Impact of microparticle formulation approaches on drug burst release: a level A IVIVC.

AIM: To study the effect of poly(d,l-lactic-co-glycolic acid) (PLGA) microparticles (MPs) preparation techniques on particle physical characterization with special emphasis on burst drug release. METHODS: A basic drug clozapine was used in combination with acid-terminated PLGA. Two approaches for MP preparation were compared; the in situ forming microparticle (ISM) and the emulsion-solvent evaporation (ESE) methods using an experimental design. The MPs obtained were compared according to their physical characterization, burst release and T80%. An in vivo pharmacokinetic study with in vitro-in vivo correlation (IVIVC) was also performed for the selected formula. RESULTS: Both methods were able to sustain drug release for three weeks. ISM produced more porous particles and was not effective as ESE for controlling burst release. A good IVIVC (R(2) = 0.9755) was attained when injecting the selected formula into rats. CONCLUSION: MPs prepared with ESE showed a minimum burst release and a level A IVIVC was obtained when administered to rats.

Hydrophilic versus hydrophobic porogens for engineering of poly(lactide-co-glycolide) microparticles containing risedronate sodium.

OBJECTIVE: The aim of this study was to investigate the effect of two mechanistically different porogens, namely: the hydrophilic hydroxy-propyl-ß-cyclodextrin and the hydrophobic porogens (mineral oil and corn oil) in producing open/closed pored engineered polylactide-co-glycolic-acid microspheres suitable for pulmonary delivery of risedronate sodium (RS). MATERIALS AND METHODS: Surface morphology of the microspheres was studied and they were characterized for entrapment efficiency (%EE), particle size, and porosity as well as aerodynamic and flow properties. Selected formulae were investigated for in vitro drug release and deposition behavior using next generation impactor. Furthermore, the safety of the free drug and the selected prepared systems was assessed by MTT viability test performed on Calu-3 cell line. RESULTS AND DISCUSSION: The current work revealed that HP-ß-CD produced open-pored microspheres, while oils produced closed pored microspheres. Modulation of preparation parameters generated porous RS microspheres with high %EE, sustained drug release profile up to 15 days, suitable geometric and aerodynamic particle sizes and excellent flow properties. The safety of HP-ß-CD systems was higher than the systems utilizing oil as porogen. CONCLUSION: Porogen type affected the behavior of the microspheres as demonstrated by the various characterization experiments, with microspheres prepared using HP-ß-CD being superior to those prepared using oils as porogens.

Brain delivery of olanzapine by intranasal administration of transfersomal vesicles.

The aim of this study was to investigate the presence of a possible direct correlation between vesicle elasticity and the amount of drug reaching the brain intranasally. Therefore, transfersomes were developed using phosphatidylcholine (PC) as the lipid matrix and sodium deoxycholate (SDC), Span® 60, Cremophor® EL, Brij® 58, and Brij® 72 as surfactants. The influence of the type of surfactant and PC-to-surfactant ratio on vesicle morphology, size, membrane elasticity, drug entrapment, and in vitro drug release was studied. The prepared transfersomes were mainly spherical in shape, with diameters ranging from 310 to 885 nm. Transfersomes containing SDC and Span 60 with optimum lipid-to-surfactant molar ratio showed suitable diameters (410 and 380 nm, respectively) and deformability indices (17.68 and 20.76 mL/sec, respectively). Values for absolute drug bioavailability in rat plasma for transfersomes containing SDC and those containing Span 60 were 24.75 and 51.35%, whereas AUC(0-360 min) values in rat brain were 22,334.6 and 36,486.3 ng/mL/min, respectively. The present study revealed that the deformability index is a parameter having a direct relation with the amount of the drug delivered to the brain by the nasal route.

Hyaluronic acid-entecavir conjugates-core/lipid-shell nanohybrids for efficient macrophage uptake and hepatotropic prospects.

