title: Olsalazine is contraindicated during pelvic radiation therapy: results of a double-blind, randomized clinical trial.
abstract: OBJECTIVE
  A randomized clinical trial from Great Britain suggested a possible beneficial effect of acetylsalicylate in the prevention of radiation-induced bowel toxicity. Olsalazine is an orally administered drug designed to deliver 5-aminosalicylate to the large bowel with minimal systemic absorption. A randomized clinical trial was undertaken to assess the effectiveness of olsalazine in preventing acute diarrhea in patients receiving pelvic radiation therapy.
  
  
  METHODS
  Patients receiving pelvic radiation therapy were randomized, in double-blind fashion, to olsalazine 250 mg, two capsules twice daily, or an identical appearing placebo, two capsules twice daily. Patients were then evaluated weekly during radiation therapy for the primary study endpoint, diarrhea, as well as rectal bleeding, abdominal cramping, and tenesmus.
  
  
  RESULTS
  The study was closed early, after entry of 58 evaluable patients, when a preliminary analysis showed excessive diarrhea in patients randomized to olsalazine. The incidence and severity of diarrhea were worse in patients randomized to olsalazine (p = 0.0036). Sixty percent of the patients randomized to olsalazine experienced Grade 3 or 4 diarrhea compared to only 14% randomized to placebo. There was also a trend toward higher incidence and greater severity of abdominal cramping in patients who were randomized to olsalazine (p = 0.084).
  
  
  CONCLUSIONS
  Administration of olsalazine during pelvic radiation therapy resulted in an increased incidence and severity of diarrhea. Olsalazine is contraindicated in patients receiving pelvic radiation therapy.
authors.affiliation: Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Martenson
authors.forename: G
authors.initials: G
authors.lastname: Hyland
authors.forename: C G
authors.initials: CG
authors.lastname: Moertel
authors.forename: J A
authors.initials: JA
authors.lastname: Mailliard
authors.forename: J R
authors.initials: JR
authors.lastname: O'Fallon
authors.forename: R T
authors.initials: RT
authors.lastname: Collins
authors.forename: R F
authors.initials: RF
authors.lastname: Morton
authors.forename: H H
authors.initials: HH
authors.lastname: Tewfik
authors.forename: R L
authors.initials: RL
authors.lastname: Moore
authors.forename: A R
authors.initials: AR
authors.lastname: Frank
authors.forename: R E
authors.initials: RE
authors.lastname: Urias
authors.forename: R L
authors.initials: RL
authors.lastname: Deming
mesh_terms: D000368:Aged; D000636:Aminosalicylic Acids; D000075202:Contraindications; D003672:Defecation / Q000187:drug effects; D003967:Diarrhea / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D010386:Pelvic Neoplasms / Q000532:radiotherapy*; D013035:Spasm / Q000139:chemically induced
chemical_list: D000636:Aminosalicylic Acids; C032587:olsalazine