Combination of Paclitaxel and R-flurbiprofen loaded PLGA nanoparticles suppresses glioblastoma growth on systemic administration

Malignant gliomas are highly lethal. Delivering chemotherapeutic drugs to the brain in sufficient concentration is the major limitation in their treatment due to the blood-brain barrier (BBB). Drug delivery systems may overcome this limitation and can improve the transportation through the BBB. Paclitaxel is an antimicrotubule agent with effective anticancer activity but limited BBB permeability. R-Flurbiprofen is a nonsteroidal antienflammatory drug and has potential anticancer activity. Accordingly, we designed an approach combining R-flurbiprofen and paclitaxel and positively-charged chitosan-modified poly-lactide-co-glycolic acid (PLGA) nanoparticles (NPs) and to transport them to glioma tissue. NPs were characterized and, cytotoxicity and cellular uptake studies were carried out in vitro. The in vivo efficacy of the combination and formulations were evaluated using a rat RG2 glioma tumor model. Polyethylene glycol (PEG) modified and chitosan-coated PLGA NPs demonstrated efficient cytotoxic activity and were internalized by the tumor cells in RG2 cell culture. In vivo studies showed that the chitosan-coated and PEGylated NPs loaded with paclitaxel and R-flurbiprofen exhibited significantly higher therapeutic activity against glioma. In conclusion, PLGA NPs can efficiently carry their payloads to glioma tissue and the combined use of anticancer and anti-inflammatory drugs may exert additional anti-tumor activity.

Preclinical evaluation of a biobetter candidate: Pharmacokinetics and pharmacodynamics of GX-G3 in healthy and neutropenia-induced rats

Neutropenia is a condition of an abnormally low number of neutrophils which render patients more susceptible to infections, especially to bacterial infections, as the condition may become life threatening and deadly without prompt medical attention. Various factors such as, anticancer drugs, radiotherapy, infectious diseases, congenital defects, or vitamin B12/B9 deficiency can trigger neutropenia. GX-G3, a human hybrid (hy) Fc-fused granulocyte colony stimulating factor (G-CSF), was developed as next-generation G-CSF for the treatment of cancer therapy-induced neutropenia. In this study, with the aim of investigating this promising potential next-generation G-CSF, comparative pharmacokinetic and pharmacodynamic studies were conducted in healthy and neutropenia-induced rats. It was found that t_1/2 of GX-G3 is longer than same mass injection of filgrastim and pegfilgrastim and AUEC_last (area under theeffect-time curve from time zero to the last measurable ANC level) of absolute neutrophil count showed a significant increase after GX-G3 injection compared with filgrastim and pegfilgrastim in healthy rats. Besides, in duration of neutropenia after the same mass injection GX-G3 showed about 3.3 days of reduction effect compared with that of filgrastim, and 1.3 days of reduction effect compared with that of pegfilgrastim in neutropenia-induced rats. These results demonstrate that the half-life of GX-G3 is longer than pegfilgrastim and GX-G3 is more effective than filgrastim and pegfilgrastim in neutropenia-induced rats.

Characterization of bevacizumab by dynamic light scattering while maintaining its native structure

Bevacizumab, is a humanized monoclonal antibody and patents on Avastin® (Bevacizumab, Roche) will expire in the US in 2019 and in Europe in 2022. Therefore, bevacizumab is a popular target for biosimilar developers. One of the most common problems in the formulation of antibody drugs is protein aggregation. Dynamic light scattering (DLS) is a well-established method for the determination of hydrodynamic dimensions, aggregates, and aggregation points of proteins. In contradistinction to other techniques that require diluted samples or specific conditions, proteins and aggregates can maintain their native structure during DLS measurements. In recent studies, bevacizumab was characterized by DLS using diluted samples. In this study, we aimed at investigating the hydrodynamic dimensions, aggregates, and aggregation onset of bevacizumab (Altuzan®, Turkey, Roche) by DLS, while maintaining its native structure. The intensity, volume, and number-based particle size distribution profiles of the test samples were evaluated and the aggregation onset of the formulation was successfully determined against increasing temperature. It is shown that the preservation of the native structure of commercial formulations in DLS measurements provides an opportunity to the characterization of commercial products and development of biosimilars.

Simultaneous Determination of Dexpanthenol, Lidocaine Hydrochloride, Mepyramine Maleate and their Related Substances by a RP-HPLC Method in Topical Dosage Forms

The pharmaceutical combination of dexpanthenol (DPA), lidocaine hydrochloride (LIH) and mepyramine maleate (MAM) is used for their anti-allergic, anti-inflammatory, anti-pruritic, anesthetic and antiseptic properties. The present study was aimed to develop and validate a new, first and rapid high performance liquid chromatographic method for simultaneous determination of DPA, LIH and MAM in the presence of their stress-induced degradation products in pharmaceutical gel/fluigel formulations. The chromatographic separation was performed on an Inertsil ODS-3 V, 250 × 4.6 mm (5 μm) column using a gradient mobile phase of an aqueous solution of ammonium acetate (0.01 M) and methanol mixture at gradient flow rates of 1.3 mL/min and 1.5 mL/min with detection at 230 nm. The retention times for DPA, LIH and MAM were ~3.28 min, 11.67 min and 12.99 min, respectively. The method was validated in accordance with International Conference on Harmonisation guidelines. Calibration curves were linear in the ranges of 9-54 μg/mL for MAM and LIH and 30-180 μg/mL for DPA with satisfactory correlation coefficients (R2 > 0.999). The mean % recoveries obtained were found to be 99.9% for MAM, 100.3% for LIH and 99.3% for DPA. Precision % RSD was <2. Robustness results were uniform, there were no marked changes, so method is highly validated. All drugs were subjected to stress conditions and degradation products were separated with acceptable peak tailing (T ≤ 2) and good resolution (Rs > 2). The validated method therefore can be adapted for quality control procedures of the drugs in pharmaceutical dosage forms and their stability studies.

