International Journal of Pharmaceutics (v.386, #1-2)
Editorial Board (iii).
Targeted antifungal delivery system: β-Glucosidase sensitive nystatin–star poly(ethylene glycol) conjugate by Eliška Bílková; Aleš Imramovský; Vladimír Buchta; Miloš Sedlák (1-5).
A new targeted intravenous conjugate of nystatin with pentaerythritol poly(ethylene glycol)ether has been prepared and characterised (NY4–sPEG, M = 25 160). The conjugate contains a β-d-glucopyranoside molecular switch sensitive to β-glucosidases (E.C.18.104.22.168), which are specifically present in the enzyme outfit of fungal pathogens. The investigated conjugate is stable under in vitro conditions for 24 h (solution of phosphate buffer pH = 7.4). Spectrophotometrically controlled releasing of nystatin in model medium containing β-glucosidase ((Aspergillus niger) 2 mg/mL, 66.6 units/g; pH 7.4, 2 × 10−2 M), reported decomposition half-life of conjugate τ 1/2 = (88 ± 2) s. This implies that releasing of nystatin is controlled only enzymatically.
Keywords: Nystatin; Star poly(ethylene glycol); Drug polymer conjugates; β-Glucosidase sensitivity; Controlled release in vitro;
Inhalation performance of pollen-shape carrier in dry powder formulation with different drug mixing ratios: Comparison with lactose carrier by Meer Saiful Hassan; Raymond Lau (6-14).
In this study, the drug delivery performance of pollen-shape hydroxyapatite (HA) carriers is assessed and compared with conventional lactose (LA) carriers. Budesonide (Bd) is used as the model drug. Three drug mixing ratios of 2:1, 10:1 and 45:1 (carrier:drug, w/w) are used. The attachment of the drug with the carrier is characterized by sieving test. It is found that the drug content in the blends with HA particles is higher than the blends with LA. In vitro inhalation experiments are also conducted in an Andersen cascade impactor (ACI) equipped with a Rotahaler® at gas flow rates of 30 and 60 L/min. The HA blends show high emitted dose (ED) of 82–90% at 30 L/min while the LA blends are observed to have ED of 69–82% at the same conditions. The high emission of the HA blends also allows high fine particle fraction (FPF) of 10–18% while the FPF of the LA blends are 3–15%. At a gas flow rate of 60 L/min, all the HA and LA blends show compatible ED (83–95% for HA blends and 82–84% for LA blends) and FPF (19–41% for HA blends and 21–34% for LA blends).
Keywords: Dry powder inhalation; Drug carrier; Pollen-shape; Drug mixing ratio; Emitted dose; Fine particle fraction;
Novel thymopentin release systems prepared from bioresorbable PLA–PEG–PLA hydrogels by Yan Zhang; Xiaohan Wu; Yaru Han; Fei Mo; Yourong Duan; Suming Li (15-22).
Copolymers were synthesized by ring opening polymerization of l- or d-lactide in the presence of dihydroxyl PEG with molar mass of 6000, 12,000 and 20,000, using zinc lactate as catalyst. Bioresorbable hydrogels were obtained by mixing PLLA–PEG–PLLA and PDLA–PEG–PDLA aqueous solutions due to stereocomplexation between PLLA and PDLA chains. Rheological measurements show that the hydrogels present typical viscoelastic behaviors, although degradation could occur during the gelation process. Thymopentin was taken as a model drug to evaluate the potential of PLA–PEG–PLA hydrogels as carrier of hydrophilic drugs. Various parameters such as copolymer concentration, drug load, copolymer composition and the difference between sol and gel were considered. The release profiles are characterized by an initial burst followed by slower release. Higher copolymer concentration leads to slower release rate and less burst effect due to more compact structure which disfavors drug diffusion. Similarly, higher molar mass of the copolymers disfavors the release of TP5, and hydrogels composed of both PLLA/PEG and PDLA/PEG present slower release rates than single copolymer solutions. In contrast, drug load exhibits little influence on the release profiles due to the high water solubility of TP5. In all cases, nearly 80% of TP5 is released. In vivo studies proved the potential of TP5 containing hydrogels, especially those with a concentration of 25%. Both the CD4+/CD8+ ratio and the morphology of thymus indicate the immunization efficacy of the TP5 release systems based on PLA/PEG hydrogels.
Keywords: Polylactide; Poly(ethylene glycol); Stereocomplexation; Hydrogel; Controlled release; Thymopentin;
Effects of implant diameter, drug loading and end-capping on praziquantel release from PCL implants by Changyan Li; Liang Cheng; Yaqiong Zhang; Shengrong Guo; Weiping Wu (23-29).
Praziquantel (PZQ)-loaded poly(ɛ-caprolactone) (PCL) cylindrical implants were fabricated and characterized. Implant diameter (3, 4 and 8 mm), drug loading (25% and 50%), and the end-capping were investigated to evaluate their effects on drug release. The evolution of implants with release time was conducted in terms of implant microstructure, crystallinity, drug content and molecular weight of PCL. The results showed that drug release was fastest for the implant with a diameter of 3 mm and slowest for the implant with a diameter of 8 mm; drug release from the implant with a drug content of 50% was faster than that from the implant with a drug content of 25%; the release of PZQ from the end-capped implants was slightly slower than that from the corresponding end-uncapped implants. The effect of drug loadings on PZQ release was related with diameter of the implants and the effect was weakened as diameter of the implants increased. The drug release data for all the implants were best fitted with Ritger–Peppas model, therefore Fickian diffusion was the predominant release mechanism. The evolution of implants with release time verified that PZQ was gradually released from the exterior to the interior of the implants.
Keywords: Praziquantel; Poly(ɛ-caprolactone); Cylindrical implant; Drug release; Scanning electron microscope;
Performance qualification of a new hypromellose capsule: Part I. Comparative evaluation of physical, mechanical and processability quality attributes of Vcaps Plus®, Quali-V® and gelatin capsules by M. Sherry Ku; Weiyi Li; Wendy Dulin; Fran Donahue; Dominique Cade; Hassan Benameur; Keith Hutchison (30-41).
This Part I paper describes the qualification of a new high performance hypromellose (hydroxypropyl methylcellulose, HPMC) capsule shell which contains no gelling agent and is dissolution friendly. The development history and the test results for a series of quality attributes including scanning electron microscopy, hygroscopicity, machineability, weight variation, powder leakage, mechanical strength, stability, cross-linking, animal and human pharmacokinetic results are reported. Comparisons to gelatin and HPMC capsule containing carrageenan showed the new HPMC capsule is superior in terms of mechanical strength, hygroscopicity and compatibility with a wide range of drugs. Specifically, the new HPMC capsule demonstrated improved weight variation, machineability and powder leakage than the HPMC capsule containing carrageenan. And the new capsule demonstrated a broader applicability than gelatin capsule for new drug development due to its inertness and compatibility for a wide range of excipients including those used for liquid fill formulations. In the second phase of qualification, disintegration and dissolution properties of the new HPMC were evaluated and reported in a Part II paper for 10 new clinical compounds with a variety of formulations optimized based on the biopharmaceutical classification system of solubility and permeability. Based on the superior performance, the new HPMC capsule is satisfactorily qualified and has since been used successfully for nearly 20 investigational new drug (IND) compounds.
