Dennis Douroumis

Taste masking of paracetamol by hot-melt extrusion: An in vitro and in vivo evaluation

The purpose of this study was the in vitro and in vivo evaluation of the masking efficiency of hot melt extruded paracetamol (PMOL) formulations. Extruded granules containing high PMOL loadings in Eudragit EPO (EPO) or Kollidon VA64 (VA64) were prepared by hot-melt extrusion (HME). The taste masking effect of the processed formulation was evaluated in vivo by a panel of six healthy human volunteers. In addition, in vitro evaluation was carried out by an Astree e-tongue equipped with seven sensors. Taste sensing technology demonstrated taste improvement for both polymers by correlating the data obtained for the placebo polymers and the pure APIs alone. The best masking effect was observed for VA64 at 30% PMOL loading. The e-tongue results were in good agreement with the in vivo evaluation. In vitro dissolution of the extruded granules showed rapid PMOL releases.

A Review of Hot-Melt Extrusion: Process Technology to Pharmaceutical Products

Over the last three decades industrial adaptability has allowed hot-melt extrusion (HME) to gain wide acceptance and has already established its place in the broad spectrum of manufacturing operations and pharmaceutical research developments. HME has already been demonstrated as a robust, novel technique to make solid dispersions in order to provide time controlled, modified, extended, and targeted drug delivery resulting in improved bioavailability as well as taste masking of bitter active pharmaceutical ingredients (APIs). This paper reviews the innumerable benefits of HME, based on a holistic perspective of the equipment, processing technologies to the materials, novel formulation design and developments, and its varied applications in oral drug delivery systems.

Drug–polymer intermolecular interactions in hot-melt extruded solid dispersions

The purpose of the study was to investigate and identify the interactions within solid dispersions of cationic drugs and anionic polymers processed by hot-melt extrusion (HME) technique. Propranolol HCl (PRP) and diphenhydramine HCl (DPD) were used as model cationic active substances while pH sensitive anionic methacrylic acid based methyl methacrylate copolymers Eudragit L100 (L100) and ethyl acrylate copolymer Eudragit L100-55 (Acryl EZE) (L100-55) were used as polymeric carriers. The extrudates were further characterised using various physicochemical characterisation techniques to determine the morphology, the drug state within the polymer matrices and the type of drug-polymer interactions. Molecular modelling predicted the existence of two possible H-bonding types while the X-ray photon spectroscopy (XPS) advanced surface analysis of the extrudates revealed intermolecular ionic interactions between the API amino functional groups and the polymer carboxylic groups through the formation of hydrogen bonding. The magnitude of the intermolecular interactions varied according to the drug-polymer miscibility.

Nano and microparticle engineering of water insoluble drugs using a novel spray-drying process.

In the current study nano and microparticle engineering of water insoluble drugs was conducted using a novel piezoelectric spray-drying approach. Cyclosporin A (CyA) and dexamethasone (DEX) were encapsulated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) grades of different molecular weights. Spray-drying studies carried out with the Nano Spray Dryer B-90 employed with piezoelectric driven actuator. The processing parameters including inlet temperature, spray mesh diameter, sample flow rate, spray rate, applied pressure and sample concentration were examined in order to optimize the particle size and the obtained yield. The process parameters and the solute concentration showed a profound effect on the particle engineering and the obtained product yield. The produced powder presented consistent and reproducible spherical particles with narrow particle size distribution. Cyclosporin was found to be molecularly dispersed while dexamethasone was in crystalline state within the PLGA nanoparticles. Further evaluation revealed excellent drug loading, encapsulation efficiency and production yield. In vitro studies demonstrated sustained release patterns for the active substances. This novel spray-drying process proved to be efficient for nano and microparticle engineering of water insoluble active substances.

Dissolution enhancement of poorly water-soluble APIs processed by hot-melt extrusion using hydrophilic polymers

The aim of this study was to investigate the efficiency of hydrophilic polymers to enhance the dissolution rate of poorly water-soluble active pharmaceutical ingredients (APIs) processed by hot-melt extrusion (HME). Indomethacin (INM) and famotidine (FMT) were selected as model active substances while polyvinyl caprolactam graft copolymer, soluplus (SOL) and vinylpyrrolidone-vinyl acetate copolymer grades, Kollidon VA64 (VA64) and Plasdone S630 (S630) were used as hydrophilic polymeric carriers. For the purpose of the study, drug–polymer binary blends at various ratios were processed by a Randcastle single screw extruder. The physicochemical properties and the morphology of the extrudates were evaluated through X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Increased drug loadings of up to 40% were achieved in the extruded formulations for both drugs. INM and FMT exhibited strong plasticization effects with increasing concentrations and were found to be molecularly dispersed within the polymer blends. The in vitro dissolution studies showed increased INM/FMT release rates for all formulations compared to that of pure APIs alone.

