; 02.02.02.0150.000922%Not Available
Metastases to peritoneum07.21.03.003; 16.22.02.0080.001185%Not Available
Gastrointestinal hypomotility07.02.02.0050.000527%Not Available
Musculoskeletal stiffness15.03.05.0270.002292%Not Available
Musculoskeletal discomfort15.03.04.0010.000659%Not Available
Type IV hypersensitivity reaction10.01.03.0220.000527%Not Available
Cerebral haematoma17.08.01.014; 24.07.04.0060.000395%Not Available
Nodule08.03.05.0020.000395%Not Available
Foetal death18.01.02.003; 08.04.01.0110.000659%
Haemorrhage24.07.01.002--Not Available
Postmenopausal haemorrhage24.07.03.002; 21.02.01.0020.000263%Not Available
Faecaloma07.01.03.0040.000922%Not Available
Pulmonary mass22.02.07.0040.002160%Not Available
Cutaneous lupus erythematosus23.03.02.008; 15.06.02.007; 10.04.03.0070.000395%Not Available
Colitis microscopic07.08.01.0110.000263%Not Available
Loss of proprioception17.02.07.0190.000527%Not Available
Cognitive disorder19.21.02.001; 17.03.03.0030.001686%
Major depression19.15.01.0030.000263%Not Available
Toxic skin eruption12.03.01.073; 23.03.05.003; 10.01.01.0080.000790%Not Available
Cancer pain16.32.03.004--Not Available
Metabolic disorder14.11.01.001--Not Available
Cystoid macular oedema12.02.02.005; 06.04.06.0100.000527%Not Available
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ADReCS-Target
Drug Name ADR Term Target
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