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)
Vertigo17.02.12.002; 04.04.01.0030.002423%
Viral infection11.05.04.001--Not Available
Vision blurred17.17.01.010; 06.02.06.0070.005321%
Visual acuity reduced06.02.10.012; 17.17.01.0110.000790%
Visual impairment06.02.10.0130.003662%Not Available
Vitreous detachment12.01.04.005; 06.09.01.0020.000922%Not Available
Vitreous floaters06.09.01.0050.000395%
Vomiting07.01.07.003--
Vulvovaginal discomfort21.08.02.005--Not Available
Vulvovaginal dryness21.08.02.0030.000527%
Weight decreased13.15.01.005--
Weight increased13.15.01.006--
Xanthopsia06.02.05.0020.000395%Not Available
Tubulointerstitial nephritis20.05.02.0020.000659%Not Available
Musculoskeletal disorder15.03.05.025--Not Available
Cardiotoxicity02.11.01.009; 12.03.01.0070.000263%Not Available
Acute generalised exanthematous pustulosis11.07.01.018; 10.01.01.034; 23.03.10.002; 12.03.01.0050.000527%Not Available
Performance status decreased08.01.03.0420.000790%Not Available
Retinal toxicity12.03.01.036; 06.09.03.0130.000263%Not Available
Brain oedema17.07.02.003; 12.01.10.0100.000263%
Carotid artery occlusion24.04.06.008; 17.08.01.0120.000659%Not Available
Chapped lips07.05.01.0040.000659%Not Available
Osteopenia15.02.03.003; 14.04.04.0040.001370%Not Available
Onychomadesis23.02.05.0060.000580%
General physical health deterioration08.01.03.0180.003424%Not Available
Tachyarrhythmia02.03.02.0080.000395%Not Available
Lymphangioleiomyomatosis24.09.02.004; 22.01.02.018; 01.09.01.0180.000527%Not Available
Tumour haemorrhage24.07.01.028; 16.32.03.0080.000659%
Balance disorder08.01.03.081; 17.02.02.0070.002160%Not Available
Sudden onset of sleep17.15.04.0030.000527%Not Available
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ADReCS-Target
Drug Name ADR Term Target
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