International Journal of Pharmaceutics (v.463, #1)
EDITORIAL BOARD (iii).
Pectin-coated chitosan–LDH bionanocomposite beads as potential systems for colon-targeted drug delivery by Lígia N.M. Ribeiro; Ana C.S. Alcântara; Margarita Darder; Pilar Aranda; Fernando M. Araújo-Moreira; Eduardo Ruiz-Hitzky (1-9).
This work introduces results on a new drug delivery system (DDS) based on the use of chitosan/layered double hydroxide (LDH) biohybrid beads coated with pectin for controlled release in the treatment of colon diseases. Thus, the 5-aminosalicylic acid (5ASA), the most used non-steroid-anti-inflammatory drug (NSAID) in the treatment of ulcerative colitis and Crohn's disease, was chosen as model drug aiming to a controlled and selective delivery in the colon. The pure 5ASA drug and the hybrid material prepared by intercalation in a layered double hydroxide of Mg2Al using the co-precipitation method, were incorporated in a chitosan matrix in order to profit from its mucoadhesiveness. These compounds processed as beads were further treated with the polysaccharide pectin to create a protective coating that ensures the stability of both chitosan and layered double hydroxide at the acid pH of the gastric fluid. The resulting composite beads presenting the pectin coating are stable to water swelling and procure a controlled release of the drug along their passage through the simulated gastrointestinal tract in in vitro experiments, due to their resistance to pH changes. Based on these results, the pectin@chitosan/LDH-5ASA bionanocomposite beads could be proposed as promising candidates for the colon-targeted delivery of 5ASA, with the aim of acting only in the focus of the disease and minimizing side effects.
Keywords: Drug delivery systems; Bionanocomposites; Layered double hydroxide; Chitosan; Pectin; 5-aminosalicylic acid;
A novel gastroretentive porous microparticle for anti-Helicobacter pylori therapy: Preparation, in vitro and in vivo evaluation by Shilei Hao; Yazhou Wang; Bochu Wang; Quanming Zou; Hao Zeng; Xiaoliang Chen; Xi Liu; Junyu Liu; Songke Yu (10-21).
Gastroretentive drug delivery system is a promising option for the treatment of Helicobacter pylori infection, which can prolong gastric residence time and supply high drug concentration in the stomach. In the present study, a low density system of metronidazole-loaded porous Eudragit® RS microparticle with high drug loading capacity (>25%) was fabricated via electrospray method. The porous structure and size distribution of microparticles were affected by polymer concentration and flow rate of solution. FTIR and XRD analyses indicated that drug has been entrapped into the porous microparticles. In addition, sustained release profiles and slight cytotoxicity in vitro were detected. Gamma scintigraphy study in vivo demonstrated that 131I-labeled microparticles retained in stomach for over 8 h, and about 65.50% radioactive counts were finally detected in the region of interest. The biodistribution study confirmed that hotspot of radioactivity was remaining in the stomach. Furthermore, metronidazole-loaded porous microparticles can eradicate H. pylori completely with lower dose and administration frequency of antibiotic compared with pure drug, which were also more helpful for the healing of mucosal damages. These results suggest that prepared porous microparticle has the potential to provide better treatment for H. pylori infection.
Keywords: Porous microparticles; Electrospray; Helicobacter pylori; Local delivery; SPECT/CT tomography;
Mussel-inspired polydopamine coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release by Qishan Zheng; Tianran Lin; Hanyin Wu; Liangqia Guo; Peirong Ye; Yanli Hao; Qingquan Guo; Jinzhi Jiang; FengFu Fu; Guonan Chen (22-26).
