Development of hot-melt extrusion as a novel technique for the ...

CHAPTER 7: EVALUATION OF THE INTERRELATION BETWEENINTERMOLECULAR INTERACTIONS AND TASTE MASKING EFFICIENCY OFTWO ANIONIC POLYMERS IN MELT EXTRUDED SOLID DISPERSIONS1.0 IntroductionTo date, masking the unpleasant taste of bitter APIs has been a real challenge forpatient compliance and therefore various taste masking approaches have already beendeveloped. The most commonly technologies are film casting by adding flavours orsweeteners [1,2] . Freeze-drying [2] , spary drying [4] , microencapsulation [5, 6] , fluidized bedcoating [2] , high shear mixing [7] and supercritical fluids [8] have also been reported to be usedfor taste-masking purposes. HME has been introduced as a novel approach to mask the tasteof bitter actives by enhancing drug-polymer interactions [9] .It has been reported in the literature that HME technique has successfully managed tomask the bitterness of ibuprofen and paracetamol through intermolecular forces (e.g.hydrogen bonding) between the active substance and the polymer matrix [2, 10] . In thesestudies the active substances were molecularly dispersed within the polymer matricesresulting effective taste masking of the drug‘s unpleasant taste. Solid lipid extrusion is alsoanother suitable HME approach to produce extrudates of bitter APIs with improved tasteproperties. Recently, Breitkreutz et al. developed taste masked lipid based formulation byextrusion with NXP 1210, a BCS class II drug (anti inflammatory) [11] .The taste masking evaluation of pharmaceutical dosage forms is evaluated both by invivo and/or in vitro taste analysis. For the in vitro taste masking analysis commerciallyavailable electronic tongues have been employed to evaluate the masking effect. The e -tongues demonstrate very good correlation with human taste panels, reproducibility, lowdetection limits and high sensitivity [12, 13] .Various techniques have already been reported successfully to describe various drugpolymersinteractions such as the dialysis equilibrium technique [14, 15] , UV spectroscopy[16, 17] , solid state NMR [18] , drug–polymer interaction parameter model [19] , Fourier TransformInfrared (FT-IR) and more importantly X-ray photo electron spectroscopy [16, 20] . X-rayphotoelectron spectroscopy (XPS) has proved a potent tool for the characterisation ofpolymer surfaces and it has made a significant contribution to the analysis of biomedicalpolymers. Similarly FT-IR has been accepted as sensitive technique to elucidate the structuralchanges in the active formulations [16] . The lattice-based Flory–Huggins (F–H) theory is awell known theory describing polymer–solvent or polymer–polymer interactions based on the128 | P a g e