Biodegradable levofloxacin nanoparticles for sustained ocular drug delivery

Drug delivery to ocular region is a challenging task. Only 1–2% of drug is available in eye for therapeutic action, rest of the drug is drained out through nasolachrymal drainage system and other ocular physiological barriers. To overcome these problems of conventional dosage form, novel drug delivery systems are explored like nanoparticles. In our present work, levofloxacin encapsulated poly(lactic-co-glycolic acid) nanoparticles were developed and evaluated for various parameters like particle size, ζ potential, in vitro drug release and ex vivo transcorneal permeation. Microbiological efficacy was tested against Staphylococcus aureus using cup-plate method. Precorneal residence time was studied on albino rabbits by γ scintigraphy after radiolabeling of levofloxacin by Tc-99m. Ocular tolerance was evaluated using hen’s egg chorioallantoic membrane (HET-CAM) test. The developed nanoparticles were of spherical shape with a mean particle size of 190–195?nm with a ζ potential of ?25 mV. The drug entrapment efficiency was found to be near 85%. In vitro drug release profile shows initial burst release followed by extended release up to 24?h. Microbiological assay showed equivalent zone of inhibition compared to marketed formulation. γ Scintigraphy images of developed formulation, suggested a good spread and good retention over precorneal area. The nanosuspension thus developed was retained for the longer time and drained out from the eye very slowly compared to marketed formulation as significant radioactivity was recorded in later in kidney and bladder. The developed nanosuspension with a mean score of 0.33 up to 24?h in HET-CAM assay, showed the nonirritant efficacy of developed formulation. The stability studies yielded a degradation constant less then 5?×?10^?4, proving a stable formulation with an arbitrary shelf life of 2 years.     

Formulation and evaluation of Cyclosporin A emulgel for ocular delivery

Abstract

Emulgels have been extensively covered as a promising drug delivery system for the administration of lipophilic drugs. This work was conducted to develop an emulgel formulation for Cyclosporin A (CsA) employing polycarbophil as the gelling agent for ocular delivery. The prepared emulgels were evaluated for their physical appearance, rheological behavior, drug release, stability, precorneal clearance and irritation. Results showed that CsA emulgel formulations prepared with polycarbophil exhibited acceptable physical properties and drug release, which remained consistent after storage for 3 months. A prolonged retention time was also observed on the ocular surface with improved ocular bioavailability and no irritation. Therefore, the polycarbophil-based emulgel could be exploited as a potential hydrophobic drug carrier for topical ocular drug delivery.     

服他必妥滴眼液的药理学评价(Ⅱ)──对实验性眼炎的治疗作用

采用兔眼前房穿刺模型和辣椒酊刺激性眼炎模型观察服他必妥滴眼液的抗炎作用。结果表明，该品对眼部炎症有较好的治疗作用，与0．025％地塞米松滴眼液相似，并能有效地抑制前房穿刺引起的兔眼房水蛋白质浓度升高。     

Ion- and pH-activated novel in-situ gel system for sustained ocular drug delivery

Poor bioavailability (<1%) of drugs from conventional eye drops is mainly due to the various precorneal loss factors which include rapid tear turnover, systemic drug absorption through naso-lachrymal duct, transient residence time of the drug solution in the cul-de-sac and the relative impermeability of the drugs to corneal epithelial membrane. The present study describes the formulation and evaluation of chitosan and gellan gum based novel in-situ gel system activated by dual physiological mechanisms. Chitosan (a pH-sensitive polymer) in combination with gellan gum (an ion-activated polymer) were used as gelling agent. Timolol maleate, the drug which is frequently used for glaucoma therapy was used as model drug to check the efficacy of the formulation. The developed formulation was characterized for various in vitro parameters, for example, clarity, gelation pH, isotonicity, sterility, viscosity, transcorneal permeation profile, and ocular irritation. Ocular retention was studied by gamma scintigraphy and a significant increase in retention time was observed. The formulation was also found to be nonirritant and well tolerable. The developed system can be a viable alternative to conventional eye drops for the treatment of various ocular diseases and is suitable for clinical application.     

Novel nanostructured lipid carrier-based inserts for controlled ocular drug delivery: evaluation of corneal bioavailability and treatment efficacy in bacterial keratitis

Objectives: The aim of the present study was to develop novel ofloxacin (OFX)-loaded nanostructured lipid carrier (NLC)-based inserts for ocular application for treatment of bacterial keratitis.

