European Journal of Pharmaceutics and Biopharmaceutics (v.73, #1)
Lipid – An emerging platform for oral delivery of drugs with poor bioavailability
by Subhashis Chakraborty; Dali Shukla; Brahmeshwar Mishra; Sanjay Singh (pp. 1-15).
The sole objective of pharmaceutical science is to design successful dosage forms which fulfill the therapeutic needs of the patients effectively. Development of new drug entities is posing real challenge to formulators, particularly due to their poor aqueous solubility which in turn is also a major factor responsible for their poor oral bioavailability. Lipids as carriers, in their various forms, have the potential of providing endless opportunities in the area of drug delivery due to their ability to enhance gastrointestinal solubilization and absorption via selective lymphatic uptake of poorly bioavailable drugs. These properties can be harvested to improve the therapeutic efficacy of the drugs with low bioavailability, as well as to reduce their effective dose requirement. The present communication embodies an in-depth discussion on the role of lipids (both endogenous and exogenous) in bioavailability enhancement of poorly soluble drugs, mechanisms involved therein, approaches in the design of lipid-based oral drug delivery systems with particular emphasis on solid dosage forms, understanding of morphological characteristics of lipids upon digestion, in vitro lipid digestion models, in vivo studies and in vitro–in vivo correlation.
Keywords: Lipid-based oral drug delivery; Lipase activity; Lymphatic uptake; Bioavailability enhancement; Solid dosage form; Adsorption; Lipid digestion products; In vitro lipolytic model; In vitro–in vivo correlation; Solid lipid nanoparticles
Targeting nanoparticles to M cells with non-peptidic ligands for oral vaccination
by Virginie Fievez; Laurence Plapied; Anne des Rieux; Vincent Pourcelle; Hélène Freichels; Valentine Wascotte; Marie-Lyse Vanderhaeghen; Christine Jerôme; Alain Vanderplasschen; Jacqueline Marchand-Brynaert; Yves-Jacques Schneider; Véronique Préat (pp. 16-24).
The presence of RGD on nanoparticles allows the targeting of β1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis that non-peptidic ligands targeting intestinal M cells or APCs would be more efficient for oral immunization than RGD, novel non-peptidic and peptidic analogs (RGD peptidomimitic (RGDp), LDV derivative (LDVd) and LDV peptidomimetic (LDVp)) as well as mannose were grafted on the PEG chain of PCL–PEG and incorporated in PLGA-based nanoparticles. RGD and RGDp significantly increased the transport of nanoparticles across an in vitro model of human M cells as compared to enterocytes. RGD, LDVp, LDVd and mannose enhanced nanoparticle uptake by macrophages in vitro. The intraduodenal immunization with RGDp-, LDVd- or mannose-labeled nanoparticles elicited a higher production of IgG antibodies than the intramuscular injection of free ovalbumin or intraduodenal administration of either non-targeted or RGD-nanoparticles. Targeted formulations were also able to induce a cellular immune response. In conclusion, the in vitro transport of nanoparticles, uptake by macrophages and the immune response were positively influenced by the presence of ligands at the surface of nanoparticles. These targeted-nanoparticles could thus represent a promising delivery system for oral immunization.
Keywords: Oral delivery; Vaccine; Nanoparticles; M cells targeting; Non-peptidic ligands; Immunization
Design for optimization of nanoparticles integrating biomaterials for orally dosed insulin
by Camile Baldin Woitiski; Francisco Veiga; António Ribeiro; Ronald Neufeld (pp. 25-33).
Design of nanoparticles integrating biomaterials that govern the functional behavior of orally dosed insulin is focused on improving insulin stability and absorption by facilitating its uptake and translocation throughout the intestinal membrane, while providing protection from acidic and enzymatic degradation in the gastrointestinal tract. The purpose of the study was to optimize a nanoparticle formulation by investigating the relationship between design factors and experimental data by response surface methodology. Designed nanoparticles consisting of calcium crosslinked alginate, dextran sulfate, poloxamer 188 and chitosan followed by an outermost coating of albumin are described as multilayer complex retaining insulin within the nanoparticle. A 3-factor 3-level Box–Behnken design was used to optimize nanoparticle formulation. The screened independent variables were the concentration of calcium chloride, chitosan and albumin, and the dependent variables were particle size, polydispersity index, zeta potential, entrapment efficiency and insulin release in enzyme-free simulated digestive fluids. Experimental responses of a total of 15 formulations resulted in mean nanoparticle diameters ranging from 394 to 588nm, with polydispersity index from 0.77 to 1.10, zeta potential values ranging from −36.6 to −44.5mV, and entrapment efficiency of insulin was over 85%. Insulin release from nanoparticles in enzyme-free digestive fluids was prevented during 120min in gastric conditions, and over 80% of insulin was released after 180min in simulated intestinal fluid. Based on the experimental responses and the criteria of desirability defined by constraints, solutions of 0.20% calcium chloride, 0.04% chitosan and 0.47% albumin constitute the optimum formulation of nanoparticles for orally dosed insulin.
Keywords: Insulin; Nanoparticles; Optimization; Box–Behnken design; Response surface methodology
Influences of opioids and nanoparticles on in vitro wound healing models
by Nadine B. Wolf; Sarah Küchler; Michal R. Radowski; Tobias Blaschke; Klaus D. Kramer; Günther Weindl; Burkhard Kleuser; Rainer Haag; Monika Schäfer-Korting (pp. 34-42).
