The purpose of the proposed study was to develop a unidirectional release buccal tablet which releases the drug in one direction and in a controlled manner. Various approaches including matrix tablet of drug with mucoadhesive polymers, triple layer reservoir system and peripheral coating of mucoadhesive polymer were adopted for the design of unidirectional release buccal tablet (URBT). Many mucoadhesive polymers, e.g., HPMC K4M, Carbopol, PVP K30, and Polycarbophil (Noveon AA1) were tried to achieve satisfactory mucoadhesion and predetermined drug release. Out of those, the peripheral coating of 50 mg Polycarbophil on a core tablet containing 50 mg diclofenac sodium, 10 mg HPMC, and spray dried lactose was optimized for a successful design of URBT. To mimic the one-directional drug release from URBT, a USP-II apparatus was modified, and a new device was fabricated, which mimicked unidirectional release. This novel controlled release design was evaluated for in vitro drug release study, ex vivo mucoadhesion study, in vitro drug permeation study, surface pH, and swelling index. The optimized batch (A11) of URBT was subjected to a short-term stability study. The FTIR spectrum and stability study data revealed a stable characteristic of the formulation. The in vitro dissolution data of URBT were treated by household model fitting software ‘FORTRAN’ which showed the URBT follows the Korsmeyer and Peppas model of drug release kinetics. This controlled and unidirectional release of diclofenac sodium through the buccal mucosa is superior to all other buccal formulations of diclofenac sodium

unidirectional release, buccal tablet, modified dissolution apparatus, diclofenac sodium, short-term stability study