Uptake and bioconversion of stereoisomeric dipeptide prodrugs of ganciclovir by nanoparticulate carriers in corneal epithelial cells

Purpose: The objective of this study is to investigate cellular uptake of prodrug-loaded nanoparticle (NP). Another objective is to study bioconversion of stereoisomeric dipeptide prodrugs of ganciclovir (GCV) including L-Val-L-Val-GCV (LLGCV), L-Val-D-Val-GCV (LDGCV) and d-Val-l-Val-GCV (DLGCV) in human corneal epithelial cell (HCEC) model.

Methods: Poly(_D,L-lactic-co-glycolic acid) (PLGA) NP encapsulating prodrugs of GCV were formulated under a double emulsion method. Fluorescein isothiocyanate isomer–PLGA conjugates were synthesized to fabricate biocompatible fluorescent PLGA NP. Intracellular uptake of FITC-labeled NP was visualized by a fluorescent microscope in HCEC cells.

Results: Fluorescent PLGA NP and non-fluorescent NP display similar hydrodynamic diameter in the range of 115–145?nm with a narrow particle size distribution and zeta potentials around ?13 mV. Both NP types showed identical intracellular accumulation in HCEC cells. Maximum uptake (around 60%) was noted at 3?h for NP. Cellular uptake and intracellular accumulation of prodrugs are significantly different among three stereoisomeric dipeptide prodrugs. The microscopic images show that NPs are avidly internalized by HCEC cells and distributed throughout the cytoplasm instead of being localized on the cell surface. Following cellular uptake, prodrugs released from NP gradually bioreversed into parent drug GCV. LLGCV showed the highest degradation rate, followed by LDGCV and DLGCV.

Conclusion: LLGCV, LDGCV and DLGCV released from NP exhibited superior uptake and bioreversion in corneal cells.     

更昔洛韦眼用凝胶联合干扰素治疗单纯疱疹病毒性角膜炎疗效观察

目的：探讨更昔洛韦眼用凝胶联合干扰素治疗单纯疱疹病毒性角膜炎的临床效果。方法：选取单纯疱疹病毒性角膜炎患者59例（78眼）,将其随机分为观察组和对照组,观察组29例（40眼）,采用干扰素球结膜下注射,联用更昔洛韦眼用凝胶治疗;对照组30例（38眼）,单独采用更昔洛韦眼用凝胶治疗,并对两组治疗效果进行对照分析。结果：观察组疗效明显优于对照组,差异有统计学意义（P〈0.05）。结论：应用更昔洛韦眼用凝胶联合干扰素治疗单纯疱疹病毒性角膜炎具有治愈率高、副作用少的优点,值得临床推广应用。     

Local drug delivery using poly(lactic-co-glycolic acid) nanoparticles in thermosensitive gels for inner ear disease treatment

Intratympanic (IT) therapies have been explored to address several side effects that could be caused by systemic administration of steroids to treat inner ear diseases. For effective drug delivery to the inner ear, an IT delivery system was developed using poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and thermosensitive gels to maintain sustained release. Dexamethasone (DEX) was used as a model drug. The size and zeta potential of PLGA NPs and the gelation time of the thermosensitive gel were measured. In vitro drug release was studied using a Franz diffusion cell. Cytotoxicity of the formulations was investigated using SK-MEL-31 cells. Inflammatory responses were evaluated by histological observation of spiral ganglion cells and stria vascularis in the mouse cochlea 24 h after IT administration. In addition, the biodistribution of the formulations in mouse ears was observed by fluorescence imaging using coumarin-6. DEX-NPs showed a particle size of 150.0 ± 3.2 nm in diameter and a zeta potential of −18.7 ± 0.6. The DEX-NP-gel showed a gelation time of approximately 64 s at 37 °C and presented a similar release profile and cytotoxicity as that for DEX-NP. Furthermore, no significant inflammatory response was observed after IT administration. Fluorescence imaging results suggested that DEX-NP-gel sustained release compared to the other formulations. In conclusion, the PLGA NP-loaded thermosensitive gel may be a potential drug delivery system for the inner ear.     

