International Journal of Pharmaceutics (v.449, #1-2)
Editorial Board (iii).
Comparative study of Pluronic® F127-modified liposomes and chitosan-modified liposomes for mucus penetration and oral absorption of cyclosporine A in rats by Dan Chen; Dengning Xia; Xiuying Li; Quanlei Zhu; Hongzhen Yu; Chunliu Zhu; Yong Gan (1-9).
Liposomes modified using cationic and hydrophilic nonionic polymers are 2 popular carriers for improving oral drug absorption. Cationic polymer-modified liposomes can adhere to the intestinal wall mucus (mucoadhesive type), while liposomes modified using hydrophilic nonionic polymers can penetrate across the mucus barrier (mucus-penetrating type). Chitosan-modified liposomes (CS-Lip, mucoadhesive type) and Pluronic® F127-modified liposomes (PF127-Lip, mucus-penetrating type) were engineered to investigate the differences between these mucoadhesive and mucus-penetrating systems in oral absorption of a poorly soluble drug, cyclosporine A (CyA). Stability of CS-Lip and PF127-Lip was studied in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The intestinal mucus adhesion or penetration of liposomes was studied by confocal laser scanning microcopy and fluorophotometry using coumarin 6 as the fluorescent probe. The oral absorption of CyA-loaded liposomes was also studied in Sprague-Dawley rats. In vitro and in vivo studies revealed that CS-Lip tended to aggregate in SIF, to be trapped by mucus, to remain mainly in the upper portion of the intestinal tract, and to show limited penetration ability. In contrast, PF127-Lip were more stable in the SIF and SGF, were found throughout the intestinal tract, and were able to penetrate the mucus layers to reach the epithelial surface. Pharmacokinetic analysis in rats showed that the C max and AUC0–t of PF127-Lip were 1.73- and 1.84-fold higher than those of CS-Lip, respectively (P < 0.05). In conclusion, the stability and mucus-penetrating ability of PF127-Lip in the gastrointestinal tract rendered it more suitable than the mucoadhesive CS-Lip for oral delivery CyA.
Keywords: Mucus penetration; Oral absorption; Pluronic® F127; Chitosan; Liposomes; Cyclosporine A;
99mTc-labelled nanosystem as tumour imaging agent for SPECT and SPECT/CT modalities by András Polyák; István Hajdu; Magdolna Bodnár; György Trencsényi; Zita Pöstényi; Veronika Haász; Gergely Jánoki; Győző A. Jánoki; Lajos Balogh; János Borbély (10-17).
We report the synthesis, in vitro and in vivo investigation of folate-targeted, biocompatible, biodegradable self-assembled nanoparticles radiolabelled with 99mTc, as potential new SPECT or SPECT/CT imaging agent.Nanoparticles with hydrodynamic size in the range of 75–200 nm were prepared by self-assembly of chitosan and folated poly-γ-glutamic acid, and then radiolabelled with 99mTc. The nanoparticles target tumour cells overexpressing folate receptors and internalize specifically into them to realize early tumour diagnosis detected by SPECT and SPECT/CT modalities.Rat hepatocellular carcinoma cells were used as model system. Cell specificity and tumour targeting efficacy of these nanosystems were investigated in vitro, and in vivo using SPECT and fusion nanoSPECT/CT imaging. In vitro results showed that the radiolabeled nanosystem was efficiently internalized by tumour cells. Whole-body biodistribution of the new radiolabelled, folate-targeted nanoparticles revealed higher uptake in the tumorous kidney compared to the non-tumorous contralateral side. Uptake by the lungs and thyroids was negligible, which confirmed the stability of the nanoparticles in vivo.In vivo SPECT and SPECT/CT imaging visually reinforced the uptake results and were in accordance with the biodistribution data: the new nanoparticles as a targeted contrast agent improve tumour targeting and are able to detect folate-receptor-overexpressing tumours in animal models with enhanced contrast.
Keywords: Nanoparticles; Folate-targeted; Radiolabeled; Tc-99m; SPECT; SPECT/CT; In vivo;
Solution-mediated phase transformation of different roxithromycin solid-state forms: Implications on dissolution and solubility by Marique Aucamp; Nicole Stieger; Neil Barnard; Wilna Liebenberg (18-27).