A novel pH-sensitive controlled release system is proposed by using mussel-inspired PDA coated MSNs as nanocarriers. Using PDA coating as the gatekeepers, the drug molecules are blocked in MSNs at neutral pH and released at lower pH.A novel pH-sensitive controlled release system is proposed by using mussel-inspired polydopamine (PDA) coated mesoporous silica nanoparticles (MSNs) as nanocarriers. MSNs with a large pore diameter are synthesized by using 1,3,5-trimethylbenzene as a pore-expanding agent and are modified with a PDA coating by virtue of oxidative self-polymerization of dopamine in neutral pH. PDA coated MSNs are characterized by FTIR, TEM, N2 adsorption and XPS techniques. The PDA coating can work as pH-sensitive gatekeepers to control the release of drug molecules from MSNs in response to the pH-stimulus. Doxorubicin (DOX, an anticancer drug) can be released in the acid media and blocked in the neutral media.
Keywords: Controlled release; Mesoporous silica nanoparticles; Polydopamine; Drug delivery;
Modifying theophylline microparticle surfaces via the sequential deposition of poly(vinyl alcohol-co-vinyl acetate) copolymers by Yanjun Zhao; Mannar A. Alas’ad; Stuart A. Jones (27-30).
The aim of this study was to investigate the manner in which amphiphilic poly(vinyl alcohol-co-vinyl acetate) copolymers (PVA-Ac) assembled on drug surfaces and use this information to generate a novel bi-layer polymer coating for a theophylline microparticle. Three grades of PVA-Ac, differing in hydrolysis degree and monomer distribution, were synthesised, characterised by nuclear magnetic resonance and shown to interact with theophylline when suspended in water. PVA-Ac deposition at the solid/liquid interface was driven by polymer hydrogen bond formation in a process that induced consequential structural changes in the macromolecule architecture. The most hydrophobic grades of the copolymer appeared to adsorb in a multistage process that passed through a series of equilibrium points. The PVA-Ac surface allowed two grades of the copolymer to be sequentially adsorbed and this resulted in the fabrication of a microparticle with desirable characteristics for pharmaceutical formulation production.
Keywords: Theophylline; Microparticle; Adsorption; Polyvinyl; Polymer;
In vitro evaluation of permeation, toxicity and effect of praziquantel-loaded solid lipid nanoparticles against Schistosoma mansoni as a strategy to improve efficacy of the schistosomiasis treatment by Ana Luiza Ribeiro de Souza; Tatiana Andreani; Rosimeire Nunes de Oliveira; Charlene Priscila Kiill; Fernanda Kolenyak dos Santos; Silmara Marques Allegretti; Marco Vinícius Chaud; Eliana B. Souto; Amélia M. Silva; Maria Palmira Daflon Gremião (31-37).
Adult worms of Schistosoma mansoni exposed to praziquantel (PZQ) in: (a) PBS (25 μg mL−1); (b) PBS (50 μg mL−1); (c) SLN (Eq. 25 μg mL−1); (d) SLN (Eq. 50 μg mL−1); (e) PZQ-SLN (25 μg mL−1 of PZQ); (f) PZQ-SLN (50 μg mL−1 of PZQ). Arrows indicate nanoparticles in worm tegument (magnification of 100×).Solid lipid nanoparticles (SLN) are a promising drug delivery system for oral administration of poorly-water soluble drugs because of their capacity to increase the solubility of drug molecules when loaded in their lipid matrices, with the resulting improvement of the drug bioavailability. In the present work, we have developed praziquantel (PZQ)-loaded SLN and explored the biological applications of this system for intestinal permeation of PZQ. The effect in vitro on Schistosoma mansoni culture and the cytotoxicity in HepG2 line cell were also evaluated. The results showed a significant decrease in the intestinal absorption of PZQ loaded in SLN compared to free PZQ, suggesting that the SLN matrix could act as reservoir system. In culture of S. mansoni, we observed that PZQ-loaded SLN were more effective than free PZQ, leading the death of the parasites in less time. The result was proportional to doses of PZQ (25 and 50 μg mL−1) and lipid concentration. Regarding cytotoxicity, the encapsulation of PZQ into SLN decreased the toxicity in HepG2 cells in comparison to the free PZQ. From the obtained results, PZQ-loaded SLN could be a new drug delivery system for the schistosomiasis treatment especially in marginalized communities, improving the therapeutic efficacy and reducing the toxic effects of PZQ.
