Preparation and characterization of amoxicillin mucoadhesive microparticles using solution-enhanced dispersion by supercritical CO2

The purpose of this research was to formulate and systemically evaluate in vitro and in vivo performances of mucoadhesive amoxicillin microparticles for the potential use in the treatment of gastric and duodenal ulcers, which were associated with Helicobacter pylori. The chitosan/amoxicillin microparticles were successfully prepared in a process of solution-enhanced dispersion by supercritical CO₂ (SEDS). The morphological characteristics of the mucoadhesive microparticles were studied under scanning electron microscope. The resulted microparticles with mean sizes ranged from 1.0 and 2.5?µm had good mucoadhesive properties. In vitro and in vivo mucoadhesive tests showed that chitosan/amoxicillin mucoadhesive microparticles adhered more strongly to gastric mucous layer and could retain in gastrointestinal tract for an extended period of time. The X-Ray Powder Diffractometry and Differential Scanning Calorimetry analysis demonstrated that the SEDS process was a typical physical coating process to produce drug-polymer composite microparticles, which is favourable for drugs since there is no changes in chemistry. In vitro release test showed that amoxicillin released faster in pH 1.0 hydrochloric acid (HCl) than in pH 7.8 phosphate buffer. In vivo H. pylori clearance tests were also carried out by administering amoxicillin powder and mucoadhesive microparticles to H. pylori infectious Wistar rats under fed conditions at single dose or multiple dose(s) in oral administration. The results showed that amoxicillin mucoadhesive microparticles had a better clearance effect than amoxicillin powder. In conclusion, the prolonged gastrointestinal residence time and enhanced amoxicillin stability resulting from the mucoadhesive microparticles of amoxicillin might make a contribution to H. pylori complete eradication.     

Preparation and characterization of 5-fluorouracil-loaded PLLA-PEG/PEG nanoparticles by a novel supercritical CO(2) technique

In this work, 5-fluorouracil-loaded- poly(l-lactic)-polyethylene glycol/polyethylene glycol (5-FU-loaded-PLLA-PEG/PEG) nanoparticles were prepared using a novel reverse emulsion-solution enhanced dispersion by supercritical fluids (reverse emulsion-SEDS) technique in an effort to obtain an efficient drug delivery system. In the experiment, 5-FU and PEG were dissolved in water PLLA-PEG was dissolved in organic solution, the aqueous solution was added dropwise to the organic solution under magnetic stirring, a reverse emulsion was immediately formed. The reverse emulsion was dried by a SEDS process so that 5-FU-loaded-PLLA-PEG/PEG nanoparticles (5-FU-NPs) were obtained. The particle size, size distribution, surface morphology, and physical and chemical properties of the 5-FU-NPs were investigated by laser diffraction particle size analysis, scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA). The drug encapsulation efficiency (EE), drug loading (DL), in vitro release profile and pharmacokinetics of 5-FU-NPs in rat plasma were investigated by high-performance liquid chromatography (HPLC). The in vivo tumor inhibition effect, increase in lifespan and hepatotoxicity of placebo-NPs, 5-FU and 5-FU-NPs were determined using H22 tumor-bearing ICR mice. These results collectively suggest that 5-FU-NPs prepared using SEDS have potential anti-tumor applications as a controlled drug release dosage form without harmful drug toxicity.     

超临界流体技术制备5-氟尿嘧啶聚乳酸微球

目的以5-氟尿嘧啶(5-Fu)为模型药物,制备氟尿嘧啶聚乳酸微球。方法采用超临界流体强制分散溶液技术,将5-Fu微粒化,并制备5-Fu聚乳酸微球。通过扫描电镜、激光粒度仪检测微球外形及粒径分布;气相色谱法测定二氯甲烷的残留量;恒温振荡透析法检测药物的释放度。结果25℃时,微粒化后5-Fu的乙醇饱和溶液浓度为6.43 mg.m l-1,较原料药的2.32 mg.m l-1有显著提高;所制备载药微球球形较好,表面光滑,粒径分布窄,粒径范围0.615~1.990μm,平均粒径为0.980μm;二氯甲烷残留量为0.0046%;微球载药量为2.6%,包封率为17.8%,药物释放呈缓释模式,无突释效应。结论超临界流体强制分散技术是制备5-Fu聚乳酸微球的可行方法。     

Preparation and characterization of simvastatin/hydroxypropyl-beta-cyclodextrin inclusion complex using supercritical antisolvent (SAS) process.

