You are using an unsupported browser. Please upgrade your browser to a newer version to get the best experience on DrugBank.
Identification
NameLetrozole
Accession NumberDB01006  (APRD01066)
TypeSmall Molecule
GroupsApproved, Investigational
DescriptionLetrozole (INN, trade name Femara®) is an oral non-steroidal aromatase inhibitor that has been introduced for the adjuvant treatment of hormonally-responsive breast cancer Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Letrozole blocks production of estrogens in this way by competitive, reversible binding to the heme of its cytochrome P450 unit. The action is specific, and letrozole does not reduce production of mineralo- or corticosteroids. In contrast, the antiestrogenic action of tamoxifen, the major medical therapy prior to the arrival of aromatase inhibitors, is due to its interfering with the estrogen receptor, rather than inhibiting estrogen production. Letrozole is approved by the United States Food and Drug Administration (FDA) for the treatment of local or metastatic breast cancer that is hormone receptor positive or has an unknown receptor status in postmenopausal women. Side effects include signs and symptoms of hypoestrogenism. There is concern that long term use may lead to osteoporosis, which is why prescriptions of Letrozole are often accompanied by prescriptions of osteoporosis-fighting medication such as Fosamax. Letrozole has shown to reduce estrogen levels by 98 percent while raising testosterone levels. The anti-estrogen action of letrozole is preferred by athletes and bodybuilders for use during a steroid cycle to reduce bloating due to excess water retention and prevent the formation of gynecomastia related breast tissue that is a side effect of some anabolic steroids. Usage above 2.5 mg/day is known to potentially temporarily kill sex drive. Above 5mg/day for extended periods may cause kidney problems. Letrozole has also been shown to delay the fusing of the growth plates in adolescents. This may boost the effectiveness of growth hormone, and thus Letrozole is used to treat adolescents and children with short stature.
Structure
Thumb
Synonyms
Femara
Letrozol
Letrozole
External Identifiers Not Available
Approved Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Accel-letrozole Tablets USPtablet2.5 mgoralAccel Pharma IncNot applicableNot applicableCanada
Ach-letrozoletablet2.5 mgoralAccord Healthcare Inc2010-05-03Not applicableCanada
Ag-letrozoletablet2.5 mgoralAngita Pharma Inc.Not applicableNot applicableCanada
Auro-letrozoletablet2.5 mgoralAuro Pharma Inc2013-06-12Not applicableCanada
Bio-letrozoletablet2.5 mgoralBiomed Pharma2013-02-12Not applicableCanada
Co Letrozoletablet2.5 mgoralCobalt Pharmaceuticals CompanyNot applicableNot applicableCanada
Dom-letrozoletablet2.5 mgoralDominion PharmacalNot applicableNot applicableCanada
Femaratablet, film coated2.5 mg/1oralNovartis Pharmaceuticals Corporation1997-07-31Not applicableUs
Femaratablet, film coated2.5 mg/1oralPhysicians Total Care, Inc.2005-02-10Not applicableUs
Femara 2.5mgtablet2.5 mgoralNovartis Pharmaceuticals Canada Inc1997-09-02Not applicableCanada
Ipg-letrozoletablet2.5 mgoralMarcan Pharmaceuticals IncNot applicableNot applicableCanada
Jamp-letrozoletablet2.5 mgoralJamp Pharma Corporation2011-09-30Not applicableCanada
Letrozoletablet2.5 mgoralActavis Pharma Company2010-04-28Not applicableCanada
Letrozoletablet2.5 mgoralTeva Canada Limited2010-04-282013-12-10Canada
Letrozoletablet2.5 mgoralMeliapharm Inc2011-08-292014-06-25Canada
Letrozoletablet2.5 mgoralPro Doc Limitee2013-02-14Not applicableCanada
Letrozole Suntablet2.5 mgoralTaro Pharmaceuticals IncNot applicableNot applicableCanada
Letrozole Tabletstablet2.5 mgoralFresenius Kabi Canada LtdNot applicableNot applicableCanada
Mar-letrozoletablet2.5 mgoralMarcan Pharmaceuticals Inc2013-01-08Not applicableCanada