Methods: NLC loaded with 0.3% OFX was prepared by means of high shear homogenization and 0.75% chitosan oligosaccharide lactate (COL) was added. Glycerin or PEG 400 at the range of 1 – 15% was added to NLCs as plasticizers and inserts were developed by solvent casting evaporation. Characterization, in vitro release, microbiological, ex vivo and in vivo studies were performed.

Results: The inserts developed with the addition of glycerin (Ins3_OFX) was found as optimal. The kinetic studies revealed that the release of Ins3_OFX was a combination of diffusion and swelling. Ins3_OFX was more bioadhesive in texture profile analysis studies. In the in vivo studies performed with rabbits, the pre-ocular retention time was enhanced up to 24 h and C_max was increased almost six times in comparison with commercial. The rabbits were infected with Staphylococcus aureus and keratitis was confirmed. This group was treated with Ins3_OFX and they recovered in 7 days with no significant sign of conjunctival redness and corneal opacity.

Conclusion: NLC-based inserts developed with COL and glycerin may be offered as appropriate vehicles for ocular delivery.     

Cubic liquid crystalline nanoparticles: optimization and evaluation for ocular delivery of tropicamide

The purpose of this study was to investigate the potential of cubic liquid crystalline nanoparticles for ocular delivery of tropicamide. Ultrasound-assisted fragmentation of cubic liquid crystalline bulk phases resulted in cubic liquid crystalline nanoparticles employing Pluronic F127 as dispersant. The effects of process variables such as sonication time, sonication amplitude, sonication depth, and pre-mixing time on particle size and polydispersity index was investigated using central composite design. The morphology of tropicamide-loaded nanoparticles was found to be nearly cubical in shape by transmission electron microscopy observation. Further, small angle X-ray scattering experiment confirmed the presence of D and P phase cubic structures in coexistence. The optimized tropicamide-loaded cubic nanoparticles showed in vitro corneal permeation of tropicamide across isolated porcine cornea comparable to its commercial preparation, Tropicacyl®. Ocular tolerance was evaluated by Hen’s egg–chorioallantoic membrane test and histological studies. The results of in vivo mydriatic response study demonstrated a remarkably higher area under mydriatic response curve (AUC_0→1440?min) values of cubic nanoparticles over Tropicacyl® indicating better therapeutic value of cubic nanoparticles. Furthermore, tropicamide-loaded cubic nanoparticles exhibited prolonged mydriatic effect on rabbits as compared to commercial conventional aqueous ophthalmic solution.     

Physicochemical characterization and toxicological evaluation of plant-based anionic polymers and their nanoparticulated system for ocular delivery

The water-soluble fractions of mucilages and gum from the seeds of fenugreek, isphagula and mango bark exudate were isolated, purified and characterized using X-ray diffraction (XRD) spectrometry, Fourier transform infrared spectroscopy (FT-IR), maldi/GC-MS, elemental analysis, 1D (¹H and ¹³C) and 2D (HMQC, COSY) nuclear magnetic resonance spectroscopy (NMR). The fenugreek mucilage was identified to be a galactomannan chain consisting of 4 units of galactose attached to the backbone of 6 mannose units in 1:1.5 ratio. The isphagula mucilage was identified to be an arabinoxylan polysaccharide chain consisting of 4 units of arabinofuranose attached to the backbone of 9 xylopyrannose units in 1:3 ratio. The mango gum showed the presence of amylose, α-arabinofuranosyl and β-galactopyranosyl, respectively. The characterized mucilages and gum were individually formulated into nanoparticulate system using their complementarily charged polymer chitosan. The particles were observed to be spherical in shape in the range of 61.5–90 nm having zetapotential between 31 and 34 mV and PDI of 0.097–0.241. The prepared nanoparticles were observed to be nonirritant and nontoxic in vitro and in vivo upto 2000 μg/ml. Therefore, these mucilages and gum can be the alternatives of anionic polymers for the ocular drug delivery system.     