In the present study, the practically insoluble drug, simvastatin (SV), and its inclusion complex with hydroxypropyl beta-cyclodextrin (HP-beta-CD) prepared using supercritical antisolvent (SAS) process were investigated to improve the aqueous solubility and the dissolution rate of drug, thus enhancing its bioavailability. Inclusion complexation in aqueous solution and solid state was evaluated by the phase solubility diagram, differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The phase solubility diagram with HP-beta-CD was classified as A(L)-type at all temperatures investigated, indicating the formation of 1:1 stoichiometric inclusion complex. The apparent complexation constants (K(1:1)) calculated from phase solubility diagram were 774, 846 and 924 M(-1) at 25, 37 and 45+/-0.5 degrees C, respectively. No endothermic and characteristic diffraction peaks corresponding to SV was observed for the inclusion complex in DSC and PXRD. FT-IR study demonstrated the presence of intermolecular hydrogen bonds between SV and HP-beta-CD in inclusion complex, resulting in the formation of amorphous form. Aqueous solubility and dissolution studies indicated that the dissolution rates were remarkably increased in inclusion complex, compared with the physical mixture and drug alone. Moreover, SV/HP-beta-CD inclusion complex performed better than SV in reducing total cholesterol and triglyceride levels. This could be primarily attributed to the improved solubility and dissolution associated with inclusion complex between drug and HP-beta-CD. In conclusion, SAS process could be a useful method for the preparation of the inclusion complex of drug with HP-beta-CD and its solubility, dissolution rate and hypolipidemic activity were significantly increased by complexation between SV and HP-beta-CD.     

Inhalable,large porous PLGA microparticles loaded with paclitaxel: preparation,in vitro and in vivo characterization

Abstract

Large porous particles (LPPs) could be used as a useful carrier for non-invasive delivery to the deep lung. Pulmonary delivery of paclitaxel-loaded LPPs (PTX-LPPs) can help to eliminate the highly complicated and harmful solvent used in PTX parenteral formulations. PTX-LPPs with mass median aerodynamic diameter (MMAD) of 5.74?±?0.09?μm, high encapsulation efficiency and good aerosolisation properties were produced using ammonium bicarbonate as porogen. Cytotoxicity of PTX-LPPs on A549 and Calu-6 cell lines was comparable with Free-PTX. Endotracheal administration of PTX-LPPs in rats exhibited PTX plasma concentration in the therapeutic range which lasted 4-fold longer than i.v. injection. The bioavailability was measured as 51?±?7.1%. The lung targeting efficiency (T_e) of PTX-LPPs was 11.9-fold higher than i.v. administration. PTX-LPPs could deliver a higher PTX to lung with a non-toxic plasma level in a longer duration which shows their pulmonary delivery suitability.     

Solubility prediction in supercritical CO(2) using minimum number of experiments

The correlation ability and solubility prediction in supercritical carbon dioxide of a proposed equation were studied. The work involved the solubilities of nicotinic acid and p-acetoxyacetanilide in supercritical carbon dioxide using a dynamic flow solubility system at 35-75 degrees C and 100-200 bar. The generated experimental solubility data together with 21 data sets collected from the literature were used to evaluate the correlation ability of available empirical equations. The average absolute relative deviations (AARD) for the empirical equations are 12.6-24.8%. The prediction capability of the modified empirical relationship was studied with six experimental data points as a training set. Then, solubility at other temperatures and pressures were predicted. The AARD between predicted solubilities and observed values is 17%.     

Sustained-release tablets of indomethacin-loaded microcapsules: preparation, in vitro and in vivo characterization

Indomethacin (IDM) was encapsulated in gelatin-cellulose acetate phthalate (CAP) microcapsules (A) by complex coacervation method and in CAP microcapsules (B) by simple coacervation method. Microcapsules A and B, having mean diameters of 38.24 and 35.74 microm, respectively, were used to prepare sustained-release tablets A and B. The activation energy of thermal degradation for tablets A and B was calculated based on differential scanning calorimetry (DSC) to be 258.9 and 284.8 kcal/mol, respectively. In vitro release profiles showed no burst effect and release t(1/2) of the two sustained-release tablets were found to be 41.30+/-1.86 and 33.25+/-2.84 min, respectively, while that of IDM plain tablets C was 6.30+/-0.39 min (P<0.01). In vitro release of IDM from tablets A and B could be described by Higuchi equation and zero-order kinetics, respectively. After per os (po) administration with physiological saline, their irritation to rat stomach was obviously reduced in comparison with tablets C. Pharmacokinetic study in rabbits showed that t(max) was delayed and C(max) lowered compared with tablets C and the values of AUC(0-24 h) of the three tablets were very close.     

