Effect of acid secretion blockade by omeprazole on the relative bioavailability of orally administered furazolidone in healthy volunteers.
OBJECTIVE
The administration of omeprazole may interfere with the absorption of orally administered drugs by reducing gastric pH and hence tablet dissolution. The aim of this study was to investigate the effects of a 5 day administration of omeprazole on the pharmacokinetics of furazolidone.


METHODS
Eighteen healthy (nine male and nine female) volunteers were selected. The study had an open randomized two-period crossover design with a 21 day washout period between the phases. Serum concentrations of furazolidone were measured by reversed-phase h.p.l.c. with ultraviolet detection.


RESULTS
Administration of omeprazole caused a significant reduction of Cmax [0.34 microg x ml(-1) (range 0.25-0.43) vs 0.24 microg x ml(-1) (range 0.15-0.34)] with no significant delay in absorption tmax [2.5 h (range 1.85-3.0) vs 2.4 h (range 2.06-2.71)].


CONCLUSIONS
Furazolidone was rapidly absorbed after oral administration. Short-term treatment with omeprazole did alter the relative bioavailability of this drug, probably through an effect on absorption kinetics or first-pass metabolism.
Calafatti
S A
SA
Clinical Pharmacology and Gastroenterology Unit, São Francisco University Medical School, Bragança Paulista, SP, Brazil.
Ortiz
R A
RA
Deguer
M
M
Martinez
M
M
Pedrazzoli
J
J
D000284:Administration, Oral; D000328:Adult; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D001682:Biological Availability; D018592:Cross-Over Studies; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D005664:Furazolidone / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D005744:Gastric Acid / Q000378:metabolism*; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009853:Omeprazole / Q000627:therapeutic use*
D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D005664:Furazolidone; D009853:Omeprazole