Keywords: Praziquantel; Solid lipid nanoparticles; Schistosomiasis; Schistosoma mansoni; Cytotoxicity; HepG2 cells;
Biorelevant dissolution of poorly soluble weak acids studied by UV imaging reveals ranges of fractal-like kinetics by Andreas Niederquell; Martin Kuentz (38-49).
Much pharmaceutical research has been invested into drug dissolution testing and its mathematical modeling. Even today, there is no complete understanding of the dissolution process but novel imaging tools have been introduced into pharmaceutics that may spur further scientific advancement. We used UV imaging to study the intrinsic dissolution of various poorly soluble acidic model drugs to understand the effects of heterogeneity on early intrinsic drug dissolution using a biorelevant medium: celecoxib, ketoprofen, naproxen, and sulfathiazole. All compounds were characterized using X-ray powder diffraction and thermal analysis. Raman spectroscopy and scanning electron microscopy were employed before and after the initial dissolution phase. As a result, ranges of fractal-like dissolution behavior were found with all model compounds. Intrinsic dissolution rate exhibited a power law mainly at early time points. Subsequently, after several minutes, pseudo-equilibrium was reached with a nearly constant dissolution rate. Further research should investigate whether compounds other than acids demonstrate similar early dissolution kinetics in biorelevant media. The observed fractal-like intrinsic dissolution behavior has several pharmaceutical implications. This study primarily helps us to better understand in vitro dissolution testing, particularly on a miniaturized scale. This improved understanding of early dissolution events may advance future correlations with in vivo data. Therefore, fractal-like dissolution should be considered during biopharmaceutical modeling.
Keywords: Drug dissolution; Surface dissolution; UV imaging; Fractal-like kinetics; Heterogeneity;
Dynamics of aerosol size during inhalation: Hygroscopic growth of commercial nebulizer formulations by Allen E. Haddrell; James F. Davies; Rachael E.H. Miles; Jonathan P. Reid; Lea Ann Dailey; Darragh Murnane (50-61).
The size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath®, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide® Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi© (60 mg/mL tobramycin and 2.25 mg/mL NaCl, pH 5.5–6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model to represent nebulizer formulations may not be representative of the actual behavior of the aerosolized drug solutions.
Keywords: Nebulizer; Hygroscopic growth; Mass flux; Inhalation; Commercial formulations;
Comparative pharmaceutical evaluation of brand and generic clobetasone butyrate ointments by Yoshihisa Yamamoto; Toshiro Fukami; Tatsuo Koide; Yoshinori Onuki; Toyofumi Suzuki; Koichi Metori; Noriko Katori; Yukio Hiyama; Kazuo Tomono (62-67).
In the present study, we performed comprehensive pharmaceutical evaluation among an original clobetasone butyrate (CLB) ointment product and three generic products. Although spherocrystal images were observed under a polarizing microscope for only Kindavate®, the original product, distribution of active and inactive ingredients was chemically equivalent between the original and generic medicine by the attenuated total reflection infrared spectroscopy. These results suggest that the spherocrystals observed in Kindavate® are composed of hydrocarbon. On GC/MS, it was revealed that linear alkanes having 25–27 carbon atoms are densely present in Sun White®, the base used in Kindavate®. On the other hand, linear alkanes having 22–31 carbon atoms were broadly distributed in most other white petrolatums. In the CLB ointment products, the distribution equivalent of linear alkane to Sun White® was observed only in Kindavate®. Thus, the GC/MS method is extremely useful for identification of white petrolatum used in the ointment.A similar amount of CLB among the pharmaceutical products was detected in the skin tissue by skin accumulation test, although there were the differences in rheological properties and the quality of white petrolatum.The present results will be very useful for pharmacists in selecting medicine products that match the needs of the patient. Such pharmaceutical information will help spread objective knowledge about products in the future, and will contribute to the appropriate selection of medication.
