In vitro and in vivo studies on the complexes of glipizide with water-soluble β-cyclodextrin–epichlorohydrin polymers

The purpose of this study was to evaluate the potential of a newly modified cyclodextrin derivative, water-soluble β-cyclodextrin–epichlorohydrin polymer (β-CDP), as an effective drug carrier to enhance the dissolution rate and oral bioavailability of glipizide as a poorly water-soluble model drug. Inclusion complexes of glipizide with β-CDP were prepared by the co-evaporation method and characterized by phase solubility, dissolution, and differential scanning calorimetry. The solubility curve was classified as type A_L, which indicated the formation of 1:1 complex between glipizide and β-CDP. β-CDP had better properties of increasing the aqueous solubility of glipizide compared with HP-β-CD. The dissolution rate of drug from the β-CDP complexes was significantly greater than that of the corresponding physical mixtures indicating that the formation of amorphous complex increased the solubility of glipizide. Moreover, the increment in drug dissolution rate from the glipizide/β-CDP systems was higher than that from the corresponding ones with HP-β-CD, which indicated that β-CDP could provide greater capability of solubilization for poorly soluble drugs. Furthermore, in vivo study revealed that the bioavailability of glipizide was significantly improved by glipizide /β-CDP inclusion complex after oral administration to beagle dogs.     

In vitro and in vivo evaluation of the safety and stability of the TAXUS® Paclitaxel-Eluting Coronary Stent

Functional aspects of the styrene-b-isobutylene-b-styrene triblock copolymer (SIBS) which is incorporated into a drug-eluting stent (DES) coating are described. The SIBS copolymer is employed on the TAXUS^® Paclitaxel-Eluting Coronary Stent as a carrier for paclitaxel (PTx). Optical and scanning electron microscopic analysis of stents explanted from rabbit and porcine models after 2 years and 6 months, respectively, showed that the SIBS coating maintained physical integrity. Gel permeation chromatography (GPC) of the copolymer extracted from the coating verified that no polymer degradation occurred over the same period of time. The coating on TAXUS^® Stents was shown to maintain physical integrity after 400 million cycles of pulsatile or mechanical (tensile) fatigue, simulating 10 years real time use. Inspection of the samples compared to untested controls showed no change in the coating under these cyclic simulated conditions. Films prepared with the same formulation found on TAXUS^® Stents maintained mechanical strength and resistance throughout the time of testing. Intentional defects introduced into the stent coating were shown to have only a minimal impact on PTx release. These data support the suitability of the SIBS copolymer as a drug carrier for DES applications.     

In vitro and in vivo assessment of the biocompatibility of an Mg–6Zn alloy in the bile

There is a great clinical need for biodegradable bile duct stents. Biodegradable stents made of an Mg–6Zn alloy were investigated in both vivo animal experiment and in vitro cell experiments. During the in vivo experiments, blood biochemical tests were performed to determine serum magnesium, serum creatinine (CREA), blood urea nitro-gen (BUN), serum lipase (LPS), total bilirubin (TB) and glutamic-pyruvic transaminase (GPT) levels. Moreover, tissue samples of common bile duct (CBD), liver and kidney were taken for histological evaluation. In the in vitro experiments, primary mouse extrahepatic bile duct epithelial cells (MEBDECs) were isolated and cultured. Cytotoxicity testing was carried out using the MTT method. Flow cytometry analyses with propidium iodide staining were performed to evaluate the effect of Mg–6Zn alloy extracts on cell cycle. The in vivo experiments revealed no significant differences (P > 0.05) in serum magnesium, CREA, BUN, LPS, TB or GPT before and after the operation. Based on the HE results, hepatocytes, bile duct epithelial cells, renal glomerulus and renal tubule tissues did not present significant necrosis. In the in vitro experiments, the cell relative growth rate curve did not change significantly from 20 to 40 % extracts. In vitro experiments showed that 20–40 % Mg–6Zn extracts are bio-safe for MEBDECs. In vivo experiments showed that Mg–6Zn stents did not affect several important bio-chemical parameters or, harm the function or morphology of the CBD, kidney, pancreas and liver. Our data suggested that this Mg–6Zn alloy is a safe biocompatible material for CBD.     