Keywords: Hypromellose capsule; Machineability; Mechanical properties; Compatability; Physical stability; In vivo performance;
Percutaneous penetration modifiers and formulation effects by Diksha Kaushik; Aurora Costache; Bozena Michniak-Kohn (42-51).
The enhancement/retardation of percutaneous permeation of diethyl-m-toluamide (DEET) in the presence of five percutaneous penetration modifiers (laurocapram, 3-dodecanoyloxazolidin-2-one (N-0915), S,S-dimethyl-N-(4-bromobenzoyl) iminosulfurane (DMBIS), S,S-dimethyl-N-(2-methoxycarbonylbenzenesulfonyl) iminosulfurane (DMMCBI) and tert-butyl 1-dodecyl-2-oxoazepan-3-yl-carbamate (TBDOC)) was investigated. These permeation modifiers were formulated in either water, propylene glycol (PG), ethanol or polyethylene glycol 400 (PEG 400). The permeation studies indicated that laurocapram enhanced DEET permeation in PG, but retarded in PEG 400. Likewise, N-0915 acted as a retardant with ethanol and PEG 400, but not with water. DMBIS decreased the permeation with ethanol as compared to permeation with water, PEG 400 or PG. Similarly, DMMCB acted as a retardant with ethanol and PEG 400, but not with water or PG. TBDOC formulations revealed its activity as a retardant with ethanol, but behaved as enhancer with water, PG and PEG 400. In addition, penetration modifier interactions with stratum corneum ceramide were investigated using chemical modeling. This investigation is significant since it confirms the role of pharmaceutical formulations and shows for the first time that an enhancer can become a retardant or vice versa depending upon the vehicle in which it is applied to the skin. Hence, we should be using the term “penetration modifiers” for all such compounds.
Keywords: Penetration modifiers; Stratum corneum; Modifier ratio; Enhancers; Retardants;
Study of the critical points of experimental HPMC–NaCMC hydrophilic matrices by L. Contreras; L.M. Melgoza; R. Villalobos; I. Caraballo (52-60).
The purpose of the present work was to study the existence of critical points on the drug release and water uptake behaviour of ternary hydrophilic matrix tablets and to study the possibility of simplifying a ternary to a binary system. The ternary hydrophilic matrix tablets were prepared between 40 and 100% (w/w) of KCl, HPMC and NaCMC. Dissolution studies were carried out using the paddle method and the water uptake studies were measured using the modified Enslin apparatus and the behaviour of the kinetic parameters was studied. According to the percolation theory, both studies confirm the existence of critical points; those were related to the excipients percolation tresholds. The percolation thresholds for the binary hydrophilic matrix tablets were found between 28.7–40.7% (v/v) of HPMC and 38.6–53.9% (v/v) of NaCMC. For the ternary hydrophilic matrix tablets, the existence of a critical barrier between 54 and 61% (v/v) KCl (60–70%, w/w of KCl) was found. In the studied ternary systems HPMC and NaCMC showed that is not possible to simplify the system but they present a partial collaboration in order to establish the gel layer. The knowledge of this critical barrier will be useful in order to optimize the design of the ternary hydrophilic matrix systems.
Keywords: Hydrophilic matrix tablets; HPMC; NaCMC; Percolation theory; Excipient percolation threshold;
Understanding polymer–lipid solid dispersions—The properties of incorporated lipids govern the crystallisation behaviour of PEG by Johan Unga; Pär Matsson; Denny Mahlin (61-70).
A deeper insight into the crystallisation process of semi-crystalline polymers during formation of solid dispersions is crucial to improve control of product qualities in drug formulation. In this study we used PEG 4000 with 12 different lipids as a model system to study the effect that incorporated components may have on the crystallisation of the polymer. The lipids were melted with PEG 4000 and the crystallisation of the polymer studied with differential scanning calorimetry (DSC) and small angle X-ray diffraction (SAXD). PEG 4000 can crystallise into lamellar structures with either folded or fully extended polymer chains. All lipids increased the fraction of the folded form and lowered the crystallisation temperatures. Some lipids were incorporated to a high extent into the amorphous domains of the PEG lamellae and thereby swelling the structure, which also resulted in a high degree of chain folding. Partial least squares (PLS) modelling indicated that small hydrophilic lipids increased the folding of PEG and that large non-polar lipids retarded the unfolding during secondary crystallisation. This work shows that there is a large difference in the behaviour of PEG depending on lipid added. Differences are explained in terms of molecular properties for the lipids, demonstrated by the use of PLS modelling to describe the behaviour of PEG solid dispersions.
Keywords: Lipids; Polyethylene glycol; Solid state; Solid dispersions; Stability; Multivariate data analysis; Principal component analysis; Partial least squares projection to latent structures;
Effect of drug chirality on the skin permeability of ibuprofen by F. Cilurzo; E. Alberti; P. Minghetti; C.G.M. Gennari; A. Casiraghi; L. Montanari (71-76).
The in vitro passive diffusion of S-ibuprofen (S-IB) and RS-ibuprofen (RS-IB) through human epidermis was determined to study the effects of drug chirality. S-IB has a lower melting point (T m = 54 °C) than RS-IB (T m = 77 °C) and, therefore, a greater solubility (S-IB: 127 ± 1 μg/mL; RS-IB: 81 ± 1 μg/mL). Supersaturated plasters were prepared by using a poly(dimethylsiloxane) adhesive and Eugragit® RL and propylene glycol as antinucleant agents. The in vitro skin permeation profiles were determined by Franz cells and human epidermis obtained from three different donors. The permeation profiles of S-IB from saturated solutions resulted statistically higher than those of RS-IB (p < 0.002). When plasters were used, no differences were noticeable between the enantiomer and racemate (p > 0.17). The latter unexpected results could be explained considering that the RS-IB or S-IB in vitro release rate constants, determined using 3% w/w or 6% w/w loaded plasters, were not statistically different, suggesting that the drug diffusivity within the adhesive matrix represented the rate limiting step to the skin absorption.
Keywords: S-Ibuprofen; Supersaturation; Human skin permeability; Medicated plaster; Chirality;
Investigation of intrinsic dissolution behavior of different carbamazepine samples by Selma Šehić; Gabriele Betz; Šeherzada Hadžidedić; Silvia Kocova El-Arini; Hans Leuenberger (77-90).