Development of an enhanced formulation for delivering sustained release of buprenorphine hydrochloride

To control the minimum effective dose, and reduce the number and quantity of administered potent drugs are unique features of advanced drug delivery in situ forming gel formulation. The efficacy, consistency, and increasing the application of existing injection therapies can be enhanced through optimization of controlled released systems by using FDA approved biodegradable PLGA (poly-d,l-lactide-co-glycolide) polymer. The purpose of this study was to develop different in situ forming implant (ISFI) formulations of buprenorphine hydrochloride for post treatment of drug addicts, acute and chronic pains.The drug releases from different ISFIs membranes with and without Tween 80 were compared over a period of time. Kinetic equation followed the Korsmeyer–Peppas model, as the plots showed high linearity. The influence of this additive on polymer properties was investigated using differential scanning calorimetry (DSC), and the membranes structure was studied by X-ray diffractometry (XRD) and scanning electron microscope (SEM).Data revealed that Tween 80 modified the drug release pattern using diffusion mechanism and decreased the glass transition temperature (T_g) significantly. The degree of crystallinity was decreased after phase inversion which helps the dissolution of drug from membrane. The porosity of modified membranes was in accordance with release profiles.These findings suggest four different in situ forming implant formulations which can release various dose of the buprenorphine hydrochloride in a prolonged time. Also this surfactant can be an attractive additive for modifying the release rate of drugs from PLGA-based membrane drug delivery systems.     

Poly(lactic-co-glycolic acid) nanoparticles for sustained release of allyl isothiocyanate: characterization,in vitro release and biological activity

The objective of this study is to establish the ability of entrap allyl isothiocyanate (AITC) into polymeric nanoparticles to extend its shelf life and enhance its antiproliferative properties. Natural compounds, such as AITC, have showed multi-targeting activity resulting in a wide-range spectrum of therapeutic properties in chronic and degenerative diseases, conversely with most current pharmaceutical drugs showing single targeting activity and often result in drug resistance after extended administration periods. Apparently, AITC-loaded poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) reduced AITC degradation and volatility and were able to extend AITC shelf life compared with free AITC (65% vs. 20% in 24?h, respectively). Cell viability and uptake of AITC-loaded nanoparticles were studied in vitro, showing that the protection and sustained release of AITC from polymeric NPs involved a larger toxicity of tumoral cells. These nanoparticles could be used as protective systems for enhancing a biological activity.     

Ivermectin-loaded microparticles for parenteral sustained release: in vitro characterization and effect of some formulation variables

Ivermectin (IVM) is a BCS II drug with potent antiparasitic activity in veterinary applications. In this study, poly(lactide-co-glycolide) (PLGA) and poly(DL-lactide) (PLA) Ivermectin-loaded microparticles were prepared by the simple emulsion (O/W) solvent evaporation method in order to obtain sustained release formulations for parenteral applications. The effects of polymer end-groups (ester or free acid) and the addition of the hydrophilic polyvinylpyrrolidone polymer (PVP) in in vitro drug release profiles were also studied. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis showed that IVM was present in an amorphous state or as a molecular dispersion within the polymers or theirs mixtures with PVP and that a PVP-drug complex was formed. Drug entrapment efficiency in the microparticles (>90%) was independent of the polymer composition, the end groups and the presence of PVP. However, microscopic (SEM) observations showed that the addition of PVP led to more porous microparticles accompanied by the increased rates of drug release.     

Biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres for sustained release of risperidone: Zero-order release formulation

The preparation and investigation of sustained-release risperidone-encapsulated microspheres using erodible poly(D, L-lactide-co-glycolide) (PLGA) of lower molecular weight were performed and compared to that of commercial Risperdal Consta^? for the treatment of schizophrenia. The research included screening and optimizing of suitable commercial polymers of lower molecular weight PLGA50/50 or the blends of these PLGA polymers to prepare microspheres with zero-order release kinetics properties. Solvent evaporation method was applied here while studies of the risperidone loaded microsphere were carried out on its drug encapsulation capacity, morphology, particle size, as well as in vitro release profiles. Results showed that microspheres prepared using 50504A PLGA or blends of 5050-type PLGAs exerted spherical and smooth morphology, with a higher encapsulation efficiency and nearly zero-order release kinetics. These optimized microspheres showed great potential for a better depot preparation than the marketed Risperdal Consta^?, which could further improve the patient compliance.     

Dual sustained release delivery system for multiple route therapy of an antiviral drug

Abstract

Context: The first successful molecule against herpes infections was Acyclovir, which competes with new generations in the market, with its potential activity. The major physicochemical constraints and pharmacokinetics of Acyclovir such as low solubility, poor permeability, less half-life, high dose has initiated many researchers to develop diverse modified release dosage forms.

Objective: The objective of this work was to design polymeric nanoparticles of Acyclovir and then incorporate the drug-loaded nanoparticles within an in situ gelling system to provide dual sustained release effect, whereby the duration of action and bioavailability through different routes of administration could be improved.

Materials and methods: The formulation was designed through 3² factorial design, first developing the nanoparticles using Polycaprolactone and Pluronic F127 by Solvent evaporation process, followed by dispersion of the suspended nanoparticles into thermosensitive in situ gelling system of Pluronic F127 with Carbopol.