In vitro and in vivo biocompatibility of graded hydroxyapatite–zirconia composite bioceramic

To obtain bioceramics with good osteoinductive ability and mechanical strength, graded hydroxyapatite–zirconia (HA–ZrO₂) composite bioceramics were prepared in this work. The biocompatibility of the bioceramics was investigated in vitro based on acute toxicity and cytotoxicity tests and hemolysis assay. Results showed the studied graded HA–ZrO₂ had little toxicity to mouse and L929 mouse fibroblasts. Also, hemolysis assay indicated a good blood compatibility of the bioceramics. Based on the results of in vitro tests, animal experiments were performed on white New Zealand rabbits by implantation into hip muscles and femur. It was found that the graded HA–ZrO₂ composite bioceramics exhibited superior osteoinductive ability, which may be a promising bioceramics implant.     

Spray drying formulation of albendazole microspheres by experimental design. In vitro–in vivo studies

Both an experimental design and optimization techniques were carried out for the development of chitosan–pectin–carboxymethylcellulose microspheres to improve the oral absorption of albendazole as a model drug. The effect of three different factors (chitosan, pectin and carboxy methyl cellulose concentrations) was studied on five responses: yield, morphology, dissolution rate at 30 and 60?min, and encapsulation efficiency of the microspheres. During the screening phase, the factors were evaluated in order to identify those which exert a significant effect. Simultaneous multiple response optimizations were then used to find out experimental conditions where the system shows the most adequate results. The optimal conditions were found to be: chitosan concentration, 1.00% w/v, pectin concentration 0.10% w/v and carboxymethylcellulose concentration 0.20% w/v. The bioavailability of the loaded drug in the optimized microspheres was evaluated in Wistar rats which showed an area under curve (AUC) almost 10 times higher than the pure drug.     

In vitro and in vivo evaluation of paclitaxel–lapatinib-loaded F127 pluronic micelles

The aim of this study was to evaluate the in vitro and in vivo efficacy of paclitaxel–lapatinib-loaded Pluronic micelles. Lapatinib and pluronic sensitize the cancerous cells to paclitaxel via efflux pump inhibition. In addition, pluronic polymers can trigger intrinsic apoptosis pathways. Furthermore, micellar system can passively target the chemotherapeutic agents by enhanced permeability and retention effect. The paclitaxel–lapatinib-loaded micelles were characterized in means of encapsulation efficacy and size. The in vitro analyses were performed by MTT assay and uptake studies. Real-time imaging and in vivo anti-tumor efficacy studies were also performed. The prepared micelles have acceptable encapsulation ratio and size. Hemolysis assay confirmed that the micelles are hemo-compatible. MTT assay demonstrated that drug-loaded micelles have superior cytotoxicity compared with the naked drugs. The confocal microscopy and flowcytometry analyses showed that micelles are mainly internalized by endocytosis. According to the results of the in vivo imaging, the micelles are accumulated within liver. In vivo anti-tumor efficacy studies confirmed that tumor inhibition of drug-loaded micelles was significant compared to Intaxel^®.     

In vitro and in vivo degradation of poly(l-lactide-co-glycolide) films and scaffolds

Poly(l-lactide-co-glycolide) (PLGA) was synthesized using a biocompatible initiator, zirconium acetylacetonate. In vitro and in vivo degradation properties of PLGA films (produced by solvent casting, 180 μm thick) and PLGA scaffolds (produced by an innovated solvent casting and particulate leaching, 3 mm thick) were evaluated. The samples were either submitted for degradation in phosphate buffered saline (PBS) at 37 °C for 30 weeks, or implanted into rat skeletal muscles for 1, 4, 12, 22 and 30 weeks. The degradation was monitored by scanning electron microscopy, atomic force microscopy, weight loss, and molecular weight changes (in vitro), and by microscopic observations of the materials’ morphology after histological staining with May-Grunwald-Giemsa (in vivo). The results show that the films in both conditions degraded much faster than the scaffolds. The scaffolds were dimensionally stable for 23 weeks, while the films lost their integrity after 7 weeks in vitro. The films’ degradation was heterogenous—degradation in their central parts was faster than in the surface and subsurface regions due to the increased concentration of the acidic degradation products inside. In the scaffolds, having much thinner pore walls, heterogenous degradation due to the autocatalytic effect was not observed.     

