Pharmaceutical Research (v.27, #1)
Liquid Perfluorocarbons as Contrast Agents for Ultrasonography and 19F-MRI by Raquel Díaz-López; Nicolas Tsapis; Elias Fattal (1-16).
Perfluorocarbons (PFCs) are fluorinated compounds that have been used for many years in clinics mainly as gas/oxygen carriers and for liquid ventilation. Besides this main application, PFCs have also been tested as contrast agents for ultrasonography and magnetic resonance imaging since the end of the 1970s. However, most of the PFCs applied as contrast agents for imaging were gaseous. This class of PFCs has been recently substituted by liquid PFCs as ultrasound contrast agents. Additionally, liquid PFCs are being tested as contrast agents for 19F magnetic resonance imaging (MRI), to yield dual contrast agents for both ultrasonography and 19F MRI. This review focuses on the development and applications of the different contrast agents containing liquid perfluorocarbons for ultrasonography and/or MRI: large and small size emulsions (i.e. nanoemulsions) and nanocapsules.
Keywords: emulsions; liquid perfluorocarbons; MRI; nanocapsules; nanoemulsions; ultrasonography; ultrasound contrast agents
N 1,N 12 -Diacyl Spermines: SAR Studies on Non-viral Lipopolyamine Vectors for Plasmid DNA and siRNA Formulation by Hassan M. Ghonaim; Shi Li; Ian S. Blagbrough (17-29).
To study the efficiency of novel synthetic N 1,N 12-diacyl spermines on DNA and siRNA binding, and to compare their transfection efficiency with viability in cell lines.Five long chain N 1,N 12-diacyl lipopolyamines: N 1,N 12-[didecanoyl, dimyristoyl, dimyristoleoyl, distearoyl and dioleoyl]-1,12-diamino-4,9-diazadodecane were synthesized from the naturally occurring polyamine spermine. Their abilities to condense DNA and to form nanoparticles were characterized. Transfection efficiencies were studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with N 4,N 9-regioisomers. Also, the abilities of these novel compounds to bind to siRNA-forming nanoparticles were studied using a RiboGreen intercalation assay, and their abilities to deliver fluorescein-tagged siRNA into cells were quantified and compared with TransIT-TKO.By incorporating two long aliphatic chains and varying their acylation position, length, and oxidation state in a stepwise manner, we show efficient p and siRNA formulation and delivery to primary skin and cancer cell lines. Although two C14 chains (both saturated or both mono-cis-unsaturated) were efficient transfecting agents, they were highly toxic. N 1,N 12-Dioleoyl spermine efficiently binds to and delivers pDNA and siRNA with high cell viability even in a primary skin cell line. It is a novel, efficient non-viral vector in the presence of serum.
Keywords: gene delivery; primary skin cells; siRNA delivery; transfection; TransIT-TKO
Assessment of Nasal Spray Deposition Pattern in a Silicone Human Nose Model Using a Color-Based Method by Vipra Kundoor; Richard N. Dalby (30-36).
To develop a simple and inexpensive method to visualize and quantify droplet deposition patterns.Deposition pattern was determined by uniformly coating the nose model with Sar-Gel® (a paste that changes from white to purple on contact with water) and subsequently discharging sprays into the nose model. The color change was captured using a digital camera and analyzed using Adobe® Photoshop. Several tests were conducted to validate the method. Deposition patterns of different nasal sprays (Ayr, Afrin, and Zicam) and different nasal drug delivery devices (Afrin nasal spray and PARI Sinustar nasal nebulizer) were compared. We also used the method to evaluate the effect of inhaled flow rate on nasal spray deposition.There was a significant difference in the deposition area for Ayr, Afrin, and Zicam. The deposition areas of Afrin nasal spray and PARI Sinustar nasal nebulizer (2 min and 5 min) were significantly different. Inhaled flow rate did not have a significant effect on the deposition pattern.Lower viscosity formulations (Ayr, Afrin) provided greater coverage than the higher viscosity formulation (Zicam). The nebulizer covered a greater surface area than the spray pump we evaluated. Aerosol deposition in the nose model was not affected by air flow conditions.
Keywords: air flow; bioequivalence; deposition pattern; formulation; nasal spray; spray pattern
Factors Affecting the Stability of Nanoemulsions—Use of Artificial Neural Networks by Amir Amani; Peter York; Henry Chrystyn; Brian J. Clark (37-45).
