There is provided a tablet suitable for sublingual administration comprising microparticles of a pharmacologically-effective amount of buprenorphine, or a pharmaceutically-acceptable salt thereof; particles of a pharmacologically-effective amount of naloxone or a pharmaceutically-acceptable salt thereof; a disintegrant; and particles of a weak acid provided in a sufficient amount to enable the provision of a pH of between about 4.0 and about 6.5 and maintenance of pH within that range for no more than about 3 minutes after administration to a patient.