Sustained release indomethacin-loaded solid lipid microparticles based on solidified reverse micellar solution (SRMS): in vitro and in vivo evaluation

Solidified reverse micellar solutions (SRMS) were formulated using phospholipid (Phospholipon 90H) and triglyceride (Softisan 154) in the ratios of 1:1, 2:1 and 1:2, respectively. SLMs were prepared by melt homogenization technique. Characterization based on yield, mean particle diameter and morphology, pH, thermal analysis and encapsulation efficiency (EE%) were carried out on the SLMs. In vitro release was carried out in simulated intestinal fluid (SIF, pH 7.5), while the anti-inflammatory and ulcerogenic properties were studied using rats. From the results, the mean particle diameter of SLMs ranged from 2.19 ± 0.05 μm to 20.77 ± 0.03 μm. Maximum EE% of 96, 93 and 94 % were obtained and showed significant variation within the batches (p < 0.05). The release profile of indomethacin-loaded SLMs showed about 82-99 % drug release at 13 h. Indomethacin-loaded SLMs showed good anti-inflammatory and gastro-protective effects, and could be formulated for once-daily administration, either orally or parenterally, under controlled conditions.     

Preparation and characterization of fentanyl-loaded PLGA microspheres: in vitro release profiles

We developed several kinds of fentanyl-loaded poly(L-lactide-co-glycolide) (PLGA) microspheres (FMS) for sustained release of fentanyl. FMS were prepared by an emulsion solvent-evaporation method. In this study, the influences of several preparation parameters, such as initial drug loading, polymer concentration, and solvent volume on the release patterns of fentanyl were investigated. Furthermore, it has been well noted that the detection of fentanyl is extremely difficult because its clinical dose level is very low, about 1-3 ng/ml, in cancer-patient treatment. Therefore, we also developed a rapid and sensitive determination method for fentanyl in systemic circulation by employing gas chromatography (GC) system. Fentanyl was slowly released from FMS over 15 days with a quasi-zero order property. From the results, our FMS may be good formulations to deliver the analgesics and suitable for the treatment of severe pain over long periods.     

Reduction in burst release after coating poly(D,L-lactide-co-glycolide) (PLGA) microparticles with a drug-free PLGA layer

The high initial burst release of a highly water-soluble drug from poly (D,L-lactide-co-glycolide) (PLGA) microparticles prepared by the multiple emulsion (w/o/w) solvent extraction/evaporation method was reduced by coating with an additional polymeric PLGA layer. Coating with high encapsulation efficiency was performed by dispersing the core microparticles in peanut oil and subsequently in an organic polymer solution, followed by emulsification in the aqueous solution. Hardening of an additional polymeric layer occurred by oil/solvent extraction. Peanut oil was used to cover the surface of core microparticles and, therefore, reduced or prevented the rapid erosion of core microparticles surface. A low initial burst was obtained, accompanied by high encapsulation efficiency and continuous sustained release over several weeks. Reduction in burst release after coating was independent of the amount of oil. Either freshly prepared (wet) or dried (dry) core microparticles were used. A significant initial burst was reduced when ethyl acetate was used as a solvent instead of methylene chloride for polymer coating. Multiparticle encapsulation within the polymeric layer increased as the size of the core microparticles decreased (< 50 µm), resulting in lowest the initial burst. The initial burst could be controlled well by the coating level, which could be varied by varying the amount of polymer solution, used for coating.     

Preparation, characterization and in vivo assessment of the bioavailability of glycyrrhizic acid microparticles by supercritical anti-solvent process

In this study, glycyrrhizic acid (GA) microparticles were successfully prepared using a supercritical anti-solvent (SAS) process. Carbon dioxide and ethanol were used as the anti-solvent and solvent, respectively. The influences of several process parameters on the mean particle size (MPS), particle size distribution (PSD) and total yield were investigated. Processed particle sizes gradually decreased as temperature and solution flow rate increased. In addition, processed particle sizes increased from 119 to 205 nm as GA concentration increased. However, CO₂ flow rate did not significantly affect particle size. The optimized process conditions were applied, those included temperature (65 °C), pressure (250 bar), CO₂ and drug solution flow rate (15 and 8 mL min⁻¹), drug concentration in ethanol (20 mg mL⁻¹). Microparticles with a span of PSD ranging from 95 and 174 nm, MPS of 128 nm were obtained, and total yield was 63.5%. The X-ray diffraction patterns of glycyrrhizic acid microparticles show apparent amorphous nature. Fourier transform infrared (FT-IR) spectroscopy results show that no chemical structural changes occurred. The in vitro dissolution tests showed that the GA microparticles exhibited great enhancement of dissolution performance when compared to GA original drug. Furthermore, the in vivo studies revealed that the microparticles provided improved pharmacokinetic parameter after oral administration to rats as compared with original drug.     