Med-letrozoletablet2.5 mgoralGeneric Medical Partners Inc2010-04-28Not applicableCanada
Myl-letrozoletablet2.5 mgoralMylan Pharmaceuticals Ulc2011-09-082016-06-28Canada
Mylan-letrozoletablet2.5 mgoralMylan Pharmaceuticals UlcNot applicableNot applicableCanada
Nat-letrozoletablet2.5 mgoralNatco Pharma (Canada) Inc2015-02-03Not applicableCanada
PHL-letrozoletablet2.5 mgoralPharmel IncNot applicableNot applicableCanada
PMS-letrozoletablet2.5 mgoralPharmascience Inc2010-04-28Not applicableCanada
Ran-letrozoletablet2.5 mgoralRanbaxy Pharmaceuticals Canada Inc.2011-10-04Not applicableCanada
Riva-letrozoletablet2.5 mgoralLaboratoire Riva Inc2014-02-11Not applicableCanada
Sandoz Letrozoletablet2.5 mgoralSandoz Canada Incorporated2010-04-27Not applicableCanada
Stason-letrozoletablet2.5 mgoralVpi Pharmaceuticals IncNot applicableNot applicableCanada
Teva-letrozoletablet2.5 mgoralTeva Canada Limited2013-07-08Not applicableCanada
Van-letrozoletablet2.5 mgoralVanc Pharmaceuticals Inc2015-06-08Not applicableCanada
Zinda-letrozoletablet2.5 mgoralStason Pharmaceuticals Inc2013-06-18Not applicableCanada
Approved Generic Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Apo-letrozoletablet2.5 mgoralApotex Inc2012-06-11Not applicableCanada
Letrozoletablet, film coated2.5 mg/1oralRebel Distributors Corp2011-06-03Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralSun Pharmaceutical Industries Limited2015-09-09Not applicableUs
Letrozoletablet2.5 mg/1oralRoxane Laboratories, Inc.2011-06-03Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralDr. Reddy's Laboratories Limited2011-06-03Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralZydus Pharmaceuticals (USA) Inc.2011-06-03Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralLannett Company, Inc.2014-10-29Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralAv Kare, Inc.2015-01-02Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralAPP Pharmaceuticals, LLC2011-06-04Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralTeva Pharmaceuticals USA Inc2011-06-03Not applicableUs
Letrozoletablet2.5 mg/1oralJiangsu Hengrui Medicine Co., Ltd.2013-05-16Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralAccord Healthcare, Inc.2011-06-02Not applicableUs
Letrozoletablet2.5 mg/1oralBreckenridge Pharmaceutical, Inc.2011-06-04Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralKAISER FOUNDATION HOSPITALS2015-02-05Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralCadila Healthcare Limited2011-06-03Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralApotex Corp.2012-05-31Not applicableUs
Letrozoletablet2.5 mg/1oralINDICUS PHARMA LLC2011-06-15Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralPhysicians Total Care, Inc.2011-05-04Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralAmerican Health Packaging2014-08-20Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralMylan Pharmaceuticals Inc.2011-04-22Not applicableUs
Letrozoletablet, film coated2.5 mg/1oralKremers Urban Pharmaceuticals Inc.2011-06-03Not applicableUs
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International BrandsNot Available
Brand mixturesNot Available
SaltsNot Available
Categories
UNII7LKK855W8I
CAS number112809-51-5
WeightAverage: 285.3027
Monoisotopic: 285.101445377
Chemical FormulaC17H11N5
InChI KeyInChIKey=HPJKCIUCZWXJDR-UHFFFAOYSA-N
InChI
InChI=1S/C17H11N5/c18-9-13-1-5-15(6-2-13)17(22-12-20-11-21-22)16-7-3-14(10-19)4-8-16/h1-8,11-12,17H
IUPAC Name
4-[(4-cyanophenyl)(1H-1,2,4-triazol-1-yl)methyl]benzonitrile
SMILES
N#CC1=CC=C(C=C1)C(N1C=NC=N1)C1=CC=C(C=C1)C#N
Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as diphenylmethanes. These are compounds containing a diphenylmethane moiety, which consists of a methane wherein two hydrogen atoms are replaced by two phenyl groups.
