Unaltered ibuprofen-induced faecal blood loss upon coadministration of moclobemide

The influence of moclobemide on ibuprofen-induced faecal blood loss was investigated in 24 volunteers. The subjects were randomly assigned to one of two groups and received from day 1 until day 14 either moclobemide 150 mg t.i.d. (group A) or placebo t.i.d. (group B). On days 8-14, when moclobemide concentrations in group A were at steady state, all volunteers additionally received ibuprofen (600 mg t.i.d). From day 15 to 21, all subjects received placebo alone. Faecal blood loss (FBL) was quantified daily by the 51Cr-labelled erythrocyte method. As expected for ibuprofen, a significant increase in FBL during the second week of the study was observed. There was no difference in FBL between the two treatment groups (moclobemide or placebo). Similar FBL values were observed in both groups (group A vs B): during the first week the FBL values were (mean +/- SD) 0.40 +/- 0.23 ml/day vs 0.55 +/- 0.53 ml/day on days 1-3 and 0.40 +/- 0.21 ml/day vs 0.37 +/- 0.13 ml/day on days 4-7. The increase in FBL during the second week was comparable in both groups, with and without moclobemide (days 8-10: 0.78 +/- 0.59 ml/day vs 0.80 +/- 0.58 ml/day; days 11-14: 1.49 +/- 0.95 ml/day vs 1.28 +/- 0.62 ml/day). A decline in FBL was observed during the third week under placebo in both groups, but baseline values were not reached during the observation period. Again there was no difference between the two groups (days 15-17: 0.91 +/- 0.52 ml/day vs 0.92 +/- 0.47 ml/day; days 18-21: 0.74 +/- 0.30 ml/day vs 0.68 +/- 0.48 ml/day). No statistically significant interaction was found between week and type of treatment, indicating that no significant influence of moclobemide on the ibuprofen-induced faecal blood loss occurred. No notable pharmacokinetic interaction between moclobemide and ibuprofen was observed. Moclobemide plasma concentration-time profiles with and without concomitantly administered ibuprofen were superimposable. The results demonstrate that the concomitant administration of ibuprofen and moclobemide to healthy volunteers does not result in a clinically significant interaction, either at the pharmacodynamic (faecal blood loss) or at the pharmacokinetic level.