International Journal of Pharmaceutics (v.470, #1-2)

Display OmittedThe efficacy of the combined chemo–photothermal therapy, using a mesoporous silica-coated gold nanorods loaded DOX (pGNRs@mSiO2-DOX), was consistently tested both in vitro and in vivo. The prepared nanoparticles that were characterized using transmission electron microscopy (TEM), UV–vis absorption spectroscopy and zeta potential showed high doxorubicin loading capacity in addition to its pH-responsive release. The pGNRs@mSiO2-DOX photo-heat conversion characteristic found to be stable for several repeated NIR irradiated doses was tested in simulated body fluid. In vitro results showed that pGNRs@mSiO2-DOX causes a significant damage in breast cancer cell line MCF-7 compared to free DOX. Contrary to this, it showed low toxicity to human amnion wish cells compared to CTAB coated GNRs and free DOX. In vivo results showed that intravenous administration of pGNRs@mSiO2-DOX (1.7 mg/kg) markedly suppresses the growth of subcutaneous Ehrlich carcinoma in female Balb mice (p  < 0.0001). Consistently, histopathological examination revealed a complete loss of tumor cellular details for mice that received the combined treatment. Based on the obtained results, this passively targeted pGNRs@mSiO2-DOX could specifically deliver drug and excessive local heat to tumor sites achieving high combined therapeutic efficacy.
Keywords: Gold nanorods; Mesoporous silica; Combined chemo–photothermal therapy; Drug delivery; pH responsive drug release; MCF-7 cell line;

In-line monitoring of pellet coating thickness growth by means of visual imaging by Nika Oman Kadunc; Rok Šibanc; Rok Dreu; Boštjan Likar; Dejan Tomaževič (8-14).
Display OmittedCoating thickness is the most important attribute of coated pharmaceutical pellets as it directly affects release profiles and stability of the drug. Quality control of the coating process of pharmaceutical pellets is thus of utmost importance for assuring the desired end product characteristics. A visual imaging technique is presented and examined as a process analytic technology (PAT) tool for noninvasive continuous in-line and real time monitoring of coating thickness of pharmaceutical pellets during the coating process. Images of pellets were acquired during the coating process through an observation window of a Wurster coating apparatus. Image analysis methods were developed for fast and accurate determination of pellets’ coating thickness during a coating process. The accuracy of the results for pellet coating thickness growth obtained in real time was evaluated through comparison with an off-line reference method and a good agreement was found. Information about the inter-pellet coating uniformity was gained from further statistical analysis of the measured pellet size distributions. Accuracy and performance analysis of the proposed method showed that visual imaging is feasible as a PAT tool for in-line and real time monitoring of the coating process of pharmaceutical pellets.
Keywords: Coating thickness; Pellets; PAT; Fluid-bed coating; Visual imaging; Quality assurance;

New classification of directly compressible (DC) excipients in function of the SeDeM Diagarm Expert System by Josep M. Suñé-Negre; Manel Roig; Roser Fuster; Carmen Hernández; Ramon Ruhí; Encarna García-Montoya; Pilar Pérez-Lozano; Montserrat Miñarro; Josep R. Ticó (15-27).
As a methodology for characterizing substances with regard to its viability in direct compression, the SeDeM Diagram Expert System may be considered a new tool in terms of the number of parameters applied and its optimization.The paper is based on the experimental SeDeM characterization study of 51 directly compressible (DC) excipients. After selecting the parameters, and comparing the corresponding results, the choices available within the SeDeM Expert System could be expanded. Through applied variants, the maximum and optimal values of the DC diluent excipient were precisely defined and the mathematical limits of the parameters, functions and parametric indices that define the level of direct compressibility were established.These studies have allowed us to propose a new classification of excipients CD based on its rheological and compressibility capability, resulting in a periodic table of CD excipients. It has been determined that the best excipient for direct compression should have an index of good compression (IGC) of 8.832.
Keywords: SeDeM; Direct compression (DC); Tablet excipient; Optimal DC excipient; Tablet preformulation; Good compression index (IGC);