The aim of this study was to identify the dominant factors affecting the stability of nanoemulsions, using artificial neural networks (ANNs).A nanoemulsion preparation of budesonide containing polysorbate 80, ethanol, medium chain triglycerides and saline solution was designed, and the particle size of samples with various compositions, prepared using different rates and amounts of applied ultrasonic energy, was measured 30 min and 30 days after preparation. Using ANNs, data were modelled and assessed. The derived predictive model was validated statistically and then used to determine the effect of different formulation and processing input variables on particle size growth of the nanoemulsion preparation as an indicator of the preparation stability.The results indicated that the data can be satisfactorily modelled using ANNs, while showing a high degree of complexity between the dominant factors affecting the stability of the preparation.The total amount of applied energy and concentration of ethanol were found to be the dominant factors controlling the particle size growth.
Keywords: artificial neural networks; budesonide; microemulsion; nanoemulsion; particle size; stability
The Targeting Behavior of Folate-Nanohydrogel Evaluated by Near Infrared Imaging System in Tumor-Bearing Mouse Model by Jian Zhang; Dawei Deng; Zhiyu Qian; Fei Liu; Xinyang Chen; Lianxiao An; Yueqing Gu (46-55).
To synthesize P[(Folate-Allylamine)-co-(N-isopropylacrylamine)- co-Acrylamide] (P(FoAAn-co-NIPA-AAm), folate-NHG) with appropriate diameter and lower critical solution temperature (LCST) for targeting to folate receptor (FR) expressing tumors.Folate-NHG was synthesized by free-radical precipitation polymerization method reported in our previous work and other reports. LCST, diameter and morphology of folate-NHG were characterized by UV-vis spectrophotometer, laser particle size analyzer (LPSA) and transmission electron microscope (TEM), respectively. No.12 near infrared dye (NIRD-12) was entrapped into folate-NHG by hydrophobic association to trace the in vivo dynamic behavior of folate-NHG. This process was evaluated by a homemade near infrared (NIR) imaging system.Spherical folate-NHG with diameter of about 50 nm and LCST of about 40°C was successfully synthesized. The photo stability of NIRD-12 was strengthened after being entrapped into folate-NHG, which enabled NIRD-12 to better trace the in vivo dynamic process of folate-NHG. Folate-NHG showed good targeting capability for all three folate receptor expressing tumor models (SMMC-7721, Bel-7402 and HeLa) with different sizes, and this accumulation could last for more than 96 h. D-folate-NHG, synthesized with double amount of FoAAn, showed better targeting effect for SMMC-7721 tumor model than that of folate-NHG.Folate-NHG could actively accumulate in three models of folate receptor positive tumors with different sizes and keep retention for more than 96 h, which enables it to be used as a diagnostic reagent or anti-tumor drug carrier for tumor therapy.
Keywords: active targeting; folate receptor; nanohydrogel; NIR imaging; tumor
Local Delivery of Ferrociphenol Lipid Nanocapsules Followed by External Radiotherapy as a Synergistic Treatment Against Intracranial 9L Glioma Xenograft by Emilie Allard; Delphine Jarnet; Anne Vessières; Sandrine Vinchon-Petit; Gérard Jaouen; Jean-Pierre Benoit; Catherine Passirani (56-64).
The goal of the present study was to evaluate the efficacy of a new organometallic drug, ferrociphenol (Fc-diOH), in combination with external radiotherapy in intracerebral 9L glioma model. We tested the hypothesis that the combination of external radiotherapy with Fc-diOH could potentiate the action of this drug.9L cells were treated with Fc-diOH-LNCs (from 0.01 to 1 µmol/L) and irradiated with external radiotherapy (from 2 to 40 Gy). In vivo assessment was evaluated by the inoculation of 9L cells in Fisher rats. Chemotherapy with Fc-diOH-LNCs (0.36 mg/rat) was administered by means of convection-enhanced delivery (CED), and the treatment was followed by three irradiations of 6 Gy doses (total dose = 18 Gy). In vitro evaluations evidenced that a combined treatment with Fc-diOH-LNCs and irradiations showed synergistic antitumor activity on 9L cells. Combining cerebral irradiation with CED of Fc-diOH-LNCs led to a significantly longer survival and the existence of long-term survivors compared to Fc-diOH-LNCs-treated animals (p < 0.0001) and to the group treated with blank LNCs + radiotherapy (p = 0.0079).The synergistic effect between ferrociphenol-loaded LNCs and radiotherapy was due to a closely oxidative relationship. Upon these considerations, Fc-diOH-LNCs appear to be an efficient radiosensitive anticancer drug delivery system.