Results and discussion: The characterization of the nanoparticles and its sol-gel system performed through zeta sizer, SEM, XRD, TG-DSC, FTIR and rheology helped to optimize the formulation. The drug release could be sustained to 60% and 30% at eight hours, for the nanoparticles and their in situ gel systems, respectively, with non-Fickian diffusion mechanism of drug release. The test for % cell viability with NIH3T3 cell line revealed low level of toxicity for the nanoparticles.

Conclusion: The statistical significance obtained for the trail formulations experimentally proved its suitability for this dosage form design to achieve desired level of drug release.     

pH敏感型盐酸左氧氟沙星眼用即型凝胶的制备及其体外释放考察

目的研制具有缓释作用的pH敏感型盐酸左氧氟沙星眼用即型凝胶。方法以卡波普为凝胶基质,以羟丙甲基纤维素为增稠剂,以溶液的粘度、即型凝胶形成能力及盐酸左氧氟沙星含量为评价指标,确定制备处方和工艺,并以优选处方进行体外释放考察。结果经实验,其优选处方为盐酸左氧氟沙星0.1 g,羟丙甲基纤维素E 50 LV 2.0 g,卡波普9 400.3g,磷酸氢二钠0.35 g,磷酸二氢钠0.45 g,氯化钠0.50 g,尼泊金乙酯0.03 g,加水共制成100 ml。体外释放结果显示其释药平缓,具有较好的缓释特征。结论优选处方工艺稳定,质量控制方法可靠,适用于pH敏感型盐酸左氧氟沙星眼用即型凝胶的制备和评价。     

Fluconazole-loaded solid lipid nanoparticles topical gel for treatment of pityriasis versicolor: formulation and clinical study

Solid lipid nanoparticles (SLNs) are very potential formulations for topical delivery of antifungal drugs. Hence, the purpose of this research was to formulate the well-known antifungal agent Fluconazole (FLZ)-loaded SLNs topical gel to improve its efficiency for treatment of Pityriasis Versicolor (PV). FLZ-SLNs were prepared by modified high shear homogenization and ultrasonication method using different concentration of solid lipid (Compritol 888 ATO, Precirol ATO5) and surfactant (Cremophor RH40, Poloxamer 407). The physicochemical properties and the in vitro release study for all FLZ-SLNs were investigated. Furthermore, the optimized FLZ-SLN formula was incorporated into gel using Carpobol 934. A randomized controlled clinical trial (RCT) of potential batches was carried out on 30 well diagnosed PV patients comparing to market product Candistan^® 1% cream. Follow up was done for 4?weeks by clinical and KOH examinations. The results showed that FlZ-SLNs were almost spherical shape having colloidal sizes with no aggregation. The drug entrapment efficiency ranged from 55.49% to 83.04%. The zeta potential values lie between ?21 and ?33?mV presenting good stability. FLZ showed prolonged in vitro release from SLNs dispersion and its Carbapol gel following Higuchi order equation. Clinical studies registered significant improvement (p?® cream.     

In vitro release characteristics and cellular uptake of poly(D,L-lactic-co-glycolic acid) nanoparticles for topical delivery of antisense oligodeoxynucleotides

The efficacy of antisense oligodeoxynucleotides (AsODNs) is compromised by their poor stability in biological fluids and the inefficient cellular uptake due to their size and negative charge. Since chemical modifications of these molecules have resulted in a number of non-antisense activities, incorporation into particulate delivery systems has offered a promising alternative. The aim of this study was to evaluate various poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles for AsODN entrapment and delivery. PLGA nanoparticles were prepared using the double emulsion solvent evaporation method. The influence of formulation parameters such as PLGA concentration and volume ratio of internal aqueous phase volume (Va1) to organic phase volume (Vo) to external aqueous phase volume (Va2) on particle size, polydispersity index (PDI) and zeta potential (ZP) was investigated using a full factorial study. The particle size increased with increasing PLGA concentrations and volume ratios, with an interaction detectable between the two factors. AsODN entrapment efficiencies ranged between 49.97% and 54.95% with no significant difference between various formulations. By fitting the in vitro release profiles to a dual first order release model it was shown that the AsODN release occurred via two processes: a diffusion controlled process in the early phase (25 to 32% within one day) and a PLGA degradation process in the latter (39 to 70% after 14 days). Cellular uptake studies using primary corneal epithelial cells suggested active transport of nanoparticles via endocytosis. PLGA nanoparticles therefore show potential to successfully entrap AsODNs, transport them into cells and release them over time due to polymer erosion.