Using PVA and TPGS as combined emulsifier in nanoprecipitation method improves characteristics and anticancer activity of ibuprofen loaded PLGA nanoparticles

In the preparation of nanoparticles (NPs) by the nanoprecipitation method, emulsifiers play a key role for NPs' characteristics. The present study aimed to investigate the combined emulsifier effect on ibuprofen loaded poly(lactic-co-glycolic acid) (PLGA) NPs' characteristics and anticancer activity. Ibuprofen loaded PLGA NPs were prepared by nanoprecipitation using different concentrations of PVA (poly(vinyl alcohol)) or PVA-TPGS (d-α-tocopherol polyethylene glycol 1000 succinate) combination as emulsifier. It was found that encapsulation efficiencies of NPs varied between 17.9 and 41.9 % and the highest encapsulation efficiency was obtained with 0.5% PVA + 0.1% TPGS (coded as PLGA PVA/TPGS NPs). PLGA PVA/TPGS NPs were characterized and compared with PLGA PVA NPs, which was obtained by 0.5% PVA alone. Polydispersity index of PLGA PVA/TPGS and PLGA PVA NPs were found to be 0.08 and 0.15, respectively. Incorporation of TPGS with PVA slightly decreased the initial ibuprofen release. Transmission electron microscopy analyses demonstrated a nearly uniform particle size distribution and spherical particle shape of the PLGA PVA/TPGS NPs. Additionally, PLGA PVA/TPGS NPs were significantly more cytotoxic than PLGA PVA NPs on the MCF-7 (human breast adenocarcinoma cells) and Caco-2 (human epithelial colorectal adenocarcinoma) cells (p<0.05). Also PLGA PVA/TPGS NPs were not cytotoxic on normal cells (L929, mouse healthy fibroblast cells) (p>0.05). In conclusion, these results indicated that using a combination of TPGS and PVA as an emulsifier in nanoprecipitation could be a promising approach for preparing ibuprofen loaded PLGA NPs because of their improved characteristics and anticancer activity.

Preparation and Characterization of Biocompatible Chitosan Nanoparticles for Targeted Brain Delivery of Peptides

Here, we describe a nanocarrier system that can transfer chitosan nanoparticles loaded with either small peptides such as the caspase inhibitor Z-DEVD-FMK or a large peptide like basic fibroblast growth factor across the blood-brain barrier. The nanoparticles are selectively directed to the brain and are not measurably taken up by the liver and spleen. Intravital fluorescent microscopy provides an opportunity to study the penetration kinetics of nanoparticles loaded with fluorescent agents such as Nile red. Nanoparticles functionalized with anti-transferrin antibody and loaded with peptides efficiently provided neuroprotection when systemically administered either as a formulation bearing a single peptide or a mixture of them. Failure of brain permeation of the nanoparticles after inhibition of vesicular transcytosis by imatinib as well as when nanoparticles were not functionalized with anti-transferrin antibody indicates that this nanomedicine formulation is rapidly transported across the blood-brain barrier by receptor-mediated transcytosis.

Development and validation of a LC-FL method for the simultaneous determination of doxorubicin and celecoxib in nanoparticulate fixed dose combination (NanoFDC)

An isocratic reversed phase HPLC method for the simultaneous determination of doxorubicine (DOX) and celecoxib (CXB) out of a nanoparticulate fixed dose combination (NanoFDC) was developed and validated. Linearity of the results was demonstrated from 1-11 μg/mL for both components. Lower limits of detection were determined as 7 ng/mL for DOX and 13 ng/mL for CXB. Total run time was approximately 15 min.

DEVELOPMENT AND VALIDATION OF HPLC ANALYTICAL METHODS USED-FOR DETERMINATION OF ASSAY, CONTENT UNIFORMITY AND DISSOLUTION OF IMMEDIATE RELEASE CANDESARTAN CILEXETIL 32 MG TABLETS

New analytical methods have been developed and validated on high performance liquid chromatography (HPLC) to assess the assay, content uniformity and dissolution of immediate release candesartan cilexetil 32 mg tablets. Method development studies were performed on cyano column. Mobile phase of assay and content uniformity test consisted of mixture of 0.05 M phosphate buffer, pH 4.5 and methanol (40 : 60, v/v) adjusted to pH 4.0 with trifluoroacetic acid, whereas mobile phase of dissolution test consisted of mixture of I mM phosphate buffer and acetonitrile (50 : 50, v/v) adjusted to pH 2.0 with trifluoroacetic acid. Mobile phases were pumped at flow rate of 1.0 mL/min, ultraviolet-visible (UV) detector was operated at 254 nm, injection volume was set at 20 μL, column temperature was held at 25⁰C. Dissolution medium was 0.05 M phosphate buffer, pH 6.5 including 0.70% (w/v) polysorbate 20. Validation studies met acceptance criteria of system suitability, specificity, linearity and range, accuracy, precision, detection limit (LOD), quantitation limit (LOQ) and robustness parameters.

Systemically administered brain-targeted nanoparticles transport peptides across the blood-brain barrier and provide neuroprotection

Although growth factors and anti-apoptotic peptides have been shown to be neuroprotective in stroke models, translation of these experimental findings to clinic is hampered by limited penetration of peptides to the brain. Here, we show that a large peptide like the basic fibroblast growth factor (bFGF) and a small peptide inhibitor of caspase-3 (z-DEVD-FMK) can effectively be transported to the brain after systemic administration by incorporating these peptides to brain-targeted nanoparticles (NPs). Chitosan NPs were loaded with peptides and then functionalized by conjugating with antibodies directed against the transferrin receptor-1 on brain endothelia to induce receptor-mediated transcytosis across the blood-brain barrier (BBB). Pre-ischemic systemic administration of bFGF- or z-DEVD-FMK-loaded NPs significantly decreased the infarct volume after 2-hour middle cerebral artery occlusion and 22-hour reperfusion in mice. Co-administration of bFGF- or z-DEVD-FMK-loaded NPs reduced the infarct volume further and provided a 3-hour therapeutic window. bFGF-loaded NPs were histologically detected in the brain parenchyma and also restored ischemia-induced Akt dephosphorylation. The neuroprotection was not observed when receptor-mediated transcytosis was inhibited with imatinib or when bFGF-loaded NPs were not conjugated with the targeting antibody, which enables them to cross the BBB. Nanoparticles targeted to brain are promising drug carriers to transport large as well as small BBB-impermeable therapeutics for neuroprotection against stroke.