Keywords: convection-enhanced delivery; glioma; iron; lipid nanocapsules; radiotherapy
Cross-Interaction Chromatography: A Rapid Method to Identify Highly Soluble Monoclonal Antibody Candidates by Steven A. Jacobs; Sheng-Jiun Wu; Yiqing Feng; Deidra Bethea; Karyn T. O’Neil (65-71).
To develop a high-throughput cross-interaction chromatography screening method to rapidly identify antibody candidates with poor solubility using microgram quantities of purified material.A specific recombinant antibody or bulk polyclonal IgG purified from human serum was chemically coupled to an NHS-activated chromatography resin. The retention times of numerous monoclonal antibodies were determined on this resin using an HPLC and compared to the solubility of each antibody estimated by ultrafiltration.Retention times of the antibodies tested were found to be inversely related to solubility, with antibodies prone to precipitate at low concentrations in PBS being retained longer on the columns with broader peaks. The technique was successfully used to screen microgram quantities of a panel of therapeutic antibodies to identify candidates with low solubility in PBS.The cross-interaction chromatography methods described can be used to screen large panels of recombinant antibodies in order to discover those with low solubility. Addition of this tool to the array of tools available for characterization of affinity and activity of antibody therapeutic candidates will improve selection of candidates with biophysical properties favorable to development of high concentration antibody formulations.
Keywords: aggregation; cross-interaction chromatography; monoclonal antibody; protein solubility
The Application of Electrostatic Dry Powder Deposition Technology to Coat Drug-Eluting Stents by Ravi Kumar Nukala; Harikrishna Boyapally; Ian J. Slipper; Andy P. Mendham; Dennis Douroumis (72-81).
A novel methodology has been introduced to effectively coat intravascular stents with sirolimus-loaded polymeric microparticles.Dry powders of the microparticulate formulation, consisting of non-erodible polymers, were produced by a supercritical, aerosol, solvent extraction system (ASES). A design of experiment (DOE) approach was conducted on the independent variables, such as organic/CO2 phase volume ratio, polymer weight and stirring-rate, while regression analysis was utilized to interpret the influence of all operational parameters on the dependent variable of particle size. The dry powders, so formed, entered an electric field created by corona charging and were sprayed on the earthed metal stent. Furthermore, the thermal stability of sirolimus was investigated to define the optimum conditions for fusion to the metal surfaces.The electrostatic dry powder deposition technology (EDPDT) was used on the metal strut followed by fusion to produce uniform, reproducible and accurate coatings. The coated stents exhibited sustained release profiles over 25 days, similar to commercial products. EDPDT-coated stents displayed significant reduced platelet adhesion.EDPDT appeared to be a robust accurate and reproducible technology to coat eluting stents.
Keywords: coating; drug eluting stents; electrostatic deposition; platelet adhesion; supercritical fluids
Using Polymer Chemistry to Modulate the Delivery of Neurotrophic Factors from Degradable Microspheres: Delivery of BDNF by James P. Bertram; Millicent F. Rauch; Kaliq Chang; Erin B. Lavik (82-91).
Brain-derived neurotrophic factor (BDNF) plays an important role in neuroprotection and repair, but long-term delivery from polymer systems has been challenging. We investigated the role the chemistry of the polymer played in loading and delivery of BDNF via microspheres, which are suitable for minimally invasive administration.We synthesized polymers based on PLGA and PEG to determine what components augmented loading and delivery. We characterized microspheres fabricated from these polymers using a battery of tests, including sizing, in vitro release, and bioactivity of the BDNF using PC12 cells engineered to express the trkB receptor.We found that a triblock polymer of PLGA, PLL, and PEG led to the delivery of BDNF for periods of time greater than 60 days and that the BDNF delivered was bioactive. The microsphere size was amendable to injection via a 30 gauge needle, allowing minimally invasive delivery.PLGA-PLL-PEG leads to greater loading and longer-term delivery of BDNF than PLGA or a blend of the polymers. We hypothesize that the introduction of an amphiphilic PLGA-based polymer increases the interaction of the BDNF with the polymer and leads to release that more closely correlates with the degradation of the polymer.