The aim of the present study was to investigate the effect of the variability of commercially available carbamazepine (CBZ) samples on the intrinsic dissolution behavior in order to recommend a strategy to maintain product quality by monitoring the variability of critical parameters of the bulk drug.Extensive physical characterization of nine anhydrous CBZ samples from three different sources and their respective dihydrates showed that the commercial anhydrous CBZ samples exhibited the same polymorphic form, but different morphology and particle size distribution which led to a variation in the kinetics of conversion from anhydrous to the dihydrate CBZ and therefore to variation in the kinetics of solubility.Disc intrinsic dissolution rate (DIDR) tests showed different intrinsic dissolution behavior of the samples, whereby the transition points of anhydrous to dihydrate conversion varied between 15 and 25 min. On the other hand, converting the anhydrous CBZ's to dihydrate eliminated the variation in intrinsic dissolution behavior.Tablets of the different CBZs and Ludipress® were prepared by direct compression. The amount of CBZ dissolved after 15 min showed the same rank order as the rank order of the transition points determined by intrinsic dissolution test. Therefore, the intrinsic dissolution test with specific acceptance criteria can be a valuable and simple tool for monitoring, respectively reducing the variability of the CBZ bulk material.
Keywords: Carbamazepine; Polymorphism; Dihydrate; Intrinsic dissolution; Phase transformation;
Lubrication properties of potential alternative lubricants, glycerin fatty acid esters, to magnesium stearate by Takeaki Uchimoto; Yasunori Iwao; Yuki Ikegami; Takashi Murata; Takashi Sonobe; Atsuo Miyagishima; Shigeru Itai (91-98).
To study the usefulness of glycerin fatty acid ester Poem TR-FB® (TR-FB) and Poem TR-HB® (TR-HB) as lubricants, pressure transmission ratio, ejection force, disintegration time, and tensile strength were measured at different concentrations and mixing times for granules and tablets. When each lubricant was mixed at 0.1–3.0%, the increase in the pressure transmission ratio that was equal to or greater than that of Mg-St as well as the reduction in the ejection force was observed at a low concentration in both TR-FB and TR-HB, proving that they have excellent lubrication performance. The granules that were lubricated with TR-FB and TR-HB at even low concentration of 0.4% showed a more stable and sufficiently lower ejection force than with Mg-St from the first tablet after the start of compression. When they were mixed for 5–60 min, while the mixture with Mg-St showed a low pressure transmission ratio of 82% and a high ejection force of 500 N in the first tablet even when the mixing time was 60 min, a high pressure transmission ratio and a low ejection force were observed in TR-FB and TR-HB from the first tablet after mixing for 5–60 min, and these were maintained thereafter. As for the disintegration time and the tensile strength, a prolonged disintegration time and a decreased tensile strength, which are disadvantages of Mg-St, were not observed in TR-FB and TR-HB. Based on these results, it was concluded that TR-FB and TR-HB are useful as alternative lubricants to Mg-St.
Keywords: Glycerin fatty acid esters; Magnesium stearate; Lubricant properties; Tablet characteristics; Tabletting;
Kinetic studies of nitrofurazone photodegradation by multivariate curve resolution applied to UV-spectral data by Michele De Luca; Sílvia Mas; Giuseppina Ioele; Filomena Oliverio; Gaetano Ragno; Romà Tauler (99-107).
This work aims at describing the kinetic model of nitrofurazone photodegradation by a novel chemometric technique, hybrid hard–soft multivariate curve resolution (HS-MCR). The study was applied to UV-spectral data from the photolysis of nitrofurazone solutions at different concentrations and exposed under varying illuminance power. The HS-MCR method was able to elucidate the kinetics of the photodegradation process and to determine the rate constants, and estimating at the same time the pure spectra of the degradation products. Exposure to light of the drug gave a first rapid isomerization to the syn-form that in turn underwent degradation furnishing a mixture of yellow-red products. The photodegradation process could be explained with a kinetic model based on three consecutive first-order reactions (A > B, B > C and C > D). These results were confirmed by application of the MCR procedure to the analysis of the data obtained from HPLC-DAD analysis of the nitrofurazone samples at different reaction times. The kinetic model was observed to be dependent on experimental conditions. The samples at higher concentrations showed rate constants lower than the diluted samples, whereas an increase of the rate of all degradation processes was observed when the light power also increased. This work shows the power of the hybrid hard- and soft-multivariate curve resolution as a method to deeply study degradation processes of photolabile drugs.
Keywords: Nitrofurazone; Photodegradation; Kinetic model; Hybrid hard–soft multivariate curve resolution; MCR;
Bicellar systems for in vitro percutaneous absorption of diclofenac by L. Rubio; C. Alonso; G. Rodríguez; L. Barbosa-Barros; L. Coderch; A. De la Maza; J.L. Parra; O. López (108-113).
This work evaluates the effect of different bicellar systems on the percutaneous absorption of diclofenac diethylamine (DDEA) using two different approaches. In the first case, the drug was included in bicellar systems, which were applied on the skin and, in the second case, the skin was treated by applying bicellar systems without drug before to the application of a DDEA aqueous solution. The characterization of bicellar systems showed that the particle size decreased when DDEA was encapsulated. Percutaneous absorption studies demonstrated a lower penetration of DDEA when the drug was included in bicellar systems than when the drug was applied in an aqueous solution. This effect was possibly due to a certain rigidity of the bicellar systems caused by the incorporation of DDEA. The absorption of DDEA on skin pretreated with bicelles increased compared to the absorption of DDEA on intact skin. Bicelles without DDEA could cause certain disorganization of the SC barrier function, thereby facilitating the percutaneous penetration of DDEA subsequently applied. Thus, depending on their physicochemical parameters and on the application conditions, these systems have potential enhancement or retardant effects on percutaneous absorption that result in an interesting strategy, which may be used in future drug delivery applications.
Keywords: Bicellar systems; Diclofenac; In vitro percutaneous absorption; Vehicle; Drug delivery system;
Development of sulforaphane-encapsulated microspheres for cancer epigenetic therapy by D.P. Do; S.B. Pai; S.A.A. Rizvi; M.J. D'Souza (114-121).
Even though conventional chemotherapeutic management of cancer has reduced morbidity and mortality to a great extent, virtually all chemotherapeutic agents cause damage to healthy cells, necessitating exploration of novel anticancer agents that exert their effects through an alternate mode of action. Objectives of our research were twofold. First, we explored the promising potential of histone deacetylase inhibitor sulforaphane for epigenetic therapy for cancer as this therapeutic approach aims to reverse aberrant epigenetic modifications that affect gene expression. In vitro cell culture studies performed using B16 and S91 melanoma cells showed that sulforaphane inhibited growth and proliferation of cancer cells by downregulating deacetylation enzymes. The second part of our research investigated polymeric drug delivery systems to increase therapeutic efficacy and to minimize potential side effects of R,S-sulforaphane. Albumin microspheres encapsulating sulforaphane were developed by spray drying. Microspheres were characterized for their morphology, size and zeta potential. Cell culture studies using melanoma cells and in vivo studies in melanoma tumor-bearing C57BL/6 mice demonstrated that albumin based polymeric delivery system was efficacious and has the potential to enhance the therapeutic effect and anticancer activity of sulforaphane.
