Microencapsulation of acetaminophen into poly(L-lactide) by three different emulsion solvent-evaporation methods

Controlled release evaluation of paracetamol loaded amine functionalized mesoporous silica KCC1 compared to microcrystalline cellulose based tablets

In the pharmaceutical manufacturing, drug release behavior development is remained as one of the main challenges to improve the drug effectiveness. Recently, more focus has been done on using mesoporous silica materials as drug carriers for prolonged and superior control of drug release in human body. In this study, release behavior of paracetamol is developed using drug-loaded KCC-1-NH2 mesoporous silica, based on direct compaction method for preparation of tablets. The purpose of this study is to investigate the utilizing of pure KCC-1 mesoporous silica (KCC-1) and amino functionalized KCC-1 (KCC-1-NH2) as drug carriers in oral solid dosage formulations compared to common excipient, microcrystalline cellulose (MCC), to improve the control of drug release rate by manipulating surface chemistry of the carrier. Different formulations of KCC-1 and KCC-NH2 are designed to investigate the effect of functionalized mesoporous silica as carrier on drug controlled-release rate. The results displayed the remarkable effect of KCC-1-NH2 on drug controlled-release in comparison with the formulation containing pure KCC-1 and formulation including MCC as reference materials. The pure KCC-1 and KCC-1-NH2 are characterized using different evaluation methods such as FTIR, SEM, TEM and N2 adsorption analysis.

Optimising poly(lactic-co-glycolic acid) microparticle fabrication using a Taguchi orthogonal array design-of-experiment approach

The objective of this study was to identify, understand and generate a Taguchi orthogonal array model for the formation of 10-50 μm microparticles with applications in topical/ocular controlled drug delivery. Poly(lactic-co-glycolic acid) (PLGA) microparticles were fabricated by the single emulsion oil-in-water method and the particle size was characterized using laser diffraction and scanning electronic microscopy (SEM). Sequential Taguchi L12 and L18 orthogonal array (OA) designs were employed to study the influence of ten and eight parameters, respectively, on microparticle size (response). The first optimization step using the L12 design showed that all parameters significantly influenced the particle size of the prepared PLGA microparticles with exception of the concentration of poly(vinyl alcohol) (PVA) in the hardening bath. The smallest mean particle size obtained from the L12 design was 54.39 μm. A subsequent L18 design showed that the molecular weight of PLGA does not significantly affect the particle size. An experimental run comprising of defined parameters including molecular weight of PLGA (89 kDa), concentration of PLGA (20% w/v), concentration of PVA in the emulsion (0.8% w/v), solvent type (ethyl acetate), organic/aqeuous phase ratio (1:1 v/v), vortexing speed (9), vortexing duration (60 seconds), concentration of PVA in hardening bath (0.8% w/v), stirring speed of hardening bath (1200 rpm) and solvent evaporation duration (24 hours) resulted in the lowest mean particle size of 23.51 μm which was predicted and confirmed by the L18 array. A comparable size was demonstrated during the fabrication of BSA-incorporated microparticles. Taguchi OA design proved to be a valuable tool in determining the combination of process parameters that can provide the optimal condition for microparticle formulation. Taguchi OA design can be used to correctly predict the size of microparticles fabricated by the single emulsion process and can therefore, ultimately, save time and costs during the manufacturing process of drug delivery formulations by minimising experimental runs.

Polymeric Microsphere Formulation for Colon Targeted Delivery of 5-Fluorouracil Using Biocompatible Natural Gum Katira

Controlled release delivery system of chemotherapeutic agents at the site of colon endorses modern drug-entrapped delivery tools, which release the entrappedagents at a controlled rate for anextended period providing patient compliance and additional protection from the degradinggastric environment. Thus, the present study was aimed to develop and optimize a novel polymeric microsphere of 5-fluorouracil (5-FU) using natural gum katira to obtain an optimal therapeutic response at the colon. Due course of experimentation, in-vivo safety profile of the gum katira in an animal model was established. Modified solvent extraction/evaporation technique wasemployed to encapsulate 5-FU in the natural polymeric microsphere and was characterized using in-vitro studies to investigate particle size, morphology, encapsulation efficiency and release of the drug from developed formulation. Formulated and optimized polymeric microsphere of 5-FU using gum katira polymer own optimal physicochemical characteristics with a fine spherical particle with size ranged from 210.37±7.50 to 314.45±7.80 µm.Targeted microsphere exhibited good cytotoxicity and also has high drug entrapment efficiency, and satisfactory release pattern of the drug within a time frame of 12 h. Finally, we foresee that the optimized polymeric gum katiramicrosphere of 5-FU could be a promising micro-carrier for efficient colon drug targeting delivery tool with improved chemotherapeutic efficacy against colon cancer.

