Ciprofloxacin Loaded Bovine Serum Albumin Microspheres： Prepa-ration and Drug Release Characterization In Vitro

Ciprofloxacin loaded microspheres were prepared by spray drying technique, with bovine serum albumin as the natural biodegradable wall materials. The obtained microspheres, using aqueous system, were organic solvent-free. The diameters of the spherical microspheres were in the range of 1-5 1:4. The drug entrapment of microspheres, formulated with different ciprofloxacin/albumin ratios as 1:1, 1:2 and 1:4, were 46.93%, 32.96% and 20.56% (n=3). And the encapsulation efflciencies for ciprofloxacin during spray drying were higher than 90%. Thermal denaturation programs at different temperatures (100-120℃) for different time intervals (3-6-12 h) were further processed to stabilize the spray-dried microspheres. The higher the extent for thermal denaturation, the slower the rate of ciprofloxacin released from microspheres in vitro. So the release rate of ciprofloxacin from microspheres can be controlled by modifing the conditions of thermal denaturation.     

Plasticized Drug‐Loaded Melt Electrospun Polymer Mats: Characterization,Thermal Degradation,and Release Kinetics

Melt electrospinning (MES) was used to prepare fast dissolving fibrous drug delivery systems in the presence of plasticizers. This new method was found promising in the field of pharmaceutical formulation because it combines the advantages of melt extrusion and solvent‐based electrospinning. Lowering of the process temperature was performed using plasticizers in order to avoid undesired thermal degradation. Carvedilol (CAR), a poorly water‐soluble and thermal‐sensitive model drug, was introduced into an amorphous methacrylate terpolymer matrix, Eudragit® E, suitable for fiber formation. Three plasticizers (triacetin, Tween® 80, and polyethylene glycol 1500) were tested, all of which lowered the process temperature effectively. Scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and Raman microspectrometry investigations showed that crystalline CAR turned into an amorphous form during processing and preserved it for longer time. In vitro dissolution studies revealed ultrafast drug dissolution of the fibrous samples. According to the HPLC impurity tests, the reduced stability of CAR under conditions applied without plasticizer could be avoided using plasticizers, whereas storage tests also indicated the importance of optimizing the process parameters during MES. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1278–1287, 2014     

Fabrication of Hierarchical Polymeric Thin Films by Spin Coating Toward Production of Amorphous Solid Dispersion for Buccal Drug Delivery System: Preparation,Characterization, and In Vitro Release Investigations

The landscape of thin films is continuously evolving as an attractive self-administration mean to drive patient compliance. This work reports incorporation of drugs into various polymeric compositions using spin coating technology to screen amorphous solid dispersion film formation for buccal applications. Polarized light microscopy and differential scanning calorimetry were used for characterization. Physical stability was assessed after films storage at 0% RH/25°C for 6 months. Chlorpheniramine maleate, theophylline, and famotidine were used as model drugs and mixed with Opadry amb II^® or Kollicoat IR^®. Acryl-EZE II^® or Zein was also used as surface (design I) or surface and base polymers (design II). Of all the drug-Opadry combinations, only chlorpheniramine was amorphously dispersed up to 25% (w/w). In contrast, Kollicoat IR^® resulted in amorphous dispersions of all the tested drugs, suggesting that it has a better solubilization capacity. Drugs prepared in design II achieved higher in vitro release compared to respective design I, indicating that lower content of Acryl-EZE II^® or Zein can decrease drug release over 3 h. It has been also revealed that Zein could improve physical stability of the aged theophylline solid-dispersed films. Release kinetics of model drugs were satisfactory when described by first-order kinetics, facilitated through anomalous transport of both diffusion and polymer swelling.     

Bovine Serum Albumin–Loaded Pectinate Beads as Colonic Peptide Delivery System: Preparation and In Vitro Characterization

Objective of this study was to prepare a drug delivery system for therapeutic peptides that are degraded in the upper part of the gastrointestinal tract due to degradation activity of the enzymes. Delivering peptide to the colon in which enzymatic activity is low is next hope for absorption of these agents. Pectin, a naturally occurring water soluble polysaccharide, as a matrix for peptide delivery was studied. Degradation of pectin by the colonic enzymes makes it suitable for colon-specific delivery of drugs. Bovine serum albumin (BSA) was used as a model peptide. Calcium pectinate beads were prepared by extruding BSA-loaded pectin solution to an agitating calcium chloride solution, and gelled spheres were formed instantaneously by an ionotropic gelation reaction. The effect of several factors such as concentration of pectin, concentration of calcium chloride, and total drug loading on the pattern of drug release in the dissolution medium was studied. Prepared beads showed good resistance in the release medium. The entrapment efficiency of the beads was high (between 63% and 99%). Entrapment efficiency of BSA was reversely dependent to the amount of the drug loaded in the beads. The amount of BSA loaded on the beads affects pattern of drug release. The concentration of the pectin showed the highest impact on the rate of drug release. Presence of the pectiolytic enzymes facilitated the drug release from the beads.     

