Applying the Taguchi design for optimized formulation of sustained release gliclazide chitosan beads: an in vitro/in vivo study

Formulation, Pharmacokinetics evaluation, and IVIVC Assessment of Gliclazide Multiparticulates in Rat Model

In vitro and in vivo studies of gliclazide (GLZ)-loaded freeze-dried alginate-gelatin (AL-GL) beads were carried out, aiming to modify its oral bioavailability. Crosslinked freeze-dried GLZ AL-GL beads (particle size: 1.5- and 3.0-mm) were prepared. In vitro evaluation of GLZ AL-GL beads included SEM, DSC, FT-IR, and release rate study in gradient media. In vivo study was single-dose (4 mg/kg), randomized, parallel-group design, two-treatment (T: test GLZ AL-GL beads and R: reference product Diamicron® 30-mg MR tablet) conducted in 96 healthy rats. Each group was subdivided into 2 sub-groups (G1 and G2) having different blood sampling schemes for up to 72 h. Assessment of level A in-vitro-in-vivo correlation (IVIVC) model was carried out. AL-GL beads successfully increased GLZ release rate compared to R. GLZ percent released (Q_4h) was 109.34, 86.85, and 43.43% for 1.5-mm and 3.0-mm beads and R, respectively. DSC analysis confirmed the interaction of AL-GL via crosslinking. No chemical interaction of GLZ has occurred as proved by FT-IR. Relative bioavailability (T/R) for AUC_0-∞ was 132.45% for G1 and 146.16% for G2. No significant differences between T and R in the primary pharmacokinetic parameters were determined. T_max values were found to be earlier in the case of G1 than those of G2. A secondary absorption peak of GLZ was clearly detected in the case of R while its sharpness was minimized in T. High IVIVC was established, and hence, the proposed in vitro release model perfectly correlated with the in vivo study. The current study design might be a platform to enable panoramic view for GLZ variability in vivo.

Optimization of gliclazide loaded alginate-gelatin beads employing central composite design

Objective: The aim of this study was to optimize the formulation of alginate-gelatin (AL-GL) beads containing gliclazide (GLZ) employing design of experiments (DOE).Significance: DOE enabled identification of the interaction between the studied factors, deep understanding of GLZ release pattern and acceleration of the optimization process.Methods: A three-factor, three-level face centered design was employed. The effects of GLZ content (GLZ%, X₁), polymer ratio (AL:GL ratio, X₂), crosslinker concentration (glutaraldehyde, GA%, X₃), and their interaction on incorporation efficiency (IE) and release rate were studied. The optimized formulation was prepared using numerical optimization and evaluated by DSC, FT-IR, SEM and release rate studies.Results: Increasing GA% (X₃) decreased IE (Y₁) with the highest magnitude of effect among the studied factors. On the other hand, increasing alginate content in AL:GL ratio (X₂) increased IE (Y₁). The amount of GLZ released Q_0.5h, Q_2h(pH 1.2) and Q_4h(pH 7.4) decreased by increasing GLZ% (X₁) and AL:GL ratio (X₂). Both drug content and AL:GL ratio appeared to affect water penetration into the gel matrix and drug release. Generally, there was a direct relationship between GA% (X₃) and GLZ release in pH 1.2 (Q_0.5h and Q_2h). However, in pH 7.4 (Q_4h), increasing GA% decreased GLZ release. In addition, increasing GA% caused deviation from zero-order release model. The actual responses of the optimized formulation were in close agreement with the predicted ones.Conclusion: The selected factors and their levels studied in the optimization design were useful for tailoring the anticipated formulation characteristics and GLZ release pattern.

Microencapsulation of eucalyptol in polyethylene glycol and polycaprolactone using particles from gas-saturated solutions