In vitro and in vivo evaluation of ketotifen fumarate-loaded silicone hydrogel contact lenses for ocular drug delivery

The purpose of this work was to evaluate the usefulness of silicone hydrogel contact lenses loaded with ketotifen fumarate for ocular drug delivery. First, silicone contact lenses were prepared by photopolymerization of bitelechelic methacrylated polydimethylsiloxanes macromonomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, and N,N-dimethylacrylamide using ethylene glycol dimethacrylate as a cross-linker and Darocur 1173 as an initiator followed by surface plasma treatment. Then, the silicone hydrogel matrices of the contact lenses were characterized by equilibrium swelling ratio (ESR), tensile tests, ion permeability, and surface contact angle. Finally, the contact lenses were loaded with ketotifen fumarate by pre-soaking in drug solution to evaluate drug loading capacity, in vitro and in vivo release behavior of the silicone contact lenses. The results showed that ESR and ion permeability increase, and the surface contact angle and tensile strength decreased with the increase of DMA component in the silicone hydrogel. The drug loading and in vitro releases were dependent on the hydrogel composition of hydrophilic/hydrophobic phase of the contact lenses. In rabbit eyes, the pre-soaked contact lenses sustained ketotifen fumarate release for more than 24?h, which leads to a more stable drug concentration and a longer mean retention time in tear fluid than that of eye drops of 0.05%.     

In-vivo bioavailability and lymphatic uptake evaluation of lipid nanoparticulates of darunavir

Darunavir is effective against wild-type and PI-resistant HIV, and has an oral bioavailability of 37%. It needs to be combined with ritonavir, which increases the bioavailability to 82%. The aim of this study was to evaluate the in-vivo efficacy of the darunavir-SLN and demonstrate lymphatic transport as a contributing pathway in increasing the drug bioavailability. The SLN was prepared by hot-homogenization technique using GMS as lipid. In-vitro drug release from SLN at the 12th hour was retarded (80.6%) compared to marketed tablet (92.6%). Ex-vivo apparent permeability of the freeze-dried SLN across everted rat intestine was 24?×?10^?6 at 37?°C and 5.6?×?10^?6 at 4?°C. The presence of endocytic process inhibitors like chlorpromazine and nystatin reduced it to 18.8?×?10^?6 and 20.2?×?10^?6, respectively, which established involvement of endocytic mechanism in the uptake of SLN. In-vivo pharmacokinetic studies on rats demonstrated increase in the AUC of SLN (26) as compared to that of marketed tablet (13.22), while the presence of lymphatic uptake inhibitor cycloheximide lowered the AUC of SLN to 17.19 which further led credence to the involvement of lymphatic uptake behind improved bioavailability. The detection of darunavir in the lymphatic fluid of the rats administered with darunavir-SLN further reinforced the conclusion of SLN being taken up by the lymphatic system.     

Pulmonary delivery of nanosized alendronate for decorporation of inhaled heavy metals: formulation development,characterization and gamma scintigraphic evaluation

Abstract

Context: Medical management of heavy metal toxicity including radioactive ones is the cause of concern because of their increased use in energy production, healthcare and mining. As inhalation is one of the primary routes for internalization, a formulation is needed to trap metal(s) at the portal of entry itself.

Objective: Objective was to formulate and characterize a nanonized dry powder inhaler (DPI) formulation of alendronate sodium as potential inhalable antidote for chelating metal toxicants.

Methods. In vitro binding studies of alendronate with respect to seven non-radioactive heavy metals were carried out using UV-spectroscopy and HPLC. Nanonizing of alendronate particles was achieved by antisolvent precipitation using Pluronic-F68 as stabilizer. Characterization was done with the help of SEM, TEM FT-IR, XRD, DSC, NMR spectroscopy and PSD studies. In vitro and in vivo pulmonary deposition studies were carried out using gamma scintigraphy, followed by a limited pharmacokinetic study in humans.

Results. In vitro binding studies confirmed the chelating action of alendronate. Anderson cascade impaction showed that nano-alendronate exhibited significantly higher respirable fraction (58.25?±?1.32%) compared to the micronized form (28.7?±?0.59%). Scintigraphy results showed significant increase in the alveolar deposition of drug post-nanonizing.

Conclusion: Results strongly indicate the role of nano-alendronate DPI as potential inhalable antidote for neutralizing heavy metal toxicity, including radio-metal contamination.     

Biochemical and pharmacological profile of a tetrasubstituted furanone as a highly selective COX-2 inhibitor