Display OmittedUsing second generation mucoadhesives may enhance targeting antibiotics for eradication of Helicobacter pylori from the stomach for the treatment of peptic ulcer. The aim of this research was to prepare and characterise ethylcellulose/chitosan microspheres containing clarithromycin with their surfaces functionalised with concanavalin A to produce a floating-mucoadhesive formulation. The microspheres were prepared using an emulsification-solvent evaporation method. Particle size, surface morphology, in vitro buoyancy profile, zeta potential, drug entrapment efficiency, in vitro drug release and release kinetics of the particles were determined. Lectin was conjugated to the microsphere surface using two-stage carbodiimide activation and confirmed using FTIR, fluorescence studies and zeta potential measurements. Conjugation ranged from 11 to 15 μg Con A/mg microspheres which represents over 56% efficiency although there was some drug loss during the conjugation process. Conjugation did not have a significant effect on the buoyancy and release of drug from the microspheres using a mucus diffusion model with 53% and 40% of drug released from unconjugated and conjugated microspheres within 12 h. Conjugation improved mucoadhesion and interaction with porcine gastric mucin compared to unconjugated microspheres. The buoyancy and improved mucoadhesion of the microspheres provides potential for delivery of clarithromycin and other drugs to the stomach.
Keywords: Helicobacter pylori; Microspheres; Ethylcelluose; Chitosan; Concanavalin A; Mucoadhesive;

Stability study of full-length antibody (anti-TNF alpha) loaded PLGA microspheres by S. Marquette; C. Peerboom; A. Yates; L. Denis; I. Langer; K. Amighi; J. Goole (41-50).
Display OmittedAntibodies (Abs) require the development of stable formulations and specific delivery strategies given their susceptibility to a variety of physical and chemical degradation pathways. In this study, the encapsulation of an antibody into polylactide-co-glycolide (PLGA) based microspheres was explored to obtain a controlled-release of the incorporated drug. In order to avoid stability issues, a solid-in-oil-in-water (s/o/w) method was preferred. The solid phase was made of anti-TNF alpha monoclonal antibody (MAb) spray-dried microparticles, and the PLGA microspheres were produced using two different polymers (i.e., Resomer® RG505 and Resomer® RG755S). The stability of the MAb incorporated into the microspheres was investigated under three conditions (5 ± 3 °C, 25 ± 2 °C/60% RH and 40 ± 2 °C/75% RH) for 12 weeks. During this stability study, it was demonstrated that the MAb loaded PLGA microspheres were stable when stored at 5 ± 3 °C and that the Resomer® RG755S, composed of 75% (w/w) lactic acid as PLGA, was preferred to preserve the stability of the system.Storage at temperatures higher than 5 °C led to antibody stability issues such as aggregation, fragmentation and loss of activity. The release profiles were also altered. Physical ageing of the system associated with changes in the glass transition temperature and enthalpy of relaxation was noticed during the storage of the MAb loaded PLGA microspheres.
Keywords: Microspheres; Encapsulation; Antibody; PLGA; Stability;

Synthesis, characterization and mechanistic-insight into the anti-proliferative potential of PLGA-gemcitabine conjugate by Vaibhav Khare; Smit Kour; Noor Alam; Ravindra Dharr Dubey; Ankit Saneja; Mytre Koul; Ajai Prakash Gupta; Deepika Singh; Shashank K. Singh; Ajit K. Saxena; Prem N. Gupta (51-62).
Display OmittedGemcitabine, a nucleoside analogue, is used in the treatment of various solid tumors, however, its efficacy is limited by rapid metabolism by cytidine deaminase and fast kidney excretion. In this study, a polymeric conjugate of gemcitabine was prepared by covalent coupling with poly(lactic-co-glycolic) acid (PLGA), in order to improve anticancer efficacy of the drug. The prepared conjugate was characterized by various analytical techniques including FTIR, NMR and mass spectroscopic analysis. The stability study indicated that the polymeric conjugate was more stable in plasma as compared to native gemcitabine. Further, in vitro cytotoxicity determined in a panel of cell lines including pancreatic cancer (MIAPaCa-2), breast cancer (MCF-7) and colon cancer (HCT-116), indicated that the cytotoxic activity of gemcitabine was retained following conjugation with polymeric carrier. In the nucleoside transportation inhibition assay, it was found that the prepared conjugate was not dependent on nucleoside transporter for entering into the cells and this, in turn, reflecting potential implication of this conjugate in the therapy of transporter- deficient resistance cancer. Further, the cell cycle analysis showed that the sub-G1 (G0) apoptotic population was 46.6% and 60.6% for gemcitabine and PLGA gemcitabine conjugate, respectively. The conjugate produced remarkable decrease in mitochondrial membrane potential, a marker of apoptosis. In addition, there was a marked increase in PARP cleavage and P-H2AX expression with PLGA gemcitabine conjugate as compared to native gemcitabine indicating improved apoptotic activity. The findings demonstrated the potential of PLGA gemcitabine conjugate to improve clinical outcome of gemcitabine based chemotherapy of cancer.
Keywords: Gemcitabine; PLGA; Apoptosis; Cytotoxicity; Polymer drug conjugate;