Gastrointestinal Responsive Polymeric Nanoparticles for Oral Delivery of Insulin: Optimized Preparation,Characterization, and In Vivo Evaluation

Gastrointestinal responsive polymeric nanospheres (NPs) based on hydroxypropyl methylcellulose phthalate were prepared using spontaneous emulsification solvent diffusion method for improved oral administration of insulin. The NPs prepared under optimized conditions have an encapsulation efficiency of 90% and a particle size of about 200 nm. In vitro drug release experiments demonstrated that the NPs exhibited a gradient release profile of loaded drug when the pH value gradually increased from 3.0 to 7.4. Enzyme resistance experiments showed that under simulated gastrointestinal conditions, the NPs protected more than 60% of the drug from being degraded by trypsin. The oral hypoglycemic experiments revealed that insulin-loaded NPs could significantly reduce blood glucose levels in diabetic rats with a relative bioavailability of 8.6%. Ex vivo imaging investigation of rat tissues showed that the drug-loaded NPs could promote the absorption of insulin in the ileum and colon. The work described here suggests that the gastrointestinal responsive polymeric NPs may be promising candidates for improving gastrointestinal tract delivery of hydrophilic biomacromolecules. Accordingly, the results indicated that hydroxypropyl methylcellulose phthalate NPs with gastrointestinal stimuli responsiveness could be a promising candidate for oral insulin delivery.     

Diffusion Modeling and In Vitro Release Kinetics Studies of Curcumin−Loaded Superparamagnetic Nanomicelles in Cancer Drug Delivery System

The purpose of this study was to investigate in vitro drug release kinetics and to develop diffusion model of curcumin loaded Pluronic F127/Oleic acid(OA)-Fe₃O₄ nanoparticles. The prepared superparamagnetic nanoparticles by co-precipitation technique were characterized by the average size, size distribution, crystallinity, colloidal stability and magnetic property. The release of curcumin was triggered by an acidic environment in pH 5.0 of phosphate buffer saline. Release data of various curcumin loading (15, 25 and 30 ppm) were fitted using non-linear first?order, second?order, Higuchi and Korsmeyer?Peppas model. All the curcumin release mechanism followed Korsmeyer?Peppas model with n values less than 0.45 indicating the Fickian diffusion of curcumin from the prepared nanomicelles. The dynamic of controlled drug release of dilute curcumin loading was well described by a combination of diffusion and first-order release rate. The corresponding diffusion coefficient and kinetic rate were 9.1 × 10^?7 cm²?min^?1 and 6.51 × 10^?7 min^?1, which were used as controlled release to achieve the desired curcumin constant release rate in the delivery system.     

Formulation and Characterization of Spray-Dried Powders Containing Vincristine-Liposomes for Pulmonary Delivery and Its Pharmacokinetic Evaluation From In Vitro and In Vivo

Vincristine (VCR) has been used in the treatment of lung cancer. To improve its efficacy, the designs of elevating lung exposure to drug and decreasing the clearance with extended time were brought out. Pulmonary delivery is regarded as a good choice in pulmonary diseases treatment. Spray-drying is a technology for the preparation of drugs that can be delivered to lung via a dry powder inhaler. The results showed an appropriate particle size and shape for the pulmonary delivery. The aerosol behaved a sustained-release profile while VCR solution released rapidly within 10 h. The antitumor activity was characterized by 3-(4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide assay, and half maximal inhibitory concentration values of VCR-liposomes spray-dried powder were 24.42 ± 1.88 nM and 55.28 ± 4.76 nM in MCF-7 and A549 cells, respectively. Compared with the free VCR, the aerosol performed better pharmacokinetic behavior: increased maximum concentration (630.8%) and systemic exposure (429.6%) and decreased elimination half-life (81.1%). The clearance was decreased by 83.2%. Comprehensively, the pulmonary delivery seemed to be a recommendable way to effectively treat the pulmonary disease.     