Eucalyptol is the natural cyclic ether which constitutes the bulk of terpenoids found in essential oils of Eucalyptus spp. and is used in aromatherapy for treatment of migraine, sinusitis, asthma and stress. It acts by inhibiting arachidonic acid metabolism and cytokine production. Chemical instability and volatility of eucalyptol restrict its therapeutic application and necessitate the need to develop an appropriate delivery system to achieve extended release and enhance its bioactivity. However, the synthesis method of the delivery system must be suitable to prevent loss or inactivation of the drug during processing. In this study, supercritical carbon dioxide (scCO₂) was explored as an alternative solvent for encapsulation and co-precipitation of eucalyptol with polyethylene glycol (PEG) and/or polycaprolactone (PCL) using the particles from gas-saturated solution (PGSS) process. Polymers and eucalyptol were pre-mixed and then processed in a PGSS autoclave at 45 °C and 80 bar for 1 h. The mixture in scCO₂ was micronized and characterized. The presence of eucalyptol in the precipitated particles was confirmed by infrared spectroscopy, gas chromatography and mass spectrometry. The weight ratios of PEG–PCL blends significantly influenced loading capacity and encapsulation efficiency with 77% of eucalyptol encapsulated in a 4 : 1 composite blend of PEG–PCL. The particle size distribution of the PGSS-micronized particles ranged from 30 to 260 μm. ScCO₂ assisted microencapsulation in PEG and PCL reduced loss of the volatile drug during a two-hour vaporization study and addition of PCL extended the mean release time in simulated physiological fluids. Free radical scavenging and lipoxygenase inhibitory activities of eucalyptol formulated in the PGSS-micronized particles was sustained. Findings from this study showed that the scCO₂-assisted micronization can be used for encapsulation of volatile drugs in polymeric microparticles without affecting bioactivity of the drug.

Application of supercritical carbon dioxide as an alternative solvent for microformulation of the volatile unstable drug, eucalyptol in polymeric composites.

Preparation and optimization of poly (lactic acid) nanoparticles loaded with fisetin to improve anti-cancer therapy

Fisetin is a natural flavonoid with promising antitumor activity, whereas its clinical application is limited by its hydrophobic property. In this study, we aimed to load fisetin into poly(lactic acid) (PLA) nanoparticles to increase fisetin's solubility and therapeutic efficacy. Based on spontaneous emulsification solvent diffusion (SESD) method, the formulation of PLA nanoparticles was optimized by two successive experimental designs. One-factor-at-a-time variation experiments were first applied to investigate the effects of four process variables on three responses, including drug encapsulation efficiency, average particles size and cumulative drug release ratio, followed by determining the possible ranges of these variables. Subsequently, the combinations of four variables at best levels were evaluated using a Taguchi orthogonal array design with regard to the same three responses. Eventually, the nanoparticle prepared by optimized procedure showed a narrow size distribution around 226.85 ± 4.78 nm with a high encapsulation efficiency of 90.35%. The incorporation of fisetin in nanoparticles was subsequently confirmed by FT-IR and DSC spectroscopy. Furthermore, cytotoxicity assay against HCT116 colon cancer cells in vitro and antitumor test in a xenograft 4T1 breast cancer model in vivo demonstrated that the antitumor effect of drug-loaded nanoparticles was superior to that of free drug solution.

Particle agglomeration of chitosan-magnesium aluminum silicate nanocomposites for direct compression tablets

Exfoliated nanocomposites of chitosan-magnesium aluminum silicate (CS-MAS) particles are characterized by good compressibility but poor flowability. Thus, the aims of this study were to investigate agglomerates of CS-MAS nanocomposites prepared using the agglomerating agents water, ethanol, or polyvinylpyrrolidone (PVP) for flowability enhancement and to evaluate the agglomerates obtained as direct compression fillers for tablets. The results showed that the addition of agglomerating agents did not affect crystallinity, but slightly influenced thermal behavior of the CS-MAS nanocomposites. The agglomerates prepared using water were larger than those prepared using 95% ethanol because high swelling of the layer of chitosonium acetate occurred, allowing formation of solid bridges and capillary force between particles, leading to higher flowability and particle strength. Incorporation of PVP resulted in larger agglomerates with good flowability and high strength due to the binder hardening mechanism. The tablets prepared from agglomerates using water showed lower hardness, shorter disintegration times and faster drug release than those using 95% ethanol. In contrast, greater hardness and more prolonged drug release were obtained from the tablets prepared from agglomerates using PVP. Additionally, the agglomerates of CS-MAS nanocomposites showed good carrying capacity and provided desirable characteristics of direct compression tablets.

Triptolide and celastrol loaded silk fibroin nanoparticles show synergistic effect against human pancreatic cancer cells

