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)
Ill-defined disorder08.01.03.049--Not Available
Polyp16.02.02.005; 08.01.06.010--Not Available
Pituitary tumour benign16.37.02.001; 05.03.05.0030.000263%Not Available
Bone lesion15.02.04.0160.000790%Not Available
Disease progression08.01.03.0380.021153%
Disease recurrence08.01.03.0500.001633%Not Available
Drug intolerance08.06.01.013--Not Available
Neoplasm recurrence16.16.02.0040.000263%Not Available
Hepatic lesion09.01.08.0050.000790%Not Available
Hepatobiliary disease09.01.08.003--Not Available
Immunosuppression10.03.02.0010.000263%Not Available
Investigation13.18.01.004--Not Available
Metastasis16.22.01.0010.001844%Not Available
Renal impairment20.01.03.0100.002898%Not Available
Non-cardiac chest pain22.12.02.009; 08.01.08.0060.000395%
Poor quality sleep19.02.05.005; 17.15.04.0020.000527%Not Available
Retinal pigment epithelial tear06.09.03.0160.000263%Not Available
Effusion08.01.03.0520.000263%Not Available
Hypophagia07.01.06.010; 19.09.01.004; 14.03.01.0060.000527%Not Available
Pelvic discomfort21.10.01.012; 20.02.03.012; 07.01.06.0200.000527%Not Available
Muscle swelling15.05.03.0150.000263%Not Available
Osteonecrosis of jaw24.04.05.005; 15.02.04.0100.004873%
Ovarian haemorrhage24.07.03.009; 21.11.02.0060.000395%
Mixed liver injury09.01.07.0150.000659%Not Available
Genital discomfort21.10.01.0070.000527%Not Available
Liver injury12.01.17.012; 09.01.07.0220.000395%Not Available
Organising pneumonia22.01.02.0080.001054%Not Available
Adverse reaction08.06.01.0180.000659%Not Available
Decreased vibratory sense17.02.07.0130.000527%Not Available
Low birth weight baby18.04.02.0030.001054%Not Available
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ADReCS-Target
Drug Name ADR Term Target
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