Drug covalently bound to polymers had formed, lately, platforms with great promise in drug delivery. These drug polymer conjugates (DPC) boosted drug loading and controlled medicine release with targeting ability. Herein, the ability of entecavir (E) conjugated to hyaluronic acid (HA) forming the core of vitamin E coated lipid nanohybrids (EE-HA LPH), to target Kupffer cells and hepatocyte had been proved. The drug was associated to HA with efficiency of 93.48 ± 3.14 % and nanohybrids loading of 22.02 ± 2.3 %. DiI labelled lipidic nanohybrids improved the macrophage uptake in J774 cells with a 21 day hepatocytes retention post intramuscular injection. Finally, in vivo biocompatibility and safety with respect to body weight, organs indices and histopathological alterations were demonstrated. Coating with vitamin E and conjugation of E to HA (a CD44 ligand), could give grounds for prospective application for vectored nano-platform in hepatitis B.

Moxifloxacin-loaded in situ synthesized Bioceramic/Poly(L-lactide-co-ε-caprolactone) composite scaffolds for treatment of osteomyelitis and orthopedic regeneration.

High local intraosseous levels of antimicrobial agents are required for adequate long-term treatment of chronic osteomyelitis (OM). In this study, biodegradable composite scaffolds of poly-lactide-co-ε-caprolactone/calcium phosphate (CaP) were in-situ synthesized using two different polymer grades and synthesis pathways and compared to composites prepared by pre-formed (commercially available) CaP for delivery of the antibiotic moxifloxacin hydrochloride (MOX). Phase identification and characterization by Fourier transform infra-red (FTIR) spectroscopy, X-ray powder diffraction (XRPD) and scanning electron microscope (SEM) confirmed the successful formation of different CaP phases within the biodegradable polymer matrix. The selected in-situ formed CaP scaffold showed a sustained release for MOX for six weeks and adequate porosity. Cell viability study on MG-63 osteoblast-like cells revealed that the selected composite scaffold maintained the cellular proliferation and differentiation. Moreover, it was able to diminish the bacterial load, inflammation and sequestrum formation in the bones of OM-induced animals. The results of the present work deduce that the selected in-situ formed CaP composite scaffold is a propitious candidate for OM treatment, and further clinical experiments are recommended.

Polypeptide and glycosaminoglycan polysaccharide as stabilizing polymers in nanocrystals for a safe ocular hypotensive effect.

Improved ocular delivery of a poorly soluble anti-glaucoma drug, acetazolamide (ACZ), in a stable nanosuspension (NS) was the main target of the study. The anionic polypeptide, poly-γ-glutamic acid (PG) and the glycosaminoglycan, hyaluronic acid, were used to stabilize ACZ-NS prepared using the antisolvent precipitation (AS-PT) coupled with sonication technique. To endue in site biocompatibility with high tolerability, soya lecithin (SL) phospholipid has been also combined with polyvinyl alcohol (PVA). NS with uniform PS in the range 100-300 nm, high ζ > ±20 mV, and enhanced saturation solubility were produced. Targeting solvent removal with control on future particle growth, post-production processing of NS was done using spray drying. The carriers' composition and amount relative to ACZ-NS were optimized to allow for the production of a redispersible dry crystalline powder. Particles crystallinity was confirmed using X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) in liquid and spray dried NS. The modified Draize test proved the safety and tolerability following application to rabbit eyes accompanying an efficient ocular hypotensive activity using a steroid glaucoma model.

Novel thymoquinone lipidic core nanocapsules with anisamide-polymethacrylate shell for colon cancer cells overexpressing sigma receptors.

The biggest challenge in colorectal cancer therapy is to avoid intestinal drug absorption before reaching the colon, while focusing on tumor specific delivery with high local concentration and minimal toxicity. In our work, thymoquinone (TQ)-loaded polymeric nanocapsules were prepared using the nanoprecipitation technique using Eudragit S100 as polymeric shell. Conjugation of anisamide as a targeting ligand for sigma receptors overexpressed by colon cancer cells to Eudragit S100 was carried out via carbodiimide coupling reaction, and was confirmed by thin layer chromatography and 1H-NMR. TQ nanocapsules were characterized for particle size, surface morphology, zeta potential, entrapment efficiency % (EE%), in vitro drug release and physical stability. A cytotoxicity study on three colon cancer cell lines (HT-29, HCT-116, Caco-2) was performed. Results revealed that the polymeric nanocapsules were successfully prepared, and the in vitro characterization showed a suitable size, zeta potential, EE% and physical stability. TQ exhibited a delayed release pattern from the nanocapsules in vitro. Anisamide-targeted TQ nanocapsules showed higher cytotoxicity against HT-29 cells overexpressing sigma receptors compared to their non-targeted counterparts and free TQ after incubation for 48 h, hence delineating anisamide as a promising ligand for active colon cancer targeting.

