Polyvinyl Alcohol/Chitosan Single-Layered and Polyvinyl Alcohol/Chitosan/Eudragit RL100 Multi-layered Electrospun Nanofibers as an Ocular Matrix for the Controlled Release of Ofloxacin: an In Vitro and In Vivo Evaluation.

A novel nanofiber insert was prepared with a modified electrospinning method to enhance the ocular residence time of ofloxacin (OFX) and to provide a sustained release pattern by covering hydrophilic polymers, chitosan/polyvinyl alcohol (CS/PVA) nanofibers, with a hydrophobic polymer, Eudragit RL100 in layers, and by glutaraldehyde (GA) cross-linking of CS-PVA nanofibers for the treatment of infectious conjunctivitis. The morphology of the prepared nanofibers was studied using scanning electron microscopy (SEM). The average fiber diameter was found to be 123 ± 23 nm for the single electrospun nanofiber with no cross-linking (OFX-O). The single nanofibers, cross-linked for 10 h with GA (OFX-OG), had an average fiber diameter of 159 ± 30 nm. The amount of OFX released from the nanofibers was measured in vitro and in vivo using UV spectroscopy and microbial assay methods against Staphylococcus aureus, respectively. The antimicrobial efficiency of OFX formulated in cross-linked and non-cross-linked nanofibers was affirmed by observing the inhibition zones of Staphylococcus aureus and Escherichia coli. In vivo studies using the OFX nanofibrous inserts on a rabbit eye confirmed a sustained release pattern for up to 96 h. It was found that the cross-linking of the nanofibers by GA vapor could reduce the burst release of OFX from OFX-loaded CS/PVA in one layer and multi-layered nanofibers. In vivo results showed that the AUC0-96 for the nanofibers was 9-20-folds higher compared to the OFX solution. This study thus demonstrates the potential of the nanofiber technology is being utilized to sustained drug release in ocular drug delivery systems.

Anti-Adherent Biomaterials for Prevention of Catheter Biofouling.

Medical device-associated infections present a leading global healthcare challenge, and effective strategies to prevent infections are urgently required. Herein, we present an innovative anti-adherent hydrogel copolymer as a candidate catheter coating with complementary hydrophobic drug-carrying and eluting capacities. The amphiphilic block copolymer, Poloxamer 188, was chemically-derivatized with methacryloyl moieties and copolymerized with the hydrogel monomer, 2-hydroxyethyl methacrylate. Performance of the synthesized copolymers was evaluated in terms of equilibrium swelling, surface water wettability, mechanical integrity, resistance to encrustation and bacterial adherence, and ability to control release of the loaded fluoroquinolone antibiotic, ofloxacin. The developed matrices were able to provide significant protection from fouling, with observed reductions of over 90% in both adherence of the common urinary pathogen Escherichia coli and encrusting crystalline deposits of calcium and magnesium salts relative to the commonly employed hydrogel, poly (hydroxyethyl methacrylate). Additionally, the release kinetics of a loaded hydrophobic drug could be readily tuned through facile manipulation of polymer composition. This combinatorial approach shows significant promise in the development of suitable systems for prevention of catheter-associated infections.

Co-Amorphous Formation of High-Dose Zwitterionic Compounds with Amino Acids To Improve Solubility and Enable Parenteral Delivery.

Solubilization of parenteral drugs is a high unmet need in both preclinical and clinical drug development. Recently, co-amorphous drug formulation has emerged as a new strategy to solubilize orally dosed drugs. The aim of the present study is to explore the feasibility of using the co-amorphous strategy to enable the dosing of parenteral zwitterionic drugs at a high concentration. A new screening procedure was established with solubility as the indicator for co-amorphous co-former selection, and lyophilization was established as the method for co-amorphous formulation preparation. Various amino acids were screened, and tryptophan was found to be the most powerful in improving the solubility of ofloxacin when lyophilized with ofloxacin at a 1:1 weight ratio, with more than 10 times solubility increase. X-ray powder diffraction showed complete amorphization of both components, and an elevated Tg compared with the theoretical value was observed in differential scanning calorimetry. Fourier transform infrared spectroscopy revealed that hydrogen bonding and π-π stacking were possibly involved in the formation of a co-amorphous system in the solid state. Further solution-state characterization revealed the involvement of ionic interactions and π-π stacking in maintaining a high concentration of ofloxacin in solution. Furthermore, co-amorphous ofloxacin/tryptophan at 1:1 weight ratio was both physically and chemically stable for at least 2 months at 40 °C/75% RH. Lastly, the same screening procedure was validated with two more zwitterionic compounds, showing its promise as a routine screening methodology to solubilize and enable the parenteral delivery of zwitterionic compounds.

