Disclosed herein is the use of an opioid antagonist of the given formula, for the preparation of a medicament for use in the treatment or prevention of a peripherally mediated opioid-induced side effect, in particular opioid-induced bowel dysfunction or opioid-induced constipation, wherein the medicament is for administration twice a day to a human and the medicament is formulated to provide a daily dose of the opioid antagonist in an amount of from 5mg to 100mg.