1. DFU (5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furanone) was identified as a novel orally active and highly selective cyclo-oxygenase-2 (COX-2) inhibitor.
2. In CHO cells stably transfected with human COX isozymes, DFU inhibited the arachidonic acid-dependent production of prostaglandin E₂ (PGE₂) with at least a 1,000 fold selectivity for COX-2 (IC₅₀=41±14 nM) over COX-1 (IC₅₀>50 μM). Indomethacin was a potent inhibitor of both COX-1 (IC₅₀=18±3 nM) and COX-2 (IC₅₀=26±6 nM) under the same assay conditions. The large increase in selectivity of DFU over indomethacin was also observed in COX-1 mediated production of thromboxane B₂ (TXB₂) by Ca²⁺ ionophore-challenged human platelets (IC₅₀>50 μM and 4.1±1.7 nM, respectively).
3. DFU caused a time-dependent inhibition of purified recombinant human COX-2 with a K_i value of 140±68 μM for the initial reversible binding to enzyme and a k₂ value of 0.11±0.06 s⁻¹ for the first order rate constant for formation of a tightly bound enzyme-inhibitor complex. Comparable values of 62±26 μM and 0.06±0.01 s⁻¹, respectively, were obtained for indomethacin. The enzyme-inhibitor complex was found to have a 1 : 1 stoichiometry and to dissociate only very slowly (t_1/2=1–3 h) with recovery of intact inhibitor and active enzyme. The time-dependent inhibition by DFU was decreased by co-incubation with arachidonic acid under non-turnover conditions, consistent with reversible competitive inhibition at the COX active site.
4. Inhibition of purified recombinant human COX-1 by DFU was very weak and observed only at low concentrations of substrate (IC₅₀=63±5 μM at 0.1 μM arachidonic acid). In contrast to COX-2, inhibition was time-independent and rapidly reversible. These data are consistent with a reversible competitive inhibition of COX-1.
5. DFU inhibited lipopolysaccharide (LPS)-induced PGE₂ production (COX-2) in a human whole blood assay with a potency (IC₅₀=0.28±0.04 μM) similar to indomethacin (IC₅₀=0.68±0.17 μM). In contrast, DFU was at least 500 times less potent (IC₅₀>97 μM) than indomethacin at inhibiting coagulation-induced TXB₂ production (COX-1) (IC₅₀=0.19±0.02 μM).
6. In a sensitive assay with U937 cell microsomes at a low arachidonic acid concentration (0.1 μM), DFU inhibited COX-1 with an IC₅₀ value of 13±2 μM as compared to 20±1 nM for indomethacin. CGP 28238, etodolac and SC-58125 were about 10 times more potent inhibitors of COX-1 than DFU. The order of potency of various inhibitors was diclofenac>indomethacin∼naproxen>nimesulide∼ meloxicam∼piroxicam>NS-398∼SC-57666>SC-58125>CGP 28238∼etodolac>L-745,337>DFU.
7. DFU inhibited dose-dependently both the carrageenan-induced rat paw oedema (ED₅₀ of 1.1 mg kg⁻¹ vs 2.0 mg kg⁻¹ for indomethacin) and hyperalgesia (ED₅₀ of 0.95 mg kg⁻¹ vs 1.5 mg kg⁻¹ for indomethacin). The compound was also effective at reversing LPS-induced pyrexia in rats (ED₅₀=0.76 mg kg⁻¹ vs 1.1 mg kg⁻¹ for indomethacin).
8. In a sensitive model in which ⁵¹Cr faecal excretion was used to assess the integrity of the gastrointestinal tract in rats, no significant effect was detected after oral administration of DFU (100 mg kg⁻¹, b.i.d.) for 5 days, whereas chromium leakage was observed with lower doses of diclofenac (3 mg kg⁻¹), meloxicam (3 mg kg⁻¹) or etodolac (10–30 mg kg⁻¹). A 5 day administration of DFU in squirrel monkeys (100 mg kg⁻¹) did not affect chromium leakage in contrast to diclofenac (1 mg kg⁻¹) or naproxen (5 mg kg⁻¹).
9. The results indicate that COX-1 inhibitory effects can be detected for all selective COX-2 inhibitors tested by use of a sensitive assay at low substrate concentration. The novel inhibitor DFU shows the lowest inhibitory potency against COX-1, a consistent high selectivity of inhibition of COX-2 over COX-1 (>300 fold) with enzyme, whole cell and whole blood assays, with no detectable loss of integrity of the gastrointestinal tract at doses >200 fold higher than efficacious doses in models of inflammation, pyresis and hyperalgesia. These results provide further evidence that prostanoids derived from COX-1 activity are not important in acute inflammatory responses and that a high therapeutic index of anti-inflammatory effect to gastropathy can be achieved with a selective COX-2 inhibitor.