For efficient pain reduction in severe skin wounds, topical opioids may be a new option – given that wound healing is not impaired and the vehicle allows for slow opioid release, since long intervals of painful wound dressing changes are intended. We investigated the influence of opioids on the wound healing process via in vitro models, migration assay and scratch test. In fact, morphine, hydromorphone, fentanyl and buprenorphine increased the number of migrated HaCaT cells (spontaneously transformed keratinocytes) twofold. In the scratch test, morphine accelerated the closure of a monolayer wound (scratch). As possible slow release application forms are nanoparticulate systems like solid lipid nanoparticles (SLN) and dendritic core-multishell (CMS) nanotransporters, we evaluated the effect of unloaded nanoparticles on HaCaT cell migration, too. CMS nanotransporters did not inhibit migration, SLN even enhanced it (twofold). Applying morphine plus unloaded nanoparticles reduced morphine effects possibly due to uptake into CMS nanotransporters and adsorption to the surface of SLN. In contrast to SLN, TGF-β1 was taken up by CMS nanotransporters, too. Both nanoparticles are tolerable by skin and eye as derived from Episkin-SMTM skin irritation test and HET-CAM assay. No acute toxic effects were observed either. In conclusion, opioids as well as the investigated nanoparticulate carriers conform the essential conditions for topical pain reduction.
Keywords: Wound healing models; Topical opioids; Solid lipid nanoparticles; Dendritic core-multishell nanotransporters; Skin irritation test; HET-CAM assayAbbreviations; B; buprenorphine; BSA; bovine serum albumin; CMS; dendritic core-multishell nanotransporters; c; particle; particle concentration; F; fentanyl; FCS; fetal calf serum; H; hydromorphone; HaCaT; human adult low calcium temperature keratinocytes; M; morphine; n.s.; not significant; PBS; phosphate buffered saline; r.t.; room temperature; SD; standard deviation; SLN; solid lipid nanoparticle(s); TGF-β1; transforming growth factor β1
Polyethylenimine nanoparticles as an efficient in vitro siRNA delivery system
by Surendra Nimesh; Ramesh Chandra (pp. 43-49).
Degradation of mRNA by RNA interference is one of the most powerful and specific mechanism for gene silencing. Owing to this property, siRNAs are emerging as promising therapeutic agents for the treatment of inherited and acquired diseases, as well as research tools for the elucidation of gene function in both health and disease. Here we have explored the potential of polyethylenimine (PEI) to deliver siRNA to mammalian cells. Nanoparticles of PEI were prepared by acylating PEI with propionic anhydride followed by cross-linking with polyethylene glycol-bis(phosphate). The nanoparticles size as revealed by DLS studies was found to be ∼110nm and AFM investigations showed spherical and compact complexes with an average size of 100nm. For electro-neutralization of negative charge of siRNA higher amount of nanoparticles was required as compared to native PEI. The siRNA delivery efficiency of nanoparticles was assessed by using siRNA against gene coding for green fluorescent protein (GFP). The gene silencing efficiency of PEI nanoparticles was found to be comparable to commercially available transfecting agent Lipofectin but with reduced cytotoxicity.
Keywords: Gene silencing; Nanoparticles; Polyethylenimine; siRNA; GFP
VEGF-controlled release within a bone defect from alginate/chitosan/PLA-H scaffolds
by Beatriz De la Riva; Christian Nowak; Esther Sánchez; Antonio Hernández; Michaela Schulz-Siegmund; Martina K. Pec; Araceli Delgado; Carmen Évora (pp. 50-58).
VEGF and its receptors constitute the key signaling system for angiogenic activity in tissue formation, but a direct implication of the growth factor in the recruitment, survival and activity of bone forming cells has also emerged. For this reason, we developed a composite (alginate/chitosan/PLA-H) system that controls the release kinetics of incorporated VEGF to enhance neovascularization in bone healing. VEGF release kinetics and tissue distribution were determined using iodinated (125I) growth factor. VEGF was firstly encapsulated in alginate microspheres. To reduce the high in vitro burst release, the microspheres were included in scaffolds. Matrices were prepared with alginate (A-1, A-2), chitosan (CH-1, CH-2) or by coating the CH-1 matrix with a PLA-H (30kDa) film (CH-1-PLA), the latter one optimally reducing the in vitro and in vivo burst effect. The VEGF in vitro release profile from CH-1-PLA was characterized by a 13% release within the first 24h followed by a constant release rate throughout 5weeks. For VEGF released from composite scaffolds in vitro, bioactivity was maintained above 90% of the expected value. Despite the fact that the in vivo release rate was slightly faster, a good in vitro– in vivo correlation was found. The VEGF released from CH-1 and CH-1-PLA matrices implanted into the femurs of rats remained located around the implantation site with a negligible systemic exposure. These scaffolds provided a bone local GF concentration above 10ng/g during 2 and 5weeks, respectively, in accordance to the in vivo release kinetics. Our data show that the incorporation of VEGF into the present scaffolds allows for a controlled release rate and localization of the GF within the bone defect.
Keywords: Vascular endothelial growth factor (VEGF); Alginate; Chitosan; Poly(lactide); Bone regeneration
In vivo and in vitro anti-cancer activity of thermo-sensitive and photo-crosslinkable doxorubicin hydrogels composed of chitosan–doxorubicin conjugates
by Young Il Cho; Shinyoung Park; Seo Young Jeong; Hyuk Sang Yoo (pp. 59-65).