Keywords: Clobetasone butyrate; White petrolatum; Formulation; Imaging analysis; Rheological property; Skin accumulation;
Enhanced bioavailability of buspirone hydrochloride via cup and core buccal tablets: Formulation and in vitro/in vivo evaluation by Mohamed A.A. Kassem; Aliaa N. ElMeshad; Ahmed R. Fares (68-80).
This work aims to prepare sustained release buccal mucoadhesive tablets of buspirone hydrochloride (BH) to improve its systemic bioavailability. The tablets were prepared according to 5 × 3 factorial design where polymer type was set at five levels (carbopol, hydroxypropyl methylcellulose, sodium alginate, sodium carboxymethyl cellulose and guar gum), and polymer to drug ratio at three levels (1:1, 2:1 and 3:1). Mucoadhesion force, ex vivo mucoadhesion time, percent BH released after 8 h (Q8h) and time for release of 50% BH (T 50%) were chosen as dependent variables. Additional BH cup and core buccal tablets were prepared to optimize BH release profile and make it uni-directional along with the tablets mucoadhesion. Tablets were evaluated in terms of content uniformity, weight variation, thickness, diameter, hardness, friability, swelling index, surface pH, mucoadhesion strength and time and in vitro release. Cup and core formula (CA10) was able to adhere to the buccal mucosa for 8 h, showed the highest Q8h (97.91%) and exhibited a zero order drug release profile. Pharmacokinetic study of formula CA10 in human volunteers revealed a 5.6 fold increase in BH bioavailability compared to the oral commercial Buspar® tablets. Conducting level A in vitro/in vivo correlation showed good correlation (r 2 = 0.9805) between fractions dissolved in vitro and fractions absorbed in vivo.
Keywords: Buspirone HCl; Mucoadhesive dosage forms; Buccal tablets; Cup and core tablets; Pharmacokinetic study; LC/MS/MS;
Investigation of thermo-sensitive amphiphilic micelles as drug carriers for chemotherapy in cholangiocarcinoma in vitro and in vivo by Xuefeng Wang; Songgang Li; Ziwei Wan; Zhiwei Quan; Qinggang Tan (81-88).
Cholangiocarcinoma is an epithelial cancer of the bile ducts with poor prognosis and, in recent years, a rapidly increasing incidence. In this study, nano-sized thermo-sensitive micelles were investigated as drug carriers to improve chemotherapy in cholangiocarcinoma. Thermo-sensitive amphiphilic block copolymer, P-(N,N-isopropylacrylamide-co-N-hydroxymethylacrylamide)-b-caprolactone [P-(NIPAAm-co-NHMAAm)-b-PCL] with lower critical solution temperature (LCST) at about 38 °C was synthesized. Doxorubicin (DOX)-loaded micelles were prepared by dialysis method. The micelles exhibited a sustained and temperature-dependent DOX release. Toxicity of the blank micelles for human cholangiocarcinoma (QBC939) cells was minimal both in vitro and in vivo. In contrast, the DOX-loaded micelles effectively inhibited proliferation and induced apoptosis of QBC939 cells in vitro (p < 0.05) and inhibited tumor growth in nude mice by 21.49%. These results indicated that thermo-sensitive amphiphilic micelles are a promising and effective drug carrier, and show potential for improving chemotherapy for cholangiocarcinoma.
Keywords: Cholangiocarcinoma; Micelle; Amphiphilic block copolymer; Thermo-sensitive; Drug carriers;
Effect of binders on the release rates of direct molded verapamil tablets using twin-screw extruder in melt granulation by David Cheng Thiam Tan; William Wei Lim Chin; En Hui Tan; Shiqi Hong; Wei Gu; Rajeev Gokhale (89-97).