Pancreatic cancer is a lethal disease with a dreadful 5-year survival rate of only 5%. In spite of several treatment options, the prognosis still remains extremely poor. Therefore, novel therapy strategies with combinations of drugs are urgently required to combat this fatal disease. Triptolide (TPL) and celastrol (CL), two main compounds in traditional Chinese medicine isolated from Thunder God Vine, have a broad range of bioactivities including anticancer activity. Silk fibroin (SF), a naturally occurring protein with several unique properties, is an ideal carrier material. In this study, we prepared TPL and CL loaded silk fibroin nanoparticles (TPL-SFNPs and CL-SFNPs) by a modified desolvation method and evaluated their synergistic effects against human pancreatic cancer cells. Both SFNPs were characterized for particle size and zeta potential. The entrapment efficiency, drug loading, and drug release profiles were evaluated by HPLC. The cytotoxicity and synergistic effect of SFNPs were investigated in MIA PaCa-2 and PANC-1 human pancreatic cells. The results showed that the particle sizes of TPL-SFNPs and CL-SFNPs were 166.4 ± 4.6 nm and 170.4 ± 2.3 nm, with a mean zeta potential -27.2 ± 2.0 mV and -25.5 ± 2.57 mV, respectively. TPL-SFNPs and CL-SFNPs have a drug loading of 57.0 ± 4.7 μg mg-1 and 63.5 ± 3.8 μg mg-1 along with an encapsulation efficiency of 81.8 ± 2.8% and 87.0 ± 5.1%, respectively. Drug release studies revealed that a rapid release of the drugs from SFNPs was observed at pH 4.5 (lysosomal pH) and a delayed release was observed at pH 7.4 (plasma pH). TPL-SFNPs (IC50 3.80 and 4.75 nM) and CL-SFNPs (IC50 0.38 and 0.64 μM) were 2-3 fold more potent against MIA PaCa-2 and PANC-1 cells than free TPL (IC50 11.25 and 11.58 nM) and CL (IC50 0.84 and 1.23 μM). Furthermore, co-treatment with TPL-SFNPs and CL-SFNPs increased the growth inhibition of the same cells significantly in comparison with TPL-SFNPs or CL-SFNPs alone. Almost all combination index (CI) values, calculated using the CompuSyn software, were <1, suggesting that the growth inhibition effect of TPL-SFNPs in combination with CL-SFNPs was synergistic rather than additive, further suggesting that this novel combination may offer a potential treatment for pancreatic cancer.

Novel alginate hydrogel core-shell systems for combination delivery of ranitidine HCl and aceclofenac

A novel hydrogel system was successfully developed based on core-shell approach for the delivery of ranitidine HCl and aceclofenac. Aceclofenac-loaded alginate microspheres coated with eudragit L-100 was used as core material and that of freeze-thaw cross-linked chitosan-PVA gels containing ranitidine HCl served as the shell-forming material. The alginate microspheres coated with eudragit L-100 showed drug encapsulation efficiency of 56.06±1.12 to 68.03±2.16% and had average particle sizes of 551.29±25.92 to 677.18±27.05 μm. The viscosity of chitosan-PVA gels ranged between 505.74±1.04 and 582.41±2.09 cps. The formulations were characterized by FTIR, SEM and polarized microscopy analyses. The release of ranitidine HCl was comparatively higher in acidic medium (pH 1.2) than in alkaline medium (pH 7.4). The release of aceclofenac became slower in alkaline medium (pH 7.4) and continued up to 3.5 h. Super case-II transport mechanism was assumed for the release of ranitidine HCl in both media; whereas non-Fickian (anomalous) diffusion mechanism predominated in the release of aceclofenc. Thus, hydrogel-based core-shell formulations were found suitable for simultaneous delivery of aceclofenac and ranitidine HCl which could minimize the chances of excessive gastric acid secretion through suitable ranitidine HCl release in gastric region.

Development of chitosan-based nanoparticles through inter-polymeric complexation for oral drug delivery

The possibility of inter-polymeric complexation of cationic chitosan and anionic egg albumin stabilized with PEG 400 to develop novel nanoparticles for oral delivery of alprazolam by heat coagulation method at pH 5.4 and 80 °C. Nine formulations were prepared by changing the concentration of chitosan, PEG 400 and heating time. The alprazolam entrapment efficiency of these nanoparticles was in the range of 68.12±1.27 to 99.37±4.86%. These nanoparticles were characterized by FTIR, DSC, P-XRD and FE-SEM analysis. Average particle diameter, poly-dispersity index and zeta potential of these nanoparticles were found 259.60 nm, 0.501, and -9.00 mV, respectively. The in vitro drug release from these alprazolam-loaded nanoparticles showed sustained drug release over a period of 24h. In conclusion, these newly developed chitosan-egg albumin-PEG nanoparticles were found to be a promising vehicle for sustained release delivery of lipophilic drugs.

Intranasal delivery of chitosan nanoparticles for migraine therapy

OBJECTIVE

The objective of the research was to formulate and evaluate sumatriptan succinate-loaded chitosan nanoparticles for migraine therapy in order to improve its therapeutic effect and reduce dosing frequency.

MATERIAL AND METHODS

The Taguchi method design of experiments (L9 orthogonal array) was applied to obtain the optimized formulation. The sumatriptan succinate-loaded chitosan nanoparticles (CNPs) were prepared by ionic gelation of chitosan with tripolyphosphate anions (TPP) and Tween 80 as surfactant.