Doxorubicin was chemically conjugated to acrylated chitosan in order to obtain sustained-release profiles of doxorubicin from thermo-responsive and photo-crosslinkable hydrogels. Chitooligosaccharide was acrylated with glycidyl methacrylate and subsequently conjugated to doxorubicin via an amide linkage. A mixture of doxorubicin–chitosan conjugates, acrylated Pluronic, and doxorubicin formed physical gels at 37°C. Photo-irradiation was subsequently performed to chemically crosslink the physical hydrogel at 37°C. Chitooligosaccharide–doxorubicin conjugates in the doxorubicin hydrogels significantly reduced burst release of free doxorubicin from doxorubicin hydrogels compared hydrogels without the conjugates. Upon incubating doxorubicin hydrogels at 37°C, chitosan–doxorubicin conjugates were confirmed to be degraded into more hydrophilic oligomers by reversed-phase chromatography. In vitro cytotoxicity assay using released media from doxorubicin hydrogels showed that degraded chitosan–doxorubicin had cytotoxicity comparable to free doxorubicin. Athymic nude mice bearing human lung adenocarcinoma were subjected to intra-tumoral injections of physical hydrogels. After photo-crosslinking injected hydrogels using surgical catheters, tumor sizes, body weights, and survivals were measured for 1month. Released media from doxorubicin hydrogels exerted similar cytotoxicities to free doxorubicin, and the tumor volume was significantly reduced for 1month compared to other samples. Thus, doxorubicin hydrogels containing doxorubicin conjugates can be employed as a novel injectable anti-cancer drug aiming to achieve sustained release of doxorubicin for several weeks against solid tumors.
Keywords: Doxorubicin; Conjugate; Hydrogel; Chitosan; Pluronic; Anti-cancer
Interactions between poly(ethylene glycol) and protein in dichloromethane/water emulsions. 2. Conditions required to obtain spontaneous emulsification allowing the formation of bioresorbable poly(d,l lactic acid) microparticles
by Aurélie Malzert-Fréon; Karin Schönhammer; Jean-Pierre Benoît; Frank Boury (pp. 66-73).
From microscopic observations, it was established that an oil-in-water emulsion with droplets of a size in the micrometer range can spontaneously form at room temperature without additional external stirring as soon as a solvent that is only partly miscible to water-like dichloromethane (DCM) is put in contact with an aqueous mixture of polyethylene glycol (PEG) and a protein. Experimental results show that emulsification only occurs if the system simultaneously includes PEG with middle chain, an organic solvent partly miscible to water and for which PEG affinity is sufficiently high, and a protein. From adsorption kinetics, it appears that this spontaneous emulsification process is related to the rapid diffusion of DCM towards water through the formation of interfacial turbulences, once the accumulation of PEG close to the DCM/water interface occurs. The oil droplets formed would be then stabilized by adsorbed protein molecules. Since the presence of polylactic acid in the organic phase did not prevent the emulsion formation, we studied the feasibility of formulating microparticles using this polymer. From results, it appears that microcapsules with a polymeric shell, with a homogeneous size of about 50μm and able to encapsulate a model hydrophobic drug, such as amiodarone, can be obtained by using this spontaneous emulsification method.
Keywords: Abbreviations; BSA; bovine serum albumin; DCM; dichloromethane; HEWL; hen egg-white lysozyme; PEG; poly(ethylene glycol); PLA; poly(lactic acid); SEM; scanning electron microscopy; γ; eq; surface tension at equilibriumPEG; Lysozyme; BSA; Spontaneous emulsification; Microparticles; Pendant drop tensiometer
Colon targeting with bacteria-sensitive films adapted to the disease state
by Youness Karrout; Christel Neut; Daniel Wils; Florence Siepmann; Laetitia Deremaux; Luc Dubreuil; Pierre Desreumaux; Juergen Siepmann (pp. 74-81).
The aim of this study was to identify novel polymeric films allowing for the site-specific delivery of drugs to the colon of patients suffering from inflammatory bowel diseases. Ethylcellulose was blended with different types of bacteria-sensitive starch derivatives. The water uptake and dry mass loss kinetics of the systems were monitored upon exposure to media simulating the contents of the stomach, small intestine and colon (including fresh fecal samples from Crohn’s Disease and Ulcerative Colitis patients). Importantly, ethylcellulose:Nutriose FB 06 and ethylcellulose:Peas starch N-735 films showed highly promising water uptake and dry mass loss kinetics in all the investigated media, indicating their potential to minimize premature drug release in the upper gastro-intestinal tract, and allowing for controlled release once the colon is reached. This can be attributed to the fact that the starch derivatives serve as substrates for the enzymes, which are secreted by the bacteria present in the colon of inflammatory bowel disease patients. Thus, the identified new polymeric films are adapted to the pathophysiological conditions in the gastro-intestinal tract in the disease state. Furthermore, Nutriose is known to provide pre-biotic effects, which can be of great benefit for these patients.
Keywords: Controlled drug delivery; Colon targeting; Polysaccharide; Ethylcellulose; Film coating
Comparative evaluation of polymeric and amphiphilic cyclodextrin nanoparticles for effective camptothecin delivery
by Yasemin Çirpanli; Erem Bilensoy; A. Lale Doğan; Sema Çaliş (pp. 82-89).
