EFFECT OF SHORT-TERM AND LONG-TERM TREATMENT WITH OMEPRAZOLE ON THE ABSORPTION AND SERUM LEVELS OF COBALAMIN

Aims: To evaluate absorption of protein-bound and unbound cyanocobalam in before and during treatment with omeprazole, and cobalamin levels i n patients on long-term treatment with omeprazole. Methods: In eight f ormer duodenal ulcer patients absorption of unbound and protein-bound cobalamin was determined by measuring 24-h urinary excretion of unboun d Co-58-cyanocobalamin or protein-bound Co-57-cyanocobalamin during a modified Schilling test. Tests were performed before and during treatm ent with 20 mg and 40 mg omeprazole daily for 9 days. Serum cobalamin levels were assessed in 25 patients with gastro-oesophageal reflux dis ease (GERD) before and during long-term maintenance therapy with omepr azole. Mean treatment duration was 56 months (range 36-81 months). Res ults: Urinary excretion of unbound cobalamin was unchanged with both d osages of omeprazole. Excretion of Co-57-cyanocobalamin, however, decr eased 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 omeprazol e (1.25+/-0.26 vs. 0.29+/-0.06%; P < 0.02). Mean serum cobalamin level s (+/-S.E.M.) before and during therapy with omeprazole in GERD patien ts were 298+/-27 and 261+/-16 pg/mL (normal range 180-900 pg/mL), resp ectively (P = N.S.). Conclusions: Absorption of protein-bound, but not unbound, cyanocobalamin is decreased when measured by a modified Schi lling test during treatment with omeprazole. However, no change in ser um cobalamin levels was observed in patients with GERD after treatment with omeprazole for up to 7 years.