An aquaporin 4 antisense oligonucleotide loaded, brain targeted nanoparticulate system design

Aquaporins (AQPs), members of the water-channel protein family, are highly expressed in brain tissue especially in astrocytic end-feet. They are important players for water hemostasis during development of cytotoxic as well as vasogenic edema. Increased expression of AQPs is important in pathophysiology of neurological diseases such as neuroinflammation and ischemia. Unfortunately, there are a few pharmacological inhibitors of AQP4 with several side effects limiting their translation as a drug for use in clinical conditions. Another therapeutic approach is using antisense oligonucleotides (ASOs) to block AQP4 activity. These are short, synthetic, modified nucleic acids that bind RNA to modulate its function. However, they cannot pass the blood brain barrier (BBB). To overcome this obstacle we designed a nanoparticulate system made up of chitosan nanoparticles surface modified with PEG and conjugated with monoclonal anti transferrin receptor-1 antibody via streptavidin-biotin binding. The nanocarrier system could be targeted to the transferrin receptor-1 at the brain endothelial capillaries through monoclonal antibodies. It is hypothesized that the nanoparticles could pass the BBB via receptor mediated transcytosis and reach brain parenchyma. Particle size, zeta potential, loading capacity and release profiles of nanoparticles were investigated. It was observed that all types of chitosau (CS) nanoparticles had positive zeta potential values and nanoparticle particle size distribution varied between 100 and 800 nm. The association efficiency of ASOs into the nanoparticles was between 80-97% and the release profiles of the nanoparticles exhibited an initial burst effect followed by a controlled release. The results showed that the designed chitosan based nanocarriers could be a promising carrier system to transport nucleic acid based drugs to brain parenchyma.

Squalenoyl adenosine nanoparticles provide neuroprotection after stroke and spinal cord injury

There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, such as adenosine, are inefficient upon systemic administration because of their fast metabolization and rapid clearance from the bloodstream. Here, we show that conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allows prolonged circulation of this nucleoside, providing neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This Article shows, for the first time, that a hydrophilic and rapidly metabolized molecule such as adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

Formulation and evaluation of clozapine orally disintegrating tablets prepared by direct compression

In this study, clozapine orally disintegrating tablets (ODTs) were prepared by direct compression method. Disintegration time, resistance to crushing of tablets, porosity, friability, dissolution tests were performed and dissolution profiles of ODTs were investigated. Morphological and interaction studies were also performed. Friability values were found to be less than 1%. All tablet formulations disintegrated within 1 min and fulfilled the 3 min disintegration time required for ODTs given in the European Pharmacopoeia. More than 85% of the labeled amount of clozapine was dissolved in 15 min from the ODTs. No interaction or changes were found between active substance and excipients. As a result of the studies, ODT formulations developed in this study can be suggested as promising formulations, which assist development and manufacturing a generic product of clozapine.

Histologic and histomorphometric assessment of eggshell-derived bone graft substitutes on bone healing in rats

OBJECTIVE

The objective of this study was to histologically and histomorphometrically evaluate the efficacy of the new formulations of eggshell-derived calcium carbonate in rats.

STUDY DESIGN

The study was conducted on 30 adult male rats. Four standardized and circular intrabony defects were created in the both maxilla and mandibula of each animal. Three different graft materials were prepared as follows: 1) Material A: Eggshell-derived calcium carbonate combined with carrageenan gel, 2) Material B: Eggshell-derived calcium carbonate combined with xanthan gum gel, and 3) Material C: Eggshell-derived calcium carbonate powder. The right mandibular defect sites were grafted with Material A in all animals, and defects on the left were grafted with Material B. Defects on the right side of maxilla were received Material C in all animals, and all left maxillary defects were remained untreated as controls. The animals were sacrificed either postoperatively on the 15th day, postoperatively on the 30th day or postoperatively on the 45th day. Histomorphometric measurements were made of the areas of newly formed bone, necrotic bone, fibrous tissue and residual graft material.

RESULTS

Material A exhibited the highest level of osteoid formation followed by Material B and Material C on the 45th day. In terms of osteoid formation, statistically significant differences were observed between graft materials and controls at 45th day compared to 15th and 30th day (p<0.05).

CONCLUSIONS

Eggshell-derived graft substitutes in both gel and powder forms are biocompatible materials which may have the potential to enhance the new bone formation. Key words:Bone graft material, bone defects, eggshell, histopathological evaluation, rat.

Counterfeit/Copy Drugs: Patients Safety in the Heart

Some studies demonstrate that a large proportion of copy drugs contain lower levels of active substances and higher impurity levels than reference drugs. The number of copy drugs failing to meet internationally recognised quality criteria consequences of patients receiving lower doses of active substances than expected. In addition, possible clinical effect of impurities must be considered. Counterfeiting of drugs exhibits a significant and growing threat to human health and public safety.一些研究表明，大部分的仿制药品含有比参考药品更低级别的活性物质和更高级别的杂质。 能满足国际公认质量标准的仿制药品导致患者接受比预期更少剂量的活性物质。 此外，必须考虑杂质可能导致的临床效应。 假冒药品对人类健康和公共安全造成重大威胁，并且此威胁正在增加。

Evaluation of drug-excipient interaction in the formulation of celecoxib tablets

In the present study, the possible interactions between celecoxib and some excipients (colloidal silicon dioxide (Aerosil), microcrystalline cellulose (Avicel PH 102), lactose anhydrous, magnesium stearate, cross-povidone and talc) were evaluated by examining the pure drug or drug-excipient powder mixtures which were stored under different conditions (25 +/- 2 degrees C, 60% RH +/- 5% RH or 40 + 2 degrees C, 75% RH +/- 5% RH) and different period (30 or 60 days) using DSC, FT-IR and HPLC. In order to investigate the possibility of celecoxib-excipient interaction in aqueous medium, dispersions of the pure drug or drug in physical powder mixture (1:1 w/w) in water (1%, w/v) were also prepared and evaluated by FT-IR and HPLC at day 0 and day 7 (40 +/- 2 degrees C). The interaction between celecoxib and magnesium stearate or colloidal silicon dioxide were determined in the aqueous dispersions by FT-IR. Different tablet formulations with or without excipients tested were prepared, and assessed for drug dissolution and permeability.