An integrated vitamin E-coated polymer hybrid nanoplatform: A lucrative option for an enhanced in vitro macrophage retention for an anti-hepatitis B therapeutic prospect.

A platform capable of specifically delivering an antiviral drug to the liver infected with hepatitis B is a major concern in hepatology. Vaccination has had a major effect on decreasing the emerging numbers of new cases of infection. However, the total elimination of the hepatitis B virus from the body requires prolonged therapy. In this work, we aimed to target the liver macrophages with lipid polymer hybrid nanoparticles (LPH), combining the merit of polymeric nanoparticles and lipid vesicles. The hydrophilic antiviral drug, entecavir (E), loaded LPH nanoparticles were optimized and physicochemically characterized. A modulated lipidic corona, as well as, an additional coat with vitamin E were used to extend the drug release enhance the macrophage uptake. The selected vitamin E coated LPH nanoparticles enriched with lecithin-glyceryl monostearate lipid shell exhibited high entrapment for E (80.47%), a size ≤ 200 nm for liver passive targeting, extended release over one week, proven serum stability, retained stability after refrigeration storage for 6 months. Upon macrophage uptake in vitro assessment, the presented formulation displayed promising traits, enhancing the cellular retention in J774 macrophages cells. In vivo and antiviral activity futuristic studies would help in the potential application of the ELPH in hepatitis B control.

Chitosan-calcium phosphate composite scaffolds for control of post-operative osteomyelitis: Fabrication, characterization, and in vitro-in vivo evaluation.

Osteomyelitis is a progressive inflammatory disease requiring prolonged systemic treatment with high antibiotic doses, and is very challenging to be treated. The use of locally applied antibiotics loaded on a biodegradable carrier at surgery sites is hypothesized to prevent post-operative osteomyelitis, while providing site-specific drug release. In this work, chitosan-based calcium phosphate composites were prepared and loaded with moxifloxacin hydrochloride. The in-situ formation of calcium phosphates within the composite was experimentally confirmed by Fourier transform infra-red spectroscopy, X-ray powder diffraction, and scanning electron microscopy. Results showed that the composites provided complete drug release over three days, and the selected composite formulation induced differentiation and proliferation of osteoblasts, while reducing bacterial count, inflammation and intra-medullary fibrosis in bone tissue specimens of osteomyelitis-induced animal model. Hence, we can conclude that the in situ prepared antibiotic-loaded calcium phosphate chitosan composite is promising in preventing post-operative osteomyelitis, and is worthy of clinical experimentation.

Near IR responsive targeted integrated lipid polymer nanoconstruct for enhanced magnolol cytotoxicity in breast cancer.

Advances in cancer nanotechnology aim at improving specificity and effectiveness for tumor treatment. Amalgamation of different treatment modalities is expected to provide better cancer combating. Herein, We developed a long circulating nanocarrier comprising trastuzumab (TZB) surface modified polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) co-encapsulating magnolol (Mag) and gold nanoparticles (GNPs). A modified single step nanoprecipitation method was adopted ensuring particle coating with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) while co-encapsulating GNPs. TZB was then anchored on NPs surface using a carbodiimide chemistry. The cytotoxicity of the developed system was evaluated with and without photothermal irradiation. NPs cellular uptake was then followed using confocal microscopical imaging. A hybrid matrix composed of PLGA/TPGS and surface decorated with TZB with a conjugation efficiency of ˃65%, was confirmed via FTIR, 1HNMR. GNPs could only be included in the NPs, when placed in the organic phase as evidenced by the shifted GNPs surface plasmonic resonance and confirmed via imaging coupled with energy dispersive X-ray analysis. Optimized NPs (136.1 ± 1.3 nm, -8.2 ± 1 mV and Mag encapsulation efficiency of 81.4 ± 1.8%) were able to boost Mag cytotoxicity on breast cancer cells while providing a selective multifunctional therapy with an added photothermal effect.