Design of Controlled Release System for Paracetamol Based on Modified Lignin

The influence of lignin modification on drug release and pH-dependent releasing behavior of oral solid dosage forms was investigated using three different formulations. The first formulation contains microcrystalline cellulose (MCC 101) as the excipient and paracetamol as the active pharmaceutical ingredient (API). The second formulation includes Alcell lignin and MCC 101 as the excipient and paracetamol, and the third formulation consists of carboxylated Alcell lignin, MCC 101 and paracetamol. Direct compaction was carried out in order to prepare the tablets. Lignin can be readily chemically modified due to the existence of different functional groups in its structure. The focus of this investigation is on lignin carboxylation and its influence on paracetamol control release behavior at varying pH. Results suggest that carboxylated lignin tablets had the highest drug release, which is linked to their faster disintegration and lower tablet hardness.

Redox-responsive solid lipid microparticles composed of octadecyl acrylate and allyl disulfide

Redox-responsive solid lipid microparticles were prepared by an emulsification photo-polymerization method. Octadecyl acrylate (ODA) and a cross-linker (i.e. allyl disulfide (ADS) and octadiene (ODE)) were dissolved in dichloromethane, it was emulsified in poly(vinyl alcohol) solution, and the resulting O/W emulsion was irradiated with UV light. On the scanning electron microscope micrographs, the microparticles were sphere-like and they were not markedly different from the oil droplets in size. Using the atomic compositions analyzed by energy dispersive X-ray spectroscopy, the ODA to cross-linker molar ratio of ODA/ADS microparticles and ODA/ODE ones were calculated to be 1:0.13 and 1:0.15, respectively. In the FT-IR spectra of the microparticles, the signal of the vinyl group was hardly detected, implying that the monomer and the cross-linkers participated in the photo-polymerization. In differential scanning calorimetry study, ODA/ADS microparticles and ODA/ODE ones exhibited their endothermic peaks around 42.9 and 41.3 °C, respectively, possibly due to the melting of polymeric ODA. Dithiothreitol (DTT, a reducing agent) concentration had little effect on the release degree of dye loaded in ODA/ODE microparticles. Whereas, DTT concentration had a significant effect on the release degree of dye loaded in ODA/ADS microparticles. The release degree at 26 °C was weakly affected by DTT concentration. When the temperature was 37 °C, DTT concentration had a strong effect on the release degree. The disulfide cross-linker (i.e. ADS) can be broken to thiol compounds by the reducing agent, resulting in an increase in the release degree.

Controlled delivery of the popular nonsteroidal anti-inflammatory drug, paracetamol, from chitosan-g-polyacrylamide microspheres prepared by the emulsion crosslinking technique

In this paper, chitosan-graft-polyacrylamide (CS-g-PAAm) microspheres as drug delivery matrices of paracetamol were prepared by the emulsion crosslinking technique, using glutaraldehyde (GA) as a crosslinker. Graft copolymer of chitosan with acrylamide was synthesized using cerium (IV) ammonium nitrate (CAN). The microspheres formed had average particle sizes in the range of 78-252 μm. Paracetamol entrapment efficiency was found to vary between 31.89% and 72.61%, as determined by UV spectroscopy. Drug release in acidic and phosphate buffer solutions (pH 1.2 and 7.4) of the CS-g-PAAm microspheres was influenced by formulation factors such as the concentration of CS-g-PAAm, the paracetamol/polymer ratio (w/w), and the amount of crosslinker.

Prospects of pharmaceuticals and biopharmaceuticals loaded microparticles prepared by double emulsion technique for controlled delivery

Several methods and techniques are potentially useful for the preparation of microparticles in the field of controlled drug delivery. The type and the size of the microparticles, the entrapment, release characteristics and stability of drug in microparticles in the formulations are dependent on the method used. One of the most common methods of preparing microparticles is the single emulsion technique. Poorly soluble, lipophilic drugs are successfully retained within the microparticles prepared by this method. However, the encapsulation of highly water soluble compounds including protein and peptides presents formidable challenges to the researchers. The successful encapsulation of such compounds requires high drug loading in the microparticles, prevention of protein and peptide degradation by the encapsulation method involved and predictable release, both rate and extent, of the drug compound from the microparticles. The above mentioned problems can be overcome by using the double emulsion technique, alternatively called as multiple emulsion technique. Aiming to achieve this various techniques have been examined to prepare stable formulations utilizing w/o/w, s/o/w, w/o/o, and s/o/o type double emulsion methods. This article reviews the current state of the art in double emulsion based technologies for the preparation of microparticles including the investigation of various classes of substances that are pharmaceutically and biopharmaceutically active.