Keywords: BDNF; PEG; PLGA; microparticle; microsphere
Bioequivalence Tests Based on Individual Estimates Using Non-compartmental or Model-Based Analyses: Evaluation of Estimates of Sample Means and Type I Error for Different Designs by Anne Dubois; Sandro Gsteiger; Etienne Pigeolet; France Mentré (92-104).
The main objective of this work is to compare the standard bioequivalence tests based on individual estimates of the area under the curve and the maximal concentration obtained by non-compartmental analysis (NCA) to those based on individual empirical Bayes estimates (EBE) obtained by nonlinear mixed effects models.We evaluate by simulation the precision of sample means estimates and the type I error of bioequivalence tests for both approaches. Crossover trials are simulated under H 0 using different numbers of subjects (N) and of samples per subject (n). We simulate concentration-time profiles with different variability settings for the between-subject and within-subject variabilities and for the variance of the residual error.Bioequivalence tests based on NCA show satisfactory properties with low and high variabilities, except when the residual error is high, which leads to a very poor type I error, or when n is small, which leads to biased estimates. Tests based on EBE lead to an increase of the type I error, when the shrinkage is above 20%, which occurs notably when NCA fails.For small n or data with high residual error, tests based on a global data analysis should be considered instead of those based on individual estimates.
Keywords: bioequivalence tests; non-compartmental analysis; nonlinear mixed effects model; pharmacokinetics; SAEM algorithm
A Novel Gastro-Retentive Osmotic Pump Capsule Using Asymmetric Membrane Technology: In Vitro and In Vivo Evaluation by Jin Guan; Liying Zhou; Yusheng Pan; Haitao Han; Hongtao Xu; Weisan Pan (105-114).
The purpose of this paper is to develop a novel gastro-retentive osmotic pump capsule using asymmetric membrane technology.The physical characteristics of capsule walls and drug delivery behaviors of the system were compared through different coating solutions. The formulation with the glycerin and diethyl phthalate ratio of 5:4 appears to be the best. The thickness of asymmetric membranes was evaluated by withdrawing speed. The relation between the two can be fitted to a linear model. The floating abilities were investigated through filling polyethylene oxide of different molecular weight into the capsules. WSR N-80 (molecular weight 200000) is chosen for the longest floating time. Central composite design-response surface methodology was used to investigate the influence of factors on the responses. The in vivo pharmacokinetics were studied in beagle dogs.A second-order polynomial equation was fitted to the data, and the actual response values are in good accordance with the predicted ones. The optimized formulation displays a complete drug delivery, zero-order release rate and 12 h floating time. The in vivo study results clearly indicate the controlled and sustained release of Famotidine from the system, and the relative bioavailability of this preparation is about 1.605 in comparison to that of the marketed preparation.
Keywords: asymmetric membrane; central composite design; famotidine; gastro-retentive osmotic pump capsule; pharmacokinetic study
Efficiency of Fatty Acids as Chemical Penetration Enhancers: Mechanisms and Structure Enhancement Relationship by Sarah A. Ibrahim; S. Kevin Li (115-125).
The present study evaluated the effects of fatty acids commonly present in cosmetic and topical formulations on permeation enhancement across human epidermal membrane (HEM) lipoidal pathway when the fatty acids saturated the SC lipid domain without cosolvents (Emax).HEM was treated with neat fatty acids or fatty acid suspensions to determine Emax. A volatile solvent system was used to deposit fatty acids on HEM surface to compare fatty acid enhancer efficiency in topical volatile formulations with Emax. To elucidate permeation enhancement mechanism(s), estradiol (E2β) uptake into fatty acid-treated SC lipid domain was determined. Emax of fatty acids was shown to increase with their octanol solubilities and decrease with their lipophilicities, similar to our previous findings with other enhancers. Emax of solid fatty acids was shown to depend on their melting points, an important parameter to the effectiveness of the enhancers. The E2β uptake results suggest that enhancer-induced permeation enhancement across HEM is related to enhanced permeant partitioning into the SC lipid domain.The results suggest Emax as a model for studying the permeation enhancement effect of the fatty acids and their structure enhancement relationship.
