title: Effect of short- and long-term treatment with omeprazole on the absorption and serum levels of cobalamin.
abstract: OBJECTIVE
  To evaluate absorption of protein-bound and unbound cyanocobalamin before and during treatment with omeprazole, and cobalamin levels in patients on long-term treatment with omeprazole.
  
  
  METHODS
  In eight former duodenal ulcer patients absorption of unbound and protein-bound cobalamin was determined by measuring 24-h urinary excretion of unbound 58Co-cyancobalamin or protein-bound 57Co-cyanocobalamin during a modified Schilling test. Tests were performed before and during treatment with 20 mg and 40 mg omeprazole daily for 9 days. Serum cobalamin levels were assessed in 25 patients with gastro-oesophageal reflux disease (GERD) before and during long-term maintenance therapy with omeprazole. Mean treatment duration was 56 months (range 36-81 months).
  
  
  RESULTS
  Urinary excretion of unbound cobalamin was unchanged with both dosages of omeprazole. Excretion of 57Co-cyanocobalamin, however, decreased significantly during treatment with both 20 mg omeprazole (mean +/- S.E.M.: 1.31 +/- 0.20 vs. 0.54 +/- 0.17%; P < 0.02) and 40 mg omeprazole (1.25 +/- 0.26 vs. 0.29 +/- 0.06%; P < 0.02). Mean serum cobalamin levels (+/- S.E.M.) before and during therapy with omeprazole in GERD patients were 298 +/- 27 and 261 +/- 16 pg/mL (normal range 180-900 pg/mL), respectively (P = N.S.).
  
  
  CONCLUSIONS
  Absorption of protein-bound, but not unbound, cyanocobalamin is decreased when measured by a modified Schilling test during treatment with omeprazole. However, no change in serum cobalamin levels was observed in patients with GERD after treatment with omeprazole for up to 7 years.
authors.affiliation: Department of Gastroenterology, Free University Hospital, Amsterdam, The Netherlands.
authors.forename: B E
authors.initials: BE
authors.lastname: Schenk
authors.forename: H P
authors.initials: HP
authors.lastname: Festen
authors.forename: E J
authors.initials: EJ
authors.lastname: Kuipers
authors.forename: E C
authors.initials: EC
authors.lastname: Klinkenberg-Knol
authors.forename: S G
authors.initials: SG
authors.lastname: Meuwissen
mesh_terms: D000328:Adult; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D004381:Duodenal Ulcer / Q000188:drug therapy; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use*; D013997:Time Factors; D014805:Vitamin B 12 / Q000097:blood* / Q000652:urine
chemical_list: D000897:Anti-Ulcer Agents; D009853:Omeprazole; D014805:Vitamin B 12