Comparison of different failure tests for pharmaceutical tablets: Applicability of the Drucker–Prager failure criterion by Vincent Mazel; Harona Diarra; Virginie Busignies; Pierre Tchoreloff (63-69).
Display OmittedSeveral tests can be used to study the strength of pharmaceutical tablets. Equations exist in the literature to transform the failure force measured into a failure stress which can be considered as a characteristic of the strength of the material. For each failure test, the stress state at failure is different, and as a consequence, the failure stresses obtained are also different. It would thus be interesting to find a failure criterion to unify the different results. In this study four different tests were performed on pharmaceutical compacts of various densities: diametral compression, three-point flexure, biaxial flexure and uniaxial compressive tests. The Drucker–Prager criterion was tested as a possible fracture envelope. The results showed that this criterion is well suited to explain the failures obtained by diametral compression, three-point flexure and biaxial flexure. Nevertheless, for the uniaxial compressive test, the use of this criterion led to a significative underestimation of the experimental value of the failure stress. As a consequence, the Drucker–Prager criterion must be used with caution and is not able to explain all the failures that can occur in a pharmaceutical compact.
Keywords: Tablet; Tensile strength; Diametral compression; Three-point flexure; Biaxial flexure; Uniaxial compressive test;

Display OmittedThe purpose of the study was to perform a comparative analysis of the technical performance, respective costs and environmental effect of two invasive analytical methods (HPLC and UV/visible–FTIR) as compared to a new non-invasive analytical technique (Raman spectroscopy). Three pharmacotherapeutic models were used to compare the analytical performances of the three analytical techniques. Statistical inter-method correlation analysis was performed using non-parametric correlation rank tests. The study’s economic component combined calculations relative to the depreciation of the equipment and the estimated cost of an AQC unit of work. In any case, analytical validation parameters of the three techniques were satisfactory, and strong correlations between the two spectroscopic techniques vs. HPLC were found. In addition, Raman spectroscopy was found to be superior as compared to the other techniques for numerous key criteria including a complete safety for operators and their occupational environment, a non-invasive procedure, no need for consumables, and a low operating cost. Finally, Raman spectroscopy appears superior for technical, economic and environmental objectives, as compared with the other invasive analytical methods.
Keywords: Raman spectroscopy; Cytotoxic drugs; Analytical quality control; Safety; Hospital environment; Pharmacoeconomic considerations;

Monitoring process induced attrition of drug substance particles within formulated blends by John F. Gamble; Magnus Hoffmann; Helen Hughes; Paul Hutchins; Mike Tobyn (77-87).
Display OmittedThe aim of the study was to investigate the impact of unit processing steps such as blending, cone milling and powder feeding systems on the particle size of a formulated API. The particle properties of a single component (API) within formulated samples were tracked using an image based particle characterisation system with an integrated Raman probe. In addition to the primary aim, the impact of excipient selection was also assessed.The study demonstrated the ability to track the size and shape of particles of a single component within a blended system. Process induced attrition can affect significant changes in the size and shape characteristics of the API particles. Whilst blending and cone milling were found to have minimal impact on the API properties, significant particle attrition was induced through transmission of the formulations through a powder feeding system. The impact of excipients within the formulated blends on API attrition propensity was observed to be low.The findings suggest that the propensity for particles to undergo process induced attrition should be taken into consideration when designing a manufacturing process and/or relating initial particle properties to the performance of intermediate or final dosage forms.
Keywords: Attrition; Particle size; Raman spectroscopy; Imaging; Pharmaceuticals;