KingdomOrganic compounds
Super ClassBenzenoids
ClassBenzene and substituted derivatives
Sub ClassDiphenylmethanes
Direct ParentDiphenylmethanes
Alternative Parents
Substituents
  • Diphenylmethane
  • Benzonitrile
  • Heteroaromatic compound
  • 1,2,4-triazole
  • Azole
  • Azacycle
  • Organoheterocyclic compound
  • Nitrile
  • Carbonitrile
  • Hydrocarbon derivative
  • Organonitrogen compound
  • Aromatic heteromonocyclic compound
Molecular FrameworkAromatic heteromonocyclic compounds
External Descriptors
Pharmacology
IndicationFor the extended adjuvant treatment of early breast cancer in postmenopausal women who have received 5 years of adjuvant tamoxifen therapy. Also for first-line treatment of postmenopausal women with hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer. Also indicated for the treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy.
PharmacodynamicsLetrozole is an aromatase inhibitor used in the treatment of breast cancer. Aromatase inhibitors work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization. As breast tissue is stimulated by estrogens, decreasing their production is a way of suppressing recurrence of the breast tumor tissue.
Mechanism of actionLetrozole is a nonsteroidal competitive inhibitor of the aromatase enzyme system; it inhibits the conversion of androgens to estrogens. In adult nontumor- and tumorbearing female animals, letrozole is as effective as ovariectomy in reducing uterine weight, elevating serum Leuteinizing hormone (LH), and causing the regression of estrogen-dependent tumors. In contrast to ovariectomy, treatment with letrozole does not lead to an increase in serum (folicile stimulating hormone (FSH). Letrozole selectively inhibits gonadal steroidogenesis but has no significant effect on adrenal mineralocorticoid or glucocorticoid synthesis.
Related Articles
AbsorptionRapidly and completely absorbed. Absorption is not affected by food.
Volume of distributionNot Available
Protein bindingNot Available
Metabolism

Primarily hepatic via CYP3A4 and CYP2A6. Letrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P450 subunit of the enzyme, resulting in a reduction of estrogen biosynthesis in all tissues. It is metabolized slowly to an inactive metabolite whose glucuronide conjugate is excreted renally, representing the major clearance pathway.

SubstrateEnzymesProduct
Letrozole
4,4'-methanol-bisbenzonitrileDetails
Route of eliminationNot Available
Half life2 days
ClearanceNot Available
ToxicityNot Available
Affected organisms
  • Humans and other mammals
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
ADMET
Predicted ADMET features
PropertyValueProbability
Human Intestinal Absorption+0.9965
Blood Brain Barrier+0.9737
Caco-2 permeable+0.6347
P-glycoprotein substrateNon-substrate0.8391
P-glycoprotein inhibitor INon-inhibitor0.8087
P-glycoprotein inhibitor IINon-inhibitor0.9147
Renal organic cation transporterNon-inhibitor0.5908
CYP450 2C9 substrateNon-substrate0.7898
CYP450 2D6 substrateNon-substrate0.9116
CYP450 3A4 substrateNon-substrate0.6843
CYP450 1A2 substrateNon-inhibitor0.8374
CYP450 2C9 inhibitorNon-inhibitor0.9071
CYP450 2D6 inhibitorNon-inhibitor0.923
CYP450 2C19 inhibitorInhibitor0.8993
CYP450 3A4 inhibitorInhibitor0.6451
CYP450 inhibitory promiscuityHigh CYP Inhibitory Promiscuity0.7027
Ames testNon AMES toxic0.6371
CarcinogenicityNon-carcinogens0.8926
BiodegradationNot ready biodegradable0.9864
Rat acute toxicity1.9916 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9261
hERG inhibition (predictor II)Non-inhibitor0.8817
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Pharmacoeconomics
Manufacturers
  • Novartis pharmaceuticals corp
  • Mylan pharmaceuticals inc
Packagers
Dosage forms
FormRouteStrength
Tablet, film coatedoral2.5 mg/1
Tabletoral2.5 mg
Tabletoral2.5 mg/1
Prices
Unit descriptionCostUnit
Femara 2.5 mg tablet16.87USD tablet
DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.