Keywords: Sulforaphane; Delivery system; Epigenetic therapy; Microspheres; Histone deacetylase inhibitors; Albumin;
Intracellular fate of octaarginine-modified liposomes in polarized MDCK cells by Takahiro Fujiwara; Hidetaka Akita; Hideyoshi Harashima (122-130).
Octaarginine (R8)-modified liposomes have been used to deliver therapeutic substances into cells owing to the efficient cellular uptake via macropinocytosis. Recent analyses revealed that R8-modified liposomes are mainly taken up via macropinocytosis, and escape from endosomes efficiently to avoid lysosomal degradation in non-polarized NIH–3T3 cells. In the present study, we evaluated the intracellular fate of R8-modfied liposomes in polarized MDCK cells, comparing their trafficking with that of conventional cationic liposomes by confocal laser scanning microscopy (CLSM). In contrast to what occurs in NIH–3T3 cells, R8-modified liposomes are internalized by MDCK cells equally well via clathrin-mediated endocytosis and macropinocytosis. The most salient characteristic in subsequent intracellular trafficking in MDCK cells is that R8-modified liposomes become trapped in the endosomal compartment and subsequently, a portion of them colocalizes with the Golgi apparatus. Similar colocalization with the Golgi apparatus was observed for octalysine (K8)-modified liposomes. In contrast, cationic liposomes were found to colocalize predominantly with lysosomes stained with lysotracker. Collectively, in polarized MDCK cells, cationic peptide-modified liposomes may be subjected to a different sorting pathway from that used for liposomes composed of cationic lipids.
Keywords: Golgi apparatus; Cationic peptide; Nanoparticles; Confocal microscopy;
A new sol–gel silica nanovehicle preparation for photodynamic therapy in vitro by Lin Zhou; Ji-Hua Liu; Jian Zhang; Shao-Hua Wei; Yu-Ying Feng; Jia-Hong Zhou; Bo-Yang Yu; Jian Shen (131-137).
We report a facile silica nanovehicle preparation procedure for hydrophobic drug delivery, which is carried out in water without adding any surfactant and additional catalyst. This strategy includes hydrophobic drug nanopaticle preparation by reprecipitation method and in situ hydrolyzation and polymerization to encapsulate this naoparticle using only N-(β-amimoethyl)-γ-aminopropyltyiethoxysilane (AETPS). To demonstrate this technique hypocrellin A (HA), a hydrophobic photosensitizing anticancer drug, is embedded into silica nanovehicle using this simple method. The resulting HA encapsulated nanovehicles (HANV) are monodisperse and stable in aqueous solution. Comparative studies with free HA and entrapped HA have demonstrated that the encapsulation effect on the embedded photosensitizer nanoparticle significantly enhances the efficacy of singlet oxygen generation and, thereby, the in vitro photodynamic efficacy.
Keywords: Silica nanovehicle; Hypocrellin A; Photodynamic therapy; Drug delivery system;
In-line quantification of drug and excipients in cohesive powder blends by near infrared spectroscopy by C.V. Liew; A.D. Karande; P.W.S. Heng (138-148).
This work was aimed at investigating the utility of near infrared (NIR) spectroscopy for simultaneous in-line quantification of drug and excipients in cohesive powder blends in a bin blender. A model formulation containing micronized chlorpheniramine maleate (μCPM), lactose, microcrystalline cellulose (MCC) and magnesium stearate (MgSt) was selected for the blending study. An optical head comprising a sapphire window mounted on the lid of the bin was used to collect in-line NIR spectral data of the powder blends. Validated partial least square (PLS) calibration models were used to quantify each component from the NIR spectra of the blends. Additionally, effects of premixing by sieving and high shear mixing and use of an internal prism fixed within the bin on the mixing performance of each component were studied. The statistical results obtained for PLS calibration models and their validation showed the sensitivity of NIR for accurate quantification of blend components. The blend prepared with high shear premixing and with prism achieved uniformity more rapidly than that with high shear premixing but without prism during blending in a bin blender. Premixing using sieving proved to be inadequate for uniform mixing of the blend components as none of the components except MgSt achieved uniform distribution after the preset blending time when blended in the bin blender. This study demonstrated that by high speed sampling and rapid spectral acquisition, distribution of individual blend components can be assessed with high accuracy during blending. Furthermore, high shear premixing facilitated rapid distribution and uniformity achievement of blend components. This technique may be used to monitor the relative distribution of individual blend components in real time and thus, to assess the performance of a bin blender for mixing of cohesive multi-component powder blends during development and production.
Keywords: Cohesive powder blend; Near infrared (NIR) spectroscopy; In-line quantification; IBC bin blender; Prism; Premixing;
Multivariate statistical approach to optimizing sustained-release tablet formulations containing diltiazem hydrochloride as a model highly water-soluble drug by Shingo Kikuchi; Kozo Takayama (149-155).
A multivariate statistical technique was applied to designing a tablet for the sustained release over 24 h of diltiazem hydrochloride, a model highly water-soluble drug. Tablets of a hydrophilic matrix composed of dextran derivatives and hypromellose were prepared. The formulations were optimized using a nonlinear-response surface method incorporating thin-plate spline interpolation (RSM-S). A bootstrap (BS) resampling method was used to estimate the confidence intervals of the optimal formulations. The response surfaces estimated by RSM-S visualized the effects of the formulation factors, and the optimal release profile for diltiazem was predicted quantitatively as a function of the quantities of the formulation factors, using RSM-S. The simultaneous optimal solutions and their confidence intervals were estimated using RSM-S and BS resampling. The results clearly indicate nonlinear relationships between the formulation factors and the response variables. The observed responses of the optimal preparation coincided well with the predicted responses. The optimal hydrophilic matrix tablet allowed almost zero-order release of diltiazem hydrochloride for 24 h. In conclusion, an oral sustained-release tablet formulation, active over a long period, was successfully optimized using RSM-S, and the reliability of the optimal solution was evaluated using BS resampling.
Keywords: Simultaneous optimization; Confidence interval; Sustained release; Highly water-soluble drug; Hydrophilic matrix tablet; Quality by design;
Efficient preparation and PEGylation of recombinant human non-glycosylated erythropoietin expressed as inclusion body in E. coli by Yin-Jue Wang; Yong-Dong Liu; Jing Chen; Su-Juan Hao; Tao Hu; Guang-Hui Ma; Zhi-Guo Su (156-164).