Liquid Crystalline Systems Based on Glyceryl Monooleate and Penetration Enhancers for Skin Delivery of Celecoxib: Characterization,In Vitro Drug Release,and In Vivo Studies

Celecoxib (CXB) is a widely used anti-inflammatory drug that also acts as a chemopreventive agent against several types of cancer, including skin cancer. As the long-term oral administration of CXB has been associated with severe side effects, the skin delivery of this drug represents a promising alternative for the treatment of skin inflammatory conditions and chemoprevention of skin cancer. We prepared and characterized liquid crystalline systems based on glyceryl monooleate and water containing penetration enhancers which were primarily designed to promote skin delivery of CXB. Analysis of their phase behavior revealed the formation of cubic and hexagonal phases depending on the systems' composition. The systems' structure and composition markedly affected the in vitro CXB release profile. Oleic acid reduced CXB release rate, but association oleic acid/propylene glycol increased the drug release rate. The developed systems significantly reduced inflammation in an aerosil-induced rat paw edema model. The systems' composition and liquid crystalline structure influenced their anti-inflammatory potency. Cubic phase systems containing oleic acid/propylene glycol association reduced edema in a sustained manner, indicating that they modulate CXB release and permeation. Our findings demonstrate that the developed liquid crystalline systems are potential carriers for the skin delivery of CXB.     

Diosmin Nanocrystal–Loaded Wafers for Treatment of Diabetic Ulcer: In Vitro and In Vivo Evaluation

This work aimed at loading of diosmin nanocrystals into alginate-based wafers for treatment of highly exuding diabetic ulcer in rats using topical route of administration. For this purpose, different formulation variables and preparation techniques to enhance the flexibility and adhesion properties of the prepared sodium alginate (SA) wafers were carried out. The prepared wafers were characterized regarding hydration capacity, bioadhesion, scanning electron microscope, and Fourier-transform infrared spectroscopy. Efficacy of treating diabetic ulcer was studied using diabetic-induced rat model using streptozotocin. Results obtained showed that using SA:gelatin with 1.5%/1.5% w/w gave acceptable wafers with a sustained release of diosmin over 8 h. A complete re-epithelialization, well-organized dermal layers, well-formed granulation tissue, and mature collagen bundles were observed in treated rats. It was concluded that combination of gelatin with SA provided an excellent wafer as a promising medicated wound dressing holding diosmin nanocrystals while maintaining its stability.     

Application of Box-Behnken Design in the Preparation,Optimization, and In Vitro Evaluation of Self-Assembly–Based Tamoxifen- and Doxorubicin-Loaded and Dual Drug–Loaded Niosomes for Combinatorial Breast Cancer Treatment

This study was developed with the objective to prepare self-assembled niosomes to support sufficient entrapment and sustained drug release of the drugs having different solubility and mechanisms. In the current work, Tamoxifen- and Doxorubicin-loaded niosomes were prepared for combinatorial breast cancer treatment with statistical optimization by Box-Behnken experimental design. Atomic force microscopy revealed a spherical shape morphology of the niosomes. The entrapment efficiencies for the drugs were found to be 74.3% and 72.7% for Tamoxifen and Doxorubicin, respectively. The drug release experiments at different pH values displayed a sustained release up to 3 days. Fourier transform infrared spectroscopy and differential scanning calorimetry showed a robust drug-excipient compatibility. The niosomes were stable over a period of 6 months with no significant changes. In vitro cytotoxicity studies on MCF-7 cell line showed a 15-fold improvement (0.01 μg per mL) and a better synergistic effect of the niosomes in comparison to the free drug combination (0.15 μg per mL). Moreover, the nanocarrier uptake studies by fluorescence microscopy and flow cytometry showed a good distribution and greater uptake of the niosomes throughout the cells. These results suggest a profound therapeutic application of the niosomes for a combinatorial breast cancer treatment.     