Calcium phosphate cement: in vitro and in vivo studies of the α-tricalcium phosphate-dicalcium phosphate dibasic-tetracalcium phosphate monoxide system

In this paper, calcium phosphate cement consisting of -tricalcium phosphate (-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was investigated in vitro and in vivo. Measurements of compressive strength against soaking time in simulated body fluid (SBF) showed a rapid increase of the hardness for the first 7 days. The gained strength was retained up to 1 year and the maximal mean value was 94.7 (±14.4) MPa. X-ray diffraction (XRD) and scanning electron microscopy (SEM) presented precipitates of hydroxyapatite (HA) after mixing, also after soaking in SBF and after implantation in rat subcutaneous tissues. However, the conversion to HA happened in different ways between in vitro and in vivo exposures. Histologic examinations showed that the cement causes the same reactions at the interface with surrounding soft tissues as HA. The authors consider the cement to be a promising material as a bone substitute, bone cement or dental material, however, further studies in a paste form and in bone tissue environments are necessary.     

In vitro–in vivo correlation study for the dermatopharmacokinetics of terbinafine hydrochloride topical cream

Background: To investigate the relationship between dermatopharmacokinetic (DPK) tape stripping from in vitro and in vivo using 1% terbinafine hydrochloride topical cream as the model formulation.

Methodology: In vitro and in vivo tape strippings were conducted on separated pig ear skin used as a biological membrane for franz diffusion cell testing and the non-hairy skin area at the ventral forearms of healthy volunteers, respectively. Terbinafine (1%) topical cream was applied to the skin for 0.5, 2, and 4?h. The drug profiles of terbinafine across the stratum corneum were determined immediately (time 0?h), and at 0.5, 1, 2, and 4?h after removing the formulation. The amounts of terbinafine were analyzed by a validated high-performance liquid chromatography-ultraviolet method. The area under the curve (AUC) and the maximum amounts of terbinafine absorption (Q_max) were obtained from pharmacokinetic software. Partition coefficient (K_SC/veh) and diffusion parameter (D/L²) were derived from the Fick’s second law equation. During the schedule time of 8?h, the deviations of in vitro and in vivo data were 6.61 and 30.46% for AUC and Q_max, respectively. There was insignificant difference of the K_SC/veh and the D/L² between excised pig ear and human skin. In addition, K_SC/veh and D/L² at T_max of 2?h were used to predict the AUC presented the value of 4.7481 %h whereas the true value calculated from pharmacokinetic software provided the value of 5.9311 %h differing from each other in approximate of 20%.

Conclusions: In vitro tape stripping using the separated pig ear skin as a viable membrane of the franz diffusion cell testing demonstrates the potential to represent in vivo tape stripping in human for topical bioavailability/bioequivalence study of terbinafine hydrochloride 1% topical cream.     

In vitro and in vivo evaluation of chitosan–gelatin scaffolds for cartilage tissue engineering

Chitosan–gelatin polyelectrolyte complexes were fabricated and evaluated as tissue engineering scaffolds for cartilage regeneration in vitro and in vivo. The crosslinker for the gelatin component was selected among glutaraldehyde, bisepoxy, and a water-soluble carbodiimide (WSC) based upon the proliferation of chondrocytes on the crosslinked gelatin. WSC was found to be the most suitable crosslinker. Complex scaffolds made from chitosan and gelatin with a component ratio equal to one possessed the proper degradation rate and mechanical stability in vitro. Chondrocytes were able to proliferate well and secrete abundant extracellular matrix in the chitosan–gelatin (1:1) complex scaffolds crosslinked by WSC (C1G1_WSC) compared to the non-crosslinked scaffolds. Implantation of chondrocytes-seeded scaffolds in the defects of rabbit articular cartilage confirmed that C1G1_WSC promoted the cartilage regeneration. The neotissue formed the histological feature of tide line and lacunae in 6.5 months. The amount of glycosaminoglycans in C1G1_WSC constructs (0.187 ± 0.095 μg/mg tissue) harvested from the animals after 6.5 months was 14 wt.% of that in normal cartilage (1.329 ± 0.660 μg/mg tissue). The average compressive modulus of regenerated tissue at 6.5 months was about 0.539 MPa, which approached to that of normal cartilage (0.735 MPa), while that in the blank control (3.881 MPa) was much higher and typical for fibrous tissue. Type II collagen expression in C1G1_WSC constructs was similarly intense as that in the normal hyaline cartilage. According to the above results, the use of C1G1_WSC scaffolds may enhance the cartilage regeneration in vitro and in vivo.     