Conventional manufacturing of pharmaceutical tablets often involves single processes such as blending, granulation, milling and direct compression. A process that minimizes and incorporates all these in a single continuous step is desirable. The concept of omitting milling step followed by direct-molding of tablets utilizing a twin-screw extruder in a melt granulation process using thermoplastic binders was explored. The objective of this study was to investigate the effect of combining hydrophilic binder (HPMC K4M, PEO 1M), and hydrophobic binder (Compritol® ATO 888, Precirol® ATO 5) on the release profiles of direct-molded tablets and direct-compressed tablets from milled extrudates using a quality-by-design approach. It was identified that hydrophilic binder type and process significantly affects (p = 0.005) the release profiles of verapamil. Moreover, two-way interaction analysis demonstrated that the combination of process with type of hydrophilic polymer (p = 0.028) and the type of hydrophilic polymer with polymer ratio (p = 0.033) significantly affected the release profiles. The formulation release kinetics correlated to Higuchi release model and the mechanism correlated to a non-Fickian release mechanism. The results of the present study indicated that direct-molded tablets with different release profiles can be manufactured without milling process and through a continuous melt granulation using twin-screw extruder with appropriate thermoplastic binder ratio.
Keywords: Melt granulation; Hot melt extruder; Direct mold; Modified release; Hydrophobic; Hydrophilic;
Stabilisation of proteins via mixtures of amino acids during spray drying by Ankur Ajmera; Regina Scherließ (98-107).
Biologicals are often formulated as solids in an effort to preserve stability which generally requires stabilising excipients for proper drying. The purpose of this study was to screen amino acids and their combinations for their stabilising effect on proteins during spray drying. Catalase, as model protein, was spray dried in 1 + 1 or 1 + 2 ratios with amino acids. Some amino acids namely arginine, glycine and histidine showed good retention of catalase functionality after spray drying and subsequent storage stress. A 1 + 1 combination of arginine and glycine in a 1 + 2 ratio with catalase resulted in a tremendously good stabilising effect. Storage at high temperature/humidity also showed beneficial effects of this combination. To evaluate whether this was a general principle, these findings were transferred to an antigenic protein of comparable size and supramolecular structure (haemagglutinin) as well as to a smaller enzyme (lysozyme). Upon spray drying with the combination of amino acids it could be shown that both proteins remain more stable especially after storage compared to the unprotected protein. The combination of arginine and glycine is tailored to the needs of protein stabilisation during spray drying and may hence be utilised in dry powder formulation of biomolecules with superior stability characteristics.
Keywords: Thermal stability; Amorphous matrix; Water replacement; Catalase; Lysozyme; Haemagglutinin;
Encapsulation and controlled release of hydrophilic pesticide in shell cross-linked nanocapsules containing aqueous core by Chuxiang Sun; Ke Shu; Wei Wang; Zhao Ye; Ting Liu; Yuxiang Gao; Hua Zheng; Guanghua He; Yihua Yin (108-114).
In this study, amphiphilic biocopolymers, synthesized by mixing azidobenzaldehyde (Az) and an aqueous solution of carboxymethyl chitosan (CMCS), which self-assemble into nanocapsules with a aqueous core (ACN) in aqueous media followed by photo-cross-linking to obtain shell cross-linked nanocapsules, were used to develop a controlled release pesticide system. The system was characterized by TEM and DLS. Its encapsulation efficiency was determined. The obtained result showed that it is efficient to encapsulate methomyl reaching encapsulation efficiency as high as 90% in an aqueous medium at pH 4.0, which is mainly attributed to the hydrogen bonding adsorption between methomyl molecules and the inner surface of nanocapsules. Release profiles of methomyl from methomyl-loaded nanocapsules in an aqueous solution at pH 6.0 were shown to be diffusion controlled with a half-release time (t 1/2) of 36.3–69.5 h from different samples. The shell cross-linking and its degree of cross-linking are assumed to be responsible for this diffusion behavior. The insecticidal activity test in laboratory showed that the control efficacy of methomyl-loaded nanocapsules against the armyworm larvae was significantly superior to the original. The relative control efficacy still maintained 100% over 7 days.
Keywords: Shell cross-linked; Nanocapsule; Encapsulation; Controlled release; Pesticide;