Keywords: chemical penetration enhancers; corticosterone; Emax ; estradiol; fatty acids; skin
Positively-Charged, Porous, Polysaccharide Nanoparticles Loaded with Anionic Molecules Behave as ‘Stealth’ Cationic Nanocarriers by Archibald Paillard; Catherine Passirani; Patrick Saulnier; Maya Kroubi; Emmanuel Garcion; Jean-Pierre Benoît; Didier Betbeder (126-133).
Stealth nanoparticles are generally obtained after modifying their surface with hydrophilic polymers, such as PEG. In this study, we analysed the effect of a phospholipid (DG) or protein (BSA) inclusion in porous cationic polysaccharide (NP+) on their physico-chemical structure and the effect on complement activation.NP+s were characterised in terms of size, zeta potential (ζ) and static light scattering (SLS). Complement consumption was assessed in normal human serum (NHS) by measuring the residual haemolytic capacity of the complement system.DG loading did not change their size or ζ, whereas progressive BSA loading lightly decreased their ζ. An electrophoretic mobility analysis study showed the presence of two differently-charged sublayers at the NP+ surface which are not affected by DG loading. Complement system activation, studied via a CH50 test, was suppressed by DG or BSA loading. We also demonstrated that NP+s could be loaded by a polyanionic molecule, such as BSA, after their preliminary filling by a hydrophobic molecule, such as DG.These nanoparticles are able to absorb large amounts of phospholipids or proteins without change in their size or zeta potential. Complement studies showed that stealth behaviour is observed when they are loaded and saturated either with anionic phospholipid or proteins.
Keywords: haemolytic CH50 test; nanomedicine; phospholipid; protein; ‘soft’ electrophoresis
Mathematical Model to Predict Skin Concentration of Drugs: Toward Utilization of Silicone Membrane to Predict Skin Concentration of Drugs as an Animal Testing Alternative by Kenji Sugibayashi; Hiroaki Todo; Takeshi Oshizaka; Yoko Owada (134-142).
To calculate the skin concentration of active ingredients in cosmetics and topical pharmaceuticals using silicone membrane permeation.A series of parabens were used as model ingredients. Skin concentration of parabens was calculated using silicone membrane permeability. Their partition coefficient from formulations to the silicone membrane was determined by the membrane permeation profiles, and used to calculate their silicone membrane concentration, under an assumption that the membrane is one homogenous diffusion layer. The same procedure was applied for hairless rat skin.The calculated concentration of parabens in silicone membrane was very close to their observed values. However, the skin concentration calculated by skin permeability was not similar to the observed concentration. Re-calculation was performed under the assumption that the skin consists of two diffusion layers. This modification using permeation data through full-thickness and stripped skin enabled precise prediction of the skin concentration of parabens. In addition, the partition coefficient to the silicone membrane was useful to estimate their skin concentration.Ingredient concentration in skin can be precisely predicted using diffusion equations and partition coefficients through permeation experiments using a silicone membrane. The calculated in-skin concentration is useful for formulation studies of cosmetics and topical pharmaceuticals.
Keywords: hairless rat skin; membrane permeation; paraben; silicone membrane; skin concentration
The Pharmacokinetics of the Weakly Protein-Bound Anionic Compound Diatrizoate in Serum and Synovial Fluid of the Horse by Anna Buus Frost; Frank Larsen; Susan Weng Larsen; Jesper Østergaard; Maj Halling Thomsen; Stefan Stürup; Pia Haubro Andersen; Claus Larsen (143-150).
To establish a pharmacokinetic model for the model drug, sodium diatrizoate (DTZ), allowing joint disappearance kinetics to be estimated from serum appearance kinetics following intra-articular administration, and to calculate the relative joint exposure after intravenous and intra-articular DTZ administration (Fiv/IA).Each of five horses received an aqueous solution of 3.9 mg/kg sodium diatrizoate both intravenously and intra-articularly separated by a one-week wash out period. Serum and synovial samples were collected over 7 h and analyzed for content of model compound using inductively coupled plasma mass spectrometry.Differential equations were used for describing the transport of DTZ between the joint and the central compartment. The three-compartment lag-time model obtained demonstrates that the rate of drug appearance in the systemic circulation equals the rate of disappearance from the joint compartment. Following intravenous and intra-articular administration, an average Fiv/IA of 0.04% (n = 4) was calculated based on the synovial fluid profiles of DTZ.This study implies that aspects of the intra-articular fate of DTZ can be obtained from serum data in case synovial fluid samplings are limited, for various possible reasons. The low Fiv/IA may stimulate future research in the field of intra-articular administration of anti-osteoarthritic drugs.