     

Development of gatifloxacin-loaded cationic polymeric nanoparticles for ocular drug delivery

The present investigation aimed at improving the ocular bioavailability of gatifloxacin by prolonging its residence time in the eye and reducing problems associated with the drug re-crystallization after application through incorporation into cationic polymeric nanoparticles. Gatifloxacin-loaded nanoparticles were prepared via the nanoprecipitation and double emulsion techniques. A 50:50 Eudragit® RL and RS mixture was used as cationic polymer with other formulation parameters varied. Prepared nanoparticles were evaluated for size, zeta potential, and drug loading. An optimized formulation was selected and further characterized for in vitro drug release, cytotoxicity, and antimicrobial activity. The double emulsion method produced larger nanoparticles than the nanoprecipitation method (410?nm and 68?nm, respectively). Surfactant choice also affected particle size and zeta potential with Tween 80 producing smaller-sized particles with higher zeta potential than PVA. However, the zeta potential was positive at all experimental conditions investigated. The optimal formulation produced by double emulsion technique and has achieved 46% drug loading. This formulation had optimal physicochemical properties with acceptable cytotoxicity results, and very prolonged release rate. The particles antimicrobial activities of the selected formulation have been tested against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and showed prolonged antimicrobial effect for gatifloxacin.     

Design,characterization, and evaluation of aceclofenac-loaded Eudragit RS 100 nanoparticulate system for ocular delivery

The aim of the present study was to develop and evaluate positively charged nanoparticles of aceclofenac for ocular delivery. The nanoparticles were prepared by the nanoprecipitation method using Eudragit RS 100. The optimized nanoparticles were found to have narrow particle size range (238.9?±?8?nm) with nearly spherical shape, positive zeta potential (40.3?±?3.8). Higher entrapment efficiency of aceclofenac (94.53?±?1.0%) with prolonged in vitro drug release profiles was also observed. Powder X-ray diffraction and differential scanning calorimetry studies indicated decrease in crystallinity of drug within the nanoparticulate polymeric matrix. The formulation was found to have higher permeation as compared to aceclofenac aqueous solution. Nanoparticle formulation was found to be quite stable and well tolerated with no signs of corneal damage. The in vivo studies involving the arachidonic acid-induced ocular inflammation in rabbits showed optimal efficacy of the nanoparticles with significantly higher inhibition of polymorphonuclear leukocytes migration (p?<?0.05) and lid closure scores.     

眼部的给药屏障和给药途径

近年来,眼部药物递送系统越来越受到重视,本文综述了目前眼部给药的主要屏障包括角膜、结膜屏障,血房水屏障、血视网膜屏障等,以及一些新的给药途径和给药方法如结膜下、巩膜给药和离子电渗疗法等。以环孢素A为例介绍了一些克服眼部屏障的给药方法。尽管眼部给药系统目前已取得了进展,但药物递送到眼的后段仍有较大的难度,需要进一步开发更有效的眼部药物递送系统。     

Novel cubosome based system for ocular delivery of acetazolamide

Acetazolamide is the drug of choice for glaucoma treatment in an emergency. However, it is not available in any topical formulation and it is available only as systemic tablets. Despite its efficiency as a drug in decreasing intraocular pressure, it has negative systemic effects as renal toxicity and metabolic acidosis. Moreover, it suffers from poor aqueous solubility and low corneal permeability limiting its ocular bioavailability and its use topically. Cubosomes have enormous advantages as a drug delivery system, most importantly, high surface area, thermal stability, and ability to encapsulate hydrophobic, amhiphilic, and hydrophilic molecules. Herein, we have exploited the unique properties of cubosomes as a novel nano-delivery system for acetazolamide as eye drops dosage form for glaucoma treatment. Different acetazolamide-loaded cubosomes have been developed and evaluated. The best-optimized formulation (F5), was cubic shaped structure, with an average particle size of 359.5 ± 2.8 nm, surface charge −10.8 ± 3.2 mV, and 59.8% entrapment efficiency. Ex-vivo corneal permeation studies have revealed a 4-fold increase in acetazolamide permeability coefficient compared to that stated in the literature. F5 showed superior therapeutic efficacy represented by a 38.22% maximum decrease in intraocular pressure vs. 31.14 and 21.99% decrease for the commercial Azopt^® eye drops and Cidamex^® tablets, respectively. It also exhibited higher (AUC_0–10) compared to Azopt^® eye drops and Cidamex^® tablets by 2.3 and 3 times, respectively. F5 showed mean residence time 4.22 h vs. 2.36 and 2.62 h for Azopt^® and Cidamex^® with no eye irritation observed according to the modified Draize test. To the best of our knowledge, this is the first study for developing acetazolamide-loaded cubosomes as the topical delivery system for glaucoma treatment.     

