Effect of lipid on physicochemical properties of solid lipid nanoparticle of paclitaxel

The aim of this study was to compare physicochemical properties of solid lipid nanoparticles (SLN) made from different lipids. To make small, stable, uniform and highly encapsulated SLNs, many factors such as the components (lipid, stabilizer) and preparation condition (sonication time, power) can be considered. Out of those, we selected solid lipid as lipid matrix to investigate an effect on SLNs. The SLNs were characterized by particle size, zeta potential, solubility and in vitro release study. In this study, SLNs showed different physicochemical properties and release profiles according to used solid lipid. In case of particle size, M-SLN showed biggest particle size (412.5?±?29.4?nm) and highest encapsulation efficiency (61.2?±?4.8?%). And, B-SLN showed highest cumulative drug percentage (85.0?±?1.7?%, 24?h) in release study. These results suggest that lipids type affect physicochemical properties and release profile of SLN.     

Effect of physicochemical properties on intranasal nanoparticle transit into murine olfactory epithelium

Small molecular weight drugs, peptides, and nanoparticles have previously been shown to localize in the central nervous system after intraneural administration. A basic understanding of direct nose-to-brain drug delivery, particularly for nanoparticles with different physicochemical characteristics, remains unclear. In this study, fluorescence microscopy and stereology were used to track intranasally administered chitosan-coated polystyrene (C-PS) or polysorbate-coated polystyrene (P80-PS) nanoparticles (100?nm or 200?nm in diameter) in olfactory and respiratory nasal epithelia and olfactory bulbs in mice. Chitosan coating caused particles to adhere to the extracellular mucus which could provide useful modality for paracellular drug transport. Nanoparticle transport was exclusively transcellular. None of the nanoparticle formulations showed preference for uptake into olfactory axons over other nasal epithelial cells. Both 100?nm PS and 100?nm P80-PS were observed in olfactory epithelial cells but were absent from the olfactory bulbs; therefore, it is speculated that an optimal nanoparticle diameter for axonal transport is <100?nm in mice.     

Influence of physicochemical properties on dissolution of drugs in the gastrointestinal tract

The rate-limiting step to absorption of drugs from the gastrointestinal (GI) tract is often dissolution from the dosage form. Consideration of the Noyes-Whitney dissolution model shows that drug diffusivity, solubility in the gastrointestinal contents, the surface area of the solid wetted by the lumenal fluids and the GI hydrodynamics all play a role in determining the in vivo dissolution rate. Solubility in the GI contents is determined by aqueous solubility, crystalline form, drug lipophilicity, solubilization by native surfactants and co-ingested foodstuffs, and pK(a) in relation to the GI pH profile. Compounds with aqueous solubilities lower than 100 microg/ml often present dissolution limitations to absorption. The dose:solubility ratio of the drug provides an estimate of the volume of fluids required to dissolve an individual dose, and when this volume exceeds 1 l, dissolution is often problematic. The surface area of a drug available for dissolution depends on the particle size of the solid and its ability to be wetted by lumenal fluids. Other physiological factors that can play a role in dissolution include the viscosity of the lumenal contents, through its effect on the diffusivity, and mixing and flow patterns within the gut. In order to better predict in vivo dissolution of drugs, dissolution tests which more adequately simulate the physiological conditions are needed.     

Characterisation of fenofibrate dissolution delivered by a self-microemulsifying drug-delivery system