Quantum dots synthesis and biological applications as imaging and drug delivery systems

Semiconductor quantum dots (QDs) synthesized by metal ions and colloid stabilizers have been explored as promising probes in advanced imaging techniques, tumor diagnostic agents, and drug delivery systems. The ability to modulate QDs surface chemistry through particle—shape control, surface coating, and surface functionalization—has rendered them a valuable tool in biological sciences. The tremendous advances in nanotechnology revealed the unique properties of QD crystals in both in vitro and in vivo conditions. In this review, we summarize the recent trends in QD synthesis, surface modification, and biological applications particularly for cancer targeting and treatment.

Mesoporous silica nanoparticles in nanotechnology

Mesoporous silica nanoparticles (MSNs) are a versatile drug delivery system that can be used for loading of different guest molecules such as peptides, proteins, anticancer agents, and genetic material. MSNs are considered promising drug carriers due to their tuneable particle size, pore structure, and surface functionalization. Thus, MSNs provide opportunities for their effective application in a wide variety of fields. In the current review, we discuss both conventional and advanced MSNs synthesis methods, including their applications for drug delivery, gatekeepers, and biosensors. In addition, the research progress in biocompatibility, cytotoxicity, and internalization mechanisms is reported.

Orally disintegrating dosage forms and taste-masking technologies; 2010

Introduction: In the last decade the development of orally disintegrating tablets (ODTs) and thin-film platforms has grown enormously in the field of pharmaceutical industry. A wide variety of new masking technologies combined with the aforementioned platforms have been developed in order to mask the taste of bitter active substances and achieve patient compliance. The commercial success and viability of such products requires the development of robust formulations with excellent palatability, disintegration times, physicochemical stability and pharmacokinetic profiles. Areas covered: In this review, emerging taste-masking technologies applied to solid dosage form manufacturing are summarized. The unique features and principles of taste-masking approaches used with ODT platforms are discussed, including the advantages and limitations of each technology. A brief discussion is also included on the taste masking of thin-film technologies, owing to their similar applications and requirements. Expert opinion: This review elucidates the unique features of current commercially available or highly promising ODT and thin-film technologies, along with taste-masking approaches used in the manufacturing of oral solid dosage forms. A better understanding of these drug delivery approaches will help researchers to select the appropriate platform, or to develop innovative products with improved safety, compliance and clinical value.

In vitro and in silico investigations of drug delivery via zeolite BEA

A combination of experiment and theory has been used to assess the potential use of the zeolite BEA as a drug delivery agent. Molecular dynamics (MD) has been used to examine the diffusion of two different drug molecules, salbutamol and theophylline, inside the zeolite BEA. MD shows that the two molecules display different diffusion behaviour, with the salbutamol molecule able to diffuse more freely than theophylline within the internal channel system of the zeolite. Several experimental techniques have been used to investigate the loading and release of the drug molecules from the BEA host. The results obtained support the observations from the modelling and suggest that modelling has an important role to play in screening zeolite–drug combinations prior to experimental investigation.

Inkjet printing of transdermal microneedles for the delivery of anticancer agents

A novel inkjet printing technology is introduced as a process to coat metal microneedle arrays with three anticancer agents 5-fluororacil, curcumin and cisplatin for transdermal delivery. The hydrophilic graft copolymer Soluplus(®) was used as a drug carrier and the coating formulations consisted of drug-polymer solutions at various ratios. A piezoelectric dispenser jetted microdroplets on the microneedle surface to develop uniform, accurate and reproducible coating layers without any material losses. Inkjet printing was found to depend on the nozzle size, the applied voltage (mV) and the duration of the pulse (μs). The drug release rates were determined in vitro using Franz type diffusion cells with dermatomed porcine skin. The drug release rates depended on the drug-polymer ratio, the drug lipophilicity and the skin thickness. All drugs presented increased release profiles (750 μm skin thickness), which were retarded for 900 μm skin thickness. Soluplus assisted the drug release especially for the water insoluble curcumin and cisplatin due to its solubilizing capacity. Inkjet printing has been shown to be an effective technology for coating of metal microneedles which can then be used for further transdermal drug delivery applications.