Effect of hydrophilic polymers on isradipine complexation with hydroxypropyl β-cyclodextrin

Complexation of isradipine with hydroxypropyl β-cyclodextrin (HPβCD) in the presence and absence of 3 hydrophilic polymers—polyvinyl pyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG)—was investigated with an objective of evaluating the effect of hydrophilic polymers on the complexation and solubilizing efficiencies of HPβCD and on the dissolution rate of isradipine from the HPβCD complexes. The phase solubility studies indicated the formation of isradipine-HPβCD inclusion complexes at a 1:1M ratio in solution in both the presence and the absence of hydrophilic polymers. The complexes formed were quite stable. Addition of hydrophilic polymers markedly improved the complexation and solubilizing efficiencies of HPβCD. Solid inclusion complexes of isradipine-HPβCD were prepared in 1:1 and 1:2 ratios by the kneading method, with and without the addition of hydrophilic polymers. The solubility and dissolution rate of isradipine were significantly improved by complexation with HPβCD. The isradipine-HPβCD (1:2) inclusion complex yielded a 9.66-fold increase in the dissolution rate of isradipine. The addition of hydrophilic polymers also markedly improved the dissolution rate of isradipine from HPβCD complexes: a 11.72-, 17.01-, and 39.23-fold increase was observed with PVP, PEG, and HPMC respectively. X-ray diffractometry and differential scanning calorimetry indicated stronger drug amorphization and entrapment in HPβCD because of the combined action of HPβCD and the hydrophilic polymers.     

Sustained-release of Cyclosporin A pellets: preparation,in vitro release,pharmacokinetic studies and in vitro–in vivo correlation in beagle dogs

The aim of this study was to develop Cyclosporin A (CsA) sustained-release pellets which could maintain CsA blood concentration within the therapeutic window throughout dosing interval and to investigate the in vitro–in vivo correlation (IVIVC) in beagle dogs. The CsA sustained-release pellets (CsA pellets) were prepared by a double coating method and characterized in vitro as well as in vivo. Consequently, the CsA pellets obtained were spherical in shape, with a desirable drug loading (7.18?±?0.17?g/100?g), good stability and showed a sustained-release effect. The C_max, T_max and AUC_0–24 of CsA pellets from the in vivo pharmacokinetics evaluation was 268.22?±?15.99?ng/ml, 6?±?0?h and 3205.00?±?149.55?ng·h/ml, respectively. Compared with Neoral®, CsA pellets significantly prolonged the duration of action, reduced the peak blood concentration and could maintain a relatively high concentration level till 24?h. The relative bioavailability of CsA pellets was 125.68?±?5.37% that of Neoral®. Moreover, there was a good correlation between the in vitro dissolution and in vivo absorption of the pellets. In conclusion, CsA pellets which could ensure a constant systemic blood concentration within the therapeutic window for 24?h were prepared successfully. Meanwhile, this formulation possessed a good IVIVC.     

In vitro and in vivo evaluation of the effects of demineralized bone matrix or calcium sulfate addition to polycaprolactone–bioglass composites