Objectives This study attempted to characterise the in‐vitro release profiles of fenofibrate (FFB) from a self‐microemulsifying drug‐delivery system (SMEDDS) for optimising formulation factors and dissolution conditions for in‐vivo absorption. Methods The study was conducted by profiling the release of FFB formulated with either a complete solution or a micronised dispersion system (MDS) in a SMEDDS composed of medium‐chain triglyceride (MCT) oil and surfactant mixtures (S_mix) of TPGS and Tweens at different ratios (K_m = TPGS/Tweens), with and without adding water. Optimised FFB SMEDDS formulations were then selected for in‐vivo bioavailability study. Key findings The release rates of FFB from TPGS/Tween 20 systems were faster than those from TPGS/Tween 80 systems at the same K_m value. In both systems, the release rates of FFB increased with a decrease in the K_m value. Furthermore, both the release rates and the amounts of FFB from MDS in the water medium decreased with an increasing percentage of S_mix added to both water contents. However, the release rates and amounts of FFB from MDSs increased with an increasing percentage of S_mix in a 0.025 M sodium lauryl sulfate (SLS) solution. It was further illustrated that the release of FFB from SMEDDSs was complete within 30 min in both the 0.025 M SLS solution and water medium, but the release of FFB from Tricor® or MDSs was limited in water medium. An optimised FFB SMEDDS with either Tween 20(E5(20)) or Tween 80(E5(80)) and one MDS were selected for a pharmacokinetic study to compare with Tricor^®. The results demonstrated that the area under the receiver operating curve and C_max values were in the order of Tricor^® > E5(80) ? E5(20) > MDS and Tricor^® ? E5(80) > E5(20) > MDS, respectively. Conclusions The absorption of drug carried by SMEDDS might not be enhanced as a result of the smaller volume of water taken with oral administration of SMEDDSs and the agitation rate of the gastrointestinal tract not being strong enough to efficiently promote the self‐microemulsification process to facilitate the in‐vivo dissolution rate.     

Effect of poloxamer on physicochemical properties of tacrolimus solid dispersion improving water solubility and dissolution rate

Tacrolimus (TCR; also FK-506 and trade name prograf^?), an antibiotic of macrolide family and a novel immunosuppressive agent, is a natural product of actinomycete Streptomyces tskubaensis. But TCR is poorly soluble in water (0.012?mg/mL), so its bioavailability is low and irregular. The aim of this study is to characterize physicochemical properties of TCR and investigate the improvement of solubility and dissolution rate of TCR solid dispersion (SD) with poloxamer. TCR SDs, consisting of various grades and ratios of poloxamer were prepared by hot-melting method and were characterized by DSC, PXRD, and FT-IR. The dissolution profile and solubility of TCR from the SDs were evaluated. SD of TCR prepared with poloxamer 188 at the ratio of 1:1 by the hot-melting method resulted in a significant increase in TCR solubility and enhanced dissolution profile over the TCR crystalline powder.     

A new biocompatible nanoparticle delivery system for the release of fibrinolytic drugs

The preparation of novel biocompatible polymeric nanoconstructs suitable to load sensitive bioactive protein agents is reported. Nanoparticles were prepared as based on hybrid polymeric matrices consisting of synthetic bioerodible alternating copolymers of maleic anhydride and n-butylvinylether hemiesterified with 2-methoxyethanol and grafted with poly(ethylene glycol) segments and monoclonal antibody single chain fragment specific for fibrin clot.

The prepared nanoparticles were loaded with proteolytic enzymes (trypsin and urokinase), encapsulating up to 2500 UI of urokinase/mg of dried nanoparticles. The release of the enzyme from nanoparticles resulted time controlled and it was assessed that in case of administration of urokinase-loaded nanoparticles, the enzyme would preserve its thrombolytic properties more efficiently in respect to free drug administration. Moreover, the nanoparticles showed a good in vitro biocompatibility, suitable for biomedical applications. The stability (shelf life) of the prepared nanostructured dosage forms was evaluated. The drug-loaded nanoparticles resulted stable under stressed conditions (35 °C for 13 weeks) in a lyophilized form and preserved their morphological and functional characteristics when stored in suspension for 18 months at 4 °C.     

Effect of polymers on dissolution from drug suspensions.

The effect of three viscosity grades of methylcellulose on the dissolution-dialysis rate of nitrofurantoin suspensions was investigated using a cell designed to provide a large surface area for dialysis. Apparent dialytic rate constants of drug dispersions and solutions were measured in 0.1 N HC1 and in pH 7.4 buffer. Samples containing methylcellulose had lower rates of dialysis, with the lowest rate being observed for samples in which the polymer was used as the suspending agent. The reduced rate of dialysis of the drug suspension containing methylcellulose is thought to be due to complexation of the drug in solution with the polymer as well as formation of microscopic regions of high viscosity surrounding the undissolved drug particles leading to a reduction in the dissolution rate of the drug. An empirical relationship was obtained to enable the estimation of the effective drug concentration in the dissolution chamber for drug dispersions. The method is based on utilizing dialysis rate data of drug solutions. This relationship could be used for comparing suspension formulations in terms of the amount of drug available for dialysis.     