Keywords: disappearance kinetics; intra-articular administration; pharmacokinetics
Inhalable Antibiotic Delivery Using a Dry Powder Co-delivering Recombinant Deoxyribonuclease and Ciprofloxacin for Treatment of Cystic Fibrosis by Yan Yang; Michael D. Tsifansky; Chia-Jung Wu; Hae In Yang; Gudrun Schmidt; Yoon Yeo (151-160).
To achieve efficient antibiotic delivery to the cystic fibrosis (CF) airway using a single inhalable powder co-encapsulating a mucolytic and an antibiotic.Inhalable dry powders containing deoxyribonuclease and/or ciprofloxacin (DNase, Cipro, and DNase/Cipro powders) were produced by spray-drying with dipalmitylphosphatidylcholine, albumin, and lactose as excipients, and their antibacterial effects were evaluated using the artificial sputum model.All powders showed mass median aerodynamic diameters below 5 µm. Both drugs were loaded in the dry powders without loss in quantity and activity. Dry powders containing DNase significantly decreased the storage modulus of the artificial sputum medium in less than 30 min. When applied to artificial sputum laden with Pseudomonas aeruginosa, Cipro/DNase powder showed better antibacterial activity than Cipro powder. The higher activity of the Cipro/DNase powder is attributable to the mucolytic activity of DNase, which promotes penetration of the dry powder into the artificial sputum and efficient dissolution and diffusion of ciprofloxacin.Inhalational delivery of antibiotics to the CF airway can be optimized when the sputum barrier is concomitantly addressed. Co-delivery of antibiotics and DNase using an inhalable particle system may be a promising strategy for local antipseudomonal therapy in the CF airway.
Keywords: artificial sputum; co-delivery; cystic fibrosis; DNase; inhalable dry powder
PEGylated PAMAM Dendrimer-Doxorubicin Conjugates: In Vitro Evaluation and In Vivo Tumor Accumulation by Saijie Zhu; Minghuang Hong; Lihong Zhang; Guotao Tang; Yanyan Jiang; Yuanying Pei (161-174).
To investigate the effects of PEGylation degree and drug conjugation style on the in vitro and in vivo behavior of PEGylated polyamidoamine (PAMAM) dendrimers-based drug delivery system.Doxorubicin (DOX) was conjugated to differently PEGylated PAMAM dendrimers by acid-sensitive cis-aconityl linkage and acid-insensitive succinic linkage to produce the products of PPCD and PPSD conjugates, respectively. In vitro evaluations including pH-dependent DOX release, cytotoxicity, cellular uptake, cell internalization mechanism, and intracellular localization were performed. Tumor accumulation was also visualized by in vivo fluorescence imaging.DOX release from PPCD conjugates followed an acid-triggered manner and increased with increasing PEGylation degree. In vitro cytotoxicity of PPCD conjugates against ovarian cancer (SKOV-3) cells increased, while cellular uptake decreased with increasing PEGylation degree. PPSD conjugates released negligible drug at any tested pH condition and were less cytotoxic. The conjugates were internalized by SKOV-3 cells via clathrin-mediated and adsorptive endocytosis, and were delivered to acidic lysosomes where DOX was released from PPCD conjugates and diffused into the nuclei. PPCD conjugates with highest PEGylation degree showed the highest tumor accumulation in mice inoculated with SKOV-3 cells.The obtained results suggested that PPCD conjugates with highest PEGylation degree would be a potential candidate for solid tumor treatment.
Keywords: acid-sensitive linkage; cellular uptake; doxorubicin; poly(amidoamine) dendrimer; poly(ethylene glycol)
The Interaction Between the Oropharyngeal Geometry and Aerosols via Pressurised Metered Dose Inhalers by T. Ehtezazi; I. Saleem; I. Shrubb; D. R. Allanson; I. D. Jenkinson; C. O’Callaghan (175-186).