The objective of this study was to improve the efficacy of polycaprolactone/bioglass (PCL/BG) bone substitute using demineralized bone matrix (DBM) or calcium sulfate (CS) as a third component. Composite discs involving either DBM or CS were prepared by compression moulding. Bioactivity of discs was evaluated by energy dispersive X-ray spectroscopy (ESCA) and scanning electron microscopy (SEM) following simulated body fluid incubation. The closest Calcium/Phosphate ratio to that of hydroxyl carbonate apatite crystals was observed for PCL/BG/DBM group (1.53) after 15 day incubation. Addition of fillers increased microhardness and compressive modulus of discs. However, after 4 and 6-week PBS incubations, PCL/BG/DBM discs showed significant decrease in modulus (from 266.23 to 54.04 and 33.45 MPa, respectively) in parallel with its highest water uptakes (36.3 and 34.7%). Discs preserved their integrity with only considerable weight loss (7.5–14.5%) in PCL/BG/DBM group. In vitro cytotoxicity tests showed that all discs were biocompatible. Composites were implanted to defects on rabbit humeri. After 7 weeks, new tissue formation and mineralization at bone-implant interface were observed for all implants. Bone mineral densities at interface were higher than that of implant site and negative controls (defects left empty) but lower than healthy bone level. However, microhardness of implant sites was higher than in vitro results indicating in vivo mineralization of implants. Addition of DBM or CS resulted with higher microhardness values at interface region (ca. 650 μm from implant) compared to PCL/BG and negative control. Histological studies revealed that addition of DBM enhanced bone formation around and into implant while CS provided cartilage tissue formation around the implant. From these results, addition of DBM or CS could be suggested to improve bone healing efficacy of PCL/BG composites.     

In vitro and in vivo biological performance of collagen-chitosan/silicone membrane bilayer dermal equivalent

Skin loss or damage affects severely the life quality of human being and can even cause death in many cases. We report here a bilayer dermal equivalent (BDE) composed of collagen-chitosan porous scaffold and silicone membrane, which can effectively induce the regeneration of dermis in an animal model of full thickness skin loss. The in vitro biosecurity test showed that the BDE had no cytotoxicity, and no remarkable sensitization and irritability. In vitro cell culture proved that the BDE had good biocompatibility to support the proliferation of fibroblasts. Animal test was performed on Bama miniature pig skin. Gross view and histological sections found plenty of fibroblasts and extracellular matrix in the regenerative scaffold after transplantation of the BDE for 4 weeks. Immunohistochemistry results proved that the BDE has the ability to support the angiogenesis of the regenerated dermis. All these results indicate that the BDE might be a promising equivalent in treating dermal loss.     

In vitro and in vivo characterization of fast dissolving tablets containing gliquidone–pluronic solid dispersion

Abstract

The main objective of this study is to increase the dissolution rate of gliquidone using its solid dispersions with pluronic F-68 by solvent evaporation method. The solid dispersion of the drug with pluronic at ratio 1:3 showed the highest dissolution efficiency (50.7%) after 10?min, so it was incorporated in fast dissolving tablets. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to study the interaction between gliquidone and pluronic in the solid state. The FTIR spectroscopic studies revealed no chemical interaction between the drug and pluronic, while the DSC results indicated the amorphous state of gliquidone in the solid dispersion. A 3² full factorial design was used to study the effect of varying concentrations of croscarmellose and sodium starch glycolate as superdisintegrants on the disintegration time and the percentage released after 10?min. The optimized formula showed a disintegration time of 39.1?±?1.2?s and 85.43%?±?5.16% released after 10?min and was selected for the in-vivo studies in rabbits. The selected formula showed significant enhancement of gliquidone bioavailability, about 1.8 times compared with the commercial Glurenor tablets.     

In vitro–in vivo correlations: general concepts,methodologies and regulatory applications

Abstract

The major objective of in vitro–in vivo correlations is to be able to use in vitro data to predict in vivo performance serving as a surrogate for an in vivo bioavailability test and to support biowaivers. Therefore, the aims of this review are: (i) to clarify the factors involved during bio-predictive dissolution method development; and (ii) the elements that may affect the mathematical analysis in order to exploit all information available. This article covers the basic aspects of dissolution media and apparatus used in the development of in vivo predictive dissolution methods, including the latest proposals in this field as well as the summary of the mathematical methods for establishing the in vitro–in vivo relationship and their scope and limitations. The incorporation of physiological relevant factors in the in vitro dissolution method is essential to get accurate in vivo predictions. Standard quality control dissolution methods do not necessarily reflect the in vivo behavior, so they rarely are useful for predicting in vivo performance. The combination of physiological based dissolution methods with physiological-based pharmacokinetics models incorporating gastrointestinal variables will lead to robust tools for drug and formulation development, nevertheless their regulatory use for biowaiver application still require harmonization of the mathematical methods proposed and more detailed recommendations about the procedures for setting up dissolution specifications.     