Preparation of intravenous stealthy acyclovir nanoparticles with increased mean residence time.

A major cause of thromboplebitis, during acyclovir (ACV) parenteral administration is the high pH of its reconstituted solution (pH 11). Its plasma half life is 2.5 h, requiring repeated administration which may result in excess of drug solubility leading to possible renal damage and acute renal failure. The present study reports the efficiency of stealthy ACV nanoparticles (NPs) to increase the mean residence time of the drug 29 times. It caused a marked decrease in thrombophlebitis when injected into rabbit's ear vein. The polymers used were (Poly lactic acid, polylactic-co-glycolic (PLGA) 85/15, PLGA 75/25, PLGA 50/50). Particles were evaluated for their encapsulation efficiency, morphology, particle size and size distribution, zeta potential, and in vitro drug release. Small NPs (280-300 nm) with 60% drug release after 48 h were obtained. Among the block copolymer used, poloxamer 407 was of superior coating properties with a coat thickness in the range of 1.5-8.3 nm and a decreased surface charge.

Dextran-based Nanocarriers for Delivery of Bioactives.

BACKGROUND: Dextran (DX) is a natural polysaccharide produced in the laboratory by fermentation of sucrose under the effect of the enzyme DX sucrase (1,6-α-D-glucan-α- glucosyltransferase). After harvesting and purification DX is subjected to cracking and separation to obtain the desired molecular weight. METHODS: The hydroxyl groups present in DX offer many sites for derivatization allowing the production of functionalized glycoconjugates biocompatible compound. DX and its derivatives are getting increased attention for use in core decoration or as carriers in novel drug delivery systems. This includes, among others, ion-pairing, self-aggregate, protein and drug conjugates. DX carriers and camouflaged particles will be dealt with in this review to give emphasis on the great versatility of this natural biocompatible polysaccharide. CONCLUSION: With the continuous development in the area of drug delivery, we believe that the unique properties of this versatile nanocarrier platform will elect it as one of the cornerstones of safe nanodelivery systems.

Defining cisplatin incorporation properties in thermosensitive injectable biodegradable hydrogel for sustained delivery and enhanced cytotoxicity.

Injectable thermoreversible chitosan (CS)/ß-glycerophosphate (ß-GP) hydrogels were developed for prolonged localized delivery of cisplatin (Cis). The effects of formulation variables on the thermoreversible hydrogels preparation as well as the impact of drug incorporation method on Cis release were studied. Antitumor activity of Cis CS/ß-GP thermoreversible hydrogels were evaluated against HCT-116 human colorectal cancer cells and MCF-7 human breast cancer cells. Incorporation of Cis to CS solution adjusted at pH 6.2 prior to hydrogel preparation deemed necessary to achieve a sustained release up to 4 days. Cis loaded CS/ß-GP thermoreversible hydrogels showed enhanced antitumor activity with about 1.2 fold and 2.05 fold that of Cis solution against HCT-116 cancer cells and MCF-7 cancer cells respectively. The obtained enhanced antitumor activity elected this delivery system for further in vivo and toxicological investigations.

Polyethylene glycol conjugated polymeric nanocapsules for targeted delivery of quercetin to folate-expressing cancer cells in vitro and in vivo.

In this work we describe the formulation and characterization of chemically modified polymeric nanocapsules incorporating the anticancer drug, quercetin, for the passive and active targeting to tumors. Folic acid was conjugated to poly(lactide-co-glycolide) (PLGA) polymer to facilitate active targeting to cancer cells. Two different methods for the conjugation of PLGA to folic acid were employed utilizing polyethylene glycol (PEG) as a spacer. Characterization of the conjugates was performed using FTIR and (1)H NMR studies. The PEG and folic acid content was independent of the conjugation methodology employed. PEGylation has shown to reduce the size of the nanocapsule; moreover, zeta-potential was shown to be polymer-type dependent. Comparative studies on the cytotoxicity and cellular uptake of the different formulations by HeLa cells, in the presence and absence of excess folic acid, were carried out using MTT assay and Confocal Laser Scanning Microscopy, respectively. Both results confirmed the selective uptake and cytotoxicity of the folic acid targeted nanocapsules to the folate enriched cancer cells in a folate-dependent manner. Finally, the passive tumor accumulation and the active targeting of the nanocapsules to folate-expressing cells were confirmed upon intravenous administration in HeLa or IGROV-1 tumor-bearing mice. The developed nanocapsules provide a system for targeted delivery of a range of hydrophobic anticancer drugs in vivo.