Camptothecin (CPT) is a potent anticancer agent. The clinical application of CPT is restricted by poor water solubility and instability under physiological conditions. Solubilization and stabilization of CPT were realized through nanoparticulate systems of amphiphilic cyclodextrins, poly(lactide-co-glycolide) (PLGA) or poly-ε-caprolactone (PCL). Nanoparticles were prepared with nanoprecipitation technique, whereas cyclodextrin nanoparticles were prepared from preformed inclusion complexes of CPT with amphiphilic cyclodextrins. Polymeric nanoparticles, on the other hand, were loaded with CPT:HP-β-CD inclusion complex to solubilize and stabilize the drug. Mean particle sizes were under 275nm, and polydispersity indices were lower than 0.2 for all formulations. Drug-loading values were significantly higher for amphiphilic cyclodextrin nanoparticles when compared with those for PLGA and PCL nanoparticles. Nanoparticle formulations showed a significant controlled release profile extended up to 12days for amphiphilic cyclodextrin nanoparticles and 48h for polymeric nanoparticles. Anticancer efficacy of the nanoparticles was evaluated in comparison with CPT solution in dimethyl sulfoxide (DMSO) on MCF-7 breast adenocarcinoma cells. Amphiphilic cyclodextrin nanoparticles showed higher anticancer efficacy than PLGA or PCL nanoparticles loaded with CPT and the CPT solution in DMSO. These results indicated that CPT-loaded amphiphilic cyclodextrin nanoparticles might provide a promising carrier system for the effective delivery of this anticancer drug having bioavailability problems.
Keywords: Camptothecin; Amphiphilic cyclodextrin; Poly(lactide-co-glycolide); Poly-ε-caprolactone; Nanoparticle; In vitro characterization; Cytotoxicity
Assessment of the percutaneous penetration of cisplatin: The effect of monoolein and the drug skin penetration pathway
by Leonardo D.D. Simonetti; Guilherme M. Gelfuso; Julie C.R. Barbosa; Renata F.V. Lopez (pp. 90-94).
It was intended to examine the in vitro penetration of cisplatin (CIS) through porcine skin in the presence of different concentrations of monoolein (MO) as well as to verify the main barrier for CIS skin penetration. In vitro skin penetration of CIS was studied from propylene glycol (PG) solutions containing 0%, 5%, 10%, and 20% of MO using Franz-type diffusion cell and porcine ear skin. Pretreatment experiments with MO and experiments with skin without stratum corneum (SC) were also carried out. Skin penetration studies of CIS showed that the presence of MO doubled the drug permeation through the intact skin. However, permeation studies through the skin without SC caused only a small enhancement of CIS permeation compared to intact skin. Moreover, pretreatment of skin with MO formulations did not show any significant increase in the flux of the drug. In conclusion, MO did not act as a real penetration enhancer for CIS, but it increased the drug partition to the receptor solution improving CIS transdermal permeation. The absence of improvement in drug permeation by MO pretreatment and by the removal of SC indicates that the SC is not the main barrier for the permeation of the metal coordination compound.
Keywords: Cisplatin; Monoolein; Skin penetration; Stratum corneum; Barrier function
Physicochemical and pharmacological characterization of novel vasoactive intestinal peptide derivatives with improved stability
by Satomi Onoue; Shingen Misaka; Yuki Ohmori; Hideyuki Sato; Takahiro Mizumoto; Mariko Hirose; Sumiko Iwasa; Takehiko Yajima; Shizuo Yamada (pp. 95-101).
Previously, [ R15,20,21, L17]-VIP-GRR (IK312532), a long-acting VIP derivative, was proposed as potential drug candidate for the treatment of asthma/COPD. The present work is aimed to elucidate solution-state stability of IK312532 and to develop further stabilized derivative with equipotent or higher biological functions. A stability study on IK312532 was carried out in solution state, and degradation mechanism was deduced by UPLC–MS and amino acid analyses. Three novel VIP derivatives were designed and chemically synthesized on the basis of stability data, being subjected to physicochemical and pharmacological characterization. Solution-state stability studies revealed the gradual degradation of IK312532, following pseudo-first-order kinetics. Chemical modification of IK312532, mainly position at 24, resulted in marked improvement of stability, although the chemical modification had no influence on the secondary structure, receptor binding, and activation of adenylate cyclase in rat lung cells. Novel derivatives also exhibited more potent neurite outgrowth in rat pheochromocytoma PC12 cells when compared to VIP and IK312532, possibly due to improved stability. Deamination of Asn at position 24 might be responsible for degradation of VIP derivative, and stability and chemical modification studies led us to the successful development of novel VIP derivatives with higher stability and biological functions.
Keywords: VIP; Stability; Receptor binding; Neurite outgrowth; UPLC–MS
Biopharmaceutical classification of drugs using intrinsic dissolution rate (IDR) and rat intestinal permeability
by Parvin Zakeri-Milani; Mohammad Barzegar-Jalali; Mandana Azimi; Hadi Valizadeh (pp. 102-106).