Preclinical assessment of scleral lens as a reservoir-based ocular therapeutic system.

PURPOSE: Bacterial keratitis is a sight threatening infection of the cornea which remains one of the most important potential complications of contact lens use. If the corneal ulcer is small, peripheral with no impending perforation present, intensive monotherapy with fluoroquinolones could be used. Therefore, a study was conducted with the objective to provide pharmacological data of the intra-ocular diffusion after administration of Ofloxacin using a scleral lens reservoir, as well as an evaluation of surface tolerability in rabbits. MATERIALS AND METHODS: Samples of corneas, aqueous humor and vitreous were collected to measure the drug levels of Ofloxacin using High Performance Liquid Chromatography. The corneas were examined by electron microscopy scanning and the eyeballs by light polarizing microscopy in order to evaluate surface tolerability. RESULTS: Ofloxacin levels found in the aqueous humor and cornea were higher than those previously reported. The mean Ofloxacin corneal levels exceeded the MIC (Minimum Inhibitory Concentration) for which 90% of isolates are indicated for all bacteria implicated in keratitis. CONCLUSION: To our knowledge, this is the first preclinical study assessing local tolerance and intra-ocular diffusion of Ofloxacin after administration using a scleral lens reservoir.

A norepinephrine coated magnetic molecularly imprinted polymer for simultaneous multiple chiral recognition.

A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element for enantioselective recognition by microchip electrophoresis. In this work, molecularly imprinted polymers were facilely prepared employing Fe3O4 nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, the produced imprinted Fe3O4@polynorepinephrine (MIP-Fe3O4@PNE) NPs have cavities complementary to three dimensional shape of template molecules favoring high binding capacity and magnetism property for easy manipulation. The MIP-Fe3O4@PNE NPs prepared with l-tryptophan, l-valine, l-threonine, Gly-l-Phe, S-(-)-ofloxacin or S-(-)-binaphthol as template molecules were packed in the polydimethylsiloxane microchannel via magnetic field as novel stationary phase to successful enantioseparation of corresponding target analysts. The MIP-Fe3O4@PNE NPs-based microchip electrophoresis system exhibited strong recognition ability, excellent high-performance, admirable reproducibility and stability, which provided a powerful protocol for separation enantiomers within a short analytical time and opened up an avenue for multiplex chiral compound assay in various systems.

Preparation and in vitro-in vivo evaluation of ofloxacin loaded ophthalmic nano structured lipid carriers modified with chitosan oligosaccharide lactate for the treatment of bacterial keratitis.

The objective of this study was to explore the potential of the nanostructured lipid carriers (NLCs) modified with chitosan oligosaccharide lactate (COL) for topical ocular application. Ofloxacin (OFX) loaded NLCs were prepared by microemulsion or high shear homogenization methods. For combination of NLCs Compritol HD5 ATO was used as solid lipid, oleic acid as liquid lipid, Tween 80 as surfactant, ethanol as co-surfactant. The optimum NLCs was modified with 0.75% COL. The properties of NLCs in the absence or presence of OFX (0.3%) were characterized as zeta potential, particle size, viscosity and pH, TEM, drug loading, encapsulation efficiency and anti-microbial properties. Ex-vivo penetration/permeation studies were performed with rabbit cornea in Franz-diffusion cells. The penetration rate of OFX from NM-COL4OFX and NH-COL4OFX were significantly higher than commercial solution. Based on the selected formulations, in vivo tests were carried out by eye-drop instillation of NLCs in rabbit. The addition of COL improved the preocular residence time, controlled the drug release and enhanced the corneal bioavailability. In conclusion, OFX COL modified NLCs prepared by high shear homogenization method could be offered as a promising strategy for ocular drug delivery.

