Sweet Potato Starch Microparticles as Controlled Drug Release Carriers: Preparation and In Vitro Drug Release

The aim of this study was to investigate the in vitro drug release behavior of sweet potato starch (SPS) microparticles intended for controlled drug delivery applications. Diclofenac sodium (DS) was used as a model drug candidate in the present study. SPS microparticles were prepared using a spray-drying technique by varying the polymer concentration and drug loading. The mean particles size of drug-loaded spray-dried SPS microparticles was between 10.3 and 13.1 µm. The mean particle size increased slightly with increase in the concentration of SPS. The mean particle size of spray-dried SPS microparticles increased from 10.3 to 13.1 µm when the concentration of SPS increased from 2 to 4% w/v. Under the current spray-drying conditions, the percentage yield of spray-dried SPS microparticles did not vary much among the various formulations and it was between 65.2 and 70.1%. The encapsulation efficiencies of SPS microparticles formulations was between 95.1–98.2%, suggesting good encapsulating ability of the SPS polymer by spary drying. Drug release from all the formulations of spray-dried SPS microparticles was controlled over period of 6 h. The cumulative amount of drug release from the spray-dried SPS microparticles decreased with an increase in the concentration of SPS, while it increases as the drug loading is increased. Release of the drug from spray-dried SPS microparticles followed Fick's law of diffusion since a good correlation coefficient (R²) was observed with the Higuchi plots (R² = 0.9928 to 0.9979).     

Preparation and characterization of poly(lactic‐co‐glycolic acid) microparticles containing DNA molecules encoding a malaria vaccine candidate

BACKGROUND: A novel ultrasonic atomization approach for the formulation of biodegradable poly(lactic‐co‐glycolic acid) (PLGA) microparticles of a malaria DNA vaccine is presented. A 40 kHz ultrasonic atomization device was used to create the microparticles from a feedstock containing 5 volumes of 0.5% w/v PLGA in acetone and 1 volume of condensed DNA which was fed at a flow rate of 18 ml h^?1. The plasmid DNA vectors encoding a malaria protein were condensed with a cationic polymer before atomization. RESULTS: High levels of gene expression in vitro were observed in COS‐7 cells transfected with condensed DNA at a nitrogen to phosphate (N/P) ratio of 10. At this N/P ratio, the condensed DNA exhibited a monodispersed nanoparticle size (Z‐average diameter of 60.8 nm) and a highly positive zeta potential of 38.8 mV. The microparticle formulations of malaria DNA vaccine were quality assessed and it was shown that the microparticles displayed high encapsulation efficiencies between 82–96% and a narrow size distribution in the range of 0.8–1.9 µm. In vitro release profile revealed that approximately 82% of the DNA was released within 30 days via a predominantly diffusion controlled mass transfer system. CONCLUSIONS: This ultrasonic atomization technique showed excellent particle size reproducibility and displayed potential as an industrially viable approach for the formulation of controlled release particles. Copyright © 2009 Society of Chemical Industry     

Preparation and characterization of miglitol-loaded Poly (d,l-lactide-co-glycolide) microparticles using high pressure homogenization-solvent evaporation method

Sustained release Miglitol-loaded poly (d, l-lactide-co-glycolide) (PLGA) microparticles were prepared using high pressure homogenization-solvent evaporation method. 2³ full factorial design was employed to study effect of independent variables (X₁-Polymer amount; X₂-Surfactant concentration and X₃-Homogenization Pressure) on percent encapsulation efficiency (%EE) as response. The microparticles produced were characterized for particle size, morphology, % EE, drug polymer compatibility and in vitro drug release. An average particle size of Miglitol-loaded PLGA microparticles was 230.1?nm and found almost spherical with smooth surface. % EE ranged from 58.7%?±?2.11 to 86.5%?±?0.24 depending on the polymer amount, surfactant concentration and homogenization pressure. An absence of chemical interaction between drug-polymer and reduction in % crystallinity of drug was confirmed by FTIR and X-ray diffraction analysis respectively. In vitro release studies showed a sustained release of Miglitol from microparticles up to 12?hrs.     