SEM/EDX and confocal Raman microscopy as complementary tools for the characterization of pharmaceutical tablets by Nikolaos Scoutaris; Kapilkumar Vithani; Ian Slipper; Babur Chowdhry; Dennis Douroumis (88-98).
The image above illustrates the capability of EDX and confocal Raman microscopy to provide chemical map of the components of pharmaceutical tablet.Display OmittedThe drug distribution on the surface of hot-melt extruded, pre-mixed hot-melt extruded and direct compressed tablet formulations was characterized by using scanning electron microscopy, energy dispersive X-ray spectroscopy (EDX) and confocal Raman spectroscopy. Formulations of paracetamol (PMOL) and Compritol® (C-888) were extruded using hot-melt extrusion at different processing temperatures and formulation compositions before being compressed into tablets. EDX and confocal Raman spectroscopy were employed to map the drug and excipient distribution, both qualitatively and quantitatively, on the surface of the tablets. The results from EDX and confocal Raman studies confirmed better uniformity and distribution of PMOL in the pre-mixed extruded formulations compared to both hot-melt extruded formulations and those obtained by means of direct compression. The quantification of the drug composition on the surface of the tablets by both EDX and confocal Raman was in good agreement with the theoretically expected values.
Keywords: Hot-melt extrusion; Energy dispersive X-ray spectroscopy; Confocal Raman; Homogeneity;

Pharmacoscintigraphic evaluation of potential of lipid nanocarriers for nose-to-brain delivery of antidepressant drug by M. Intakhab Alam; Sanjula Baboota; Alka Ahuja; Mushir Ali; Javed Ali; Jasjeet K. Sahni; Aseem Bhatnagar (99-106).
Display OmittedEfficacy of antidepressants relies upon their continued presence at the site of action (brain) over a prolonged period of time. The BBB restricts the access of antidepressants to the brain on oral as well as intravenous administration. Direct delivery (by-passing the BBB) of antidepressant drugs can increase the CSF concentration with concomitant reduction in dose and side effects. Intranasal administration of nanostructured lipid carriers (NLC) containing antidepressant drug circumvent the BBB and maintain the prolonged release at the site of action. The aim of the present study was to evaluate the enhancement in brain uptake of NLC containing duloxetine (DLX) after intranasal administration. Duloxetine loaded NLC (DLX-NLC) was evaluated pharmacoscintigraphically for drug targeting potential (DTP), drug targeting efficiency (DTE) and biodistribution studies in different organs including brain. The radiolabeling efficiency of DLX and DLX-NLC was found to be 98.41 ± 0.96 and 98.87 ± 0.82 after 30 min, respectively. The biodistribution studies exhibited higher percentage of radioactivity/g for DLX-NLC formulations in brain as compared with the DLX. The higher DTP (86.80%) and DTE (757.74%) suggested that DLX-NLC formulation has a better brain targeting efficiency than DLX solution (DTP = 65.12%; DTE = 287.34%) when administered intranasally. Moreover, the intranasal administration exhibited about 8-times higher concentration of DLX in brain when compared with the intravenous administration of DLX solution. The intranasal NLC containing DLX can be employed as an effective method for the treatment of depression.
Keywords: Pharmacoscintigraphy; DTE; DTP; Biodistribution; Radiolabeling efficiency;

Bioresponsive nanohydrogels based on HEAA and NIPA for poorly soluble drugs delivery by Elena Pérez; Ana Martínez; César Teijón; Jose M. Teijón; M. Dolores Blanco (107-119).
Display OmittedEnvironmentally sensitive hydrogels have gained considerable attention in recent years as one of the most promising drug delivery systems. In the present study, two new formulations of pH and temperature stimuli-responsive nanogels (NGs) based on poly-N-isopropylacrylamide (NIPA), N-hydroxyethyl acrylamide (HEAA) and tert-butyl 2-acrylamidoethyl carbamate (2AAECM) were synthesized and evaluated for passive targeting of paclitaxel (PTX). Nanogels were prepared by microemulsion polymerization method using N-methylenebis(acrylamide) (NMBA) as crosslinking agent. TEM images and DLS results showed nanosized spherical hydrogels. FTIR spectra confirmed the synthesis of nanogels by radical polymerization among vinyl groups of monomers. The PTX loading capacity, encapsulation efficiency and in vitro release were analyzed by HPLC. The cumulative release profile of the PTX-loaded nanohydrogels within 144 h showed a faster drug release at acid pH (pH 5), similar to those observed at lysosome compartment, whereas a fewer PTX amount was released from NGs at pH similar to plasma levels. Cellular uptake assays revealed rapid penetration and intracellular accumulation of those nanogels in MCF7, HeLa and T47D cells after 48 h incubation. MTT assays showed cell viability dependence on concentration and time incubation. Finally, the PTX effect on cell viability showed a G2/M cell arrest after using PTX-loaded NGs and pure PTX.
Keywords: Controlled release; Paclitaxel; Hydrogel; Stimuli-responsive; Passive targeting; Tumor cell;