Recombinant human erythropoietin produced by mammalian cells contains about 40% carbohydrates which maintain its stability and long residence in body. However, mammalian derived Epo has low yields and high costs of production. In this article, a cost-effective strategy of producing non-glycosylated Epo from Escherichia coli and then PEGylating it to replace the role of sugar chains was investigated. Recombinant human non-glycosylated erythropoietin (rh-ngEpo) was overexpressed as inclusion body in E. coli. As the routine inclusion body washing step resulted in poor protein recovery and purity, a new process scheme of using strong ion-exchange chromatography to purify denatured rh-ngEpo from inclusion body before refolding was developed. The purity of the denatured rh-ngEpo was increased from 59% to over 90%. Rh-ngEpo was then refolded and subsequently purified by one step of weak cation-exchange chromatography to 98% pure. Final protein yield was 129 mg/l, a significant improvement from 49 mg/l obtained via the conventional practice. The in vitro bioactivity of purified rh-ngEpo was comparable with the CHO-expressed Epo and the formation of native secondary structure was also confirmed by CD spectra. Rh-ngEpo was then modified by a 20 kDa methoxy polyethylene glycol (PEG) succinimidyl carbonate. The monoPEGylated protein, which retained 68% bioactivity, had enhanced thermal stability and a remarkably prolonged circulating half-life in rats as compared with that of the unmodified protein. These studies demonstrated the feasibility of PEGylating rh-ngEpo as a promising way for the development of new Epo drugs.
Keywords: Recombinant erythropoietin; Non-glycosylated; Refolding; Purification; PEGylation; Half-life;
Microcalorimetric and spectrographic studies on the interaction of DNA with betaxolol by Dezhi Sun; Xiangyu Xu; Min Liu; Xiangjun Sun; Jingyu Zhang; Linwei Li; Youying Di (165-171).
The interaction of calf thymus deoxyribonucleic acid (ct-DNA) with betaxolol (BET) in aqueous buffer solution (pH 7.40) has been investigated using isothermal titration calorimetry (ITC), ultraviolet absorption (UV), fluorescence spectroscopy (FS) and circular dichroism (CD). Thermodynamic parameters, i.e., equilibrium constants, standard changes of enthalpy (ΔH°), Gibbs free energy (ΔG°) and entropy (ΔS°), for the binding process of the drug to the bio-macromolecules have been derived from the calorimetric data. Analysis of the thermodynamic data indicates that there are two classes of binding sites on the DNA molecules being able to coordinate with BET molecules. One class of binding takes place at the sites formed by base pairs, which is synergistically driven by enthalpy and entropy, while the other one takes place on phosphate groups and shown as an entropy driven process. The thermodynamic behavior of the DNA–drug supramolecular system has been discussed in the light of the important weak interactions, hydrophobic force, hydrogen bond and electrostatic force, according to the UV, FS and CD spectra.
Keywords: Calf thymus deoxyribonucleic acid; Betaxolol; Thermodynamics; Spectroscopy;
Release profile of insulin entrapped on mesoporous materials by freeze–thaw method by Yuichi Tozuka; Eri Sugiyama; Hirofumi Takeuchi (172-177).
Adsorption profiles of insulin on porous materials and release profiles of insulin entrapped on folded-sheet mesoporous silica (FSM) were studied. Three types of FSM with different pore sizes (3.0, 6.1, and 9.2 nm) were used as candidates. A simple technique of repeated freezing and thawing resulted in effective adsorption of insulin on mesoporous structures. The amount of adsorbed insulin, estimated by protein assay, increased with an increase in the pore sizes of FSM used. Nitrogen sorption analysis showed that the specific surface area and pore volume decreased according to the insulin adsorption. On the release profile of insulin, the smallest pore size of FSM (3.0) was found to be a suitable material for a fast release of insulin, whereas the medium-pore FSM (6.1) held the insulin inside the pores for a longer time. Consequently, the desired release of insulin could be achieved by selecting the appropriate pore size of FSM.
Keywords: Insulin; Mesoporous silica; Adsorption; Release profile;
Characterisation of the thermal properties of ethylcellulose using differential scanning and quasi-isothermal calorimetric approaches by Hui Ling Lai; Kendal Pitt; Duncan Q.M. Craig (178-184).
The thermal behaviour of the ethylcellulose (EC), a polymer that is widely used in pharmaceutical dosage forms, has been investigated with a view to study the glass transition and higher temperature thermal events as well as to develop new approaches to characterise this complex polymer system. Samples of EC powder were studied using conventional and modulated temperature differential scanning calorimetry (MTDSC), quasi-isothermal (Qi-)MTDSC and hot stage microscopy (HSM) with simultaneous transmitted light intensity measurements. The T g was noted at circa 128–130 °C, with an accompanying baseline drift associated with a temperature dependent heat capacity change. A higher temperature combined endo/exothermic event was noted at 170–190 °C. TGA studies indicated that the exotherm was associated with oxidative degradation, with the accompanying DSC data being highly dependent on the sample encapsulation method used. The endotherm was found to be kinetically hindered, as demonstrated using Qi-MTDSC; the technique also indicated that there was little evidence for reversing processes through this transition. HSM studies indicated birefringence for the sample at low temperatures which disappeared as the material temperature approached T g but reappeared on further heating, again disappearing at circa 180 °C. Light intensity scans produced a profile similar to that seen for the DSC studies. It is proposed that the sample contains microcrystals composed of unsubstituted segments of the cellulose backbone. The implications of these findings for the understanding of the pharmaceutical behaviour and thermal characterisation of ethylcellulose are discussed.
Keywords: Ethylcellulose; Polymer; Thermal; Film coat; Controlled release;
Investigation of different formulations for drug delivery through the nail plate by Ivana Vejnovic; Linda Simmler; Gabriele Betz (185-194).
Topical therapies for nail diseases are limited by keratinized cells in the human nail plate. An optimal permeation enhancer would not only improve drug delivery through the nail plate, but would also open new possibilities for treating neighboring target sites if systemic circulation is reached. The aim of the present work was to identify permeation enhancers and to improve the understanding of physicochemical parameters that influence drug permeation. Caffeine served as the model drug, and formulations were prepared in water and 20% (v/v) ethanol/water solutions. Tested enhancers were urea, dimethyl sulfoxide (DMSO), methanol, N-acetyl-l-cysteine (NAC), docusate sodium salt (DSS), boric acid, and fungal proteins, such as hydrophobins. Permeability studies employed cadaver nails in modified Franz-type diffusion cells. The permeability coefficient of caffeine in ethanol/water was determined to be 1.56E−08 cm/s and was improved to 2.27E−08 cm/s by the addition of NAC. Formulations containing either methanol or DMSO showed the highest permeability coefficients in the range of 5–7.5E−08 cm/s. Enhancers could be classified according to their permeation enhancement: methanol > class II hydrophobins > DMSO > followed by class I hydrophobins and urea. Ethanol at a concentration of 20% (v/v) in water did not influence swelling of nail samples. Hydrophobins are suggested to be efficient in drug delivery through the nail plate.