Spray Cooling Process Factors and Quality Interactions During the Preparation of Microparticles Containing an Active Pharmaceutical Ingredient

The current work studies the spray-cooling process factors and quality interactions during the production of microparticulated solid dispersions containing piroxicam, polyethylene glycol 4000, and poloxamer 407. The Box-Behnken factorial design was used to evaluate the influence of the temperature of the molten dispersion, the percentage of poloxamer 407 in the sample, and dispersion feed rate on the microparticles. The dependent variables studied by this design were particle size, flow properties, drug content, and solubility. Microparticle characterization was done through X-ray powder diffraction, thermogravimetry, differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, and in vitro dissolution analysis. Statistical analysis showed that the factors studied in Box-Behnken factorial design significantly influenced (p < 0.05) the Carr index, the Hausner factor, and the solubility of these microparticles. The microparticles presented average diameter from 72 to 120 µm, moderate to excellent flowability, drug content between 77.5 to 99.2%, and an increase in solubility between 2.5- and 5.4-fold when compared to the solubility of the pure drug. In dissolution tests, more than 75.0% of the piroxicam present in the microparticles was released in just 2.5 minutes and the microparticles promoted a total release of the drug. In addition, microparticles increased both the release rate and the amount of drug released.     

Encapsulation of animal wax‐based organogels in alginate microparticles

Encapsulation of organogels is a novel perspective in the field of controlled drug delivery. This study reports encapsulation of lanolin based organogels within alginate microparticles. The microparticles were prepared by emulsification/internal gelation method. Microscopic studies suggested spherical shape of the microparticles. Fourier transform infrared, X‐ray diffraction and thermal studies confirmed the presence of organogels within the microparticles. Organogels containing microparticles showed improved drug (e.g., salicylic acid and metronidazole) entrapment efficiency. The release of the drugs from the microparticles was dependent on the pH of the dissolution medium. The release was diffusion mediated. The drug loaded microparticles showed antimicrobial activity against E. coli and B. subtilis. The preliminary study suggested that the encapsulation of the organogels may help prolonging the release of the drugs and hence may be tried as vehicles for controlled drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40910.     

A multiple emulsion method for loading 5‐fluorouracil into a magnetite‐loaded nanocapsule: a physicochemical investigation

The preparation of 5‐fluorouracil (5‐FU) loaded poly(lactic‐co‐glycolic acid) (PLGA) biodegradable nanocapsules containing magnetite nanoparticles was studied through the modified multiple emulsion solvent evaporation method for magnetically controlled delivery of anticancer drugs. The morphology and size distribution of the prepared magnetite/PLGA nanocapsules were investigated by transmission and scanning electron microscopy. The micrographs showed that the magnetic nanocapsules were almost spherical in shape and their mean diameter was in the nanometer range with a narrow size distribution. Fourier transform infrared and ultraviolet–visible spectroscopy confirmed incorporation of 5‐FU molecules into the PLGA matrix. The magnetite content was assessed by thermogravimetric and magnetometry analysis and the results showed a magnetite content of 35 wt% with high magnetic responsivity. Magnetometry measurements showed superparamagnetic properties of the magnetic nanocapsules with a saturation magnetization of 13.7 emu g^?1. Such biodegradable magnetic nanocapsules could be considered as an appropriate choice for drug targeting. Furthermore, the influence of some important processing parameters such as PLGA concentration, initial loading of 5‐FU and poly(vinyl alcohol) concentration on drug content, encapsulation efficiency and in vitro drug release kinetics was investigated and optimized. The drug content and encapsulation efficiency of the magnetic nanocapsules were 4–7 wt% and 60%–80%, respectively, and the nanocapsules demonstrated controlled release of 5‐FU at 37 °C in a buffer solution. All samples exhibited a burst release at the initial stage and this burst release showed its close dependence on the formulation parameters. Copyright © 2012 Society of Chemical Industry     

Spray-Dried Buccal Mucoadhesive Microparticles of Venlafaxine Based on Cress Seed Mucilage: In Vitro,in Vivo Evaluation in Rabbits