A comparative study of chitosan shielding effect on nano-carriers hydrophilicity and biodistribution.

Engineering polymer surfaces reduces nanoparticles (NPs) aggregation and phagocytosis due to effective shielding, hindering recognition by the reticuloendothelial system (RES). The shielding of NPs is complex and affected by the type of groups used in terms of charge and hydrophilicity. This will, in turn, affect NPs biodistribution which will determine the length of activity of the drug. Polysaccharides are nowadays recognized for decreasing the uptake of particulate carriers by the mononuclear phagocytic system (MPS). Chitosan is considered as an attractive candidate due to its biocompatibility, biodegradability, non-toxicity and low cost. In this study clozapine (CZP)-loaded NPs were coated with chitosan, pluronic F-68, polyethylene glycol (PEG) 4000 and polysorbate 80. The factors affecting drug encapsulation efficiency, particle size, surface charge, surface hydrophilicity, pharmacokinetics and biodistribution were studied. The results proved that although a similarity in surface hydrophilicity, chitosan-stealth NPs showed different pharmacokinetic profile and biodistribution behavior compared to polysorbate-stealth NPs.

Anticancer effect of atorvastatin nanostructured polymeric micelles based on stearyl-grafted chitosan.

The purpose of this study was to develop a new therapeutic approach for atorvastatin (ATV) adopting nanostructured polymeric micelles for its controlled delivery to the cancer cells. Amphiphilic block copolymers of stearyl chitosan (SC) and sulfated stearyl chitosan (S-SC) that could self assemble to form polymeric micelles with different degree of substitution (DS) were synthesized and characterized. The synthesized chitosan derivatives were able to self assemble and form micelles encapsulating ATV with critical micellar concentrations ranging from 6.9 to 21µg/ml, drug-loading ranging from 40% to 84.1% and encapsulation efficiency ranging from 10.4% to 35%. ATV caused a significant decrease in particle size and zeta potential of both SC and S-SC micelles. Micelles encapsulating ATV exhibited a sustained release and more cytotoxic activity against MCF 7 and HCT 116 cell lines than ATV alone. The 50% cellular growth inhibition (IC50%) of the drug decreased from 10.4 to 3.7 in case of MCF 7 and from 9.4 to 3.4 in case of HCT 116 after its loading in micelles. These results indicate that SC ATV polymeric micelles can be considered as a promising system for site specific controlled delivery of ATV to tumor cells.

Phospholipid based colloidal poloxamer-nanocubic vesicles for brain targeting via the nasal route.

In this study, new phospholipid based colloidal nanocubic vesicles encapsulating olanzapine for its brain targeting via the nasal route were developed. The nanocubic vesicles were prepared by incorporating non-ionic copolymers, poloxamer 188 or 407, in the lipid bilayer. The effect of phospholipid:poloxamer molar ratio on the physicochemical properties of the nanocubic vesicles was investigated. The in vivo behavior and brain targeting of these vesicles were evaluated in rats. TEM photographs showed that the vesicles looked spherical before adding poloxamer. However, after poloxamer incorporation, the vesicles showed a predominant cubic shape, except those containing phospholipid:poloxamer in the molar ratio 5:1 which were spherical. DSC study confirmed perturbation of the packing characteristics as well as fluidization of the lipid bilayer by the polymer with consequent formation of the nanocubic structure. The mean diameter of the vesicles was in the range of 363-645 nm. All vesicles were elastic and the elasticity was found to depend on both poloxamer type and concentration. The intranasal nanocubic vesicles were significantly more efficient in targeting olanzapine to the brain compared to the liposomal vesicles with drug targeting efficiency values of 100% and 80%, respectively, and absolute bioavailability of 37.9% and 14.9%, respectively.