This study investigated the effect of oropharyngeal geometry on inhaled aerosol characteristics via pressurised metered dose inhalers (pMDIs), both with or without spacers.Seven adult oropharyngeal models with different centreline lengths, total volumes, and degrees of constriction were employed as induction ports for a laser diffraction particle size analyser and cascade impactor. Particle size change over time, mass median aerodynamic diameter (MMAD), average median volume diameter (DV50), inhaled doses, and oropharyngeal depositions (percentage of the nominal dose) for aerosols via suspension and ultrafine pMDIs with or without spacers at 30 l/min airflow were determined.Variations in oropharyngeal geometry caused significant variations in inhaled particle size distributions, doses, oropharyngeal drug depositions, and particle size change over time when pMDIs were used without spacers. However, inhaled aerosol characteristics had marginal variations for the ultrafine pMDI plus large volume spacer (MMAD range: 0.69–0.78 µm, DV50 range: 1.27–1.36 µm, inhaled dose range: 46.46–52.92%). It was found that the amounts of inhaled aerosol particles with aerodynamic size of less than 0.83 µm via pMDIs plus large volume spacer were slightly affected by the oropharyngeal geometry.Inhaling ultrafine aerosols via spacers may reduce the effect of oropharyngeal geometry on inhaled aerosol properties.
Keywords: acute asthma exacerbations; inter-subject inhaled dose variability; oropharyngeal models; pressurised metered dose inhalers; ultrafine aerosols
Porphyrin and Galactosyl Conjugated Micelles for Targeting Photodynamic Therapy by De-Qun Wu; Ze-Yong Li; Cao Li; Jian-Jun Fan; Bo Lu; Cong Chang; Si-Xue Cheng; Xian-Zheng Zhang; Ren-Xi Zhuo (187-199).
To study the targeting and photodynamic therapy efficiency of porphyrin and galactosyl conjugated micelles based on amphiphilic copolymer galactosyl and mono-aminoporphyrin (APP) incoporated poly(2-aminoethyl methacrylate)-polycaprolactone (Gal-APP-PAEMA-PCL).Poly(2-aminoethyl methacrylate)-polycaprolactone (PAEMA-PCL) was synthesized by the combination of ring opening polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization, and then Gal-APP-PAEMA-PCL was obtained after conjugation of lactobionic acid and 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (APP) to PAEMA-PCL. The chemical structures of the copolymers were characterized, and their biological properties were evaluated in human laryngeal carcinoma (HEp2) and human hepatocellular liver carcinoma (HepG2) cells.Both APP-PAEMA-PCL and Gal-APP-PAEMA-PCL did not exhibit dark cytotoxicity to HEp2 cells and HepG2 cells. However, Gal-APP-PAEMA-PCL was taken up selectively by HepG2 cells and had the higher phototoxicity effect. Both polymers preferentially localized within cellular vesicles that correlated to the lysosomes.The results indicated that porphyrin and galactosyl conjugated polymer micelles exhibited higher targeting and photodynamic therapy efficacy in HepG2 cells than in HEp2 cells.
Keywords: drug delivery; galactosyl micelle; phototoxicity; porphyrin
Preclinical Evaluation of Linear HPMA-Doxorubicin Conjugates with pH-Sensitive Drug Release: Efficacy, Safety, and Immunomodulating Activity in Murine Model by Milada Sirova; Tomas Mrkvan; Tomas Etrych; Petr Chytil; Pavel Rossmann; Marketa Ibrahimova; Lubomir Kovar; Karel Ulbrich; Blanka Rihova (200-208).
In vivo efficacy and safety of HPMA-based copolymers armed with doxorubicin via a spacer containing pH-sensitive linkage that can be prepared within a broad range of attached drug contents (1) was tested in murine tumor models.Mice bearing T cell lymphoma EL4 or B cell lymphoma 38C13 were treated with a single dose of the conjugate (15, 25, and 75 mg Dox eq./kg i.v.) in a therapeutic regime. Anti-tumor resistance of the cured animals was proved by a second challenge with a lethal dose of tumor cells without additional treatment.The content of drug bound to the polymer is an important parameter in relation to the conjugate therapeutic efficacy. The best anti-tumor effects were produced by conjugates with 10 – 13 wt% of bound doxorubicin. Free doxorubicin up to 4.6% relative to total drug content had no impact on the treatment efficacy and acute toxicity. The conjugates induced a complete cure of mice and regular treatment-dependent development of specific anti-tumor resistance. No myelosuppression or organ damage was observed.A well-defined HPMA copolymer-doxorubicin conjugate with pH-sensitive drug release is a good candidate for clinical trials as it has remarkable anti-tumor efficacy and a favorable safety profile.
Keywords: doxorubicin; immunomodulation; murine lymphoma; N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugate; tumor resistance