The Use of Binary Polymeric Networks in Stabilizing Polyethylene Oxide Solid Dispersions

Abstract

The objective of this study was to investigate the role of amorphous domain of polyethylene oxide (PEO), a semicrystalline polymer, on the stability of drug/PEO solid dispersion. Molecular dispersion of drugs within hydrophilic low molecular weights PEOs (solid solution) has been demonstrated as a viable approach to enhance the dissolution properties and hence the oral bioavailability of poorly soluble drugs. In this system, the drug molecules are dissolved within the amorphous domain of the polymer and a miscible amorphous drug/polymer combination can result in a decrease of the polymer crystallinity, and hence increasing its amorphous fraction. This may result in increasing the drug solubility in the polymer hence affecting the stability of drug/polymer solid dispersion system. PEO is a highly crystallisable semi-crystalline polymer in natural and a rapid decrease in the amorphous fraction of the polymer may occur immediately after hot-melt extrusion resulting a forced migration of amorphous drug into nearby amorphous region. Thus, the actual concentrations of the drug within PEO solid dispersion were much higher than the concentration that we intended. Therefore, we are proposing a novel method of stabilising the amorphous drug/PEO solid dispersion by stabilising the amorphous region of PEO using another amorphous polymer. Inclusion of a miscible polymer that can increase the glass transition (Tg) of PEO (antiplasticization) or/and form strong inter-polymer interactions was used to enhance the stability of the amorphous PEO. In this study, the effects of inter-polymer interactions and miscibility between PEO and an amorphous polymer of high Tg, Eudragit ® S100, on the stability of the amorphous PEO and consequently the PEO/drug celecoxib (CX) solid dispersion was studied. Hot-melt extrusion (HME) was used to prepare different ratios of binary polymer blends of PEO/S100 (70/30, 50/50 and 30/70 w/w) and ternary solid dispersion systems containing pre-defined drug loading within the PEO/S100 polymer blends. Results from differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) suggested a great miscibility between PEO and S100 polymer blends particularly in the 50/50 ratio. After immediately HME, single Tg was observed in all ternary systems that increase with increasing S100 amount (antiplasticization). The completely absence of PXRD crystalline Bragg's peaks also suggested the full amorphous CX/polymer solid dispersion has been produced. Upon storage, CX crystallized rapidly from the CX/PEO (30/70) system within 3 days at 40°C and 75% RH, whereas it remained stable without crystallization up to 4 weeks within CX/(PEO/S100) 30/(50/50) system. Interestingly, both the stability of the amorphous PEO and CX were greater in the ternary system containing the polymer blend at 50/50 ratio than other systems. Despite of the lower Tg of 30/(50/50) system than 30/(30/70) one, the former was more stable. This indicates that the antiplasticization effects by Eudragit ® S100 were not the ...

Solid state nuclear magnetic resonance studies of hydroxypropylmethylcellulose acetyl succinate polymer, a useful carrier in pharmaceutical solid dispersions

“…The signals for carbons C11 (in A) and C13,16 (in S) were used as probes to quantify the A/S molar ratio from the experimental NMR spectra as both these carbonyl carbons exhibit similar CP kinetics ( Figure 7 and Table 3), as revealed by recording 13 C CP MAS spectra at different CP contact times, and illustrated by fitting the obtained 13 C CP polarising build-up curves (signal intensities vs. CP contact times) data (see experimental section for the equation). [40] We note that although C12 (in A) or C14,15 (in S) are well resolved, it is not possible to use them for the (semi)quantification due to the different nature of these carbons (CH 3 vs. CH 2 groups, respectively), which show significantly different CP kinetics between themselves and C11 and C13, 16. Figure 8 shows a magnified view of the signals related to the carbonyl groups of the acetate and succinate (190-160 ppm region of the 13 C CP MAS NMR spectra).…”

“…[11][12][13] This is mostly due to a synergetic effect that includes increase of the glass transition temperature (T g ) of the final mixture high T g polymers (anti-plasticising effect), reducing molecular mobility of the amorphous API and the formation of specific API-polymer interactions. [14] A number of polymers have been considered as excipients in ASDs and can be classified as polyglycols (e.g., polyethylene glycol [15] and polyethylene oxide [16] ), polyvinyl (e.g., polyvinylpyrrolidone [PVP] [17] and polyvinylpyrrolidone-polyvinyl acetate [18] ) and cellulose (e.g., hydroxypropylmethylcellulose [HPMC] [19] and HPMC acetyl succinate [HPMC-AS], [20] Figure 1).…”

“…A number of polymers have been considered as excipients in ASDs and can be classified as polyglycols (e.g., polyethylene glycol and polyethylene oxide), polyvinyl (e.g., polyvinylpyrrolidone [PVP] and polyvinylpyrrolidone‐polyvinyl acetate) and cellulose (e.g., hydroxypropylmethylcellulose [HPMC] and HPMC acetyl succinate [HPMC‐AS], Figure ).…”

Type 3 porous liquids based on non-ionic liquid phases – a broad and tailorable platform of selective, fluid gas sorbents

“…2b and ESI 5 †). 10 Given the large number of mixtures prepared, only a selection (specically Al(fum)(OH)/brominated vegetable oil, Al(fum)(OH)/PDMS and ZIF-8/PDMS) were analysed by this method. Fig.…”

Fabrication and Characterizations of Hot-Melt Extruded Nanocomposites Based on Zinc Sulfate Monohydrate and Soluplus

“…HME has been used for preparing solid dispersion formulations of active pharmaceutical ingredients [9,21]. Molecular dispersing during the HME process can transform the crystalline property of the drug to an amorphous state, and it may contribute to the improvement of dissolution and bioavailability of the drug [9,13,14,22]. In addition, HME processing of a hydrophilic drug can provide taste masking of the drug [9,23].…”