Lepidium sativum Linn. (Cruciferea) is known as garden cress or cress. Venlafaxine is prescribed in schizophrenia and anxiety. It shows a tendency of hepatic first-pass metabolism, which affects its bioavailability. The objective of this study is the extraction of cress seed mucilage and development of buccal mucoadhesive microparticles of venlafaxine based on the mucilage using a spray-drying technique. The optimized formulation was evaluated in vitro and the bioavailability of the same formulation in rabbits was assessed. Cress seed mucilage was extracted and used to prepare microparticles with varying concentrations in formulations F1–F5 (1–5% w/w) using a spray-drying technique. The microparticles were evaluated for yield, particle size, incorporation efficiency, swelling property, in vitro mucoadhesion, and in vitro drug release. Microparticles were characterized by differential scanning colorimetry, scanning electron microscopy, and X-ray diffraction studies. In vivo evaluation was carried out in rabbits. Formulation F5 showed maximum mucoadhesion (88.38 ± 1.46%), greater incorporation efficiency (89.42 ± 2.52%), and the highest swelling index (0.93 ± 0.01) compared to the other formulations. F5 showed a marked increase in bioavailability after buccal administration (52.55%) compared to an oral route (39.40%). Time to reach C _max of 23.49 ± 0.33 ng/mL was 120 min for buccal microparticles in comparison to oral solution, which took 180 min to reach C _max of 17.98 ± 1.14 ng/mL. Cress seed mucilage is suitable for production of the mucoadhesive microparticles using a spray-drying method because significant improvement in bioavailability by buccal mucoadhesive microparticles was observed.     

Microparticles based on hydrophobically modified chitosan as drug carriers

In this work, a hydrophobically modified (HM) chitosan derivative was prepared by covalent linkage of C₁₂ groups to the chitosan backbone. HM‐chitosan microparticles were prepared according to an emulsification‐solvent evaporation method and naltrexone (NTX) was used as a model drug. For comparison, unmodified chitosan and poly lactic‐co‐glycolic acid (PLGA) microparticles were also tested as carriers for NTX. HM‐chitosan formed viscous semi‐dilute solutions, suggesting a high level of chain entanglements and hydrophobic associations. HM‐chitosan microparticles generally showed higher production yield and encapsulation efficiency, as compared with chitosan and PLGA. The burst release shown by chitosan microparticles was significantly reduced when using the HM‐chitosan derivative. An enhanced control of drug release was observed over at least 50 days. PLGA particles demonstrated inferior controlled release properties as compared to HM‐chitosan subsequent to the initial release stage. These results revealed the potential of hydrophobic modification of chitosan as a means to improve the stability and sustained delivery properties of the polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40055.     

Microencapsulation of Ketoprofen in Blends of Acrylic Resins by Spray Drying

Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1:1 and 1:3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100°C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80°C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1:3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R ², and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.     

Spray drying technique to produce controlled release formulations of zidovudine—an anti‐HIV drug

This article explores the application of spray drying technique to produce microparticles of poly(D ,L ‐lactide‐co‐glycolic acid) (PLGA), as well as di‐block copolymer of polylactic acid (PLA) and polyethylene glycol (PEG) (PLA‐PEG), containing zidovudine (AZT), an anti‐HIV drug, to achieve its controlled release over an extended period of time. Of the two polymers studied, PLGA is hydrophobic, whereas PLA‐PEG is hydrophilic and the drug, AZT is water‐soluble. Formulations were developed containing 10 and 25 wt % of AZT giving encapsulation efficiencies (EE) of 66 to 86% for PLGA and 90 to 94% for PLA‐PEG di‐block copolymer. All the formulations were characterized by Fourier transform spectroscopy (FTIR) to investigate the interaction of AZT with polymers and to characterize PLA‐PEG. NMR was also employed to confirm the formation of PLA‐PEG. X‐ray diffraction was used to understand the molecular level dispersion of AZT within the polymeric matrices, while differential scanning calorimetry was employed to assess thermal properties. Scanning electron microscopy was employed to understand the surface morphology of AZT‐loaded microparticles. In vitro release experiments performed in pH 7.4 buffer media extended the release of AZT up to 125 h with PLGA, whereas 30 h were required for releasing AZT through PLA‐PEG microparticles. Cumulative release data were fitted to an empirical equation to understand the nature of release characteristics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2011     