Impact of fillers on dissolution kinetic of fenofibrate dry foams

Abstract

Dry foam technology reveals the opportunity to improve the dissolution behavior of poorly soluble drugs tending to agglomeration due to micronization. In this study, the impact of fillers on the manufacturability, the properties of dry foams and granules as well as the dissolution kinetics of dry foam tablets was investigated using fenofibrate as a model compound. Different maltodextrins and dried glucose syrups, a maltodextrin–phosphatidylcholine complex, isomalt and a 1:1 mixture of mannitol/glucose syrup were used as filler. Within the group of maltodextrins and glucose syrups, the influences of dextrose equivalent (DE), particle morphology and botanical source of starch were investigated. Comparable macroscopic foam structures were obtained with maltodextrins and glucose syrups whereas different foam morphologies were obtained for the other fillers tested. Regarding the maltodextrins and glucose syrups, different physicochemical and particle properties had a minor impact on granule characteristics and tablet dissolution. Using the maltodextrin–phosphatidylcholine complex resulted in a low specific surface area of the granules and a slow tablet dissolution caused by a slow disintegration. In contrast, a high specific surface area and a fast release were obtained with isomalt and glucose syrup/mannitol mixture indicating that high soluble low molecular weight fillers enable the development of fast dissolving dry foam tablets.     

In vitro dissolution and oral bioavailability study of fenofibrate nanomatrix system prepared by hot-melt extrusion

Solvent evaporation method for preparation of nanomatrix has the disadvantages, such as residual organic solvent, environmental pollution, explosion-proofing and so on. To overcome these shortcomings, a series of fenofibrate nanomatrix drug delivery system (NDDS) consisting of nano-porous silica Sylysia^®350 (S350) and pH sensitive material Eudragit^® L100-55 (EL100-55) were prepared using hot-melt extrusion (HME), and their in vitro dissolution and in vivo bioavailability were compared. Finally, the formulation with the highest in vivo bioavailability was selected as the optimized formulation for DSC and PXRD characterization. The results showed that the optimized NDDS showed a higher bioavailability than the reference formulation, although there was crystalline form drug remaining in NDDS. The relative bioavailability of the optimized formulation was 157.1% compared with the commercial product Lipanthyl^®. In addition, the relative bioavailability of the optimized formulation was 124.8% in comparison with the formulation prepared by solvent evaporation method, showing that the NDDS prepared by the HME method was effective in improving the bioavailability of fenofibrate. In conclusion, HME was a promising method to prepare NDDS.     

IVIVR in oral absorption for fenofibrate immediate release tablets using dissolution and dissolution permeation methods

In a previous study it has been demonstrated that a dissolution/permeation (D/P) system can discriminate between different immediate release fenofibrate formulations. The fractions permeated were correlated with fenofibrate's in vivo exposure in rats following p.o. administration. In the present study more detailed investigations are presented using data from six fenofibrate tablets tested in vivo in humans. In these pharmacokinetic studies no significant differences between formulations in AUC but in Cmax were found. Differences between the Cmax values were not explained by the dissolution characteristics of the tablets but were rationalized on the basis of micellar entrapment and diminished mobility of the active ingredient by surfactants in the formulations. This was demonstrated by a permeation system using dialysis membranes. Thus a permeation step in addition to dissolution measurement may significantly improve the establishment of an IVIV relationship.     

IVIVR in oral absorption for fenofibrate immediate release tablets using dissolution and dissolution permeation methods

In a previous study it has been demonstrated that a dissolution/permeation (D/P) system can discriminate between different immediate release fenofibrate formulations. The fractions permeated were correlated with fenofibrate's in vivo exposure in rats following p.o. administration. In the present study more detailed investigations are presented using data from six fenofibrate tablets tested in vivo in humans. In these pharmacokinetic studies no significant differences between formulations in AUC but in Cmax were found. Differences between the Cmax values were not explained by the dissolution characteristics of the tablets but were rationalized on the basis of micellar entrapment and diminished mobility of the active ingredient by surfactants in the formulations. This was demonstrated by a permeation system using dialysis membranes. Thus a permeation step in addition to dissolution measurement may significantly improve the establishment of an IVIV relationship.     

