A dosage form for administration of two or more active pharmaceutical ingredients to a subject, comprising a first pharmaceutical composition comprising a first active pharmaceutical ingredient and optionally one or more pharmaceutically acceptable excipients in a first physical form selected from the group consisting of powder, granule, pellet, bead or mini-tablet form, and at least a second pharmaceutical composition comprising a second active pharmaceutical ingredient and optionally one or more pharmaceutically acceptable excipients in a second physical form selected from the group consisting of granule, pellet, bead, mini-tablet or tablet form, wherein the composition is characterised in that said first and second physical forms are selected to be different to minimise interactions between said first and second pharmaceutical compositions and to allow separation of said first and second pharmaceutical compositions for analysis on the basis of size difference.