The solubility and dissolution rate of active ingredients are of major importance in preformulation studies of pharmaceutical dosage forms. In the present study, passively absorbed drugs are classified based on their intrinsic dissolution rate (IDR) and their intestinal permeabilities. IDR was determined by measuring the dissolution of a non-disintegrating disk of drug, and effective intestinal permeability of tested drugs in rat jejunum was determined using single perfusion technique. The obtained intrinsic dissolution rate values were in the range of 0.035–56.8mg/min/cm2 for tested drugs. The minimum and maximum intestinal permeabilities in rat intestine were determined to be 1.6×10−5 and 2×10−4cm/s, respectively. Four classes of drugs were defined: Category I: Peff,rat>5×10−5 (cm/s) or Peff,human>4.7×10−5 (cm/s), IDR>1(mg/min/cm2), Category II: Peff,rat>5×10−5 (cm/s) or Peff,human>4.7×10−5 (cm/s), IDR<1(mg/min/cm2), Category III: Peff,rat<5×10−5 (cm/s) or Peff,human<4.7×10−5 (cm/s), IDR>1 (mg/min/cm2) and Category IV: Peff,rat<5×10−5 (cm/s) or Peff,human<4.7×10−5 (cm/s), IDR<1(mg/min/cm2). According to the results obtained and proposed classification of drugs, it is concluded that drugs could be categorized correctly based on their IDR and intestinal permeability values.
Keywords: Intrinsic dissolution rate; Intestinal permeability; Biopharmaceutics
Prediction of food effects on the absorption of celecoxib based on biorelevant dissolution testing coupled with physiologically based pharmacokinetic modeling
by Yasushi Shono; Ekarat Jantratid; Niels Janssen; Filippos Kesisoglou; Yun Mao; Maria Vertzoni; Christos Reppas; Jennifer B. Dressman (pp. 107-114).
Since the rate-determining step to the intestinal absorption of poorly soluble drugs is the dissolution in the gastrointestinal (GI) tract, postprandial changes in GI physiology, in addition to any specific interactions between drug and food, are expected to affect the pharmacokinetics and bioavailability of such drugs. In this study, in vitro dissolution testing using biorelevant media coupled with in silico physiologically based pharmacokinetic (PBPK) modeling was applied to the prediction of food effects on the absorption of a poorly soluble drug, celecoxib, from 200mg capsules. A PBPK model was developed based on STELLA® software using dissolution kinetics, solubility, standard GI parameters and post-absorptive disposition parameters. Solubility, dissolution profiles and initial dissolution rate from celecoxib 200mg capsules were measured in biorelevant and compendial media. Standard GI parameters (gastric emptying rate and fluid volume) were varied according to the dosing conditions. Disposition parameters were estimated by fitting compartmental models to the oral PK data, since intravenous data are not available for celecoxib. Predictions of food effects and average plasma profiles were evaluated using the AUC and Cmax and the difference factor ( f1). An approximately 7-fold difference in the maximum percentage dissolved was observed in in vitro dissolution tests designed to represent the fed and fasted states. By contrast, the food effect estimated by simulating the plasma profiles with the PBPK model predicted only a slight delay in the peak plasma level (∼1h), and modest increases in the Cmax and AUC of ∼1.9-fold and 1.3-fold in the fed state, respectively. The PBPK approach, combining in silico simulation coupled with biorelevant dissolution test results, thus corresponds much better to the food effect observed for celecoxib in vivo. Additionally, point estimates of AUC and Cmax as well as f1 calculations demonstrated clear advantages of using results in biorelevant rather than compendial media in the PBPK model.
Keywords: Food effects; Dissolution; Prediction; PBPK modeling; Celecoxib
A comparative study of different release apparatus in generating in vitro– in vivo correlations for extended release formulations
by N. Fotaki; A. Aivaliotis; J. Butler; J. Dressman; M. Fischbach; J. Hempenstall; S. Klein; C. Reppas (pp. 115-120).
The importance of hydrodynamics in the development of in vitro–in vivo correlations (IVIVCs) for a BCS Class II compound housed in a hydrophilic matrix formulation and for a BCS Class I compound housed in an osmotic pump formulation was assessed. In vitro release data were collected in media simulating the fasted state conditions in the stomach, small intestine and the ascending colon using the USP II, the USP III and the USP IV release apparatuses. Using the data collected with the USP II apparatus, the plasma profiles were simulated and compared with human plasma profiles obtained after administration of the same dosage forms to healthy fasted volunteers. Data obtained with the USP III and USP IV apparatuses were directly correlated with the deconvoluted human plasma profiles. In vitro hydrodynamics affected the release profile from the hydrophilic matrix. For both formulations, based on the values of the difference factor, all three apparatuses were equally useful in predicting the actual in vivo profile on an average basis. Although some hydrodynamic variability is likely with low solubility drugs in hydrophilic matrices, the hydrodynamics of USP II, III and IV may all be adequate as a starting point for generating IVIVCs for monolithic dosage forms in the fasted state.
Keywords: Release; In vitro–in vivo; correlations; Hydrodynamics; Monolithic dosage forms; Extended release; Modified release; Dissolution
Optimisation of spray-drying process variables for dry powder inhalation (DPI) formulations of corticosteroid/cyclodextrin inclusion complexes
by Helena Cabral-Marques; Rita Almeida (pp. 121-129).