Keywords: Human nail plate; Onychomycosis; Topical application; Enhancers; Hydrophobins; Permeability;
Stabilization by meglumine of an amine compound degraded by formaldehyde in tablets by Megumi Fujita; Tomohiko Ueda; Motokazu Iwata (195-200).
[3-[(2R)-[[(2R)-(3-Chlorophenyl)-2-hydroxyethyl]amino]proryl]-1H-indol-7-yloxy]acetic acid (AJ-9677), which was being developed as an antidiabetic, was observed to degrade in tablet preparations. The main degradation product in tablets, AD-9889, was a carbon adduct of the drug substance. When the drug substance was exposed to formaldehyde in aqueous solutions, a correlation was found between the level of formaldehyde and the quantity of AD-9889 formed during storage. Comprehensive one- and two-dimensional NMR analysis of the reaction product identified the location of the carbon atom which originated from formaldehyde, thus proving that AD-9889 was produced by a reaction with formaldehyde. Since it was demonstrated in our previous report that meglumine is an amine that can react with, and reduce amounts of formaldehyde, its stabilizing effect on AJ-9677 was examined. The results showed that in a solution system containing AJ-9677, formaldehyde and meglumine, meglumine reduced formaldehyde levels and suppressed degradation. Addition of meglumine into the tablet formulation of AJ-9677 was also effective in suppressing degradation and successfully stabilized the drug substance. This effect was almost certainly due to meglumine absorbing formaldehyde from around the drug substance and we believe that meglumine can be used with many other drug substances degraded by formaldehyde.
Keywords: Meglumine; Formaldehyde; Stabilization; Degradation; Tablet;
Dissolution parameters for sodium diclofenac-containing hypromellose matrix tablet by Samanta C. Mourão; Cristiane da Silva; Tania M.B. Bresolin; Cristina H.R. Serra; Valentina Porta (201-207).
Sodium diclofenac (SD) release from dosage forms has been studied under different conditions. However, no dissolution method that is discriminatory enough to reflect slight changes in formulation or manufacturing process, and which could be effectively correlated with the biological properties of the dosage form, has been reported. This study sought to develop three different formulae of SD-containing matrix tablets and to determine the effect of agitation speed in its dissolution profiles. F1, F2 and F3 formulations were developed using hypromellose (10, 20 and 30%, respectively for F1, F2 and F3) and other conventional excipients. Dissolution tests were carried out in phosphate buffer pH 6.8 at 37 °C using apparatus II at 50, 75 or 100 rpm. Dissolution efficiency (DE), T 50 and T 90 were determined and plotted as functions of the variables agitation speed and hypromellose concentration. Regarding DE, F2 showed more sensitivity to variations in agitation speed than F1 and F3. Increasing hypromellose concentration reduced DE values, independent of agitation speed. Analysis of T 50 and T 90 suggests that F1 is less sensitive to variations in agitation speed than F2 and F3. Most discriminatory dissolution conditions were observed at 50 rpm. Results suggest that the comparison of dissolution performance of SD matrix tablets should take into account polymer concentration and agitation conditions.
Keywords: Sodium diclofenac; Dissolution assay; Dissolution kinetics; Hypromellose;
Biodistribution of HuCC49ΔCH2-β-galactosidase in colorectal cancer xenograft model by Yanke Yu; Lanyan Fang; Duxin Sun (208-215).
Antibody–enzyme conjugate (AbE) has been widely studied for site-specific prodrug activation in tumors. The purpose of this study is to characterize the pharmacokinetics and tissue distribution of HuCC49ΔCH2-β-galactosidase conjugate. HuCC49ΔCH2 and β-galactosidase were chemically conjugated and injected into a LS 174T colon cancer xenograft model. A colorimetric assay was developed to quantify the HuCC49ΔCH2-β-galactosidase levels in plasma and tissues. The HuCC49ΔCH2-β-galactosidase conjugate distributed into tumor tissue as early as 6 h with the tumor/blood ratio of 5. This favored distribution of conjugate activity in the tumor tissue which was maintained up to 4 days post conjugate injection, while the conjugate was cleared rapidly from blood and other normal tissues (heart, spleen, lung, liver, kidney and stomach). At a high dose of 3000 U/kg, HuCC49ΔCH2-β-galactosidase conjugate saturated the antigen binding sites and yielded decreased tumor/normal tissue ratios compared to 1500 U/kg. These data suggest that HuCC49ΔCH2-β-galactosidase specifically target to the tumors to increase tumor selectivity.
Keywords: Biodistribution; ADEPT; HuCC49ΔCH2; Antibody; Pharmacokinetics;
MRP2 mediated drug–drug interaction: Indomethacin increases sulfasalazine absorption in the small intestine, potentially decreasing its colonic targeting by Arik Dahan; Gordon L. Amidon (216-220).
We have recently shown that efflux transport, mediated by multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP), is responsible for sulfasalazine low-permeability in the small intestine, thereby enabling its colonic targeting and therapeutic action. The purpose of the present study was to evaluate the potential pharmacokinetic interaction between indomethacin and sulfasalazine, in the mechanism of efflux transporter competition. The concentration-dependent effects of indomethacin on sulfasalazine intestinal epithelial transport were investigated across Caco-2 cell monolayers, in both apical to basolateral (AP–BL) and BL–AP directions. The interaction was then investigated in the in situ single-pass rat jejunal perfusion model. Sulfasalazine displayed 30-fold higher BL–AP than AP–BL Caco-2 permeability, indicative of net mucosal secretion. Indomethacin significantly increased AP–BL and decreased BL–AP sulfasalazine Caco-2 transport, in a concentration-dependent manner, with IC50 values of 75 and 196 μM respectively. In the rat model, higher sulfasalazine concentrations resulted in higher intestinal permeability, consistent with saturation of efflux transporter. Without indomethacin, sulfasalazine demonstrated low rat jejunal permeability (vs. metoprolol). Indomethacin significantly increased sulfasalazine P eff, effectively shifting it from BCS (biopharmaceutics classification system) Class IV to II. In conclusion, the data indicate that concomitant intake of indomethacin and sulfasalazine may lead to increased absorption of sulfasalazine in the small intestine, thereby reducing its colonic concentration and potentially altering its therapeutic effect.
Keywords: Intestinal absorption; Molecular biopharmaceutics; Efflux transport; Drug–drug interaction; Passive/active GI wall permeability;
Study of branched cationic β-cyclodextrin polymer/indomethacin complex and its release profile from alginate hydrogel by Jianyu Xin; Zhizhang Guo; Xingyu Chen; Wenfeng Jiang; Jianshu Li; Maolin Li (221-228).