Comparative evaluation of in vitro parameters of tamoxifen citrate loaded poly(lactide-co-glycolide), poly(epsilon-caprolactone) and chitosan nanoparticles

Tamoxifen (TAM), the clinical choice for the antiestrogen treatment of advanced or metastatic breast cancer, was formulated in nanoparticulate carrier systems in the form of poly(lactide-co-glycolide) (PLGA), poly-epsilon-caprolactone (PCL) and chitosan (CS) nanoparticles. The PLGA and PCL nanoparticles were prepared by a nanoprecipitation technique whereas the CS nanoparticles were prepared by the ionic gelation method. Mean particle sizes were under 260 nm for PLGA and PCL nanoparticles and around 400 nm for CS nanoparticles. Polydispersity indices were less than 0.4 for all formulations. Zeta potential values were positive for TAM loaded nanoparticles because of the positive charge of the drug. Drug loading values were significantly higher for PCL nanoparticles when compared to PLGA and CS nanoparticles. All nanoparticle formulations exhibited controlled release properties. These results indicate that TAM loaded PLGA, PCL and CS nanoparticles may provide promising carrier systems for tumor targeting.

The influence of technological parameters on the physicochemical properties of blank PLGA nanoparticles

In this work, PLGA nanoparticles were prepared by an emulsification-diffusion technique. The main objective was to optimize the preparation of formulations by evaluating the influence of the technological parameters on the physicochemical properties of PLGA nanoparticles. The effects of variations in polymer and emulsifier concentrations, and homogenization duration, rate and type on the particle size distribution, surface charge and morphology of nanoparticles were assessed. The smallest nanoparticles (177.53 +/- 2.78 nm) were obtained with a 2% PLGA (w/v) concentration in the organic phase and 3% PVA (w/v) in the aqueous phase and were prepared by an emulsification-diffusion method via ultrasonic homogenization at a power of 80 W applied for 30 s. It was observed that nanoparticles prepared by Ultra Turrax were more spherical but larger. In addition, increasing the PVA concentration in the aqueous phase, increasing the PLGA concentration in the organic phase and increasing the homogenization rate decreased the zeta potential values of PLGA nanoparticles.

Preparation and evaluation of alpha-phenyl-n-tert-butyl nitrone (PBN)-encapsulated chitosan and PEGylated chitosan nanoparticles

Alpha-phenyl-n-tert-butyl nitrone (PBN) shows its major effect by scavenging free radicals formed in the ischemia and it has the ability to penetrate through the blood brain barrier easily. The in vivo stability of PBN is very low and when administered systemically, it has a mean plasma half life of about three hours. Therefore, formulations which are able to prolong the plasma residence time of PBN are of major interest, because oxygen radicals are usually continuously formed under pathological conditions. In this study, PBN, a nitrone compound having neuroprotective properties, was encapsulated in chitosan (CS) and chitosan-poly(ethylene glycol) (CS-PEG) nanoparticles for treatment of diseases such as stroke, in which sustained free radical production is reported. The nanoparticles were characterized through particle size determination, zeta potential, encapsulation efficiency, surface morphology determinations and in vitro release studies. The surface morphologies were evaluated by transmission electron microscopy (TEM) and nanoparticles having spherical shapes were characterized. The particle size distribution was between approximately 97 nm and approximately 322 nm; and the zeta potentials varied between approximately 9 mV and approximately 33 mV. Size of the nanoparticle formulations was important for the release of PBN from nanoparticles. The quantitative determination of PBN has been evaluated by a validated analytical HPLC method. The presented chitosan-based nanotechnology opens new perspectives for testing antioxidant activity in vivo.

Preparation and characterization of salmon calcitonin-biotin conjugates

This study was performed to prepare and characterize the biotinylated Salmon calcitonin (sCT) for oral delivery and evaluate the hypocalcemic effect of biotinylated-sCTs in rats. Biotinylated sCTs was characterized by using high performance liquid chromatography (HPLC) and MALDITOF-MS. The effect of biotinylation on permeability across Caco-2 cell monolayers was examined. Their hypocalcemic effect was determined in rats. Mono- and di-bio-sCTs were separated by reverse phase HPLC. The molecular weights of mono-bio-sCT and di-bio-sCT were determined to be 3,660.5 and 3,900.2 Da, respectively. The permeability of biotinylated-sCTs across Caco-2 cell monolayers was observed with a significant enhancement compared with sCT. Intrajejunal (ij) administration of mono-bio-sCT and di-bio-sCT resulted in sustained reduction in serum calcium levels, with a maximum reduction (% max(d)) of 21.6% and 30% after 4 h and 6 h of application, respectively. The biotin conjugation of sCT may be a promising strategy for increasing the oral bioavailability of sCT and achieving sustained calcium-lowering effects.

In vitrocytotoxicity of mitoxantrone-incorporated albumin microspheres on acute promyelocytic leukaemia cells

In the present study, the preparation and characterization of bovine serum albumin (BSA) microspheres and the evaluation of the in vitro cytotoxicity of these microspheres on acute promyelocytic leukaemia (HL-60) cells were described. Mitoxantrone (MTZ)-incorporated microspheres were evaluated for particle size, drug loading, release characteristics and surface morphology. The biological effect of MTZ released from BSA microspheres was determined on an in vitro cultured HL-60 cell line, showing that, after encapsulation, MTZ still retains cytotoxic activity. For this purpose, methyl-thiazol-tetrazolium (MTT) assay was used to evaluate the in vitro cytotoxicity of MTZ-loaded microspheres. Particle size of BSA microspheres was determined between 17.61-20.38 microm and they were smooth and spherical in shape. Encapsulation efficiency of the drug-loaded microspheres was between 22.26-60.50%. For MTZ-containing microspheres, the cell death ratios were greater than 80% for all formulations. This study demonstrate that BSA microspheres were well suited for the controlled release of MTZ and were promising for anti-cancer chemotherapy.