Enantioselective recognition mechanism of ofloxacin via Cu(II)-modulated DNA.

The specific interactions of Cu(2+) with self-complementary DNA sequences involving d[G4C4(GC)2G4C4], d[(GC)10], and d[(AT)10], as well as the chiral recognition mechanism of ofloxacin enantiomers via the Cu(II)-modulated DNAs, were investigated using characterizations of circular dichroism, gel electrophoresis, FT-IR spectroscopy, UV melting measurement, electron paramagnetic resonance, and HPLC. The Cu(II)-coordinated GC-rich DNAs exhibit amplified enantioselectivity toward the S-enantiomer of ofloxacin. Especially in the case of d[G4C4(GC)2G4C4], ofloxacin enantiomers intercalate into the two adjacent guanine bases through the minor groove mediated by Cu(2+), which leads to a more favorable binding between S-ofloxacin and DNA. The highest ee value of ofloxacin enantiomers in the permeate after being adsorbed by the Cu(II)-DNA complex is obtained as 49.2% in the R-enantiomer at the [Cu(2+)]/[base] molar ratio of 0.25, while at the [Cu(2+)]/[base] molar ratio of 0.05 the highest ee value of ofloxacin enantiomers in the retentate reaches 26.3% in the S-enantiomer. This work illustrates a novel promising route to construct DNA-based chiral selectors toward certain drug enantiomers through the programmable enantioselective recognition on the basis of DNA chirality and the specific binding of transition metal ions.

Preparation of gold nanoparticles using Salicornia brachiata plant extract and evaluation of catalytic and antibacterial activity.

The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

Co-sorption of ofloxacin and Cu(II) in soils before and after organic matter removal.

Various mechanisms play roles simultaneously for antibiotic sorption on solid particles. Previous studies simply emphasized mechanisms that match the increased or decreased antibiotic sorption by metal ions, without a general concept including these diverse mechanisms in their co-sorption. We observed both increased and decreased OFL and Cu(II) sorption in their co-sorption system. The comparison of the sorption coefficients of primary adsorbate (Kd(pri)) and co-adsorbate (Kd(co)) suggested that enhanced sorption occurred at high Kd(pri) region (low primary adsorbate concentration). Competitive sorption was observed when Kd(pri) was decreased to a certain value depending on solid particle properties. We thus summarized that if the adsorbates were introduced with low concentrations, OFL (such as hydrophobic region in solid particles) and Cu(II) (such as inner-sphere complexation sites) occupied their unique high-energy sorption sites. Cu(II) complexed with the adsorbed OFL, and OFL bridged by the adsorbed Cu(II) promoted the sorption for both chemicals. With the increased concentrations, the adsorbates spread to some common sorption sites with low sorption energy, such as cation exchange and electrostatic attraction region. The overlapping of Cu(II) and OFL on these sorption sites resulted in competitive sorption at high concentrations. The previously reported apparently increased or decreased sorption in antibiotic-metal ion co-sorption system may be only a part of the whole picture. Extended study on the turning point of decreased and increased sorption relating to water chemistry conditions and solid particle properties will provide more useful information to predict antibiotic-metal ion co-sorption.

Application of organogels as oral controlled release formulations of hydrophilic drugs.