The objective of this study was to describe the solid-state forms in which roxithromycin may exist and the significant influence of solution-mediated phase transformation on the dissolution and solubility behavior of these forms. Roxithromycin may exist as: Form I (monohydrate), Form II (amorphous), Form III (anhydrate) and a mixture of Forms I and III. Form III and Mixture I/III have not been reported previously, probably due to incomplete solid-state characterization or the use of a standard production method which consistently yielded the same solid-state form. Solution-mediated phase transformations of Forms II and III to the stable Form I were proved through dissolution studies and quantification of the phase proportions, as a function of time, utilizing XRPD. This study showed that pharmacopoeial identification methods for roxithromycin do not allow accurate identification of the different solid-state forms. The various forms differed significantly in terms of dissolution profiles, which could have a marked influence on bioavailability and performance of the final dosage form. It was demonstrated that solvent replacement, during dissolution testing, masks the characteristic profile usually obtained with a metastable form undergoing solution-mediated transformation. Finally, we propose that peak dissolution concentrations should be used to give a more exact indication of the aqueous solubility enhancement ratio obtained with metastable forms of APIs.
Keywords: Roxithromycin; Solution-mediated transformation; Amorphous; Thermodynamic solubility prediction;
Comparative anti-inflammatory activity of poly(amidoamine) (PAMAM) dendrimer–dexamethasone conjugates with dexamethasone-liposomes by Arpankumar Choksi; K.V.L. Sarojini; Prashant Vadnal; Charmaine Dias; P.K. Suresh; Jayant Khandare (28-36).
Nanocarrier systems (a) liposome and (b) PAMAM dendrimers.Lipophilicity vs hydrophicility physicochemical traits are extremely important variables that are active considerations for optimizing drug delivery systems. The comparative anti-inflammatory delivery potential of dexamethasone (dex) in an encapsulation-based (liposome–lipophilic) and poly (amidoamine) (PAMAM) dendrimer prodrug conjugation-based delivery systems (hydrophilic) was performed in this work. Dendrimer prodrug conjugates were characterized by 1H NMR. The drug encapsulation efficiency for drug in liposomes was observed to be 14.02% and this was correlated with a dose-dependent tumor necrosis factor (TNF)-α inhibition (39–57% inhibition). The biological evaluation of nanocarriers for drug was demonstrated in a standard, conventionally used in vitro cell-based system for TNF-α inhibition. This served as a comparative tool to demonstrate a quantitatively higher TNF-α inhibition (67–71.48%) produced by the dendrimer–dex drug conjugate. The structure activity relationship (dose-for-dose) was inferred by relatively lesser inhibition of TNF-α by variants of PAMAM G4 (NH2) dendrimer–dex conjugates and was compared with liposomes carrying dex. In vitro results suggest that the prodrug conjugates of PAMAM dendrimer deliver dex to be more efficient in comparison with liposome-based dex in terms of higher TNF-α inhibition. This study has implications in designing efficient prodrug nanocarrier systems for delivering dex.
Keywords: Dendrimer; Drug delivery; Nanodelivery; Dexamethasone; Anti-inflammatory; TNF-α inhibition;
Triggering effect of N-acetylglucosamine on retarded drug release from a lectin-anchored chitosan nanoparticles-in-microparticles system by Hui Li; Wen-feng Dong; Jian-yuan Zhou; Xi-ming Xu; Feng-qian Li (37-43).
The aim of this study was to investigate the use of N-acetylglucosamine (NAG) to accelerate drug release from a lectin-modified carrier. A wheat germ agglutinin (WGA)-anchored salmeterol xinafoate (SalX)-loaded nanoparticles-in-microparticles system (NiMS) was prepared with an ionotropic gelation technique combined with a spray drying method. The formulated microparticles were spherical, with diameters ranging mainly from 2 to 8 μm; the drug entrapment efficiency was >70% (w/w), and the loading capacity was approximately 8% (w/w). Drug release from WGA-SalX-NiMS, within the first 4 h, was approximately 30% less than that from SalX-NiMS, indicating an effect of lectin-modification to retard drug release from the NiMS. Due to “sugar–lectin” interactions, drug release from WGA-SalX-NiMS was substantially increased after the addition of NAG to the release medium. However, no significant influence of NAG was observed on the drug release profile of SalX-NiMS without WGA anchorage. The characteristics of NAG–WGA interaction may provide valuable insights into the “triggering-effects” of specific sugars on drug release from lectin-anchored carriers. These results suggest that it is possible to control drug release from a lectin-anchored drug delivery system using a specific sugar, and that the designed novel WGA-SalX-NiMS may be a suitable formulation for chronotherapy of asthma.