Development of a peptide-containing chewing gum as a sustained release antiplaque antimicrobial delivery system

The objective of this study was to characterize the stability of KSL-W, an antimicrobial decapeptide shown to inhibit the growth of oral bacterial strains associated with caries development and plaque formation, and its potential as an antiplaque agent in a chewing gum formulation. KSL-W formulations with or without the commercial antibacterial agent cetylpyridinium chloride (CPC) were prepared. The release of KSL-W from the gums was assessed in vitro using a chewing gum apparatus and in vivo by a chew-out method. A reverse-phase high-performance liquid chromatography method was developed for assaying KSL-W. Raw material stability and temperature and pH effects on the stability of KSL-W solutions and interactions of KSL-W with tooth-like material, hydroxyapatite discs, were investigated. KSL-W was most stable in acidic aqueous solutions and underwent rapid hydrolysis in base. It was stable to enzymatic degradation in human saliva for 1 hour but was degraded by pancreatic serine proteases. KSL-W readily adsorbed to hydroxyapatite, suggesting that it will also adsorb to the teeth when delivered to the oral cavity. The inclusion of CPC caused a large increase in the rate and extent of KSL-W released from the gums. The gum formulations displayed promising in vitro/in vivo release profiles, wherein as much as 90% of the KSL-W was released in a sustained manner within 30 minutes in vivo. These results suggest that KSL-W possesses the stability, adsorption, and release characteristics necessary for local delivery to the oral cavity in a chewing gum formulation, thereby serving as a novel antiplaque agent.

Stability of Antimicrobial Decapeptide (KSL) and Its Analogues for Delivery in the Oral Cavity

PURPOSE

To investigate the stability of KSL, an antimicrobial decapeptide, and its analogues, in human saliva and simulated gastric fluid for delivery in the oral cavity.

MATERIALS AND METHODS

The degradation products of KSL in human saliva and simulated gastric fluid were separated by reversed-phase HPLC and their structures were identified by electrospray ionization-mass spectrometry. Analogues of KSL were synthesized by solid-phase synthesis procedure. Their enzymatic stabilities and antimicrobial activities were studied.

RESULTS

KSL was degraded by the peptide bond cleavages at Lys(6)-Val(7) in the human saliva and Phe(5)-Lys(6) in simulated gastric fluids. Three analogues of KSL were synthesized; the Lys(6) residue was either methylated (KSL-M), or replaced with Trp (KSL-W), or the d-form of Lys (KSL-D). The KSL analogues were much more stable than the native KSL, with the rank order of stability being KSL-D > KSL-W > KSL-M > KSL in human saliva. However, in simulated gastric fluid, while KSL-D was still stable, KSL-W was significantly degraded. In addition, KSL-D significantly lost the antimicrobial activity, whereas KSL-W completely preserved the activity against several oral bacteria. In a chewing gum formulation, KSL-W showed a more sustained release profile as compared with the native KSL.

CONCLUSION

This study suggests that KSL-W could be used as an antiplaque agent in a chewing gum formulation.

Treatment of malignant gliomas with mitoxantrone-loaded poly (lactide-co-glycolide) microspheres

OBJECTIVE

Mitoxantrone (MTZ) has potent in vitro activity against malignant glioma cell lines, but it cannot be used effectively as a systemic agent for the treatment of brain tumors because of its poor central nervous system penetration. However, MTZ-loaded poly(lactide-co-glycolide) (PLGA) microspheres may be injected into the peritumoral area and into tumor tissue to provide effective and sustained local drug concentrations without causing systemic side effects.

METHODS

Fisher rats were randomized into three groups. The first group (n = 9) was concomitantly implanted with rat glioma (RG2) cells and blank PLGA microspheres. The second group (n = 6) was implanted with RG2 cells and MTZ-loaded PLGA microspheres. The third group (n = 9) was implanted with RG2 cells, and MTZ-loaded PLGA microspheres were injected into the same area after 7 days. Animals were sacrificed on Day 15 or 35. Tumor volumes were measured after hematoxylin and eosin staining. Distribution kinetics of MTZ in the brain was determined by high-performance liquid chromatography in nine rats injected with MTZ-loaded microspheres.

RESULTS

The tumor volumes were 76 +/- 11 and 107 +/- 11 mm (mean +/- standard error) on Days 15 (n = 6) and 35 (n = 3), respectively, in the control group. In rats treated with MTZ-loaded microspheres on Day 7, tumor volumes were significantly reduced to 17 +/- 4 and 23 +/- 2 mm on Days 15 (n = 6) and 35 (n = 3), respectively. No tumor formation was observed when glioma cells and MTZ-loaded PLGA microspheres were implanted concomitantly (n = 6). No systemic side effects or parenchymal inflammatory infiltration were observed in either group of rats. Brain MTZ concentration was highest at the injection site and declined with time and distance from the injection site and with time.

CONCLUSION

These data demonstrate that MTZ-loaded PLGA microspheres can deliver therapeutic concentrations of drug to the tumor and prevent glioma growth without causing side effects. This treatment method may increase the efficiency of antineoplastic therapy and positively impact survival.

Preparation and characterization of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors in the brain

Treatment of central nervous system (CNS) diseases with potentially useful pharmaceuticals is prevented by the blood-brain barrier (BBB). The BBB is a unique protective barrier in the body. It is formed by epithelial-like tight junctions, which are expressed by the brain capillary endothelial cells. Although most molecules are potentially active in the CNS, they cannot readily enter the brain because of their properties. Antisense oligonucleotides (ODNs) have a great potential as neuropharmaceuticals; however, the large size and polar nature of nucleic acid drugs prevent these molecules from bypassing the BBB and readily entering the CNS following systemic administration. One approach to improve both the pharmacokinetics and the pharmacodynamics of ODNs involves the use of sustained-release polymer formulations, such as poly(lactide-co-glycolide) (PLGA) nanoparticulate systems. In this study, nanospheres were prepared by the emulsification diffusion technique and characterized in terms of particle size, surface morphology, encapsulation efficiency, in vitro release profiles and ODN stability. The nanospheres produced were spherical with homogenous size distribution. Nanospheres were prepared with different encapsulation efficiency. Release profiles of formulations were also evaluated. The results show that formulations with different ODN content exhibited different release profiles. Moreover, the chemical integrity of ODN during the processes was conserved. These results demonstrate that a stable ODN formulation could be prepared utilizing PLGA nanospheres as a potential delivery system for the treatment of CNS diseases.