Evaluation of polyethersulfone highflux hemodialysis membrane in vitro and in vivo

A new hemodialysis membrane manufactured by a blend of polyethersulfone (PES) and polyvinylpyrrolidone (PVP) was evaluated in vitro and in vivo. Goat was selected as the experimental animal. The clearance and the reduction ratio after the hemodialysis of small molecules (urea, creatinine, phosphate) for the PES membrane were higher in vitro than that in vivo. The reduction ratio of β₂-microglobulin was about 50% after the treatment for 4 h. The biocompatibility profiles of the membranes indicated slight neutropenia and platelet adhesion at the initial stage of the hemodialysis. Electrolyte, blood gas, and blood biochemistry were also analyzed before and after the treatment. The results indicated that PES hollow fiber membrane had a potential widely use for hemodialysis.     

Biocompatibility of polyhydroxybutyrate microspheres: in vitro and in vivo evaluation

Microspheres have been prepared from the resorbable linear polyester of β-hydroxybutyric acid (polyhydroxybutyrate, PHB) by the solvent evaporation technique and investigated in vitro and in vivo. Biocompatibility of the microspheres has been proved in tests in the culture of mouse fibroblast cell line NIH 3T3 and in experiments on intramuscular implantation of the microspheres to Wistar rats for 3 months. Tissue response to the implantation of polymeric microspheres has been found to consist in a mild inflammatory reaction, pronounced macrophage infiltration that increases over time, involving mono- and poly-nuclear foreign body giant cells that resorb the polymeric matrix. No fibrous capsules were formed around polymeric microparticles; neither necrosis nor any other adverse morphological changes and tissue transformation in response to the implantation of the PHB microparticles were recorded. The results of the study suggest that polyhydroxybutyrate is a good candidate for fabricating prolonged-action drugs in the form of microparticles intended for intramuscular injection.     

In vitro study on the influence of strontium-doped calcium polyphosphate on the angiogenesis-related behaviors of HUVECs

Angiogenesis is of great importance in bone tissue engineering, and has gained large attention in the past decade. Strontium-doped calcium polyphosphate (SCPP) is a novel biodegradable material which has been proved to be able to promote in vivo angiogenesis during bone regeneration. An in vitro culture system was developed in the present work to examine its influence on angiogenesis-related behaviors of human umbilical vein endothelial cells (HUVECs), including cell adhesion, spreading, proliferation and migration. The effects of microtopography, chemical property and the ingredients in the degradation fluid (DF) on cell behaviors were discussed. The results showed that cells attached and spread better on SCPP scaffold than on calcium polyphosphate (CPP), which might partially result from the less rough surface of SCPP scaffold and the less hydrogel formed on the surface. In addition, cell proliferation was significantly improved when treated with SCPP DF compared with the treatment with CPP DF. Statistical analysis indicated that Sr(2+) in SCPP DF might be the main reason for the improved cell proliferation. Moreover, cell migration, another important step during angiogenesis, was evidently stimulated by SCPP DF. The improved in vivo angiogenesis by SCPP might be assigned to its better surface properties and strontium in the DF. This work also provides a new method for in vitro evaluation of biodegradable materials' potential effects on angiogenesis.     

Preparation and degradation of polymers based on β-aminocaproic acid and p-alanine .1

采用熔融缩聚法制备了一种新型可降解的6-氨基己酸（6N）和β-丙氨酸（βA）的二元共聚物（PAA）,并研究了该共聚物的性能。采用红外光谱分析（FT-IR）、X射线衍射分析（XRD）、差示扫描量热分析（DSC）、热重分析（TGA）等手段对其结构进行了表征,结果表明,所合成的材料是2种单体的聚酰胺共聚物;随β-丙氨酸含量的增加,共聚物的结晶度、熔融温度呈先减小后增大的趋势,而分解温度呈依次减小的趋势,当共聚物中2种单体摩尔比为1∶1时,其为无定形共聚物。共聚物在去离子水中的降解实验结果表明,材料具有良好的降解性能;不同单体比例合成的共聚物中,共聚物的降解速率与共聚物的结晶度成反比,当聚合物中2种单体摩尔比为1∶1时,聚合物的降解速度最快,2周后几乎完全降解;整个降解过程中,降解液的pH值都维持在相对稳定的水平。在环保方面,该材料可望有良好的应用前景。