Patents
Patent NumberPediatric ExtensionApprovedExpires (estimated)
US4978672 No1994-06-032011-06-03Us
Properties
StateSolid
Experimental Properties
PropertyValueSource
melting point184-185 °CNot Available
logP2.5Not Available
Predicted Properties
PropertyValueSource
Water Solubility0.0799 mg/mLALOGPS
logP1.86ALOGPS
logP2.94ChemAxon
logS-3.5ALOGPS
pKa (Strongest Basic)2.17ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count4ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area78.29 Å2ChemAxon
Rotatable Bond Count3ChemAxon
Refractivity94.47 m3·mol-1ChemAxon
Polarizability29.59 Å3ChemAxon
Number of Rings3ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectra
Mass Spec (NIST)Not Available
Spectra
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
References
Synthesis Reference

Peter MacDonald, Ettore Bigatti, Pierluigi Rossetto, Zvi Harel, “Process for the preparation of letrozole.” U.S. Patent US20070066831, issued March 22, 2007.

US20070066831
General References
  1. Tulandi T, Martin J, Al-Fadhli R, Kabli N, Forman R, Hitkari J, Librach C, Greenblatt E, Casper RF: Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate. Fertil Steril. 2006 Jun;85(6):1761-5. Epub 2006 May 2. [PubMed:16650422 ]
External Links
ATC CodesL02BG04
AHFS Codes
  • 10:00.00
PDB EntriesNot Available
FDA labelDownload (112 KB)
MSDSNot Available
Interactions
Drug Interactions
Drug
AcetyldigitoxinAcetyldigitoxin may decrease the cardiotoxic activities of Letrozole.
AmiodaroneThe metabolism of Letrozole can be decreased when combined with Amiodarone.
AprepitantThe serum concentration of Letrozole can be increased when it is combined with Aprepitant.
ArtesunateThe serum concentration of the active metabolites of Artesunate can be reduced when Artesunate is used in combination with Letrozole resulting in a loss in efficacy.
AtazanavirThe metabolism of Letrozole can be decreased when combined with Atazanavir.
AtomoxetineThe metabolism of Letrozole can be decreased when combined with Atomoxetine.
BevacizumabBevacizumab may increase the cardiotoxic activities of Letrozole.
BexaroteneThe serum concentration of Letrozole can be decreased when it is combined with Bexarotene.
BoceprevirThe metabolism of Letrozole can be decreased when combined with Boceprevir.
BortezomibThe metabolism of Letrozole can be decreased when combined with Bortezomib.
BosentanThe serum concentration of Letrozole can be decreased when it is combined with Bosentan.
CabazitaxelThe risk or severity of adverse effects can be increased when Cabazitaxel is combined with Letrozole.
CarbamazepineThe metabolism of Letrozole can be increased when combined with Carbamazepine.
CeritinibThe serum concentration of Letrozole can be increased when it is combined with Ceritinib.
ClarithromycinThe metabolism of Letrozole can be decreased when combined with Clarithromycin.
ClemastineThe metabolism of Letrozole can be decreased when combined with Clemastine.
ClotrimazoleThe metabolism of Letrozole can be decreased when combined with Clotrimazole.
CobicistatThe metabolism of Letrozole can be decreased when combined with Cobicistat.