Towards the optimisation and adaptation of dry powder inhalers by Y. Cui; S. Schmalfuß; S. Zellnitz; M. Sommerfeld; N. Urbanetz (120-132).
Display OmittedPulmonary drug delivery by dry powder inhalers is becoming more and more popular. Such an inhalation device must insure that during the inhalation process the drug powder is detached from the carrier due to fluid flow stresses. The goal of the project is the development of a drug powder detachment model to be used in numerical computations (CFD, computational fluid dynamics) of fluid flow and carrier particle motion through the inhaler and the resulting efficiency of drug delivery. This programme will be the basis for the optimisation of inhaler geometry and dry powder inhaler formulation. For this purpose a multi-scale approach is adopted. First the flow field through the inhaler is numerically calculated with OpenFOAM® and the flow stresses experienced by the carrier particles are recorded. This information is used for micro-scale simulations using the Lattice–Boltzmann method where only one carrier particle covered with drug powder is placed in cubic flow domain and exposed to the relevant flow situations, e.g. plug and shear flow with different Reynolds numbers. Therefrom the fluid forces on the drug particles are obtained. In order to allow the determination of the drug particle detachment possibility by lift-off, sliding or rolling, also measurements by AFM (atomic force microscope) were conducted for different carrier particle surface structures. The contact properties, such as van der Waals force, friction coefficient and adhesion surface energy were used to determine, from a force or moment balance (fluid forces versus contact forces), the detachment probability by the three mechanisms as a function of carrier particle Reynolds number. These results will be used for deriving the drug powder detachment model.
Keywords: Dry powder inhaler; Carrier glass beads; Surface modification; Computational fluid dynamics; Fluid stresses on carrier; Prediction of drug detachment;

Influence of different surfactants on the technological properties and in vivo ocular tolerability of lipid nanoparticles by Antonio Leonardi; Claudio Bucolo; Giovanni Luca Romano; Chiara Bianca Maria Platania; Filippo Drago; Giovanni Puglisi; Rosario Pignatello (133-140).
Display OmittedAddition of one or more surfactant agents is often necessary for the production of nanostructured lipid and polymeric systems. The removal of residual surfactants is a required step for technological and toxicological reasons, especially for peculiar applications, such as the ophthalmic field. This study was planned to assess the technological properties of some surfactants, commonly used for the production of lipid nanoparticles, as well as their ocular safety profile. Stable and small-size solid lipid nanoparticles were obtained using Dynasan® 114 as the lipid matrix and all the tested surfactants. However, from a toxicological point of view, the nanocarriers produced using Kolliphor® P188 were the most valuable, showing no irritant effect on the ocular surface up to the highest tested surfactant concentration (0.4%, w/v). The SLN produced using Cremophor® A25 and Lipoid® S100 were tolerated up to a surfactant concentration of 0.2% by weight, while for Tween® 80 and Kolliphor® HS 15 a maximum concentration of 0.05% can be considered totally not-irritant.
Keywords: Solid lipid nanoparticles; Ocular drug delivery systems; Surfactants; Ocular safety; Eye tolerability;