Chewing gum of antimicrobial decapeptide (KSL) as a sustained antiplaque agent: preformulation study

The purpose of this study was to investigate the potential of KSL, an antimicrobial decapeptide, which has been shown to inhibit the growth of oral bacterial strains associated with caries development and plaque formation, to act as an antiplaque agent in a chewing gum formulation. A reversed-phase high-performance liquid chromatography method was developed for KSL and found to be stability-indicating. KSL was stable in acetate buffer at pH 4 and artificial saliva. On the affinity of KSL to tooth-like materials, the KSL showed favorable interaction with hydroxyapatite discs pretreated with human saliva. A chewing gum formulation of KSL was prepared based on conventional procedures and the release of KSL from the gum was studied in vitro using the chewing apparatus and in vivo by a chew-out method. The gum formulations showed promising in vitro/in vivo release profiles, in which 70-80% KSL was released in a sustained manner over 20 min of chewing time. This study suggests that KSL in a gum formulation is suitable for the delivery in the oral cavity, thereby serving as a novel antiplaque agent.

Development and Brain Delivery of Chitosan−PEG Nanoparticles Functionalized with the Monoclonal Antibody OX26

The inhibition of the caspase-3 enzyme is reported to increase neuronal cell survival following cerebral ischemia. The peptide Z-DEVD-FMK is a specific caspase inhibitor, which significantly reduces vulnerability to the neuronal cell death. However, this molecule is unable to cross the blood-brain barrier (BBB) and to diffuse into the brain tissue. Thus, the development of an effective delivery system is needed to provide sufficient drug concentration into the brain to prevent cell death. Using the avidin (SA)-biotin (BIO) technology, we describe here the design of chitosan (CS) nanospheres conjugated with poly(ethylene glycol) (PEG) bearing the OX26 monoclonal antibody whose affinity for the transferrin receptor (TfR) may trigger receptor-mediated transport across the BBB. These functionalized CS-PEG-BIO-SA/OX26 nanoparticles (NPs) were characterized for their particle size, zeta potential, drug loading capacity, and release properties. Fluorescently labeled CS-PEG-BIO-SA/OX26 nanoparticles were administered systemically to mice in order to evaluate their efficacy for brain translocation. The results showed that an important amount of nanoparticles were located in the brain, outside of the intravascular compartment. These findings, which were also confirmed by electron microscopic examination of the brain tissue indicate that this novel targeted nanoparticulate drug delivery system was able to translocate into the brain tissue after iv administration. Consequently, these novel nanoparticles are promising carriers for the transport of the anticaspase peptide Z-DEVD-FMK into the brain.

Preparation and in vitro evaluation of chitosan nanoparticles containing a caspase inhibitor

The aim of this work was to develop a formulation for Z-DEVD-FMK, a peptide which is a caspase inhibitor and has been used in experimental animal studies for a decade. Peptide loaded chitosan nanoparticles were obtained by ionotropic gelation process and Z-DEVD-FMK was quantified by an HPLC method. The influence of the initial peptide concentration on the nanoparticle characteristics and release behavior was evaluated. The CS nanoparticles have a particle diameter (Z-average) ranging from approximately 313-412 nm and a positive zeta potential (20-28 mV). The formulation with the initial peptide concentration of 400 ng/ml provided the highest loading capacity (0.46%) and the highest extent of release (65% at 24 h) suggesting the possibility to achieve a therapeutic dose. According to the data obtained, this chitosan-based nanotechnology opens new and interesting perspectives for anticaspase activity.

Preparation and characterization of poly(D,L-lactide-co-glycolide) microspheres for controlled release of human growth hormone

The purpose of this research was to assess the physicochemical properties of a controlled release formulation of recombinant human growth hormone (rHGH) encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) composite microspheres. rHGH was loaded in poly(acryloyl hydroxyethyl) starch (acHES) microparticles, and then the protein-containing microparticles were encapsulated in the PLGA matrix by a solvent extraction/evaporation method. rHGH-loaded PLGA microspheres were also prepared using mannitol without the starch hydrogel microparticle microspheres for comparison. The detection of secondary structure changes in protein was investigated by using a Fourier Transfer Infrared (FTIR) technique. The composite microspheres were spherical in shape (44.6 +/- 2.47 microm), and the PLGA-mannitol microspheres were 39.7 +/- 2.50 microm. Drug-loading efficiency varied from 93.2% to 104%. The composite microspheres showed higher overall drug release than the PLGA/mannitol microspheres. FTIR analyses indicated good stability and structural integrity of HGH localized in the microspheres. The PLGA-acHES composite microsphere system could be useful for the controlled delivery of protein drugs.

In vitro/in vivo studies on a buccal bioadhesive tablet formulation of carbamazepine

A buccoadhesive controlled-release system for delivery of carbamazepine (CBZ) was prepared by compression of hydroxypropyl methylcellulose (HPMC) and carbomer, incorporating a penetration enhancer, sodium glycodeoxycholate (GDC). The release behaviour of systems containing CBZ and various amounts of the two polymers with and without GDC was found to be non-Fickian. Formation of an interpolymer complex between HPMC and carbomer was confirmed in acidic medium by turbidity, viscosity and FT-IR measurements. Addition of the drug to the buccoadhesive formulation reduced the adhesion force significantly (p < 0.1). GDC did not have any effect on bioadhesion. Permeability of bovine buccal mucosa to CBZ was determined using Ussing diffusion chambers [1]. In vivo interaction between the tablet and tissue was examined histologically as well as by scoring mucosal irritation. Histological changes observed in the buccal epithelium after 4 h contact with the tablets containing GDC recovered completely within 24 h after removal. No measurable plasma level of CBZ was obtained either in the absence or presence of GDC.