ConivaptanThe serum concentration of Letrozole can be increased when it is combined with Conivaptan.
CrizotinibThe metabolism of Letrozole can be decreased when combined with Crizotinib.
CyclophosphamideCyclophosphamide may increase the cardiotoxic activities of Letrozole.
CyclosporineThe metabolism of Letrozole can be decreased when combined with Cyclosporine.
DabrafenibThe serum concentration of Letrozole can be decreased when it is combined with Dabrafenib.
DarunavirThe metabolism of Letrozole can be decreased when combined with Darunavir.
DasatinibThe serum concentration of Letrozole can be increased when it is combined with Dasatinib.
DeferasiroxThe serum concentration of Letrozole can be decreased when it is combined with Deferasirox.
DelavirdineThe metabolism of Letrozole can be decreased when combined with Delavirdine.
DeslanosideDeslanoside may decrease the cardiotoxic activities of Letrozole.
DexamethasoneThe serum concentration of Letrozole can be decreased when it is combined with Dexamethasone.
DigitoxinDigitoxin may decrease the cardiotoxic activities of Letrozole.
DigoxinDigoxin may decrease the cardiotoxic activities of Letrozole.
DihydroergotamineThe metabolism of Letrozole can be decreased when combined with Dihydroergotamine.
DiltiazemThe metabolism of Letrozole can be decreased when combined with Diltiazem.
DocetaxelThe risk or severity of adverse effects can be increased when Docetaxel is combined with Letrozole.
DoxycyclineThe metabolism of Letrozole can be decreased when combined with Doxycycline.
DronedaroneThe metabolism of Letrozole can be decreased when combined with Dronedarone.
EfavirenzThe serum concentration of Letrozole can be decreased when it is combined with Efavirenz.
EnzalutamideThe serum concentration of Letrozole can be decreased when it is combined with Enzalutamide.
ErythromycinThe metabolism of Letrozole can be decreased when combined with Erythromycin.
Eslicarbazepine acetateThe serum concentration of Letrozole can be decreased when it is combined with Eslicarbazepine acetate.
EtravirineThe serum concentration of Letrozole can be decreased when it is combined with Etravirine.
FluconazoleThe metabolism of Letrozole can be decreased when combined with Fluconazole.
FluvoxamineThe metabolism of Letrozole can be decreased when combined with Fluvoxamine.
FosamprenavirThe metabolism of Letrozole can be decreased when combined with Fosamprenavir.
FosaprepitantThe serum concentration of Letrozole can be increased when it is combined with Fosaprepitant.
FosphenytoinThe metabolism of Letrozole can be increased when combined with Fosphenytoin.
Fusidic AcidThe serum concentration of Letrozole can be increased when it is combined with Fusidic Acid.
IdelalisibThe serum concentration of Letrozole can be increased when it is combined with Idelalisib.
ImatinibThe metabolism of Letrozole can be decreased when combined with Imatinib.
IndinavirThe metabolism of Letrozole can be decreased when combined with Indinavir.
IsavuconazoniumThe metabolism of Letrozole can be decreased when combined with Isavuconazonium.
IsradipineThe metabolism of Letrozole can be decreased when combined with Isradipine.
ItraconazoleThe metabolism of Letrozole can be decreased when combined with Itraconazole.
IvacaftorThe serum concentration of Letrozole can be increased when it is combined with Ivacaftor.
KetoconazoleThe metabolism of Letrozole can be decreased when combined with Ketoconazole.
LopinavirThe metabolism of Letrozole can be decreased when combined with Lopinavir.
LovastatinThe metabolism of Letrozole can be decreased when combined with Lovastatin.
LuliconazoleThe serum concentration of Letrozole can be increased when it is combined with Luliconazole.
MethadoneThe serum concentration of Methadone can be increased when it is combined with Letrozole.
MifepristoneThe metabolism of Letrozole can be decreased when combined with Mifepristone.