We previously demonstrated that organogels prepared from soybean oil using 12-hydroxy stearic acid as a gelator can slowly release ibuprofen, a model lipophilic drug. In this study, we investigated the applicability of organogels as controlled release formulations of hydrophilic drugs. The release rates of theophylline and ofloxacin, which are used as model hydrophilic drugs, were significantly slower than those of ibuprofen and antipyrine (model lipophilic drugs). Furthermore, no erosion was noted during drug release from organogels. Lipophilic drug molecules are released after diffusion in organogels because all molecules fully dissolve in the gel. On the other hand, hydrophilic drug molecules need to be dissolved before they diffuse in the organogel, prior to their release from the gel. Therefore, it is speculated that the release rates of hydrophilic drugs are slower than those of lipophilic drugs. To confirm the usefulness of organogels in controlled release formulations in vivo, organogels containing ibuprofen, ofloxacin, theophylline or antipyrine were intraduodenally administered to rats. All drugs used in this study were rapidly absorbed when administered in aqueous suspensions. In contrast, the drug concentrations in plasma after administration in organogels were lower; however, the lower concentrations of drugs sustained for 10 h after administration. With organogel administration, the mean residence time of drugs was longer than that with aqueous suspension administration. In conclusion, organogels are potential candidates for controlled release formulations of not only lipophilic drugs, but also hydrophilic drugs.

A comparison between spray drying and spray freeze drying for dry powder inhaler formulation of drug-loaded lipid-polymer hybrid nanoparticles.

Lipid-polymer hybrid nanoparticles - polymeric nanoparticles enveloped by lipid layers - have emerged as a potent therapeutic nano-carrier alternative to liposomes and polymeric nanoparticles. Herein we perform comparative studies of employing spray drying (SD) and spray freeze drying (SFD) to produce inhalable dry-powder form of drug-loaded lipid-polymer hybrid nanoparticles. Poly(lactic-co-glycolic acid), lecithin, and levofloxacin are employed as the polymer, lipid, and drug models, respectively. The hybrid nanoparticles are transformed into micro-scale nanoparticle aggregates (or nano-aggregates) via SD and SFD, where the effects of (1) different excipients (i.e. mannitol, polyvinyl alcohol (PVA), and leucine), and (2) nanoparticle to excipient ratio on nano-aggregate characteristics (e.g. size, flowability, aqueous reconstitution, aerosolization efficiency) are examined. In both methods, PVA is found more effective than mannitol for aqueous reconstitution, whereas hydrophobic leucineis needed to achieve effective aerosolization as it reduces nano-aggregate agglomeration. Using PVA, both methods are equally capable of producing nano-aggregates having size, density, flowability, yield and reconstitutibility in the range ideal for inhaled delivery. Nevertheless, nano-aggregates produced by SFD are superior to SD in terms of their aerosolization efficiency manifested in the higher emitted dose and fine particle fraction with lower mass median aerodynamic diameter.

Competitive sorption and desorption behavior for three fluoroquinolone antibiotics in a wastewater treatment wetland soil.

Significant amounts of pharmaceuticals are discharged into the environment through wastewater effluent. Sorption has been shown to be a significant aqueous removal pathway for many of these compounds. Competition between ciprofloxacin (CIP), ofloxacin (OFL) and norfloxacin (NOR) and their sorption to, and desorption from, a surrogate Louisiana wastewater treatment wetland soil were investigated to gain insight into the fate and transport of the pollutants within wastewater treatment wetlands. This study was undertaken in the context of a treatment wetland that continuously receives pharmaceuticals. Therefore it is important to understand the total capacity of this soil to sorb these compounds. Sorption to this treatment wetland soil was found to provide a major and potentially long-term removal pathway for these antibiotics from wastewater. LogK(F) values for all three compounds were between 4.09 and 3.90 for sorption and 4.24 and 4.05 microg(1-1/)(n)(cm(3))(1/)(n)g(-1) for desorption. The compounds were sorbed in amounts ranging from 60% to 90% for high and low loading, respectively. The majority of the compounds were sorbed to the soil within the first 20h, indicating that treatment wetland may not need long retention times (weeks to months) in order to remove these compounds. Sorption K(D) values for competition (20 ppm of each compound for 60 ppm of total fluoroquinolones) ranged from 2300 to 3800 cm(3)g(-1) which is between both the 20 (4300-5800 cm(3)g(-1)) and 60 (1300-3000 cm(3)g(-1)) ppm single compound K(D) values, indicating that there is competition between these three compound for sorption sites. Sorption and desorption data (single component and mixture) collectively provide the following evidence: (1) NOR and, to a lesser extent, CIP outcompete OFL for sorption sites, (2) OFL sorbes to its share of "quality" sorption sites, and (3) competition only occurs for lesser "quality" binding sites.