This study aims to develop and characterise a beclomethasone diproprionate:γ-cyclodextrin (BDP:γ-CYD) complex and to optimise the variables on the spray-drying process, in order to obtain a powder with the most suitable characteristics for lung delivery. The spray-dried powder – in a mass ratio of 2:5 (BDP:γ-CYD) – was physically mixed with three carriers of different particle sizes and in different ratios.Particle-size distribution, shape and morphology, moisture content, and uniformity in BDP content of formulations were studied. In vitro aerolisation behaviour of the formulations was evaluated using the Rotahaler, and the performance was characterised based on the uniformity of emitted dose and aerodynamic particle-size distribution (respirable fraction (RF), as a percentage of nominal dose (RFN) and emitted dose (RFE)).The most suitable conditions for the preparation of BDP:γ-CYD complexes were obtained with the solution flow of 5ml/min, Tin of 70°C and Tout of 50°C.Statistically significant differences in the aerodynamic performances were obtained for formulations containing BDP:γ-CYD complexes prepared using different solution flows and different Tin ( p<0.05). RFN and RFE vary in direct proportion with Tin, while an inverse relationship was observed for the solution flow. A direct correlation between the RFE and the Tout was identified.Performance of the formulations was compared with an established commercial product (Beclotaide Rotacaps 100μg) with improved performance of RF: formulations with respitose carrier attained RFN and RFE twofold greater, and formulations based on 63–90μm fraction lactose and trehalose achieved a threefold improvement; also, all formulations showed that the percentage of dose of BDP deposited in the “oropharynx” compartment was reduced to half.
Keywords: Beclomethasone dipropionate; Cyclodextrins; DPIs; Spray-drying process
Characterization and superficial transformations on mini-matrices made of interpolymer complexes of chitosan and carboxymethylcellulose during in vitro clarithromycin release
by Marta Gómez-Burgaz; Guillermo Torrado; Santiago Torrado (pp. 130-139).
Different interpolymer complexes (IPCs) of chitosan (CS) and carboxymethylcellulose sodium salt (CMC) were used to elaborate mini-matrices containing clarithromycin (CAM). IPCs were characterized by FTIR, DSC and powder X-ray (XRD).Compression processes did not modify the physical state of CAM which was in its polymorph Form II. However, during tableting, polymer/polymer interactions occurred to form matrix systems that were confirmed by DSC.When mini-matrices were placed in acetate buffer (pH 4.2), the formation of a CAM solvate was determined by XRD, FTIR and DSC, showing the presence of incorporated crystallizing solvent molecules. Grazing incidence X-ray diffraction (GID) enabled us to profile transformations of CAM on surfaces of mini-matrices when it is in intimate contact with dissolution medium, and its conversion to a solvate form prior to its dissolution process. Besides, FTIR and DSC revealed polymer–polymer electrostatic interactions during dissolution process.Furthermore, swelling and eroding studies and in vitro drug release exhibited that when increasing the amount of CS within IPCs, swelling and erosion rates were greater and CAM release was faster. Zero-order kinetics from drug release profiles were related to linear erosion kinetics, and highlighted that erosion played an important role in drug release due to CAM poor solubility at this pH.
Keywords: Grazing incidence X-ray; Polymeric interactions; Clarithromycin; Chitosan; Sustained release
Development and characterization of extended release Kollidon® SR mini-matrices prepared by hot-melt extrusion
by Işık Özgüney; Duangratana Shuwisitkul; Roland Bodmeier (pp. 140-145).
Kollidon® SR as a drug carrier and two model drugs with two different melting points, ibuprofen and theophylline, were studied by hot-melt extrusion. Powder mixtures containing Kollidon® SR were extruded using a twin-screw extruder at temperatures 70 and 80°C for ibuprofen and 80 and 90°C for theophylline. The glass transition temperature ( Tg) and maximum torque were inversely related to ibuprofen concentrations, indicating its plasticizing effect. The results of differential scanning calorimetry (DSC) and X-ray diffraction analysis showed that ibuprofen remained in an amorphous or dissolved state in the extrudates containing drug up to 35%, whereas theophylline was dispersed in the polymer matrix. The increase in amounts of ibuprofen or theophylline in the hot-melt extrudates resulted in the increase in the drug release rates. Theophylline release rate in hot-melt extruded matrices decreased as the extrusion temperature increased. In contrast, a higher processing temperature caused the higher ibuprofen release. This was a clear indication of the plasticizing effect of ibuprofen on Kollidon® SR and a result from water uptake. Theophylline release rate from hot-melt extrudates decreased with increasing triethyl citrate (TEC) level because of the formation of a denser matrix. By adding of Klucel® LF as a water-soluble additive to the hot-melt extruded matrices, an increase in ibuprofen and theophylline release rates was obtained.
Keywords: Hot-melt extrusion; Sustained release; Kollidon; ®; SR; Ibuprofen; Theophylline
Importance of glassy-to-rubbery state transitions in moisture-protective polymer coatings
by O. Bley; J. Siepmann; R. Bodmeier (pp. 146-153).
The aim of this study was to better understand the mechanisms governing water transport in polymeric film coatings used for moisture protection. Tablets containing garlic powder were coated with Methocel® E5 (hydroxypropyl methylcellulose), Opadry® AMB [poly(vinylalcohol)-based formulation] and Eudragit® E PO [poly(methacrylate-methylmethacrylate)]. Their water content at different temperatures and relative humidities were determined. The polymers were characterized by X-ray powder diffraction and differential scanning calorimetry (DSC). The latter revealed significant physical changes in Opadry® AMB during storage, while Eudragit® E PO remained unchanged. For Opadry® AMB, a strong dependence of the vapor permeability on the water content of the system was observed. The water uptake drastically increased with increasing relative humidity and storage temperature due to structural polymer changes (glassy-to-rubbery state transition). Linear relationships between the initial uptake rate and the relative humidity or temperature were established. Storage below critical threshold values of 66% RH (at room temperature) and 16°C (at 75% RH) significantly reduced water imbibition. Opadry® AMB-based film coatings undergo a glassy-to-rubbery state transition upon storage at room temperature and elevated relative humidity, resulting in significantly increased mobility of the polymer chains and, thus, increased water uptake rates.