A series of branched cationic β-cyclodextrin polymers (CPβCDs) with designed chemical structures were synthesized from β-cyclodextrin (β-CD), epichlorohydrin (EP) and choline chloride (CC). Indomethacin (IDM), an anionic drug, was chosen as a model drug to evaluate the drug loading capacities of CPβCDs. The formation of IDM-CPβCD complex was confirmed by 1H NMR and DSC. Phase solubility studies and Job plots indicated that CPβCDs can solubilize IDM up to 100 times of its intrinsic solubility in a 1:1 complexation form. Mechanism studies with the help of adamantane revealed that the effective complexation is a combination of inclusion complexation, charge interaction and hydrophobic interaction. In addition, IDM-CPβCDs loaded alginate hydrogels were prepared and obtained controllable release profile in dissolution tests. The tunable structures of CPβCDs make them promising drug carriers with superior drug loading capacities and controllable drug release abilities.
Keywords: Branched cationic β-cyclodextrin polymers; Indomethacin; Complexation; Alginate hydrogel; Drug release;
Separation of major catechins from green tea by ultrahigh pressure extraction by Xi Jun; Zhao Shuo; Lu Bingbing; Zhang Rui; Li Ye; Shen Deji; Zhou Guofeng (229-231).
This study presents a novel extraction technique, ultrahigh pressure extraction, to obtain major catechins from green tea leaves. The effects of various high pressure level (100, 200, 300, 400, 500, 600 MPa) on the extract are examined. HPLC chromatographic analyses determine the concentration of four major catechins and caffeine. The extraction yields of active ingredients with ultrahigh pressure extraction (400 MPa pressure) for only 15 min were given the same as those of organic solvent extraction for 2 h. These excellent results for the ultrahigh pressure extraction are promising for the future separation of active ingredients from traditional Chinese herbal medicine.
Keywords: Ultrahigh pressure extraction; Catechins; Caffeine; Extraction; Green tea leaves;
Non-viral gene delivery carrier and its three-dimensional transfection system by Cai-Xia He; Yasuhiko Tabata; Jian-Qing Gao (232-242).
An increasing number of non-viral vectors are being developed for the use of gene delivery nowadays, among which cationic polymers and lipoplexes receive most attention. Most of these researches are focused on how to increase the transfection efficiency of non-viral vectors as well as the reduction of toxicity. In this review, we go over new strategies to reduce the toxicity of cationic polyplexes such as poly(ethylene-imine) and the construction of highly effective gene transfer vector lipoplexes. In addition, since transformation of gene expression system from two-dimensional (2D) substrate to 3D scaffold triggers far better transfection efficiency, the non-viral vectors applied in 3D transfection system have also been reviewed.
Keywords: Non-viral vector; Gene delivery; Polyplexes; PEI; Lipoplexes; Three-dimensional scaffolds;
A combinational supercritical CO2 system for nanoparticle preparation of indomethacin by Yuichi Tozuka; Yuta Miyazaki; Hirofumi Takeuchi (243-248).
An improved system using both supercritical antisolvent precipitation and rapid expansion from supercritical to aqueous solution (RESAS) was proposed to overcome the problem of low solubility of medicinal substances in scCO2. When the ethanol solution with IMC was sprayed into the vessel purged with scCO2, no precipitation of IMC was observed if the CO2 pressure was more than 15 MPa at 40 °C. This indicates that very small droplets of the ethanol solution with IMC could disperse in the high pressure CO2. After expansion into distilled water using an RESAS device, this same solution, in CO2 at high pressure, produced submicron particles of IMC. For the pharmaceutical application, the IMC suspension was freeze-dried and re-dispersed to the aqueous media. SEM images of freeze-dried sample showed that the suspension was composed of submicron particles with 300–500 nm. Although the average particle size of re-dispersed IMC related significantly to the pressure and temperature in the vessel on scCO2 processing, the freeze-dried sample of the IMC suspension after the treatment shows good redispersibility as a nanosuspension. This apparatus is found to be a promising way to produce fine crystals of IMC with a high yield.
Keywords: Nanocrystal; Supercritical carbon dioxide; Indomethacin;
Preparation and evaluation of anti-neuroexcitation peptide (ANEP) loaded N-trimethyl chitosan chloride nanoparticles for brain-targeting by Siling Wang; Tongying Jiang; Mingxin Ma; Yanchen Hu; Jinghai Zhang (249-255).
Anti-neuroexcitation peptide (ANEP) is a promising candidate for the treatment of neuroexcitation-associated diseases. N-Trimethyl chitosan (TMC) with different degrees of quaternization was synthesized, characterized and evaluated as a brain-targeting delivery vehicle for ANEP. ANEP-loaded TMC nanoparticles were prepared by ionic crosslinking of TMC with tripolyphosphate (TPP). The optimized formulation of nanoparticles consisted of TMC with a degree of quaternization (DQ) of 36.1% and TPP solution with a concentration of 0.6 mg/mL. The mean encapsulation efficiency and loading capacity of the optimum formulation was 80.63% and 185.4 μg/mL, respectively, while the mean particle size, zeta potential, and pH value were 255 nm, 32.0 mV and 6.61, respectively. ANEP was labeled with FITC for in vivo tissue distribution experiments. The results showed that the targetability of ANEP to brain was significantly increased by TMC nanoparticles. Absorptive-mediated transcytosis was believed to be the main pathway for the brain-targeting of FITC–ANEP–TMC/NPs. These findings demonstrate that TMC nanoparticles are potentially useful brain-targeting delivery systems for ANEP.
Keywords: Anti-neuroexcitation peptide; Brain-targeting; N-Trimethyl chitosan chloride; Nanoparticles; Biodistribution;
A continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs by Yuancai Dong; Wai Kiong Ng; Jun Hu; Shoucang Shen; Reginald B.H. Tan (256-261).
Rapid and homogeneous mixing of the solvent and antisolvent is critical to achieve submicron drug particles by antisolvent precipitation technique. This work aims to develop a continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs with spironolactone as a model drug. Continuous antisolvent production of drug nanoparticles was carried out with a SMV DN25 static mixer comprising 6–18 mixing elements. The total flow rate ranged from 1.0 to 3.0 L/min while the flow rate ratio of solvent to antisolvent was maintained at 1:9. It is found that only 6 mixing elements were sufficient to precipitate the particles in the submicron range. Increasing the number of elements would further reduce the precipitated particle size. Increasing flow rate from 1.0 to 3.0 L/min did not further reduce the particle size, while higher drug concentrations led to particle size increase. XRD and SEM results demonstrated that the freshly precipitated drug nanoparticles are in the amorphous state, which would, in presence of the mixture of solvent and antisolvent, change to crystalline form in short time. The lyophilized spironolactone nanoparticles with lactose as lyoprotectant possessed good redispersibility and showed 6.6 and 3.3 times faster dissolution rate than that of lyophilized raw drug formulation in 5 and 10 min, respectively. The developed static mixing process exhibits high potential for continuous and large-scale antisolvent precipitation of submicron drug particles.
