title: Increased INR after gefitinib and acenocoumarol co-administration.
abstract: BACKGROUND
  Drug interactions can cause many clinical problems, particularly when the drugs are administered in combination with anticancer agents.
  
  
  METHODS
  A patient required two hospitalizations due to risk of bleeding with altered INR probably due to an interaction between gefitinib and acenocoumarol, which resulted in the potentiation of the effect of the latter and acenocoumarol dose adjustment was needed. A causality assessment between the drug-drug interaction and the augmented INR was conducted according to Naranjo algorithm and was classified as a definite adverse drug reaction.
  
  
  CONCLUSIONS
  Patient's management recommended is to closely monitor for changes in the effects of coumarin derivatives, if administered concomitantly with antineoplasic agents.
authors.affiliation: Pharmacy Department, Gregorio Marañón University Hospital, Madrid, Spain. almudena.ribed@salud.madrid.org.
authors.forename: A
authors.initials: A
authors.lastname: Ribed
authors.forename: V
authors.initials: V
authors.lastname: Escudero-Vilaplana
authors.forename: E
authors.initials: E
authors.lastname: Gonzalez-Haba
authors.forename: M
authors.initials: M
authors.lastname: Sanjurjo
mesh_terms: D000074:Acenocoumarol / Q000009:adverse effects*; D000230:Adenocarcinoma / Q000188:drug therapy; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D000970:Antineoplastic Agents / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000188:drug therapy; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy; D004347:Drug Interactions; D000077156:Gefitinib; D006333:Heart Failure / Q000188:drug therapy; D006801:Humans; D019934:International Normalized Ratio; D008175:Lung Neoplasms / Q000188:drug therapy; D008297:Male; D047428:Protein Kinase Inhibitors / Q000009:adverse effects*; D011799:Quinazolines / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants; D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000074:Acenocoumarol; D000077156:Gefitinib