Efficacy of fluoroquinolones against pathogenic oral bacteria.

This article reviews the characteristics of the main fluoroquinolones used in dentistry (ciprofloxacin, levofloxacin and moxifloxacin), including pharmacokinetic/ pharmacodynamic parameters, susceptibility profiles of oral bacteria and clinical trials on their efficacy in dental practice. It seems that some of these antibiotics might represent a safe alternative in patients with allergy, intolerance, or lack of response to beta-lactams.

Evaluation of Clostridium difficile-associated diarrhea with a drug formulary change in preferred fluoroquinolones.

BACKGROUND: Recent publications report that gatifloxacin might be associated with a greater incidence of Clostridium difficile-associated diarrhea (C. difficile, CDAD) than are other fluoroquinolones. We performed a drug use evaluation to examine this issue after adding gatifloxacin to the formulary and changing from levofloxacin to gatifloxacin as the preferred oral fluoroquinolone in 10 Department of Veterans Affairs (VA) medical centers in the northeastern United States. OBJECTIVES: To estimate (1) the overall incidence of CDAD before and after the change from levofloxacin to gatifloxacin as the preferred oral fluoroquinolone and (2) the incidence rates for ciprofloxacin, levofloxacin, and gatifloxacin separately. METHODS: Using the VA's Pharmacy Benefits Management database, the total number of days of antibiotic therapy was determined for all inpatients and outpatients of the 10 medical centers who filled at least 1 antibiotic prescription between July 1, 2003, and June 30, 2004. This time frame was chosen because it included 6 months before and 6 months after the change in the preferred oral fluoroquinolone from levofloxacin to gatifloxacin for the VA health system on January 1, 2004. For the same study period and medical centers, the electronic medical records of all inpatients and outpatients with an entry for a positive C. difficile toxin were reviewed. Positive toxins that occurred within 6 weeks of a previous positive result in the same patient were excluded. Exact Poisson tests were used to compare the incidence rates of CDAD (number of CDAD cases per 1,000 days of antibiotic treatment) for antibiotics overall, the fluoroquinolones as a group, non-fluoroquinolone antibiotics, and the individual fluoroquinolones, com-paring the 6-month time periods before (pre-change) versus after (post-change) the addition of gatifloxacin as the preferred oral fluoroquinolone. RESULTS: Of 505 cases of CDAD in the 12-month study period, 413 (81.7%) were associated with antibiotic use in the previous 6 weeks. Among anti-biotic users, incidence rates of CDAD were 166 per 72,114 days of antibiotic therapy in the pre-change period (2.3 cases per 1,000 days of antibiotics) versus 247 per 72,354 days in the post-change period (3.4 cases per 1,000 days of antibiotics, P < 0.001). Fluoroquinolones accounted for 54.8% of the CDAD cases in the pre-change period and 67.2% in the post-change period, representing a 22.6% relative increase in the percentage of CDAD cases that were associated with fluoroquinolone use. The CDAD incidence rates per 1,000 days of fluoroquinolone therapy were 3.7 in the pre-change period versus 7.0 in the post-change period (P < 0.001). Among fluoroqui-nolone users, gatifloxacin accounted for none of the cases of CDAD in the pre-change period when it was nonformulary and 65.1% of the cases in the post-change period, for an incidence rate of 7.6 (108 per 14,239 days). The CDAD incidence rates per 1,000 antibiotic days for patients treated with ciprofloxacin were 4.6 (24 per 5,260 days) in the pre-change period and 7.4 (40 per 5,429 days) in the post-change period, a nonsignificant trend (P = 0.079). The incidence rate of CDAD for levofloxacin increased significantly from 3.9 (75 per 19,417 days) in the pre-change period to 10.7 (44 per 4,108 days) in the post-change period (P < 0.001). The incidence rates of CDAD in the post-change period did not differ significantly for ciprofloxacin, levofloxacin, and gatifloxacin (P = 0.119). CONCLUSIONS: There was an increase in the incidence of CDAD among all antibiotic users and fluoroquinolone users, but not among users of non-fluoroquinolone antibiotics, in the period following the formulary change from levofloxacin to gatifloxacin as the preferred fluoroquinolone. However, rates of CDAD among the 3 fluoroquinolone antibiotics in the post-change period were not significantly different, and levofloxacin was the only fluoroquinolone that was associated with a significant increase in the rate of CDAD between the pre-change and post-change periods. These findings suggest that the increase in the CDAD incidence rate was probably not attributable to the addition of gatifloxacin to the formulary.