MitotaneThe serum concentration of Letrozole can be decreased when it is combined with Mitotane.
ModafinilThe serum concentration of Letrozole can be decreased when it is combined with Modafinil.
NafcillinThe serum concentration of Letrozole can be decreased when it is combined with Nafcillin.
NefazodoneThe metabolism of Letrozole can be decreased when combined with Nefazodone.
NelfinavirThe metabolism of Letrozole can be decreased when combined with Nelfinavir.
NetupitantThe serum concentration of Letrozole can be increased when it is combined with Netupitant.
NevirapineThe metabolism of Letrozole can be decreased when combined with Nevirapine.
NicotineThe metabolism of Letrozole can be decreased when combined with Nicotine.
NilotinibThe metabolism of Letrozole can be decreased when combined with Nilotinib.
OlaparibThe metabolism of Letrozole can be decreased when combined with Olaparib.
OsimertinibThe serum concentration of Letrozole can be increased when it is combined with Osimertinib.
OuabainOuabain may decrease the cardiotoxic activities of Letrozole.
PaclitaxelThe risk or severity of adverse effects can be increased when Paclitaxel is combined with Letrozole.
PalbociclibThe serum concentration of Letrozole can be increased when it is combined with Palbociclib.
PentobarbitalThe metabolism of Letrozole can be increased when combined with Pentobarbital.
PhenobarbitalThe metabolism of Letrozole can be increased when combined with Phenobarbital.
PhenytoinThe metabolism of Letrozole can be increased when combined with Phenytoin.
PosaconazoleThe metabolism of Letrozole can be decreased when combined with Posaconazole.
PrimidoneThe metabolism of Letrozole can be increased when combined with Primidone.
RanolazineThe metabolism of Letrozole can be decreased when combined with Ranolazine.
RifabutinThe metabolism of Letrozole can be increased when combined with Rifabutin.
RifampicinThe metabolism of Letrozole can be increased when combined with Rifampicin.
RifapentineThe metabolism of Letrozole can be increased when combined with Rifapentine.
RitonavirThe metabolism of Letrozole can be decreased when combined with Ritonavir.
SaquinavirThe metabolism of Letrozole can be decreased when combined with Saquinavir.
SildenafilThe metabolism of Letrozole can be decreased when combined with Sildenafil.
SiltuximabThe serum concentration of Letrozole can be decreased when it is combined with Siltuximab.
SimeprevirThe serum concentration of Letrozole can be increased when it is combined with Simeprevir.
St. John's WortThe serum concentration of Letrozole can be decreased when it is combined with St. John's Wort.
StiripentolThe serum concentration of Letrozole can be increased when it is combined with Stiripentol.
SulfisoxazoleThe metabolism of Letrozole can be decreased when combined with Sulfisoxazole.
TamoxifenThe serum concentration of Letrozole can be decreased when it is combined with Tamoxifen.
TelaprevirThe metabolism of Letrozole can be decreased when combined with Telaprevir.
TelithromycinThe metabolism of Letrozole can be decreased when combined with Telithromycin.
TiclopidineThe metabolism of Letrozole can be decreased when combined with Ticlopidine.
TocilizumabThe serum concentration of Letrozole can be decreased when it is combined with Tocilizumab.
TrastuzumabTrastuzumab may increase the cardiotoxic activities of Letrozole.
VenlafaxineThe metabolism of Letrozole can be decreased when combined with Venlafaxine.
VerapamilThe metabolism of Letrozole can be decreased when combined with Verapamil.
VoriconazoleThe metabolism of Letrozole can be decreased when combined with Voriconazole.
ZiprasidoneThe metabolism of Letrozole can be decreased when combined with Ziprasidone.
Food Interactions
  • Take without regard to meals. Food slows absorption without decreasing the quantity absorbed.

Targets

Kind
Protein
Organism
Human
Pharmacological action
yes
Actions
antagonist
General Function:
Oxygen binding
Specific Function:
Catalyzes the formation of aromatic C18 estrogens from C19 androgens.
