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)
Bone sequestrum15.02.04.0420.000395%Not Available
Cardiac sarcoidosis10.02.06.004; 02.04.02.0380.000263%Not Available
Cerebral venous sinus thrombosis24.01.04.021; 17.08.03.0060.000395%Not Available
Congestive hepatopathy09.01.06.027; 02.05.04.0180.000395%Not Available
Dilated cardiomyopathy02.04.01.0170.000263%Not Available
Drug ineffective for unapproved indication12.09.02.002; 08.06.01.0380.001238%Not Available
Dry age-related macular degeneration06.09.03.0300.000580%Not Available
Gait inability17.02.05.069; 08.01.02.0110.001370%Not Available
Haemoperitoneum07.07.02.007; 24.07.02.065; 12.01.17.0070.000263%Not Available
Hepatic cytolysis09.01.07.0360.000790%Not Available
Hormone receptor positive breast cancer21.05.01.028; 16.10.01.0180.000263%Not Available
Illness08.01.03.091--Not Available
Immune thrombocytopenia10.02.01.083; 01.08.01.0130.000659%Not Available
Inferior vena cava dilatation24.03.04.0150.000263%Not Available
Intestinal metastasis16.22.02.029; 07.21.01.0210.000263%Not Available
Lung opacity22.12.01.0060.000659%Not Available
Metastases to bladder16.22.02.030; 20.03.04.0140.000395%Not Available
Metastases to muscle16.22.02.035; 15.09.03.0300.000395%Not Available
Metastases to ovary21.11.01.019; 16.22.02.0370.000263%Not Available
Mucosal disorder08.01.06.0290.000527%Not Available
Myelosuppression01.03.03.0150.000922%Not Available
Osteoma cutis23.10.01.014; 16.26.01.0140.001159%Not Available
Ovarian cancer stage III21.11.01.020; 16.12.04.0070.000395%Not Available
Ovarian cancer stage IV21.11.01.021; 16.12.04.0080.000263%Not Available
Serous cystadenocarcinoma ovary21.11.01.024; 16.12.04.0100.000527%Not Available
Superficial vein thrombosis24.01.02.0160.000395%Not Available
Systemic scleroderma24.03.03.052; 23.03.02.025; 15.06.01.024; 10.04.07.009; 07.11.02.0090.000527%Not Available
Therapy partial responder08.06.01.0640.000263%Not Available
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ADReCS-Target
Drug Name ADR Term Target
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