title: Fatal interaction between clarithromycin and colchicine in patients with renal insufficiency: a retrospective study.
abstract: BACKGROUND
  Clarithromycin is frequently used to treat community-acquired pneumonia in elderly persons. Like erythromycin, it may interact with other drugs by interfering with metabolism by cytochrome P450 enzymes and with the P-glycoprotein transporter system. Colchicine, used for treatment of acute gout and for prophylaxis, may cause bone marrow toxicity. It is metabolized by CYP3A4 and is transported by P-glycoprotein. Initial case reports suggested potentially fatal interactions between clarithromycin and colchicine.
  
  
  METHODS
  A retrospective study was conducted with 116 patients who were prescribed clarithromycin and colchicine during the same clinical admission. Case-control comparisons were made between patients who received concomitant therapy with the 2 drugs and patients who received sequential therapy. We assessed the clinical presentations and outcomes of the 2 patient groups and analyzed the risk factors associated with fatal outcomes.
  
  
  RESULTS
  Nine (10.2%) of the 88 patients who received the 2 drugs concomitantly died. Only 1 (3.6%) of the 28 patients who received the drugs sequentially died. Multivariate analysis of the 88 patients who received concomitant therapy showed that longer overlapped therapy (relative risk [RR], 2.16; 95% confidence interval [CI], 1.41-3.31; P< or =.01), the presence of baseline renal impairment (RR, 9.1; 95% CI, 1.75-47.06; P<.001), and the development of pancytopenia (RR, 23.4; 95% CI, 4.48-122.7; P<.001) were independently associated with death.
  
  
  CONCLUSIONS
  Clarithromycin increases the risk of fatal colchicine toxicity, especially for patients with renal insufficiency. Since there are other drugs for treatment of pneumonia and gout, these 2 drugs should not be coprescribed, because of the risk of fatality.
authors: Research Center of Infection and Immunology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
authors: I F N
authors: IF
authors: Hung
authors: A K L
authors: AK
authors: Wu
authors: V C C
authors: VC
authors: Cheng
authors: B S F
authors: BS
authors: Tang
authors: K W
authors: KW
authors: To
authors: C K
authors: CK
authors: Yeung
authors: P C Y
authors: PC
authors: Woo
authors: S K P
authors: SK
authors: Lau
authors: B M Y
authors: BM
authors: Cheung
authors: K Y
authors: KY
authors: Yuen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects; D017291:Clarithromycin / Q000009:adverse effects*; D003078:Colchicine / Q000009:adverse effects*; D000075202:Contraindications; D004347:Drug Interactions; D005260:Female; D006074:Gout Suppressants / Q000009:adverse effects; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D051437:Renal Insufficiency / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate
chemical_list: D000900:Anti-Bacterial Agents; D006074:Gout Suppressants; D017291:Clarithromycin; D003078:Colchicine