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(R) 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(R), whilst work of adhesion continued to increase with Carbopol 934(R) 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(R) 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. (C) 2002 Published by Elsevier Science B.V.