Stability of poly(L-lysine)-complexed plasmid DNA during mechanical stress and DNase I treatment

The aim of this study was to investigate the formation and stability of complexes between plasmid DNA (pDNA) and poly(L-lysine) (PLL). Formation of pDNA/PLL complexes with various ratios was determined by a fluorescence spectrophotometric method using fluorescamine. The effects of sonication, vortexing, and exposure to DNase I on the stability of free pDNA and pDNA/PLL complexes are discussed. A linear correlation between PLL added and PLL bound was obtained with overall reaction efficiency of 84.2-92.6%. Sonication degraded both free and PLL-complexed pDNA within 15 sec of vortexing. However, vortexing did not alter the stability of free and complexed pDNA. Dramatic increase in the protection of pDNA in pDNA/PLL complexes was observed in the DNase I digestion experiment; 68.1-89.0% of total pDNA in the pDNA/PLL complexes was protected from DNase I digestion compared to only 19.2% of total pDNA that remained undegraded after DNase I treatment of free pDNA. An increase in the PLL/pDNA ratio led to an increase in the protection of supercoiled pDNA; 15.5-38.2% of supercoiled pDNA pin PLL/pDNA complexes was protected after DNase I treatment. The results show that complexation of pDNA with PLL can stabilize the supercoiled structure of pDNA for the development of biodegradable microspheres as a delivery system for pDNA. Stability of pDNA/PLL complex can be monitored by PicoGreen dye and fluorescence densitometric assay methods.

Influence of formulation parameters on the characteristics of poly(D, L-lactide-co-glycolide) microspheres containing poly(L-lysine) complexed plasmid DNA

This study describes the influence of polymer type, surfactant type/concentration, and target drug loading on the particle size, plasmid DNA (pDNA) structure, drug loading efficiency, in vitro release, and protection from DNase I degradation of poly(D, L-lactide-co-glycolide) (PLGA) microspheres containing poly(L-lysine) (PLL) complexed pDNA. PLGA microspheres containing pDNA-PLL were prepared using the water-in-oil-in-water (w-o-w) technique with poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) as surfactants in the external aqueous phase. A complex ratio of 1:0.33 (pDNA-PLL, w/w) enhanced the stability of pDNA during microsphere preparation. Higher pDNA-PLL loading efficiency (46.2%) and supercoiled structure (64.9%) of pDNA were obtained from hydrophobic PLGA (M(w) 31000) microspheres compared with hydrophilic PLGA or low-molecular-weight PLGA microspheres. The particle size decreased from 6.6 to 2.2 microm when the concentration of PVA was increased from 1 to 7%. At the same concentration of surfactant, PVA stabilized microspheres showed higher pDNA-PLL loading efficiency (46.2%) than PVP stabilized microspheres (24.1%). Encapsulated pDNA in PLGA microspheres was protected from enzymatic degradation and maintained in the supercoiled form. The pDNA-PLL microspheres showed in vitro release of 95.9 and 84.9% within 38 days from the low-molecular-weight PLGA and hydrophilic PLGA microspheres, respectively, compared to 54.2% release from the hydrophobic, higher-molecular-weight PLGA microspheres. The results suggest loading and release of pDNA-PLL complex can be influenced by surfactant concentration and polymer type.

Preparation and characterization of poly (D,L-lactide-co-glycolide) microspheres for controlled release of poly(L-lysine) complexed plasmid DNA

PURPOSE

To produce and characterize controlled release formulations of plasmid DNA (pDNA) loaded in poly (D,L-lactide-co-glycolide) (PLGA) microspheres both in free form and as a complex with poly (L-lysine).

METHODS

Poly (L-lysine) (PLL) was used to form pDNA/PLL complexes with complexation ratio of 1:0.125 and 1:0.333 w/w to enhance the stability of pDNA during microsphere preparation and protect pDNA from nuclease attack. pDNA structure, particle size, zeta potential, drug loading, in vitro release properties, and protection from DNase I were studied.

RESULTS

The microspheres were found to be spherical with average particle size of 3.1-3.5 microm. Drug loading of 0.6% was targeted. Incorporation efficiencies of 35.1% and 29.4-30.6% were obtained for pDNA and pDNA/PLL loaded microspheres respectively. Overall, pDNA release kinetics following the initial burst did not correlate with blank microsphere polymer degradation profile suggesting that pDNA release is convective diffusion controlled. The percentage of supercoiled pDNA in the pDNA and pDNA/PLL loaded microspheres was 16.6 % and 76.7-85.6% respectively. Unencapsulated pDNA and pDNA/PLL degraded completely within 30 minutes upon the addition of DNase I. Encapsulation of DNA/PLL in PLGA microspheres protected pDNA from enzymatic degradation.

CONCLUSIONS

The results show that using a novel process, pDNA can be stabilized and encapsulated in PLGA microspheres to protect pDNA from enzymatic degradation.

Formulation and in vitro/in vivo investigation of carbamazepine controlled-release matrix tablets

Carbamazepine controlled-release tablet formulations containing hydroxypropyl methylcellulose (HPMC) as matrix material at different concentrations were developed and evaluated in vitro and in vivo. The formulation containing 10% HPMC (HPMC-10) showed a controlled-release profile comparable to that of a commercially available, controlled-release carbamazepine preparation (Tegretol CR 200). The kinetics of controlled-release carbamazepine tablets was examined in eight healthy volunteers. The peak plasma concentration of 1.99 +/- 0.56 micrograms.ml-1 was obtained for HPMC-10 at 15.0 +/- 9.0 h, and 1.33 +/- 0.35 micrograms.ml-1 for Tegretol CR 200 at 15.2 +/- 8.9 h, and AUC0-infinity values of 85.2 +/- 30.8 micrograms.h.ml-1 and 76.9 +/- 20.7 micrograms.h.ml-1, respectively. Developed formulation (HPMC-10) was found to be bioequivalent to Tegretol CR 200 and, controlled release was obtained with smoother concentration-time curve resulting in less fluctuations.