Keywords: Static mixers; Spironolactone; Oral bioavailability; Antisolvent precipitation; Dissolution rate;
Preparation of MPEG–PLA nanoparticle for honokiol delivery in vitro by XiuLing Zheng; Bing Kan; MaLing Gou; ShaoZhi Fu; Juan Zhang; Ke Men; LiJuan Chen; Feng Luo; YingLan Zhao; Xia Zhao; YuQuan Wei; ZhiYong Qian (262-267).
Honokiol (HK) shows potential application in cancer treatment, but its poor water solubility restricts clinical application greatly. In this paper, monomethoxy poly(ethylene glycol)–poly(lactic acid) (MPEG–PLA) was synthesized by ring-opening polymerization and processed into nanoparticle for honokiol delivery. Chemical structure of the synthesized polymer was confirmed by 1H NMR, and its molecular weight was determined by gel permeation chromatography (GPC). Honokiol loaded MPEG–PLA nanoparticles were prepared by solvent extract method. And particle size distribution, morphology, drug loading, drug release profile and anticancer activity in vitro were studied in detail. The described honokiol loaded MPEG–PLA nanoparticles in this paper might be a novel formulation for honokiol delivery.
Keywords: Honokiol; MPEG–PLA; Solvent extract method; Nanoparticles;
Self-assembled drug delivery systems. Part 5: Self-assemblies of a bolaamphiphilic prodrug containing dual zidovudine by Yiguang Jin; Ningning Qi; Li Tong; Dawei Chen (268-274).
A bolaamphiphilic prodrug containing dual zidovudine, pentadecanedioyl dizidovudine (PDDZ), was prepared. The vesicular self-assemblies were formed in aqueous media through injecting the methanol solution of PDDZ into water. Hydrophobic interaction between lipid chains should drive molecular self-assembly. The nonionic surfactant, Tween 20, was used to increase the physical stability of self-assemblies because the surfactant micelles could prevent the assemblies from aggregating. The doping hydroxylpropylmethylcellulose (HPMC) slowed down the degradation of prodrugs due to adsorption. The self-assemblies were nanoscale with the mean particle size of 156 nm. Degradation of PDDZ was very slow in buffered solutions, but very rapid in enzyme and plasma, and the parent drug zidovudine (AZT) was the unique product. PDDZ self-assemblies showed strong anti-HIV activity on MT4 cell model. The 50% effective concentration (EC50) of PDDZ was 5 nM, equal to that of AZT. PDDZ was rapidly eliminated from circulation and mainly distributed into liver, spleen and testis followed by the rapid production of AZT after intravenous administration of the self-assemblies to rabbits. Macrophages in liver, spleen and testis are the reservoir of HIV so that the macrophage targeting effect of PDDZ self-assemblies would benefit to anti-HIV therapy. The self-assemblies composed of bolaamphiphilic PDDZ are a promising self-assembled drug delivery system (SADDS).
Keywords: Anti-HIV; Bolaamphiphilic; Macrophage; Nanotechnology; Prodrug; Molecular self-assembly; Zidovudine;
Bioadhesion and oral absorption of enoxaparin nanocomplexes by Wei Sun; Shirui Mao; Yanjun Wang; Varaporn B. Junyaprasert; Tingting Zhang; Lidong Na; Juan Wang (275-281).
Polyelectrolyte complexes (PEC) formed between chitosan derivatives and enoxaparin were prepared by a self-assembly process and were characterized in terms of particle size and surface charge. The morphology was observed by atomic force microscopy (AFM). The colloidal stability and bioadhesion of the PEC were characterized by dynamic light scattering (DLS). The absorption of enoxaparin in rats was evaluated by activated partial thromboplastin time (APTT) assay. It was shown that the prepared PEC had a spherical shape with positive charge and a mean diameter in the range of 200–600 nm. An increase in temperature led to a decrease in particle size (ca. 10%) with an increased kcps value (ca. 10–20%) for the PEC studied, depending on the polymer structure. Thiolation and methylation of chitosan could significantly improve the corresponding PEC's bioadhesion and hence the oral absorption of enoxaparin. A good relationship between bioadhesion and in vivo absorption was established. However, PEC of PEGylated chitosan did not display a significantly enhanced permeation of enoxaparin compared with unmodified chitosan. In conclusion, the oral bioavailability of enoxaparin can be enhanced by improving the bioadhesive properties of PEC via the chemical modification of chitosan employed.
Keywords: Chitosan; Thiolated chitosan; Trimethyl chitosan; PEGylation; Enoxaparin; Polyelectrolyte complex; Bioadhesion; Oral absorption;
Preparation and evaluation of self-nanoemulsified drug delivery systems (SNEDDSs) of matrine based on drug–phospholipid complex technique by Jinghua Ruan; Jie Liu; Di Zhu; Tao Gong; Fumei Yang; Xiaojiang Hao; Zhirong Zhang (282-290).
To enhance oral bioavailability of matrine, a dedicated and newly emerging drug system called self-nanoemulsifying drug delivery system (SNEDDSs) was developed. Phospholipid complex (MPC) was prepared using solvent-evaporation method to improve the liposolubility of matrine. Solubilization test, infrared spectroscopy (IR) and differential scanning calorimetry (DSC) analysis were employed to confirm the formation of MPC. A rational experimental design was adopted to optimize the properties of SNEDDSs. Eight SNEDDSs prototypes were obtained to form nanoemulsion spontaneously based on optimization experiments. Among them, MPC prepared exhibited excellent solubility. SNEDDSs 2 (composition: Lauroglycol FCC, Cremophor EL and Transcutol HP; ratio: 6:4:1) was selected as the optimal formulation, with a mean droplet size in the range of 65–80 nm and 8.34% of the leakage rate, exhibiting instantaneous emulsion formation with only one flask inversion. Media pH and dilution factor showed no effect on the droplet size. The oral absorption of matrine in rats via SNEDDSs delivery was investigated. C max was increased dramatically from 4.12 to 6.52 and 7.95 μg/mL in case of matrine, MPC and MPC-SNEDDS. In parallel to C max, prolonged T max from 0.39 to 0.50 h, and 3.00 h could be observed. AUC0–t of MPC-SNEDDSs was significantly higher than other two counterparts. In conclusion, the absolute bioavailability of matrine drastically increased from 25% to 84.6% by the formation of MPC-SNEDDS, with an outstanding relative bioavailability of 338%, suggesting its great potential for clinical application.
Keywords: SNEDDSs; Bioavailability of matrine; Enhanced oral bioavailability;