Preparation of Ibuprofen Microparticles by Antisolvent Precipitation Crystallization Technique: Characterization,Formulation, and In Vitro Performance

This study demonstrates the preparation and characterization of ibuprofen (IBP) microparticles with some excipients by a controlled crystallization technique with improved dissolution performance. Using the optimum concentrations pluronic F127, hydroxypropyl methyl cellulose, D-mannitol, and l-leucine in aqueous ethanol, the IBP microparticles were prepared. The dissolution tests were performed in phosphate buffer saline using a United States Pharmacopoeia dissolution tester at 37°C. The Raman spectroscopy was used to investigate the interactions and distribution of the IBP with the additives in the microcrystals. The prepared IBP microparticles showed higher dissolution compared to that of the smaller sized original IBP particles. The Raman data revealed that the excipients with a large number of hydroxyl groups distributed around the IBP particle in the crystal enhanced the dissolution of the drug by increasing the drug-solvent interaction presumably through hydrogen bonding. The Raman mapping technique gave an insight into the enhanced dissolution behavior of the prepared IBP microparticles, and such information will be useful for developing pharmaceutical formulations of hydrophobic drugs. The controlled crystallization was a useful technique to prepare complex crystals of IBP microparticles along with other additives to achieve the enhanced dissolution profile.     

Thermosensitive PEG–PCL–PEG Hydrogel Controlled Drug Delivery System: Sol–Gel–Sol Transition and In Vitro Drug Release Study

In this article, biodegradable and low molecular weight poly(ethylene glycol)–poly(ε-caprolactone)–poly(ethylene glycol) (PEG–PCL–PEG, PECE) triblock copolymers were successfully synthesized. Aqueous solution of the obtained PECE copolymers underwent sol–gel–sol transition as temperature increased which was flowing sol at room temperature and then turned into nonflowing gel at body temperature. Sol–gel–sol phase transition behaviors of aqueous PECE solutions were studied using rheometry and test tube-inverting method, which were affected by many factors, including the heating/cooling procedure and different additives in copolymers aqueous solution. In vitro drug release behavior was studied using bovine serum albumin (BSA) and Vitamin B₁₂ (VB₁₂) as model drugs, and the PECE hydrogel could protect BSA from acidic degradation for 1 week at least. Therefore, PECE hydrogel is believed to be promising for injectable in situ gel-forming controlled drug delivery system due to their great thermosensitivity and biodegradability. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3707–3717, 2009     

In Vitro Evaluation of Reversible and Irreversible Cytochrome P450 Inhibition: Current Status on Methodologies and their Utility for Predicting Drug–Drug Interactions

It is widely accepted that today's practice of polypharmacy inevitably increases the incidence of drug-drug interactions (DDIs). Serious DDI is a major liability for any new chemical entity (NCE) entering the pharmaceutical market. As such, pharmaceutical companies employ various strategies to avoid problematic compounds for clinical development. A key cause for DDIs is the inhibition of cytochrome P450 enzymes (CYPs) that are responsible for metabolic clearance of many drugs. Screening for inhibition potency of CYPs by NCEs has therefore become a routine practice during the drug discovery stage. However, in order to make proper use of DDI data, an understanding of the strengths and weaknesses of the various experimental systems in current use is required. An illustrated review of experimental practices is presented with discussion of likely future developments. The combination of high quality in vitro data generation and the application of in vivo CYP inhibition modelling approaches should allow more informed decisions to be made in the search for drug molecules with acceptable DDI characteristics.     

Solid Lipid Particles for Oral Delivery of Peptide and Protein Drugs III — the Effect of Fed State Conditions on the In Vitro Release and Degradation of Desmopressin

The effect of food intake on the release and degradation of peptide drugs from solid lipid particles is unknown and was therefore investigated in vitro using different fed state media in a lipolysis model. Desmopressin was used as a model peptide and incorporated into solid lipid particles consisting of trimyristin (TG14), tripalmitin (TG16), and tristearin (TG18), respectively. Fasted state and fed state media with varying phospholipid and bile salt concentrations, as well as fed state media with milk and oleic acid glycerides, respectively, were used as the release media. The presence of oleic acid glycerides accelerated the release of desmopressin significantly from all solid lipid particles both in the presence and absence of lipase. The presence of oleic acid glycerides also reduced the degradation rate of desmopressin, probably due to the interactions between the lipids and the protease or desmopressin. Addition of a medium chain triglyceride, trilaurin, in combination with drug-loaded lipid particles diminished the food effect on the TG18 particles, and trilaurin is therefore proposed to be a suitable excipient for reduction of the food effect. Overall, the present study shows that strategies to reduce food effect, such as adding trilaurin, for lipid particle formulations should be considered as drug release from such formulations might be influenced by the presence of food in the gastrointestinal tract.     