左氧氟沙星/PLGA亚微粒的制备、表征和体外释药考察

目的:制备左氧氟沙星/PLGA亚微粒,并进行相关表征和体外释放行为考察.方法:采用纳米共沉淀法制备左氧氟沙星/PLGA亚微粒,采用激光粒度分析仪以及扫描电镜分别进行亚微粒粒度测定和形貌分析.同时采用紫外-可见分光光度法(UV)测定其载药量与体外药物释放行为.结果:经过激光粒度分析仪测定,所制备的左氧氟沙星/PLGA亚微粒粒径为197 ～230 nm,Zeta电位为-24 mv.扫描电镜观察亚微粒呈圆形/椭圆形,分布均匀.UV法测定亚微粒的载药量为6.25％～9.38％,包封产率为12.45％ ～46.59％.体外释放结果显示相比于商品化左氧氟沙星滴眼液,所制备的左氧氟沙星/PLGA亚微粒具有良好的缓释效果.结论:通过纳米共沉淀法成功制备粒径均一,高载药量的左氧氟沙星PLGA亚微粒,同时能实现药物的缓慢释放,减少给药次数的目的.     

Preparation, characterization, and in vivo anti-ulcer evaluation of pantoprazole-loaded microparticles.

Pantoprazole is an important drug in the treatment of acid-related disorders. This work concerns the preparation and characterization of gastro-resistant pantoprazole-loaded microparticles prepared using an O/O emulsification/solvent evaporation technique. The in vivo activity of the pantoprazole-loaded Eudragit S100 microparticles was carried out in rats. Furthermore, tablets containing the microparticles were also investigated. Microparticles presented spherical and smooth morphologies (SEM) and they remained intact in the inner surface of tablets. DSC and IR analyses showed that pantoprazole was physically and molecularly dispersed in the polymer. In vivo anti-ulcer evaluation showed that the microparticles were able to protect rat stomachs against ulcer formation, while the drug aqueous solution did not present activity. Drug dissolution profiles from tablets demonstrated slower release than untabletted microparticles. Weibull equation was the best model for describing the drug release profiles from microparticles and tablets. As regards the acid protection, tablets showed a satisfactory drug protection in acid medium (61.05 +/- 8.09% after 30 min).     

Preparation, characterization and in vivo evaluation of amorphous atorvastatin calcium nanoparticles using supercritical antisolvent (SAS) process

In this work, amorphous atorvastatin calcium nanoparticles were successfully prepared using the supercritical antisolvent (SAS) process. The effect of process variables on particle size and distribution of atorvastatin calcium during particle formation was investigated. Solid state characterization, solubility, intrinsic dissolution, powder dissolution studies and pharmacokinetic study in rats were performed. Spherical particles with mean particle size ranging between 152 and 863 nm were obtained by varying process parameters such as precipitation vessel pressure and temperature, drug solution concentration and feed rate ratio of CO2/drug solution. XRD, TGA, FT-IR, FT-Raman, NMR and HPLC analysis indicated that atorvastatin calcium existed as anhydrous amorphous form and no degradation occurred after SAS process. When compared with crystalline form (unprocessed drug), amorphous atorvastatin calcium nanoparticles were of better performance in solubility and intrinsic dissolution rate, resulting in higher solubility and faster dissolution rate. In addition, intrinsic dissolution rate showed a good correlation with the solubility. The dissolution rates of amorphous atorvastatin calcium nanoparticles were highly increased in comparison with unprocessed drug by the enhancement of intrinsic dissolution rate and the reduction of particle size resulting in an increased specific surface area. The absorption of atorvastatin calcium after oral administration of amorphous atorvastatin calcium nanoparticles to rats was markedly increased.     

Preparation of biodegradable poly(+/-)lactide microparticles using a spray-drying technique

Drug containing biodegradable poly(+/-)lactide microparticles were prepared by using a spray-drying technique. Formulations containing model drugs in either a dissolved (progesterone) or dispersed state (theophylline) were spray-dried. The spray-drying method was less dependent on the solubility characteristics of the drug when compared with traditional microencapsulation techniques such as phase separation or solvent evaporation techniques. Differential scanning calorimetry and scanning electron microscopy were used to characterize the microparticles. The drug release profiles were characterized by a rapid release phase (burst effect) followed by a slow release phase, the extent of each phase being dependent on the drug loading.     