Keywords: Moisture protection; Coating; Glass transition temperature; Polymer; Storage stability
Strongly enhanced dissolution rate of fenofibrate solid dispersion tablets by incorporation of superdisintegrants
by P. Srinarong; J.H. Faber; M.R. Visser; W.L.J. Hinrichs; H.W. Frijlink (pp. 154-161).
In this study, it was shown that the incorporation of superdisintegrants in solid dispersion tablets containing a high drug load can strongly enhance the dissolution rate of the highly lipophilic drug fenofibrate. In addition, the dissolution rate was more increased when the superdisintegrant was incorporated in the drug containing solid dispersions than when it was physically mixed with the solid dispersions. The dissolution rate enhancement strongly depended on the type of superdisintegrants and increased in the order Polyplasdone® XL-10® XL≪Ac-Di-Sol®≈Primojel®. The dissolution behavior also depended on the type of hydrophilic carriers. Solid dispersion tablets based on inulin 4kDa, polyethylene glycol 20K and polyvinylpyrrolidone K30 showed a much faster dissolution than those based on mannitol and hydroxypropyl-β-cyclodextrin. Finally, inulin 4kDa-based solid dispersion tablets showed excellent storage stability, while polyethylene glycol 20K-and polyvinylpyrrolidone K30-based solid dispersion tablets did not.
Keywords: Freeze drying; Solid dispersions; Fenofibrate; Superdisintegrants; Inulin; Polyethylene glycol (PEG); Polyvinylpyrrolidone (PVP); Mannitol; Hydroxypropyl-β-cyclodextrin
In vitro and in vivo evaluation of nimesulide lyophilized orally disintegrating tablets
by Raguia Ali Shoukri; Iman Saad Ahmed; Rehab N. Shamma (pp. 162-171).
Development of a lyophilized orally disintegrating tablet (ODT) that enhanced the in vitro dissolution and in vivo absorption of nimesulide (NM), a drug with poor solubility and poor bioavailability, is presented. The ODTs were prepared by freeze-drying an aqueous dispersion of NM containing a matrix former, a sugar alcohol, and a collapse protectant. In addition, different disintegration accelerators were tested. The influence of formulation parameters on the disintegration time and in vitro dissolution of NM from ODTs along with other tablet characteristics was investigated. Results obtained from disintegration and dissolution studies showed that lyophilized ODTs disintegrated within few seconds and showed significantly faster dissolution rate of NM compared to the plain powder drug and NM in commercially available immediate release tablet Sulide®. The ODTs were also examined using differential scanning calorimetry, X-ray diffraction, and scanning electron microscope. Stability results, after 12-month storage of selected ODTs at 25°C and 60% relative humidity, were satisfactory. The extent of absorption of NM from a selected ODT when compared to an conventional immediate release tablet as a reference after administration of 100mg oral dose of NM was determined in healthy subjects using a randomized crossover design. In this study, the rate of absorption of NM from ODT was faster than that from the reference tablet, had a significantly higher ( p=0.012) peak plasma concentration, and shortened time to Cmax by 1h ( p=0.029). The extent of absorption expressed by AUC was 62% larger when compared to the commercially available tablet.
Keywords: Nimesulide; Freeze-drying; Orally disintegrating tablets; In vivo absorption; Bioavailability; Dissolution rate
Minimisation of the capping tendency by tableting process optimisation with the application of artificial neural networks and fuzzy models
by Aleš Belič; Igor Škrjanc; Damjana Zupančič Božič; Rihard Karba; Franc Vrečer (pp. 172-178).
The pharmaceutical industry is increasingly aware of the advantages of implementing a quality-by-design (QbD) principle, including process analytical technology, in drug development and manufacturing. Although the implementation of QbD into product development and manufacturing inevitably requires larger resources, both human and financial, large-scale production can be established in a more cost-effective manner and with improved efficiency and product quality. The objective of the present work was to study the influence of particle size (and indirectly, the influence of dry granulation process) and the settings of the tableting parameters on the tablet capping tendency. Artificial neural network and fuzzy models were used for modelling the effect of the particle size and the tableting machine settings on the capping coefficient. The suitability of routinely measured quantities for the prediction of tablet quality was tested. Results showed that model-based expert systems based on the contemporary routinely measured quantities can significantly improve the trial-and-error procedures; however, they cannot completely replace them. The modelling results also suggest that in cases where it is not possible to obtain sufficient number of measurements to uniquely identify the model, it is beneficial to use several modelling techniques to identify the quality of model prediction.
Keywords: Dry granulation; Tableting; Capping; ANN; Fuzzy models; Mathematical model
Quantification of microparticle coating quality by confocal laser scanning microscopy (CLSM)
by F. Depypere; P. Van Oostveldt; J.G. Pieters; K. Dewettinck (pp. 179-186).