IVIVC in oral absorption for fenofibrate immediate release tablets using a dissolution/permeation system

The usefulness of a dissolution/permeation (D/P) system to predict the in vivo performance of solid dosage forms containing the poorly soluble drug, fenofibrate, was studied. Biorelevant dissolution media simulating the fasted and fed state conditions of the human gastrointestinal tract were used in order to simulate the effect of food on the absorption of fenofibrate. Moreover, the results obtained from the D/P system were correlated with pharmacokinetic parameters obtained following in vivo studies in rats. The in vitro parameter (amount permeated in the D/P system) reflected well the in vivo performance in rats in terms of AUC and C(max) of fenofibric acid. This study thus demonstrates the potential of the D/P system as valuable tool for absorption screening of dosage forms for poorly soluble drugs.     

Improvement of the wettability and dissolution of fenofibrate compacts by plasma treatment

The goal of this study was to investigate the effect of plasma treatment on the wettability and dissolution of fenofibrate compacts. Contact angle measurements and intrinsic dissolution rate studies of untreated and plasma-treated fenofibrate compacts were conducted. The contact angle data clearly show that the wettability of the tablet surface increased with the duration of plasma treatment.Analyses of stability revealed that the surfaces which were plasma-treated for more than 1 min regained some degree of hydrophobicity after storage in air. Since their hydrophobic recovery finally reached the level observed with 1 min plasma-treated fenofibrate compacts it was deduced that permanent incorporation of hydrophilic groups had already attained saturation upon plasma irradiation for 1 min.Dissolution studies revealed the advantages of the hydrophilized surface of plasma-treated fenofibrate compacts. Due to the improved wettability of plasma-treated fenofibrate its intrinsic dissolution rate was vastly increased compared to untreated fenofibrate. This study thus demonstrates the potential of plasma treatment to enhance the wettability and dissolution behavior of poorly water-soluble drugs.     

Characterization of physicochemical properties of naproxen systems with amorphous beta-cyclodextrin-epichlorohydrin polymers

Ground mixtures of naproxen with amorphous β-cyclodextrin-epichlorohydrin soluble (βCd-EPS) or insoluble cross-linked (βCd-EPI) polymers were investigated for both solid phase characterization (Differential Scanning Calorimetry, powder X-ray Diffractometry) and dissolution properties (dispersed amount method). The effect of different grinding conditions and of drug-to-carrier ratio was also evaluated. Co-grinding induced a decrease in drug crystallinity to an extent which depended on the grinding time, and was most pronounced for the cross-linked insoluble polymer, particularly in combinations at the lowest drug content. Both cyclodextrin polymers were more effective in improving the naproxen dissolution properties, not only than the parent βCd but also than hydroxyalkyl-derivatives, and their performance was almost comparable to that of methyl-derivatives, previously found as the best carriers for naproxen. Dissolution efficiencies of naproxen from physical mixtures with βCd-EPS, thanks to the high water solubility of this Cd-derivative, were up to three times higher than those from the corresponding products with βCd-EPI. However this difference in their performance became much less evident in co-ground products and tended to progressively diminish with increasing the polymer content in the mixture, according to the better amorphizing power shown by βCd-EPI during the co-grinding process. The 10/90 (w/w) drug–carrier co-ground products exhibited the best dissolution properties, giving dissolution efficiencies about 30 times higher than that of naproxen alone.     

Preformulation studies and characterization of the physicochemical properties of amorphous polymers using artificial neural networks

The utility of artificial neural networks (ANNs) as a preformulation tool to determine the physicochemical properties of amorphous polymers such as the hydration characteristics, glass transition temperatures and rheological properties was investigated. The neural network simulator, CAD/Chem, based on the delta back-propagation paradigm was used for this study. The ANNs software was trained with sets of experimental data consisting of different polymer blends with known water-uptake profiles, glass transition temperatures and viscosity values. A set of similar data, not initially exposed to the ANNs was used to validate the ability of the ANNs to recognize patterns. The results of this investigation indicate that the ANNs accurately predicted the water-uptake, glass transition temperatures and viscosities of different amorphous polymers and their physical blends with a low % error (0-8%) of prediction. The ANNs also showed good correlation between the water-uptake and changes in the glass transition temperatures of the polymers. This study demonstrated the potential of the ANNs as a preformulation tool to evaluate the characteristics of amorphous polymers. This is particularly relevant when designing sustained release formulations that require the use of a fast hydrating polymer matrix.     