A reliable predictive factorial model for entrapment optimization of a sodium bisphosphonate into biodegradable microspheres.

The aim of this work was to optimize the encapsulation of a third generation bisphosphonate (risedronate sodium RS) into polylactide-co-glycolide (PLGA) microspheres using a double emulsion technique for implant purposes. Microspheres were prepared by w/o/w double emulsion technique using PLGA in the ratio of 50:50 and 75:25. Critical process parameters namely: polymer type and amount, drug amount and internal aqueous phase volume ratio were evaluated for their effect on entrapment efficiency (EE%) of RS. Microspheres were characterized for their entrapment efficiency, morphology and particle size by UV spectrophotometry, scanning electron microscopy, and laser diffraction respectively. A 2(4) full factorial design was used for model production. High EE% exceeding 80% were obtained through the manipulation of the previously mentioned factors. Microparticles showed smooth surface with few pores and a size ranging from 1-6 µm. The factorial mathematical model was validated by check point analysis revealing good agreement between actual and predicted values. PLGA microspheres successfully encapsulated RS at high levels with suitable size and morphology suggesting their potential use in the treatment of bone diseases as injectable implants.

Different modalities of NaCl osmogen in biodegradable microspheres for bone deposition of risedronate sodium by alveolar targeting.

Risedronate sodium was formulated into polylactide-co-glycolic acid microspheres for pulmonary delivery using the w/o/w double emulsion technique. Sodium chloride was used as osmogen in either the internal or external aqueous phase to surface-engineer the particles to achieve favorable properties. The prepared microspheres were characterized for the surface morphology, entrapment efficiency, in vitro release behavior, particle size, surface area, aerodynamic as well as powder flow properties. Furthermore, the safety of the drug and the selected formula were assessed by MTT viability test performed on Calu-3 cell line as well as histopathological lung tissue examination. A novel in vivo approach based on the radiolabeling of risedronate sodium with I(125) was developed in order to assess its deposition in the bones of male albino rats. The majority of the prepared microspheres exhibited high entrapment efficiency, sustained release profile up to 15 days, suitable geometric and aerodynamic particle sizes as well as good flow properties. The safety of the drug and the selected formula were proven by the high cell viability percentage of Calu-3 cells as well as the normal lung histology after intra-tracheal administration. The in vivo study showed high bone deposition for risedronate sodium following the pulmonary route, suggesting that it could be utilized as an alternative route of administration for delivery of bisphosphonates.

Ammonium methacrylate units polymer content and their effect on acyclovir colloidal nanoparticles properties and bioavailability in human volunteers.

Acyclovir (ACV)-Eudragit (EUD) nanoparticles (NPs) were prepared using both EUD RS 100 and RL 100 with different charge density. The effect of charge intensity on particle size, encapsulation efficiency, and in vitro dissolution was assessed. The bioavailability of ACV NP colloids were evaluated in human volunteers, compared with commercial product using a validated LC-MS/MS method with a lower limit of quantification (LLOQ) of 0.02 microg/ml. EUD RL 100 with higher ammonium groups gave smaller NPs than EUD RS 100. The surface charge of the polymer did not affect encapsulation efficiency and in vitro dissolution. In human volunteers, both F2 and F5 colloidal nanosuspensions prepared with EUD RS and RL respectively in drug to polymer ratio 1:3 sustained the oral absorption of ACV, expressed by the significant lower C(max), significant delayed T(max) and the significant higher HVD(t 50%C(max)). The mean C(max) of F2, F5, and Zovirax were 0.61+/-0.06, 0.73+/-0.07 and 0.92+/-0.21 microg/ml respectively. Furthermore, the AUC(0-12) of F2 and F5 was significantly higher than that of Zovirax((R)) with values of 4.37+/-0.88, 5.14+/-0.87 and 3.21+/-0.53 microg/ml h respectively. The higher AUC(0-12) for both F2 and F5 reflected high relative bioavailability of 136.2% and 159.9% respectively compared to commercial ACV tablets.