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The purpose of this study was to examine the effect of processing parameters on drug release profiles of microparticles. Double emulsion solvent evaporation technique was utilized to encapsulate donepezil hydrochloride which is a hydrophilic drug. The processing parameters examined were polymer amount, stirring time and volume of external aqueous phase. The morphology of microparticles was observed under light microscope and scanning electron microscope. After that, in vitro drug release testing was conducted in simulated salivary fluid (pH6.75) and simulated gastric fluid (pH1.2). The results showed that these three parameters were the significant parameter affecting drug release profiles of the microparticles.

The purpose of this study was to investigate the influence of process parameters on the characteristics of microparticles using double emulsion solvent evaporation method for encapsulation of hydrophilic drug. Donepezil hydrochloride (DPH), a reversible cholinesterase inhibitor, was selected as a model hydrophilic drug. Prior to conducting an experiment, the target particle size of microparticles was set at approximately 200 μm. The investigated process parameters include pH of outer water phase, stirring time, polymer amount, and volume of outer water phase. The results showed that DPH-loaded microparticles was successfully prepared in two steps. In the first step, the primary emulsion was prepared by dissolving DPH in distilled water before emulsifying in dichloromethane (DCM) containing different amounts of poly(butylmethacrylate-co-2-dimethylaminoethyl-methacrylate-co-methyl-methacrylate) (PBM-DM-MM) using ultrasonic probe. In the second step, the primary emulsion was emulsified in polyvinyl alcohol (PVA) solution by overhead stirrer to prepare double emulsion. After solvent evaporation, the microparticles were collected by centrifugation and washed with distilled water. Based on the statistical analysis, stirring time, polymer amount and volume of outer water phase were the main significant parameters influencing particle size of microparticles.

The objective of this research was to optimize the tasted-masked microparticles for orally disintegrating tablets containing donepezil hydrochloride using quality risk assessment and design of experiment approaches. The double emulsion solvent evaporation technique using aminoalkyl methacrylate copolymer (AMC) was used to prepare taste-masked microparticles. Factors affecting the quality of the taste-masked microparticles were analyzed using an Ishikawa diagram. A risk-ranking approach was used to rank the formulation and process risks. Furthermore, the effect of AMC quantity, stirring time, and volume of outer water phase on various responses, such as particle size, the amount of drug dissolved at 5 min (Q5) in simulated saliva fluid, and mean dissolution time (MDT) in simulated gastric fluid, was investigated using the Box-Behnken design. The optimized microparticles were then used to prepare orally disintegrating tablets (ODTs) and evaluated by in vitro and in vivo testing. The results demonstrated that particle size was influenced by the AMC amount and stirring time. Q5 was significantly affected by the amount of AMC and the volume of the outer water phase. On the other hand, these two factors had a positive effect on MDT. The optimized microparticles had a particle size of 174.45 ± 18.19 µm, Q5 of 5.04%, and MDT of 5.97 min. The ODTs with taste-masked microparticles showed acceptable in vitro dissolution with an MDT of 5 min. According to the results of a panel of six human volunteers, they greatly improved palatability.

The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.

Donepezil hydrochloride (DPH) was first launched in 1997 as a choline esterase inhibitor (ChEI). The USFDA has approved it for treatment of Alzheimer's disease since it effectively enhances cholinergic activity by slowing the clearance of acetylcholine in the brain. Although it is the most prescribed drug among ChEIs, a bitter taste with numbness to DPH is a substantial oral administration obstacle, and is a frequently reported adverse event. Several studies have been conducted to overcome this problem by adding sweeteners and flavors, application of physical barriers, preparation of ion exchange resins, and inclusion complexes. Based on the pharmacological activity, the gastrointestinal effect is a frequently reported adverse event. Therefore, novel dosage forms intended to deliver through oral, topical/transdermal, parenteral, and intranasal routes have been designed and developed. In this review, findings from recent studies on DPH are summarized, and the challenges and obstacles of DPH dosage form development are highlighted and discussed.