Coating Solid Dispersions on Microneedles via a Molten Dip‐Coating Method: Development and In Vitro Evaluation for Transdermal Delivery of a Water‐Insoluble Drug

This study demonstrates for the first time the ability to coat solid dispersions on microneedles as a means to deliver water‐insoluble drugs through the skin. Polyethylene glycol (PEG) was selected as the hydrophilic matrix, and lidocaine base was selected as the model hydrophobic drug to create the solid dispersion. First, thermal characterization and viscosity measurements of the PEG–lidocaine mixture at different mass fractions were performed. The results show that lidocaine can remain stable at temperatures up to ∼130°C and that viscosity of the PEG–lidocaine molten solution increases as the mass fraction of lidocaine decreases. Differential scanning calorimetry demonstrated that at lidocaine mass fraction less than or equal to 50%, lidocaine is well dispersed in the PEG–lidocaine mixture. Uniform coatings were obtained on microneedle surfaces. In vitro dissolution studies in porcine skin showed that microneedles coated with PEG–lidocaine dispersions resulted in significantly higher delivery of lidocaine in just 3 min compared with 1 h topical application of 0.15 g EMLA®, a commercial lidocaine–prilocaine cream. In conclusion, the molten coating process we introduce here offers a practical approach to coat water‐insoluble drugs on microneedles for transdermal delivery. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3621–3630, 2014     

Drug–Drug Interaction Potential of Marketed Oncology Drugs: In Vitro Assessment of Time-Dependent Cytochrome P450 Inhibition, Reactive Metabolite Formation and Drug–Drug Interaction Prediction

Purpose

To evaluate 26 marketed oncology drugs for time-dependent inhibition (TDI) of cytochrome P450 (CYP) enzymes. Evaluate TDI-positive drugs for potential to generate reactive intermediates. Assess clinical drug–drug interaction (DDI) risk using static mechanistic models.

Methods

Human liver microsomes and CYP-specific probes were used to assess TDI in a dilution shift assay followed by generation of K_I and k_inact. Reactive metabolite trapping studies were performed with stable label probes. Static mechanistic model was used to predict DDI risk using a 1.25-fold AUC increase as a cut-off for positive DDI.

Results

Negative TDI across CYPs was observed for 13/26 drugs; the rest were time-dependent inhibitors of, predominantly, CYP3A. The k_inact/K_I ratios for 11 kinase inhibitors ranged from 0.7 to 42.2 ml/min/μmol. Stable label trapping agent–drug conjugates were observed for ten kinase inhibitors. DDI predictions gave no false negatives, one true negative, four false positives and three true positives. The magnitude of DDI was overestimated irrespective of the inhibitor concentration selected.

Conclusions

13/26 oncology drugs investigated showed TDI potential towards CYP3A, formation of reactive metabolites was also observed. An industry standard static mechanistic model gave no false negative predictions but did not capture the modest clinical DDI potential of kinase inhibitors.     

In Vitro Drug Absorption Models. II. Salicylate,Cefoxitin, α-Methyldopa and Theophylline Uptake in Cells and Rings: Correlation with In Vivo Bioavailability

Isolated mucosal cells and everted intestinal rings have been examined as potential in vitro models for intestinal drug absorption. The uptake of salicylate, cefoxitin, -methyldopa and theophylline was characterized on the basis of time, concentration and temperature dependence and compared to in vivo drug absorption. Theophylline was well absorbed in all systems. Biochemical studies supported a passive transport mechanism, although a significant temperature dependence was observed. Salicylate, cefoxitin and -methyldopa demonstrated time- and concentration-dependent absorption. The uptake of -methyldopa was temperature-dependent in both the isolated cell and ring studies. With all drugs, cellular uptake exhibited greater variability than drug accumulation in rings. A comparison of in vitro and in vivo absorption demonstrated a good correlation between the data from in vivo studies and intestinal rings. Cellular drug uptake did not completely mimic that observed in vivo. On the basis of technical aspects of preparation, reproducibility of results, and correlation with in vivo drug bioavailability, everted intestinal rings were judged to be the best in vitro model for intestinal drug absorption.     

Polyamide Nanocapsules and Nano-emulsions Containing Parsol? MCX and Parsol? 1789: In Vitro Release, Ex Vivo Skin Penetration and Photo-Stability Studies

Purpose  

To prepare polyamide nanocapsules for skin photo-protection, encapsulating α-tocopherol, Parsol?MCX (ethylhexyl methoxycinnamate) and/or Parsol?1789 (butyl methoxydibenzoylmethane).