Nanocrystals of medium soluble actives—Novel concept for improved dermal delivery and production strategy by Xuezhen Zhai; Jürgen Lademann; Cornelia M. Keck; Rainer H. Müller (141-150).
Display OmittedAfter use in oral pharmaceutical products, nanocrystals are meanwhile applied to improve the dermal penetration of cosmetic actives (e.g. rutin, hesperidin) and of drugs. By now, nanocrystals are only dermally applied made from poorly soluble actives. The novel concept is to formulate nanocrystals also from medium soluble actives, and to apply a dermal formulation containing additionally nanocrystals. The nanocrystals should act as fast dissolving depot, increase saturation solubility and especially accumulate in the hair follicles, to further increase skin penetration. Caffeine was used as model compound with relevance to market products, and a particular process was developed for the production of caffeine nanocrystals to overcome the supersaturation related effect of crystal growth and fiber formation – typical with medium soluble compounds. It is based on low energy milling (pearl milling) in combination with low dielectric constant dispersion media (water–ethanol or ethanol–propylene glycol mixtures) and optimal stabilizers. Most successful was Carbopol® 981 (e.g. 20% caffeine in ethanol–propylene glycol 3:7 with 2% Carbopol, w/w). Nanocrystals with varied sizes can now be produced in a controlled process e.g. 660 nm (optimal for hair follicle accumulation) to 250 nm (optimal for fast dissolution). The short term test proved stability over 2 months of the present formulation being sufficient to perform in vivo testing of the novel concept.
Keywords: Nanocrystals; High pressure homogenization; Pearl milling; Dermal application; Hair follicle accumulation; Penetration enhancement;

In situ covalently cross-linked PEG hydrogel for ocular drug delivery applications by Jing Yu; Xu Xu; FuLin Yao; Zichao Luo; Ling Jin; BinBin Xie; Shuai Shi; Huixiang Ma; XingYi Li; Hao Chen (151-157).
Display OmittedAvastin® has been clinically proved to be effective in the treatment of intraocular neovascularization diseases. However, the short half-life of Avastin® need frequent administration to maintain its therapeutic efficiency. In this paper, we attempted to develop an in situ PEG hydrogels with great biocompatibility for sustained release of Avastin® to inhibit the corneal neovascularization. PEG hydrogels was formed via thiol-maleimide reaction using 4-arm PEG-Mal and 4-arm PEG-SH. The transparent hydrogel was rapidly formed under physiological conditions. By varying the concentration of 4-arm PEG-SH, PEG hydrogel with different gelling time, pore size, swelling ratio and mechanical property could be obtained. In vitro cytotoxicity indicated that the developed PEG hydrogel had no apparent cytotoxicity on L-929 cells after 7 days of incubation. In vitro release study showed the encapsulated Avastin® was sustained release from PEG hydrogels within a period of 14 days study. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis further confirmed that the released Avastin® did not undergo apparent hydrolysis within 14 days. As a conclusion, we could conclude that the developed PEG hydrogels as an injectable hydrogels might be suitable for extended Avastin® release to treat the corneal neovascularization.
Keywords: Avastin; PEG hydrogel; Corneal neovascularization; Sustained release;

Preclinical evaluation of a ricinoleic acid poloxamer gel system for transdermal eyelid delivery by Sai H.S. Boddu; Himanshu Gupta; Sindhu Prabha Bonam (158-161).
Display OmittedOur previous study has shown that pluronic lecithin organogel (PLO gel) made of ricinoleic acid has the potential for use as a transdermal eyelid delivery system. The present study deals with the evaluation of ocular tissue concentrations of dexamethasone in a rabbit model following topical application of the gel formulation onto the eyelids. The PLO gel formulation containing dexamethasone was applied to the outside of the eyelid skin. Rabbits were sacrificed at regular time intervals of 2, 4, 8, 12, 20 and 24 h. Maxidex® eye drops were used as a control. Rabbits were sacrificed and dexamethasone concentrations were analyzed in anterior segment tissues such as the cornea, conjunctiva, aqueous humor, lens, and iris-ciliary body by liquid chromatography tandem mass spectrometry (LC–MS/MS). Rabbit eyes were also examined for ocular irritation and scored using the modified Draize scoring system. No significant irritation or redness was observed in the eyes as compared to the control rabbit eyes. PLO gel formulation resulted in constant dexamethasone concentrations in the anterior segment tissues for up to 24 h, which was equivalent or higher than Maxidex® eye drops. The findings of this investigation indicate that the ricinoleic acid PLO gel formulation may be clinically effective as a new treatment modality for anterior segment diseases.
Keywords: Pluronic F127; Lecithin; Ricinoleic acid; Pluronic lecithin organogel; Rabbit eyelids; Transdermal;