介孔二氧化硅纳米粒的制备及对载药与药物溶出度的影响

目的为提高水难溶性药物的分散性及溶出度,制备介孔二氧化硅纳米粒作为水难溶性药物的载体。方法探索得到简单有效地制备球状介孔二氧化硅纳米粒的工艺条件,采用扫描电镜及氮气吸附-脱附等手段分析表征载体的外观形貌,比表面积及孔径分布,并选取水难溶性药物西洛他唑作为模型药物,以溶剂浸渍挥干法载药制得药物固体分散体,采用热分析、氮气吸附-脱附曲线以及溶出度实验研究药物固体分散体的基本性质。结果制得的二氧化硅载体的形貌近球状,粒径大小分布在200～250 nm,载体的比表面积最高可达1 101.54 m2.g-1,孔径分布主要集中在3.0～4.0 nm。载药过程对西洛他唑在载体中的存在形式没有影响,固体分散体中西洛他唑的溶出度得到显著提高,当药物与载体的质量比为1∶3时,药物60 min累计溶出达85%。结论介孔二氧化硅纳米粒有望成为水难溶性药物的优良载体。     

Effect of gamma radiation on the physicochemical properties of ciprofloxacin in solid state

The aim of this study was to determine the effect of different doses of gamma irradiation on the physicochemical properties of ciprofloxacin (CF) in solid state as a model drug. Powder of CF has been subjected to different irradiation doses: 0, 15, 25, 50 and 100 kGy from Cobalt-60 source in a Gammacell-220 at a rate of 1.15 Gray/s. The effect of radiation has been investigated using DSC, IR, spectrophotometric scanning and X-ray. The impact of irradiation on drug dissolution was also investigated. In addition, the irradiated samples were observed using scanning electron microscope (SEM). All irradiated samples showed chemical stability upon irradiation at the used irradiation doses. The DSC thermogram showed no change in the melting point (266 °C) indicating that the CF identity existed. These findings were also supported by the existence of the ciprofloxacin principal absorption bands in the IR spectra at frequencies 1,616, 1,498 and 2,845 per cm for C = O stretching band of quinolone, C-N stretching band and N-C stretching band. The decrease in the enthalpy by increasing the dose of irradiation attributed the change in crystalline ciprofloxacin to a more amorphous form. The X-ray diffraction patterns of irradiated powder showed a lesser degree of crystallinity as evidenced by fewer peaks of lower intensity compared with the non-irradiated sample. The characteristics of diffraction peaks relevant to crystalline CF virtually disappeared by increasing the dose of radiation from 15 to 100 kGy. This was also clearly demonstrated by SEM photomicrography. The rate of dissolution of CF samples was increased upon irradiation where irradiation at 100 kGy dose showed the fastest dissolution rate while non-irradiated drug samples showed the slowest dissolution rate. It was also observed that CF powder changed in color with color intensity depending on the irradiation dose. Color change is suggested to be due to surface changes in powder samples. This was verified by spectrophotometric scanning of dissolved powder from both irradiated and non-irradiated samples where no trace of any peaks was noticed in the visible range indicating that no radiolytical intermediates responsible for color change were formed during the irradiation. Thus it could be concluded that, although there were important changes in CF powder physical properties upon exposure to different doses of irradiation, the drug was chemically stable.     

Effect of position isomerism on the formation and physicochemical properties of pharmaceutical co-crystals

The effect of position isomerism on the co-crystals formation and physicochemical properties was evaluated. Piracetam was used as the model compound. Six position isomers, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5-dihydroxybenzoic acid (DHBA), were used as the co-crystal formers. Co-crystals were prepared on a 1:1 molar ratio by crystallization from acetonitrile. The solid-state properties of co-crystals were characterized using X-ray powder diffractometry (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR). All co-crystal formers formed co-crystal with piracetam except 2,6-DHBA. This failure was possibly due to steric hindrance of two bulk hydroxyl groups and preference of intra-molecular hydrogen bonding formation between hydroxyl group and carboxylic acid group. The XRD patterns of resulting co-crystal indicated that they are highly crystalline and different than parental compounds. Based on the single crystal data, P_23DHBA is orthorhombic while P_24DHBA, P_34DHBA, and P_35DHB belong to monoclinlic system. The hydrogen bonding network patterns of the co-crystals are also different. DSC data showed that the melting temperatures of resulting co-crystals are all lower than that of the starting materials. The melting point rank order of the co-crystals is: P_24DHBA > P_34DHBA > P_23DHBA > P_25DHBA > P_35DHBA. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:246–254, 2010