Development and evaluation of a novel dosage form of diltiazem HCl using ethylene vinyl acetate copolymer and sodium starch glycolate (in vitro/in vivo study)

The work aims at developing a CR formulation, with high encapsulation efficiency of diltiazem HCl, suitable for twice daily administration. Microparticles, using EVA copolymer, were prepared by coacervation‐phase separation technique, subjected to controlled extraction and vacuum freeze drying processes to generate and immobilize a non uniform initial drug concentration distribution, and evaluated in vitro and in animals. Effects of increasing initial drug concentration, varying polymer system, increasing porosity, and decreasing tortuosity, varying the size of the microparticles and the pH of the dissolution medium on the release rate were evaluated. The results indicated that the release rate from microparticles was constant (zero‐order) for an appreciable period of time but it was low for twice‐daily administration. It increased with increasing initial drug concentration, varying polymer system, increasing porosity, and decreasing tortuosity, and decreasing the size of the microparticles but the duration of constant release was shorter except for formulations containing 2.00 and 2.25% sodium starch glycolate. 10‐h duration of constant release was achieved and the zero‐order release rate was within the required rate to achieve the desired therapeutic level. The pH of the dissolution medium did not have any effect on the release rate. The results of the in vivo study indicated that in vitro dissolution correlated well with in vivo AUC_0‐10 and that there were no statistically significant differences in AUC_0‐10 and C_max between the new CR formulation and Cardizem® CD. Accordingly, a new CR formulation that delivers diltiazem HCl at a constant rate, suitable for twice daily administration was developed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation,properties, and mathematical modeling of microparticle drug delivery systems based on biodegradable amphiphilic triblock copolymers

A series of biodegradable amphiphilic A‐B‐A type triblock copolymers P(BLA‐PEG‐BLA), composed of hydrophilic poly(ethylene glycol) (PEG) as a middle block component (B) and hydrophobic poly(β‐benzyl‐L ‐aspartate) as outer polypeptide block components (A), were synthesized by copolymerization of β‐benzyl‐L ‐aspartate N‐carboxy anhydride (BLA‐NCA) and the diaminated PEG with the primary amino groups capped at both ends. These P(BLA‐PEG‐BLA) copolymers were characterized by ¹H‐NMR, DSC, and GPC. The triblock copolymers were used to prepare three kinds of drug delivery systems including Norfloxacin (INN)‐incorporated P(BLA‐PEG‐BLA) microparticles and tablets. The morphologies of the microparticles were characterized by SEM. The in vitro release properties of the microparticles and tablets in PBS were also evaluated. A mathematical model, which incorporates a linear first‐order dissolution term and the transient Fickian diffusion equation, was developed to account for the kinetics of drug release from the INN‐incorporated P(BLA‐PEG‐BLA) microparticles. The results indicated that the overall release process was well controlled by both drug dissolution and diffusion. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3869–3873, 2004     

Surfactant chain length effects on nanoparticles of biodegradable polymers for targeted drug delivery

Folic acid‐conjugated nanoparticles (NPs) of biodegradable polymer poly(lactic‐co‐glycolic acid) (PLGA), which were emulsified by long‐chain D ‐α‐tocopheryl polyethylene glycol succinate (vitamin E TPGS or simply TPGS) for targeted delivery of anticancer drugs, are prepared. The NPs were characterized for their size and size distribution, surface morphology, surface charge, drug encapsulation efficiency, and surface chemistry. The cellular uptake and the cytotoxicity of the drug‐loaded PLGA NPs were assessed in vitro with MCF7 breast cancer cells in close comparison with the corresponding Short‐chain TPGS (TPGS2k)‐coated PLGA NPs and the original drug. The long‐chain TPGS 2000 (TPGS2k)‐emulsified PLGA NPs showed great advantages over the short‐chain TPGS 1000 (TPGS1k)‐emulsified and the nude PLGA NPs. The folic acid‐conjugated TPGS2k‐emulsified PLGA NPs showed significant advantages in cellular uptake and therapeutic effects in vitro. The IC₅₀ value showed 90.4% less than that of the original drug. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Development and characterization of ceftriaxone-loaded P3HB-based microparticles for drug delivery