Chitosan nanoparticles for daptomycin delivery in ocular treatment of bacterial endophthalmitis

Abstract

Context: Chitosan nanoparticles were prepared to encapsulate daptomycin and proposed as a delivery system of this antibiotic to the eye for the treatment of bacterial endophthalmitis.

Objective: The aim of this study was to develop daptomycin-loaded nanoparticles to apply directly to the eye, as a possible non-invasive and less painful alternative for the treatment of endophthalmitis, increasing the effectiveness of treatment and reducing toxicity associated with systemic administration.

Materials and methods: Nanoparticles were obtained by ionotropic gelation between chitosan and sodium tripolyphosphate (TPP). Physicochemical and morphological characteristics of nanoparticles were evaluated, as well as determination of antimicrobial efficiency of encapsulated daptomycin and stability of the nanoparticles in the presence of lysozyme and mucin.

Results: Loaded nanoparticles presented mean particle sizes around 200?nm, low polydispersity index, and positive zeta potential. Morphological examination by scanning electron microscopy (SEM) confirmed their small size and round-shaped structure. Encapsulation efficiency ranged from 80 to 97%. Total in vitro release of daptomycin was obtained within 4?h. Determination of minimum inhibitory concentrations (MICs) showed that bacteria were still susceptible to daptomycin encapsulated into the nanoparticles. Incubation with lysozyme did not significantly affect the integrity of the nanoparticles, although mucin positively affected their mucoadhesive properties.

Discussion and conclusion: The obtained nanoparticles have suitable characteristics for ocular applications, arising as a promising solution for the topical administration of daptomycin to the eye.     

Cubosomes and other potential ocular drug delivery vehicles for macromolecular therapeutics

Introduction: Many macromolecular therapeutics designed to treat posterior segment eye diseases (PSEDs) are administered through frequent ocular injection, which can further deteriorate eye health. Due to the high frequency of injection and the high cost of the therapeutics, there is a need to develop new ways in which to deliver these therapeutics: ways which are both safer and more cost effective.

Areas covered: Using the most common PSED, age-related macular degeneration, as an example of a debilitating ocular disease, this review examines the key barriers limiting the delivery of macromolecular therapeutics to the posterior segment of the eye and defines the key requirements placed on particulate drug delivery vehicles (DDVs) to be suitable for this application. Recent developments in macromolecular drug delivery to treat this disease as well as the remaining shortcomings in its treatment are surveyed. Lastly, an emerging class of DDVs potentially suited to this application, called cubosomes, is introduced.

Expert opinion: Based on their excellent colloidal stability and high internal surface area, cubosomes hold great potential for the sustained release of therapeutics. Novel production methods and a better understanding of the mechanisms through which drug release from these particles can be controlled are two major recent developments toward successful application.     

Development and characterization of itraconazole-loaded solid lipid nanoparticles for ocular delivery

Abstract

The purpose of this study was to investigate the feasibility of entrapping water-insoluble drug itraconazole into solid lipid nanoparticles (SLNs) for topical ocular delivery. The drug-loaded SLNs were prepared from stearic acid and palmitic acid using different concentrations of polyvinyl alcohol employed as emulsifier. SLNs were prepared by the melt-emulsion sonication and low temperature-solidification method and characterized for particle size, zeta potential, drug loading and drug entrapment efficiency. The mean particle size of SLNs prepared with stearic acid ranged from 139 to 199?nm, while the SLNs prepared with palmitic acid had particle size in the range of 126–160?nm. The SLNs were spherical in shape. Stearic acid-SLNs showed higher entrapment of drug compared with palmitic acid-SLNs. Differential scanning calorimetry (DSC) and X-ray diffraction measurements showed decrease in crystallinity of drug in the SLN formulations. The modified Franz-diffusion cell and freshly excised goat corneas were used to test drug corneal permeability. Permeation of itraconazole from stearic acid-SLNs was higher than that obtained with palmitic acid-SLNs. The SLNs showed clear zone of inhibition against Aspergillus flavus indicating antimicrobial efficacy of formulations.     

COX-2抑制剂戊地昔布的合成

目的:合成COX-2抑制剂戊地昔布.方法:以苯乙酸为起始原料,经酰氯化、傅克酰化生成二苯乙酮后,与盐酸羟胺反应生成肟,再环合,磺化,氨化得戊地昔布.结果:得到的产品经IR,1H-NMR,MS和元素分析,证明是戊地昔布.结论:本合成路线简化了操作步骤,缩短反应时间,提高了收率.