In vitro availability of ofloxacin in presence of metals essential to human body.

The significance of interaction between ofloxacin and metals ions was evaluated in this study. The absorption of ofloxacin can be negatively affected by concomitant administration of agents containing metal cations. Current studies examine alterations of ofloxacin availability by metal cations and is limited to conventional metal-containing agents such as antacids and mineral supplements. The in vitro availability of ofloxacin was studied in presence of metal ions as magnesium, calcium, chromium, manganese, ferric, ferrous, cobalt, nickel, copper, zinc and cadmium in their salt form in simulated gastric juice, buffers of pH 7.4 and 9 at 37 degrees C by using a modified B.P 2002 dissolution apparatus. UV/VIS (Shimadzu 1601) spectrophotometer was used to analyze the drug by measuring absorbance at 294 nm in simulated gastric juice and at 288 nm in pH 7.4 and 9. The result showed that availability of ofloxacin slightly changed in presence of all metals in all these dissolution mediums.

Sorption of the antibiotic ofloxacin to mesoporous and nonporous alumina and silica.

Mesoporous and nonporous SiO(2) and Al(2)O(3) adsorbents were reacted with the fluoroquinolone carboxylic acid ofloxacin over a range of pH values (2-10) and initial concentrations (0.03-8 mM) to investigate the effects of adsorbent type and intraparticle mesopores on adsorption/desorption. Maximum ofloxacin adsorption to SiO(2) surfaces occurs slightly below the pK(a2) (pH 8.28) of the antibiotic and sorption diminishes rapidly at pH>pK(a2). For Al(2)O(3), maximum sorption is observed at pH values slightly higher than the adsorbent's point of zero net charge (p.z.n.c.) and less than midway between the pK(a) values of ofloxacin. The effects of pH on adsorption and ATR-FTIR spectra suggest that the zwitterionic compound adsorbs to SiO(2) solids through the protonated N(4) in the piperazinyl group and, possibly, a cation bridge; whereas the antibiotic sorbs to Al(2)O(3) solids through the ketone and carboxylate functional groups via a ligand exchange mechanism. Sorption edge and isotherm experiments show that ofloxacin exhibits a higher affinity for mesoporous SiO(2) and nonporous Al(2)O(3), relative to their counterparts. It is hypothesized that decreased ofloxacin sorption to mesoporous Al(2)O(3) occurs due to electrostatic repulsion within pore confines. In contrast, it appears that the environment within SiO(2) mesopores promotes sorption by inducing formation of ofloxacin-Ca complexes, thus increasing electrostatic attraction to SiO(2) surfaces.

Photodegradation of some quinolones used as antimicrobial therapeutics.

The photostability of the fluoroquinolones ciprofloxacin (CPX), ofloxacin (OFX), and fleroxacin (FLX) toward ultraviolet irradiation (UVA) and room light was investigated in dilute aqueous solutions. A series of photoproducts was observed by high-performance liquid chromatography (HPLC) for all three drugs. As little as 1 h of exposure to room light was enough for the formation of detectable amounts of CPX photoproducts. The major CPX photoproduct was characterized as a dimer by liquid secondary ion mass spectrometry, but its structure was not determined. Since irradiation of CPX results (as cited in ref/11) in a loss of antibacterial activity and since all substances, parent drugs as well as their photoproducts, are potential candidates for undesired drug effects, quinolone drugs should be strictly protected from all light during storage and administration.