In this study, polymer-based microparticles are used to improve the therapeutic properties of ceftriaxone (CEF) and render them safer. Poly-3-hydroxybutyrate (P3HB) and poly-3-hydroxybutyrate/polyethylene glycol (P3HB-PEG)-based microparticles were prepared by two methods: a double emulsification technique and spray-drying. The microparticles were characterized in terms of size and zeta potential, morphology, total drug loading and drug release. The microparticles had spherical shapes with diameters of a size range from 0.74 to 1.55?µm (emulsification technique) and from 3.84 to 6.51?µm (spray-drying); CEF encapsulation efficiency was around 63% and 49% for these methods respectively. The CEF release from microparticles obtained by spray-drying reached 100% after 150?h, while for microparticles obtained by emulsification technique the total release of CEF did not exceed 34% after 312?h. The release profiles could be best explained by Zero order kinetics model, Higuchi and Korsmeyer-Peppas models, as the plots showed high linearity. Antibacterial activity of the microparticles was evaluated against gram-positive and gram-negative bacterial strains. In general, CEF encapsulation in polymeric microparticles preserves the therapeutic efficacy of the CEF and provides its prolonged effect.     

Towards a better understanding of the release mechanisms of caffeine from PLGA microparticles

Poly(lactic-co-glycolic acid) (PLGA)-based microparticles can be successfully used to control the release rate of a drug and optimize the therapeutic efficacy of a medical treatment. However, the underlying drug release mechanisms can be complex and are often not fully understood. This renders system optimization cumbersome. In this study, differently sized caffeine-loaded PLGA microparticles were prepared and the swelling and drug release behaviors of single microparticles were monitored upon exposure to phosphate buffer pH 7.4. Ensembles of microparticles were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, gel permeation chromatography, and optical microscopy. The observed triphasic drug release patterns could be explained as follows. The initial burst release can be attributed to the dissolution of tiny drug crystals with direct surface access. The subsequent second drug release phase (with an about constant release rate) could be attributed to the release of drug crystals in regions, which undergo local swelling. The third release phase (again rapid, leading to complete drug exhaust) could be explained by substantial polymer swelling throughout the systems. Once a critical polymer molecular weight is reached, the PLGA chains are sufficiently hydrophilic, insufficiently entangled and the osmotic pressure created by water soluble degradation products attracts high amounts of water into the system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48710.     

Effects of polymer degradation on drug release from PLGA‐mPEG microparticles: A dynamic study of microparticle morphological and physicochemical properties

In vitro degradation and drug release of poly (DL ‐lactide‐co‐glycolic acid)‐methoxypoly(ethyleneglycol) (PLGA‐mPEG) microparticles were performed through a dynamic monitoring process, to investigate the effect of degradation on drug release from microparticles and to elucidate the dominant factor that governed the drug release kinetics. Methotrexate (MTX), an antirheumatic drug, was employed as the model drug. Drug release showed a triphasic pattern: an initial burst release followed by a lag period and subsequently a second burst release. The initial burst release was mainly caused by dissolution and diffusion of drugs at/near the surface of microparticles. During the following lag period, microparticles suffered little morphological changes, whereas the physicochemical changes of the polymer contributed to the increasing mobility of drug molecules, and then provided transport pathways for drug release. Later on, the erosion of the polymer matrix became significant. Morphology study showed that the trend of porosity change was in accordance with last phase release profile, indicating that porosity played an extremely important role in controlling drug release. The liberation pattern of mPEG was elucidated. The more pores formed, the more mPEG chains were exposed to the aqueous medium and disengaged from the polymer. Scanning electron micrography observation further confirmed these conclusions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and release characteristics of dexamethasone acetate loaded organochlorine‐free poly(lactide‐co‐glycolide) nanoparticles

Dexamethasone‐loaded poly(lactide‐co‐glycolide) (PLGA) devices are commonly used as model systems for controlled release. In this study, PLGA nanoparticles containing dexamethasone acetate were prepared by a nanoprecipitation technique in the absence of organochlorine solvents and were characterized by their mean size, ζ potential, scanning electron microscopy, and differential scanning calorimetry to develop a controlled release system. The analytical method for the quantification of dexamethasone acetate by high‐performance liquid chromatography was validated. The results show that it was possible to prepare particles at a nanometric size because the average diameter of the drug‐loaded PLGA particles was 540 ± 4 nm with a polydispersity index of 0.07 ± 0.01 and a ζ potential of ?2.5 ± 0.3 mV. These values remained stable for at least 7 months. The drug encapsulation efficiency was 48%. In vitro tests showed that about 25% of the drug was released in 48 h. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41199.     