Keywords: Salmeterol xinafoate; Chitosan; Wheat germ agglutinin; Spray drying; Nanoparticles-in-microparticles system; N-acetylglucosamine;
Spray dried inhalable ciprofloxacin powder with improved aerosolisation and antimicrobial activity by Rihab Osman; Pei Lee Kan; Gehanne Awad; Nahed Mortada; Abd-Elhameed EL-Shamy; Oya Alpar (44-58).
Modulation of chitosan and dextran microparticles encapsulating high concentration of ciprofloxacin by co-spray drying with various surface modifiers. The surface modified particles showed enhanced aerosolisation properties, high antibacterial activity against resistant respiratory pathogens and safety on the lung epithelial cells.In this study, the spray drying technique was used to prepare ciprofloxacin microparticles (CFX-MPs) for pulmonary administration. By virtue of its amphoteric properties, CFX was dissolved in either a slightly alkaline or acidic solution depending on the used polymer. Dextran and chitosan were used to prepare the MPs and modify the release characteristics of the drug. Particle surface modification was done with either DPPC or PEG. The effects of the manufacturing and formulation parameters on the drug–polymer interactions were investigated by thermal analysis and infrared spectroscopy. CFX-MPs showed improved aerosolisation properties and the encapsulated drug possessed high antimicrobial activity against two of the common and resistant respiratory pathogens: Pseudomonas aeruginosa and Staphylococus aureus. MPs were safe on the lung epithelial cells. Modulation of particle characteristics and drug release was possible by altering not only the polymer but also the type of the acid from which the powders were spray dried. MPs prepared with glutamic and aspartic acids showed better characteristics than those prepared with acetic and hydrochloric acids. Dextran modified particles showed improved aerosolisation properties and safety on lung epithelial cells.
Keywords: Spray drying; Surface modifiers; Dextran; Inhalable microparticles; Antibacterial activity;
Controlling solid lipid nanoparticle adhesion by polyelectrolyte multilayer surface modifications by Jan Henrik Finke; Hannah Schmolke; C.-P. Klages; Christel C. Müller-Goymann (59-71).
This study addresses the tunability of polyelectrolyte multilayers (PEM) toward adsorption of solid lipid nanoparticles (SLN). In SLN production for pharmaceutical applications, repellence from production equipment is desired while targeted adsorption is necessary for the functionalization of surfaces.SLN containing triglyceride/phospholipid or wax matrices were exposed to different PEM (consisting of poly(allylamine hydrochloride) (PAH), poly(diallyldimethylammonium chloride), and poly(acrylic acid)). PEM varied regarding layer architecture and surface properties by means of deposition pH, top layer variation, PEGylation with poly(acrylic acid)-graft-poly(ethylene glycol) copolymer, and thermal crosslinking. FTIR-ATR and SEM revealed SLN adhesion depending on PEM composition. Particle adsorption was tunable toward attraction as well as repellence: PEGylated PEM displayed lowest adsorption while PEM capped with PAH provided the strongest attraction of particles.Examinations at elevated temperatures resembled production conditions of SLN where these are processed as emulsions. Crystalline triglyceride SLN displayed high anisometry and, consequently, a large specific surface area. These platelets were more adherend than spherical droplets from the same formulation as an emulsion. Wax-based nanoparticles showed spherical shape, both in crystalline and molten state. However, adsorption was fostered as the fluidity of the disperse phase increased upon melting. Additionally, coalescence of adsorbed droplets took place, further increasing adsorption.
