1. Disallowed co-medication that cannot be stopped or replaced: Several potentially life-threatening drug-drug interactions (DDI) are possible when boceprevir is combined with other drugs. Therefore ALL co-medication, including over-the-counter drugs should be checked for potential DDI with DDI table in the Dutch summary of product characteristics (SPC, appendix A). If the co-medication is not mentioned in the SPC DDI table, www.HCV-druginteractions.org should be used.