Temozolomide/PLGA microparticles and antitumor activity against glioma C6 cancer cells in vitro

The purpose of the present study was to develop implantable poly(D,L-lactide-co-glycolide) (PLGA) microparticles for continuous delivery of intact 3,4-dihydro-3-methyl-4-oxoimidazo[5,1-d]-as-tetrazine-8-carboxamide (temozolomide, TM) for about a 1-month period and to evaluate its cytotoxicity against Glioma C6 cancer cells. The emulsifying-solvent evaporation process has been used to form TM-loaded PLGA microparticles. The influences of several preparation parameters, such as initial drug loading, polymer concentration, and stirring rate were investigated. Scanning electron microscopy (SEM) showed that such microparticles had a smooth surface and a spherical geometry, i.e. microspheres. The differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) results indicated that TM trapped in the microparticles existed in an amorphous or disordered-crystalline status in the polymer matrix. The release profiles of TM from microparticles resulted in biphasic patterns. After an initial burst, a continuous drug release was observed for up to 1 month. Finally, a cytotoxicity test was performed using Glioma C6 cancer cells to investigate the cytotoxicity of TM delivered from PLGA microparticles. It has been found that the cytotoxicity of TM to Glioma C6 cancer cells is enhanced when TM is delivered from PLGA polymeric carrier and, PLGA only did not affect the growth of the cells. Meanwhile, the cytotoxic activity of TM powder disappeared within 12h.     

Resolution of ephedrine in supercritical CO(2): A novel technique for the separation of chiral drugs.

Racemic ephedrine has been resolved by diastereomeric salt formation with mandelic acid using supercritical CO(2) as precipitating agent. Crystallizations were performed using the Solution Enhanced Dispersion by Supercritical Fluids (SEDS) technique. Temperature was varied between 35 and 75 degrees C, and pressures ranged from 100 to 350 bar. Resolution, determined by chiral capillary electrophoresis, is described as a function of temperature and density of the supercritical fluid. A comparison of SEDS-produced material with a conventional resolution method shows that SEDS-crystallized material exhibits identical properties to conventionally crystallized material.     

Preparation and in vitro characterization of piroxicam enteric coated pellets using powder layering technique

The objective of this study was to develop piroxicam enteric coated pellets using nonpareil seeds by powder layering technique to minimize its gastrointestinal adverse effects. Inert seeds were prepared by incorporating sugar, Avicel PH 101 and lactose. The obtained cores were then treated by PVP 10 w/v % solution using centrifugal granulator (CF-granulator) and then coated with micronized piroxicam using HPMC solution (8 w/v %) as binder. The piroxicam pellets were finally coated with different polymers (Eudragit L30D-55, Eudragit L100, Eudragit NE30D, Acryleze, or mixture of Eudragits L30D-55 and NE30D) and plasticizers (triethyl citrate and polyethylene glycol 6000). Results showed that Eudragit L30D-55 with 3% weight gain accompanied with TEC produced suitable enteric coated pellets.     

Preparation,characterization, and anticancer efficacy of evodiamine-loaded PLGA nanoparticles

Evodiamine (EVO) is a plant-derived indolequinazoline alkaloid with potential anticancer activity. However, low bioavailability caused by its poor water solubility limits it anticancer efficacy in clinic. To enhance the solubility and improve the bioavailability of EVO, a delivery system based on poly (lactic-co-glycolic acid) (PLGA) nanoparticles loaded with EVO (EVO-PLGA NPs) for treating breast cancer was prepared in this study. The physicochemical characterization and in vitro antitumor evaluation of EVO-PLGA NPs were determined. EVO-PLGA NPs could persistently control the release of EVO for 180?h. 3-[4,5-Dimethyl-2-thiazolyl]-2,5-diphenyl tetrazolium bromide (MTT) assessment and colony formation assay showed that EVO-PLGA NPs could enhance the toxicity and the proliferation inhibition effect of EVO on MCF-7 breast cancer cells. EVO-PLGA NPs did not strengthen G2/M arrest effect of EVO-treated cells after 24h incubation. Meanwhile, EVO-PLGA NPs could increase the expression of cyclin B1 and decrease the expression of β-actin. Taken together, these results suggested that -PLGA NPs is promising for improving anticancer efficacy of EVO in breast cancer therapy.