Development and evaluation of a biphasic buccal adhesive tablet for nicotine replacement therapy.

Bilayer nicotine mucoadhesive tablets were prepared and evaluated to determine the suitability of the formulation as a nicotine replacement product to aid in smoking cessation. A range of formulations containing 0-50% w/w Carbopol 934 and 0-50% w/w hydroxypropylcellulose (HPC) were prepared and tested for adhesive properties and drug release. Mucoadhesion was assessed using bovine buccal mucosa. Peak detachment force of the tablets was found to reach a maximum at 20% w/w Carbopol 934, whilst work of adhesion continued to increase with Carbopol 934 concentration. HPC concentrations of 20-30% w/w were found to provide nicotine hydrogen tartrate (NHT) release approaching zero order kinetics over a 4 h test period. A combination of 20% w/w Carbopol 934 and 20% w/w HPC was thus found to provide suitable adhesion and controlled drug release. The formulation of a bilayer tablet containing the adhesive controlled release layer (CRL) and a fast releasing layer provided an initial burst release of NHT followed by the controlled release for a period of up to 4 h. The same biphasic type of release was identified during an in vivo assessment using human volunteers This biphasic drug release could represent an improvement over current methods of nicotine replacement.