Pharmaceutical compositions comprising a therapeutically active agent and an absorption enhancer such as NAC, NAD, 5-CNAC, 4-MOAC, 4-CNAB or a salt thereof, for use in the treatment of a condition treatable by said therapeutically active agent, are provided. The compositions are for concomitant oral administration of two or more of the unit dosage form, which form together a therapeutically effective amount of the therapeutically active agent and an effective amount of the absorption enhancer. Multi-dose compositions comprising the two or more of the unit dosage form are also provided.