Enteric micro-particles for targeted oral drug delivery

This work is focused on production of enteric-coated micro-particles for oral administration, using a water-in-oil-in-water solvent evaporation technique. The active agent theophylline was first encapsulated in cellulose acetate phthalate (CAP), a pH-sensitive well-known polymer, which is insoluble in acid media but dissolves at neutral pH (above pH 6). In this first step, CAP was chosen with the aim optimizing the preparation and characterization methods. The desired release pattern has been obtained (low release at low pH, higher release at neutral pH) but in presence of a low encapsulation efficiency. Then, the CAP was replaced by a novel-synthesized pH-sensitive poly(methyl methacrylate-acrylic acid) copolymer, poly(MMA-AA). In this second step, the role of two process parameters was investigated, i.e., the percentage of emulsion stabilizer (polyvinyl alcohol, PVA) and the stirring power for the double emulsion on the encapsulation efficiency. The encapsulation efficiency was found to increase with PVA percentage and to decrease with the stirring power. By increasing the PVA content and by decreasing the stirring power, a high stable double emulsion was obtained, and this explains the increase in encapsulation efficiency found.

Preparation of smallest microparticles of poly-D,L-lactide by modified precipitation method: influence of the process parameters

Biodegradable microspheres such as those made of poly-D,L-lactide (PDLLA) are widely investigated delivery systems for drugs or antigens. The aim of this study was to examine experimental conditions in order to produce PDLLA microspheres with the best properties for controlled and sustained drug delivery by the modified precipitation method. For this purpose, the following parameters were varied: co-solvent (methanol or ethanol), the concentration of stabilizer polyvinyl alcohol (PVA), chloroform-to-water ratio and the speed and time of homogenization. Scanning electron microscopy (SEM) and stereological analysis were used to characterize the particles. The average size and morphology of the microspheres varied substantially with preparation conditions from 8.44-1.25 microm. Results showed that the smallest particles were obtained with methanol, 1% PVA and with 10 min of homogenization at 21,000 rpm.

Disodium norcantharidate loaded poly(ɛ-caprolactone) microspheres

Poly(epsilon-caprolactone) (PCL) microspheres encapsulating disodium norcantharidate (DSNC), a drug in salt form and with high water solubility, were prepared by s/o/w solvent evaporation technique and characterized in terms of size, morphology, encapsulation efficiency and drug release. The viscosity of s/o dispersion was crucial to the successful encapsulation of DSNC. Scanning electron microscopy (SEM) studies showed that the drug-loaded microspheres had coarse surface and porous internal structure. The analysis of X-ray diffraction (XRD) indicated that there was no interaction between DSNC and PCL, but the degree of crystallinity of PCL decreased with the introduction of the drug. The drug release profiles indicated an initial burst release followed by a slow release, and a further investigation into the release mechanism implied that the release of DSNC from PCL microspheres was caused by a combination of diffusion and osmotic pressure.

Application of gold nanoparticles to microencapsulation of thioridazine

Thioridazine-containing ethyl cellulose (EC) microcapsules were prepared in the presence of gold nanoparticles via the W/O/W emulsification solvent-evaporation method. The gold nanoparticles have been verified as human safe and the nondestructive physisorption of thioridazine on gold nanoparticles was corroborated with the time-of-flight second ion mass spectrometry measurements. The morphology of the formed microcapsules (ETA, containing EC, Thioridazine and Au) changed substantially because of the presence of gold nanoparticles. In addition to a prolonged controlled release, these ETA microcapsules had an enhanced thioridazine encapsulation with an efficiency over one and half times that of the microcapsules (ET) containing no nanogold particles. While data of the release kinetics for ET microcapsules fitted the apparent first-order model, corresponding data for ETA microcapsules agreed better with the Higuchi model indicating a uniform distribution of thioridazine in the monolithic-type microcapsules.