Keywords: Solid lipid nanoparticles; Colloidal drug delivery system; Layer-by-layer (LbL) coating/polyelectrolyte multilayers (PEM); PEGylation; Particle adsorption; FTIR-ATR;
An impedance-based process analytical technology for monitoring the lyophilisation process by G. Smith; E. Polygalov; M.S. Arshad; T. Page; J. Taylor; I. Ermolina (72-83).
The aim of this work was to develop a minimally invasive, impedance spectroscopy method as a novel process analytical technology for monitoring the freeze drying process. This involved the application of planar electrodes, mounted externally to a conventional glass freeze-drying vial, coupled to a high-impedance analyser. The pseudo-relaxation process arising from the composite impedance of the glass wall and product interface was recorded over a frequency range 101–106 Hz for a surrogate formulation comprising 2.5% sucrose. Features of the process (i.e. the peak amplitude, C ″ peak and characteristic peak frequency, f peak) were monitored along with the product temperature data during the entire cycle. It was demonstrated that f peak is strongly coupled to the temperature of the product (through the dependence of the product temperature on the electrical resistance of the product) whereas C ″ peak is dependent on the extent of ice sublimation and hence can be used to measure the rate of drying and end point of primary drying. This feature provides a distinct advantage over thermocouple measurements which are restricted to end point detection only. The potential to predict the end point of a cycle from C ″ peak vs. time profiles is highlighted in this work.
Keywords: Freeze drying; Impedance spectroscopy; Process analytical technology for freeze drying; End of primary drying;
Medicated hydrogels of hyaluronic acid derivatives for use in orthopedic field by Giovanna Pitarresi; Fabio Salvatore Palumbo; Filippo Calascibetta; Calogero Fiorica; Mauro Di Stefano; Gaetano Giammona (84-94).
Physical hydrogels have been obtained from hyaluronic acid derivatized with polylactic acid in the presence or in the absence of polyethylene glycol chains. They have been extemporarily loaded with antibacterial agents, such as vancomycin and tobramycin. These medicated hydrogels have been used to coat titanium disks (chosen as simple model of orthopedic prosthesis) and in vitro studies in simulated physiological fluid have been performed as a function of time and for different drug loading and polymer concentration values. Sterilization process performed on the hydrogels does not change their rheological behavior and release properties as well as the chemical structure of starting copolymers. A preliminary test has been performed by coating with the hydrogel a prosthesis that has been inserted in a seat of a lyophilized human femur, to confirm the ability of the hydrogel to adhere to the prosthesis surface also after its insertion in the implant seat. Cell compatibility of obtained hydrogels has been confirmed in vitro by using human dermal fibroblasts chosen as a model cell line. Obtained results suggest the potential use of these hydrogels in the orthopedic field, in particular for the production of antibacterial coatings of prostheses for implant in the human or animal body in the prevention and/or treatment of post surgical infections.
Keywords: Hydrogel; Graft copolymer; Hyaluronic acid; Polylactic acid; Orthopedic prosthesis;
Determination of platinum drug release and liposome stability in human plasma by CE-ICP-MS by Tam T.T.N. Nguyen; Jesper Østergaard; Stefan Stürup; Bente Gammelgaard (95-102).
An in vitro method for simultaneous assessment of platinum release and liposome stability of liposomal formulations in human plasma is demonstrated. The development and assessment of the method was performed on a PEGylated liposomal formulation containing cisplatin. Complete separation of free cisplatin, encapsulated cisplatin and cisplatin bound to plasma components was achieved by capillary electrophoresis (CE) separation and simultaneous monitoring of phosphorous (phospholipid) and platinum (cisplatin) by inductively coupled plasma mass spectrometry (ICP-MS). The method allows assessment of the encapsulation efficiency of the formulation, the physical stability of liposomes as well as cisplatin leakage in human plasma. The method was applied for studying the disintegration of liposomes and the interactions of leaked cisplatin with plasma components. Triggered release of the drug into plasma by sonication was also demonstrated. Analysis of liposomal formulations with alternative phospholipid compositions containing oxaliplatin showed similar results. Thus, the present in vitro method is suitable for mimicking the in vivo drug release profile in human plasma after administration of liposomal platinum formulations to patients. This approach may be of use in early drug development as well as in quality control.
Keywords: CE-ICP-MS; In vitro release; Stability; Cisplatin; Liposomes; Human plasma;