In this work, a novel protocol was developed for determining film coating thickness and coating quality of microparticles, based on the use of confocal laser scanning microscopy (CLSM). CLSM was found to be an adequate non-destructive technique for the quantification of the coating thickness and coating quality of individual thin-coated small particles. Combined with image analysis, it was possible to derive with high accuracy the coating thickness distribution of a representative number of microparticles. The performance of the novel methodology was assessed by the quantification of the coating thickness and coating quality of protein-coated microparticles produced by fluidized bed coating. It was found that the CLSM data on coating layer thickness were generally in good agreement with the results from chemical analysis, down to a thickness of 1–1.5μm. Using CLSM the importance of setting up the appropriate distance between the coating nozzle and the powder bed with respect to microparticle coating quality in fluidized bed processing was illustrated. Coating quality was found to decrease with increasing distance the coating droplets have to travel before impinging onto the core particles as a result of spray-drying of the coating droplets. Also, coating quality decreased with increasing viscosity of the coating droplets, resulting in reduced spreading on the cores.
Keywords: Coating quality; Coating thickness; Quantification; Confocal; Microscopy; CLSM; Microparticle; Fluid bed; Spray-drying
Cutaneous lycopene and β-carotene levels measured by resonance Raman spectroscopy: High reliability and sensitivity to oral lactolycopene deprivation and supplementation
by Ulrike Blume-Peytavi; Anne Rolland; Maxim E. Darvin; Anne Constable; Isabelle Pineau; Christiane Voit; Kristina Zappel; Gregor Schäfer-Hesterberg; Martina Meinke; Roger L. Clavez; Wolfram Sterry; Jürgen Lademann (pp. 187-194).
Carotenoids, naturally occurring lipophilic micronutrients, possess an antioxidant activity associated with protection from damage induced by free radicals.The present study investigated an innovative non-invasive method to measure cutaneous levels of lycopene and β-carotene and to monitor the distribution of orally administered lactolycopene in human skin and plasma.A double-blind placebo-controlled randomized study was performed in 25 volunteers, who were under a lycopene-deprived diet (4weeks prior to study until end of the study) and orally received either lactolycopene or placebo for 12weeks. Skin and plasma levels of lycopene and β-carotene were monitored monthly using Raman spectroscopy and HPLC, respectively.Cutaneous levels of lycopene and β-carotene monitored by resonance Raman spectroscopy showed high reliability. Irrespective of the investigated area, cutaneous levels were sensitive to lycopene deprivation and to oral supplementation; the forehead showed the closest correlation to lycopene variation in plasma.Plasma and skin levels of lycopene were both sensitive to oral intake of lactolycopene and, interestingly, also skin levels of β-carotene. Thus, oral supplementation with lycopene led to an enrichment of β-carotene in human skin, possibly due to the fact that carotenoids act in the skin as protection chains, with a natural protection against free radicals.
Keywords: Lycopene; β-Carotene; Antioxidants; Plasma and skin level; HPLC; Resonance Raman spectroscopy
Novel analytical methods for the characterization of oral wafers
by Verena Garsuch; Jörg Breitkreutz (pp. 195-201).
This study aims at compensating the lack of adequate methods for the characterization of the novel dosage forms buccal wafers by applying recent advanced analytical techniques. Fast-dissolving oral wafers need special methods for assessing their properties in drug development and quality control. For morphologic investigations, scanning electron microscopy (SEM) and near-infrared chemical imaging (NIR-CI) were used. Differences in the distribution of the active pharmaceutical ingredient within wafers can be depicted by NIR-CI. Film thickness was determined by micrometer screw and coating thickness gauge revealing no significant differences between the obtained values. To distinguish between the mechanical properties of different polymers, tensile test was performed. Suitable methods to predict disintegration behaviour are thermomechanical analysis and contact angle measurement. The determination of drug release was carried out by three different methods. Fibre-optic sensor systems allow an online measurement of the drug release profiles and the thorough analysis even within the first seconds of disintegration and drug dissolution.
Keywords: Buccal delivery; Fast-dissolving dosage form; Near-infrared chemical imaging; Fibre-optic analysis
Improvement of oral bioavailability of flurbiprofen from flurbiprofen/β-cyclodextrin inclusion complex by action of cinnarizine
by Tadakazu Tokumura; Atsushi Muraoka; Yoshiharu Machida (pp. 202-204).
Improvement of the oral bioavailability of flurbiprofen (Flu) after oral administration of flurbiprofen/β-cyclodextrin inclusion complex (Flu/β-CD) by the action of cinnarizine (CN) was investigated. Flu and Flu/β-CD were administered orally to fasted rats at a dose of 20mg/kg as Flu. Thirty minutes after drug administration, CN dissolved in pH 4.0 buffer solution or pH 4.0 buffer solution alone was administered to the rats. The dose of CN was 0.17mg/kg. Blood samples were taken from rats and Flu concentrations in plasma samples were determined by HPLC. It was found from the comparison of Flu and Flu with CN (Flu+CN) that CN had no effect on plasma concentrations of Flu after oral administration of Flu. The mean plasma levels after oral administration of Flu/β-CD with CN (Flu/β-CD+CN) were larger not only than those of Flu and Flu+CN but also than those of Flu/β-CD. The value of Cmax in Flu/β-CD+CN was significantly larger than that of Flu/β-CD. This is considered to be caused by the action of CN as a competing agent. This mechanism was supported by the result of solubility study in which Flu solubility in β-CD solution decreased with the addition of CN. It was found from these results that CN had strong ability as a competing agent in vivo.
Keywords: Flurbiprofen; β-Cyclodextrin; Competing agent; Cinnarizine; Inclusion complex; Bioavailability; Rats