RESULTS

The CNPs had a mean size of 306.8 ± 3.9 nm, a zeta potential of +28.79 mV, and entrapment efficiency of 75.4 ± 1.1%. The in vitro drug release of chitosan nanoparticles was evaluated in phosphate buffer saline pH 5.5 using goat nasal mucosa and found to be 76.7 ± 1.3% within 28 hours.

DISCUSSION

The release of the drug from the nanoparticles was anomalous, showing non-Fickian diffusion indicating that drug release is controlled by more than one process i.e. the superposition of both phenomena, a diffusion-controlled as well as a swelling-controlled release. This is clearly due to the characteristics of chitosan which easily dissolves at low pH, thus a nasal pH range of 5.5 ± 0.5 supports it very well. The mechanism of pH-sensitive swelling involves protonation of the amine groups of chitosan at low pH. This protonation leads to chain repulsion, diffusion of protons and counter ions together with water inside the gel, and the dissociation of secondary interactions.

CONCLUSION

The results suggest that sumatriptan succinate-loaded chitosan nanoparticles are the most suitable mode of drug delivery for promising therapeutic action.

Preparation, optimization, and in-vitro/in-vivo/ex-vivo characterization of chitosan-heparin nanoparticles: drug-induced gelation

Objectives

Management of blood coagulation-related diseases is currently limited by the inability to provide an adequate drug concentration in blood circulation for a long term. As a promising way to overcome this problem, the long-acting forms of these drugs have attracted many interests in recent years.

Methods

In this study, chitosan-heparin nanoparticles were prepared as a polymeric delivery system intended for the prolonged intravenous delivery of heparin where the drug was used as both the therapeutic agent and a gel-forming counter-ion. The nanoparticle preparation method was optimized using a Taguchi orthogonal array. Critical formulation variables were optimized in this study in terms of their corresponding effects on the target response of particle size. Nanoparticles were characterized by the Fourier transform infrared spectroscopy, transmission electron microscopy and zeta potential.

Key findings

The size, polydispersity index, zeta potential and encapsulation efficiency for the optimized formulation were found to be 61.33 ± 1.53 nm, 0.06, +15.7 mv and 74.16 ± 1.27%, respectively. The sizes of the prepared drug-loaded nanoparticles were stable at least 1 week at room temperature and 3 months in refrigerator.

Conclusions

The ex-vivo and in-vivo tests on the heparin-chitosan nanoparticles using activated partial thromboplastin time (aPTT) as the biological index were indicative of a smoother and longer elevation in aPTT in the presence of nanoparticulate drug.

Permeability evaluation through chitosan membranes using taguchi design

In the present study, chitosan membranes capable of imitating permeation characteristics of diclofenac diethylamine across animal skin were prepared using cast drying method. The effect of concentration of chitosan, concentration of cross-linking agent (NaTPP), crosslinking time was studied using Taguchi design. Taguchi design ranked concentration of chitosan as the most important factor influencing the permeation parameters of diclofenac diethylamine. The flux of the diclofenac diethylamine solution through optimized chitosan membrane (T9) was found to be comparable to that obtained across rat skin. The mathematical model developed using multilinear regression analysis can be used to formulate chitosan membranes that can mimic the desired permeation characteristics. The developed chitosan membranes can be utilized as a substitute to animal skin for in vitro permeation studies.

Gliclazide microcrystals prepared by two methods of in situ micronization: pharmacokinetic studies in diabetic and normal rats

The low water-solubility of gliclazide (GL) leads to a low dissolution rate and variable bioavailability. The aim of this study was to investigate the effect of micronization on the absorption and pharmacokinetics of GL after oral administration in rats. GL microcrystals were prepared using solvent-change and pH-shift methods. Scanning electron microscopy showed considerable changes in the shape and size of crystals using both methods. In the optimized formulation of each method, the particle size of treated GL was reduced about 30 (from 290 to 9.9 microm) and 61 times (to 4.76 microm) by solvent-change and pH-shift methods, respectively. Recrystallized samples showed faster dissolution rate than untreated GL particles. Glucose-lowering effect, C(max), and area under the drug concentration-time profile (area under the curve (AUC)) were compared in diabetic and normal rats. AUC and C(max) were increased by microcrystals in both groups of animals. Administration of 40 mg/kg of GL in the form of untreated drug and microcrystals obtained by solvent-change and pH-shift methods caused 12.49% and 21.04% enhancement in glucose-lowering effect of GL in diabetic rats, respectively.