title: Probable rifaximin-induced neutropenia.
abstract: OBJECTIVE
  The development of neutropenia in a patient treated with rifaximin is reported.
  
  
  CONCLUSIONS
  A 45-year-old Caucasian woman with severe ulcerative colitis arrived at the emergency department with complaints of worsening abdominal pain, nausea, and vomiting and was found to have extensive portal vein and superior mesenteric vein thrombosis with additional thrombi in the distal aortic and left common iliac arteries on an abdominal computed tomography angiography scan. A heparin i.v. drip was started, and the following day the patient underwent thrombectomy and thrombolysis with tissue plasminogen activator of the superior mesenteric vein thrombus. Secondary to rectal bleeding and a decrease of approximately 2 g in the patient's hemoglobin concentration while receiving heparin, the decision was made to forego additional use of tissue plasminogen activator for the portal vein thrombosis, and a transjugular intrahepatic portosystemic shunt (TIPS) procedure was performed to improve portal blood flow. After consultation with the gastroenterology and hepatology departments, the decision was made to initiate rifaximin 400 mg orally every eight hours for the prevention of hepatic encephalopathy after the TIPS procedure. The patient's white blood cell (WBC) count was 6800/μL on the day of rifaximin initiation. On day 4 of rifaximin treatment, the patient's WBC count reached its nadir at 1200/μL. The primary internal medicine team then decided to discontinue rifaximin therapy. During this time, the patient showed no other signs of infection. The patient's WBC count rebounded to 3300/μL three days after discontinuation of rifaximin therapy.
  
  
  CONCLUSIONS
  A 45-year-old Caucasian woman with severe ulcerative colitis developed neutropenia after the initiation of rifaximin.
authors.affiliation: University of Maryland School of Pharmacy, 20 North Pine Street, Baltimore, MD 21201, USA. lhynicka@rx.umaryland.edu
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Hynicka
authors.forename: Kathyrn N
authors.initials: KN
authors.lastname: Silva
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D005260:Female; D006501:Hepatic Encephalopathy / Q000517:prevention & control; D006801:Humans; D008875:Middle Aged; D009503:Neutropenia / Q000139:chemically induced*; D019168:Portasystemic Shunt, Transjugular Intrahepatic; D012294:Rifamycins / Q000009:adverse effects* / Q000493:pharmacokinetics; D000078262:Rifaximin
chemical_list: D000900:Anti-Bacterial Agents; D012294:Rifamycins; D000078262:Rifaximin