Preparation and in vitro characterization of poly(sebacic acid‐co‐ricinoleic acid)‐based tamoxifen citrate‐loaded microparticles for breast cancer

This study was aimed to develop an injectable polymeric drug delivery system for tamoxifen citrate (TC) using poly(sebacic acid‐co‐ricinoleic acid) [poly(SA‐RA) 70 : 30 w/w] as a drug carrier for the treatment of estrogen receptor positive breast cancer. Injectable biodegradable microparticles of TC were produced by solvent displacement technique of microencapsulation and were characterized by surface morphology (scanning electron microscopy), particle size, size distribution, physical and chemical interaction (Fourier transform infrared), nature and physical state of drug [DSC and X‐ray diffraction (XRD)], and in vitro release studies. TC loading over different concentrations was analyzed by high performance liquid chromatography (HPLC) technique. Polyanhydride microparticles obtained after lyophilization were nearly spherical in shape with smooth surface and size less than 2.5 μm. TC was dispersed in the form of amorphous state, and TC remains intact and stable during the process of microencapsulation. In vitro drug release studies demonstrated prolonged controlled release of TC with zero‐order kinetics. Stability studies revealed that the production process of microparticles itself did not affect the chemical stability of the drug and polymer forming the particle matrix. Significant difference in drug release capacity was observed in microparticles with different drug loadings, and the drug release was more sustained in microparticles prepared with high TC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sequential Release of Paclitaxel and Imatinib from Core–Shell Microparticles Prepared by Coaxial Electrospray for Vaginal Therapy of Cervical Cancer

To optimize the anti-tumor efficacy of combination therapy with paclitaxel (PTX) and imatinib (IMN), we used coaxial electrospray to prepare sequential-release core–shell microparticles composed of a PTX-loaded sodium hyaluronate outer layer and an IMN-loaded PLGA core. The morphology, size distribution, drug loading, differential scanning calorimetry (DSC), Fourier transform infrared spectra (FTIR), in vitro release, PLGA degradation, cellular growth inhibition, in vivo vaginal retention, anti-tumor efficacy, and local irritation in a murine orthotopic cervicovaginal tumor model after vaginal administration were characterized. The results show that such core–shell microparticles were of spherical appearance, with an average size of 14.65 μm and a significant drug-loading ratio (2.36% for PTX, 19.5% for IMN, w/w), which might benefit cytotoxicity against cervical-cancer-related TC-1 cells. The DSC curves indicate changes in the phase state of PTX and IMN after encapsulation in microparticles. The FTIR spectra show that drug and excipients are compatible with each other. The release profiles show sequential characteristics in that PTX was almost completely released in 1 h and IMN was continuously released for 7 days. These core–shell microparticles showed synergistic inhibition in the growth of TC-1 cells. Such microparticles exhibited prolonged intravaginal residence, a >90% tumor inhibitory rate, and minimal mucosal irritation after intravaginal administration. All results suggest that such microparticles potentially provide a non-invasive local chemotherapeutic delivery system for the treatment of cervical cancer by the sequential release of PTX and IMN.     

Manufacturing Drug Loaded Chitosan Microspheres by Spray Drying: Development,Characterization, and Potential Use in Dentistry

The aim of this work was to determine specifications for spray-drying manufacturing of sustained-release drug-loaded microparticles with potential application in dentistry. Chitosan was used as the microencapsulation polymer and ketoprofen as the model drug. A 1:1 chitosan/ketoprofen suspension was spray-dried under different operating conditions. The size distribution, morphology, total drug load, and release profile of the powders were characterized. In vitro release studies were performed with the powder samples entrapped in cellulose dialysis tubes. The microparticles produced had a narrow size distribution (mean diameter ranging from 2.11 to 3.27 µm), good sphericity, and a smooth surface. In vitro release studies showed a linear drug dissolution behavior.