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)
Lymphoedema24.09.01.001; 01.09.01.0060.000527%
Macular degeneration06.09.03.0010.000263%Not Available
Macular oedema06.04.06.0050.001317%Not Available
Malaise08.01.01.003--
Mania19.16.02.0020.000659%
Mass08.03.05.0030.000395%Not Available
Mastication disorder15.03.05.022; 17.05.03.006; 07.01.06.0160.000395%Not Available
Memory impairment19.20.01.003; 17.03.02.0030.003056%
Menopausal symptoms21.02.02.0020.000263%Not Available
Menopause26.03.01.001--Not Available
Menstruation irregular21.01.01.005; 05.05.01.008--
Metastases to liver09.04.02.004; 16.22.02.0010.005795%Not Available
Metastases to lung22.08.01.005; 16.22.02.0020.004346%Not Available
Metastases to spine16.22.02.007; 15.09.03.0070.001449%Not Available
Migraine24.03.05.003; 17.14.02.0010.001870%Not Available
Migraine with aura24.03.05.005; 17.14.02.0020.000395%Not Available
Monoplegia17.01.04.0030.001054%Not Available
Motor neurone disease17.05.05.0020.000263%Not Available
Mouth ulceration07.05.06.0040.000790%Not Available
Movement disorder17.01.02.0100.001370%Not Available
Mucosal dryness08.01.06.0010.000659%Not Available
Mucosal inflammation08.01.06.0020.000527%Not Available
Multiple fractures12.04.02.009; 15.08.02.005--Not Available
Multiple pregnancy18.08.03.0010.000527%Not Available
Muscle atrophy17.05.03.004; 15.05.03.0030.000395%Not Available
Muscle rigidity17.05.02.005; 15.05.04.0010.001185%Not Available
Muscle twitching15.05.03.0050.000263%Not Available
Muscular weakness17.05.03.005; 15.05.06.0010.002397%
Musculoskeletal pain15.03.04.0070.000790%
Myalgia15.05.02.0010.006375%
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ADReCS-Target
Drug Name ADR Term Target
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