Gene Name:
CYP19A1
Uniprot ID:
P11511
Molecular Weight:
57882.48 Da
References
  1. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
  2. Ebert AD, Bartley J, David M, Schweppe KW: [Aromatase inhibitors--theoretical concept and present experiences in the treatment of endometriosis]. Zentralbl Gynakol. 2003 Jul-Aug;125(7-8):247-51. [PubMed:14505258 ]
  3. Long BJ, Jelovac D, Handratta V, Thiantanawat A, MacPherson N, Ragaz J, Goloubeva OG, Brodie AM: Therapeutic strategies using the aromatase inhibitor letrozole and tamoxifen in a breast cancer model. J Natl Cancer Inst. 2004 Mar 17;96(6):456-65. [PubMed:15026471 ]
  4. Murphy MJ Jr: Molecular Action and Clinical Relevance of Aromatase Inhibitors. Oncologist. 1998;3(2):129-130. [PubMed:10388095 ]

Enzymes

Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
substrate
General Function:
Vitamin d3 25-hydroxylase activity
Specific Function:
Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It performs a variety of oxidation reactions (e.g. caffeine 8-oxidation, omeprazole sulphoxidation, midazolam 1'-hydroxylation and midazolam 4-hydroxylation) of structurally unrelated compounds, including steroids, fatty acids, and xenobiot...
Gene Name:
CYP3A4
Uniprot ID:
P08684
Molecular Weight:
57342.67 Da
References
  1. Preissner S, Kroll K, Dunkel M, Senger C, Goldsobel G, Kuzman D, Guenther S, Winnenburg R, Schroeder M, Preissner R: SuperCYP: a comprehensive database on Cytochrome P450 enzymes including a tool for analysis of CYP-drug interactions. Nucleic Acids Res. 2010 Jan;38(Database issue):D237-43. doi: 10.1093/nar/gkp970. Epub 2009 Nov 24. [PubMed:19934256 ]
Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
substrateinhibitor
General Function:
Steroid hydroxylase activity
Specific Function:
Exhibits a high coumarin 7-hydroxylase activity. Can act in the hydroxylation of the anti-cancer drugs cyclophosphamide and ifosphamide. Competent in the metabolic activation of aflatoxin B1. Constitutes the major nicotine C-oxidase. Acts as a 1,4-cineole 2-exo-monooxygenase. Possesses low phenacetin O-deethylation activity.
Gene Name:
CYP2A6
Uniprot ID:
P11509
Molecular Weight:
56501.005 Da
References
  1. Preissner S, Kroll K, Dunkel M, Senger C, Goldsobel G, Kuzman D, Guenther S, Winnenburg R, Schroeder M, Preissner R: SuperCYP: a comprehensive database on Cytochrome P450 enzymes including a tool for analysis of CYP-drug interactions. Nucleic Acids Res. 2010 Jan;38(Database issue):D237-43. doi: 10.1093/nar/gkp970. Epub 2009 Nov 24. [PubMed:19934256 ]
Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
substrateinhibitor
General Function:
Oxygen binding
Specific Function:
Catalyzes the formation of aromatic C18 estrogens from C19 androgens.
Gene Name:
CYP19A1
Uniprot ID:
P11511
Molecular Weight:
57882.48 Da
References
  1. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
  2. Preissner S, Kroll K, Dunkel M, Senger C, Goldsobel G, Kuzman D, Guenther S, Winnenburg R, Schroeder M, Preissner R: SuperCYP: a comprehensive database on Cytochrome P450 enzymes including a tool for analysis of CYP-drug interactions. Nucleic Acids Res. 2010 Jan;38(Database issue):D237-43. doi: 10.1093/nar/gkp970. Epub 2009 Nov 24. [PubMed:19934256 ]
Comments
comments powered by Disqus
Drug created on June 13, 2005 07:24 / Updated on August 17, 2016 12:23