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)
Myelodysplastic syndrome16.01.04.001; 01.10.04.0010.000395%
Myelofibrosis16.21.03.001; 01.13.03.0050.000263%Not Available
Myocardial infarction02.02.02.007; 24.04.04.009--
Myocardial ischaemia24.04.04.010; 02.02.02.0080.000263%Not Available
Nail disorder23.02.05.0020.000922%
Nail dystrophy23.02.05.0030.000790%Not Available
Nausea07.01.07.001--
Neoplasm16.16.02.0010.001581%Not Available
Neoplasm malignant16.16.01.0010.001712%Not Available
Nephropathy20.05.03.001--Not Available
Nephropathy toxic20.05.03.002; 12.03.01.0100.000263%Not Available
Nephrotic syndrome20.05.01.0020.000395%
Nervous system disorder17.02.10.001--Not Available
Nervousness19.06.02.003--Not Available
Neuralgia17.02.07.0050.000711%
Neuropathy peripheral17.09.03.0030.003793%Not Available
Neutropenia01.02.03.0040.005848%Not Available
Night sweats23.02.03.006; 08.01.03.0310.000843%Not Available
Nystagmus17.02.02.006; 06.05.02.0060.000263%
Obliterative bronchiolitis12.02.09.036; 22.03.01.012; 10.02.01.0960.000263%Not Available
Oedema14.05.06.010; 08.01.07.006--Not Available
Oedema peripheral14.05.06.011; 08.01.07.007; 02.05.04.0070.002634%
Oesophageal carcinoma16.13.06.001; 07.21.06.0010.000395%Not Available
Oesophageal ulcer07.04.05.0020.000527%
Oestrogen deficiency21.11.02.003; 05.05.04.003--Not Available
Oliguria20.01.03.0040.000527%Not Available
Oral discomfort07.05.05.0010.000922%Not Available
Oral pain07.05.05.0340.001054%
Osteoarthritis15.01.04.0010.001501%Not Available
Osteonecrosis24.04.05.004; 15.02.04.0070.001844%
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ADReCS-Target
Drug Name ADR Term Target
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