Use of xanthan and its binary blends with synthetic polymers to design controlled release formulations of...

Various buccoadhesive nystatin tablets formulations containing xanthan, carbopols (934P, 971P, 974P), PVP K30 or PEG 6000 or their binary blends were prepared. The powders were compressed into tablets at a constant compression pressure. Drug release behaviour, swelling and erosion indices and strength of bioadhesion in vitro to a biological membrane were investigated. The interaction between nystatin and polymers was investigated by DSC and FT-IR. Tablets containing the different types of carbopol alone consistently showed an initial burst release of drug, whereas this was not observed for matrices containing xanthan or xanthan-carbopol. The presence of PEG in xanthan-containing formulations induced an increase in dissolution rate; however, in the absence of xanthan the amount of drug release from a PEG matrix was reduced to < 15% over 8 h dissolution. The presence of PVP increased the dissolution rate of nystatin due to the relative hydrophilicity of PVP. The presence of calcium ions induced a more rigid gel in the xanthan matrix as a result of interaction between the polymer and calcium ions. Xanthan can be used in potential mucoadhesive formulations containing nystatin to produce a controlled release of the drug and the outcomes of this work may provide a suitable strategy for matrix selection to provide more efficacious treatment alternatives for candidiasis and other disease processes for significant patient populations.