In vitro studies on enhancing effect of sodium glycocholate on transbuccal permeation of morphine hydrochloride

During the perioperative period, gastric emptying rate and first-pass metabolism limit the use of peroral morphine. Buccal mucosa appears to be a potential site for delivery of morphine as it provides direct entry into the system circulation thereby avoiding the hepatic first-pass effect. However, the low permeability of the buccal epithelium results in a low flux of the drug. The use of a penetration enhancer is required to improve the bioavailability of the drug via buccal route. In this study, the enhancing effect of sodium glycocholate (GC) used at 10 mM and 100 mM concentrations on permeation of morphine hydrochloride (MPH) across the porcine buccal mucosa was studied in vitro. Furthermore, in conjunction with its permeation, accumulation of GC in the tissue with time was also studied in order to elucidate the relationship between GC and enhanced mucosal permeation of the drug. Franz diffusion cells were used in the experiments. Permeation of MPH was increased in the presence of 100 mM GC with an enhancement factor of 9.3 whereas no enhancement was obtained with 10 mM GC. The calculated permeability coefficient for MPH in the presence of 100 mM GC was 2.35 x 10(-5) cm/s. Accumulation of GC at 100 mM in the tissue appears to be more significant at 100 mM concentration which correlated well with the increased permeation of the drug. GC was diffused through the buccal epithelium significantly at 100 mM concentration. Interaction of GC with the tissue appears to be more significant at 100 mM concentration compared to 10 mM concentration, thus resulting in a significant enhancing effect.

Formulation and in vitro-in vivo evaluation of buccoadhesive morphine sulfate tablets

Buccoadhesive controlled-release systems for the delivery of morphine sulfate were prepared by compression of hydroxypropyl methylcellulose (HPMC) with carbomer (CP), which served as the bioactive adhesive compound. The release behavior of systems containing 30 mg of morphine sulfate and various amounts of the two polymers was found to be non-Fickian. The adhesion force was significantly affected by the mixing ratio of HPMC and CP in the tablet, and the weakest adhesion force was observed at a ratio of 1:1 (HPMC:CP). Interpolymer complex formation was confirmed between HPMC and CP in acidic medium by turbidity, viscosity, and FT-IR measurements. The amount absorbed (percentage of the drug loaded) of the controlled-release buccoadhesive tablets in six healthy volunteers and was 30 +/- 5%.

Physico-chemical and bioadhesive properties of polyacrylic acid polymers

In this study, influence of several physico-chemical properties of bioadhesive polyacrylic acid poylmers (Carbopol 910, Polycarbophil, Carbopol 940 and Carbopol 934 PH) are investigated. The effect of pH on the swelling of polyacrylic acid polymers was studied at constant temperature, ionic strength and osmolality. The polymers showed the pH dependence of equilibrium swelling. The bioadhesive strength of the bond formed between surface-preswollen systems and the sublingual bovine mucus was determined by tensile experiments. It was found that the least substituted polymers Polycarbophil and Carbopol 910 with low molecular weight showed the same degree of bioadhesion while highly branched polyacrylic acid polymers Carbopol 940 and 934 PH showed reduced bioadhesion.

Factors affecting the formulation of sustained release potassium chloride tablets

In this study, influence of several formulation factors on the release kinetics of potassium chloride from directly compressed matrices are investigated. Formulations containing hydrophilic (methylcellulose, carbomer), plastic (polyvinyl chloride), and wax (glycerol palmitostearate) matrix materials at concentrations of 10, 15 and 20%, incorporated with potassium chloride as active ingredient and insoluble excipients were prepared and studied in vitro using the USP XXI/NF XVI rotating paddle method. Hardness had no markedly effect on the release characteristics of formulations except for wax matrix material formulation. Results of goodness of fit analysis applied to release data had shown that the release mechanism was described by the Higuchi diffusion controlled model. Positive deviations from Higuchi equation might be due to the erosion of gel layer. Analysis of in vitro release mechanisms indicated that the most suitable results were obtained by methylcellulose and glycerol palmitostearate.

Formulation, bioavailability, and pharmacokinetics of sustained-release potassium chloride tablets

The release of potassium chloride incorporated into hydrogenated vegetable oil and hydroxypropyl methylcellulose matrix tablets was studied in vitro. The formulations containing 20% hydrogenated vegetable oil and hydroxypropyl methylcellulose showed a sustained-release profile comparable to that of a standard commercially available sustained-release preparation, containing 8 mEq potassium chloride embedded in a wax material. The formulated and standard sustained-release potassium chloride tablets were compared to a conventional enteric-coated potassium chloride tablet in 10 healthy subjects. Mean recoveries in 24-hr urine potassium levels from four dosage forms (after subtracting normal urine potassium excretion levels) were 76 +/- 32% from hydroxypropyl methylcellulose, 95 +/- 22% from hydrogenated vegetable oil-incorporated matrix tablets, 91 +/- 29% from commercially available sustained-release tablets, and 97 +/- 13% from enteric-coated tablets. There was no significant difference (P greater than 0.05) in the time to reach maximum excretion rates among the three sustained-release tablets. No significant adverse effect was experienced with any of the preparations.

Formulation and in vitro-in vivo evaluation of sustained-release lithium carbonate tablets

The release of lithium carbonate incorporated into polymethylmethacrylate, polyvinyl chloride, hydrogenated vegetable oil, and carbomer matrix tablets was studied in vitro. The formulation containing 10% carbomer showed a sustained-release profile comparable to that of a standard, commercially available, sustained-release preparation containing 400 mg lithium carbonate embedded in a composite material. In vivo the newly formulated and standard sustained-release lithium carbonate tablets were compared to an oral solution and conventional lithium carbonate tablets in 12 healthy subjects. These crossover studies showed that the sustained-release tablets produced a flatter serum concentration curve than the oral solution and conventional tablet, without loss of total bioavailability.