Preparation and in vitro characterization of diltiazem hydrochloride loaded alginate microspheres

Comparative performance evaluation of chitosan based polymeric microspheres and nanoparticles as delivery system for bacterial β-carotene derived from Planococcus sp. TRC1

β-carotene is a natural compound with immense healthcare benefits. To overcome insolubility and lack of stability which restricts its application, in this study, β-carotene from Planococcus sp. TRC1 was entrapped into formulations of chitosan‑sodium alginate microspheres (MF1, MF2 and MF3) and chitosan nanoparticles (NF1, NF2 and NF3). The maximum entrapment efficiency (%) and loading capacity (%) were 80.6 ± 4.28 and 26 ± 3.05 (MF2) and 92.1 ± 3.44 and 41.86 ± 4.65 (NF2) respectively. Korsmeyer-Peppas model showed best fit with release, revealing non-Fickian diffusion. Thermal and UV treatment exhibited higher activation energy (kJ/mol), 17.76 and 15.57 (MF2) and 37.03 and 19.33 (NF2) compared to free β-carotene (3.7 and 3.9), uncovering enhanced stability. MF2 and NF2 revealed swelling index (%) 721 ± 1.7 and 18.1 ± 1.5 (pH 6.8) and particle size 69.5 ± 3.2 μm and 92 ± 2.5 nm respectively. FESEM, FT-IR, XRD and DSC depicted spherical morphology, intactness of functional groups and masking of crystallinity. The IC₅₀ (μg ml^-1) values for antioxidant and anticancer (A-549) activities were 33.1 ± 1.7, 45.1 ± 2.8, 39.3 ± 2.9 and 31.3 ± 1.7, 27.9 ± 2.4, 25.3 ± 2.2 for β-carotene, MF2 and NF2 respectively with no significant cytotoxicity on HEK-293 cells and RBCs (p > 0.05). This comparative study of microspheres and nanoparticles may allow the diverse applications of an unconventional bacterial β-carotene with promising stability and efficacies.

PLA-PCL-PEG-PCL-PLA based micelles for improving the ocular permeability of dexamethasone: development, characterization, and in vitro evaluation

The aim of the present research was to investigate the feasibility of developing polylactide-polycaprolactone-polyethylene glycol-polycaprolactone-polylactide (PLA-PCL-PEG-PCL-PLA) based micelles to improve ocular permeability of dexamethasone (DEX). PLA-PCL-PEG-PCL-PLA copolymers were synthesized by a ring-opening polymerization method. DEX was loaded into the developed copolymers. The DEX-loaded micelles were characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS) methods. Cytotoxicity of the micelles obtained was investigated on L929 cell line. Cellular uptake was followed by fluorescence microscopy and flow cytometry analyses. The release behavior of DEX from the micelles as well as the drug release kinetics was studied. Corneal permeability was also evaluated using an ex vivo bovine model. The pentablock copolymers were successfully synthesized. The TEM results verified the formation of spherical micelles, the sizes of which was approximately 65 nm. The micelles exhibited suitable compatibility on L929 cells. The release profile showed an initial burst release phase followed by a sustained release phase, the kinetic of which was close to the Weibull's distribution model. The micelles showed higher corneal permeability in comparison to a marketed DEX eye drop. Taken together, the results indicated that the PLA-PCL-PEG-PCL-PLA micelles could be appropriate candidates for the ocular delivery of DEX, and probably other hydrophobic drugs.

Design and In Vitro Evaluation of Eudragit-Based Extended Release Diltiazem Microspheres for Once- and Twice-Daily Administration: The Effect of Coating on Drug Release Behavior

Objectives

The aim of this investigation was to develop an extended release formulation of diltiazem hydrochloride (DL) for once- and twice-daily administration, based on Eudragit (Eud) RL and RS microspheres using emulsion solvent evaporation.

Materials and Methods

Formulations with different drug-polymer concentrations were produced and characterized in terms of yield, encapsulation efficiency (EE), particle size, and surface morphology. The drug release and thermal behavior of the microspheres were also investigated. Selected microspheres were then coated with Eud RS by continuous solvent evaporation, in order to modify the microspheres' properties and burst release.

Results

According to the results, the EE was in the range of 56%-93% for uncoated microspheres. The mean particle size of microspheres was different from 470 to above 1000 μm, based on various formulation variables. No difference was observed between the mean size of particles prepared with Eud RL and Eud RS. Microspheres showed sustained release behavior, which was affected by the drug:polymer ratio as well as particle size. Coating the microspheres not only improved the EE values (82%-92%) but also reduced the mean dissolution rate as well as the burst release.

Conclusion

Microspheres prepared with DL:Eud RL ratios of 1:3 and 1:4 showed release profiles in accordance with the USP criteria for a DL extended release product for dosing every 12 and 24 h, respectively.

Oviposition Deterrent Efficacy and Characteristics of a Botanical Natural Product, Ocimum gratissimum (L.) Oil-Alginate Beads, against Aedes aegypti (L.)

This study was aimed at investigating the oviposition deterrent activity of Ocimum gratissimum (L.) essential oil (O. gratissimum oil) and its product, Ocimum gratissimum (L.)- alginate beads (beads), against Aedes aegypti (Ae. aegypti) mosquitoes. Chemical analysis of O. gratissimum oil obtained by hydrodistillation, using gas chromatography-mass spectroscopy techniques, presented eugenol (67.38%) and Z-β-ocimene (14.95 %) as major constituents. Good characteristics of beads were obtained by the orifice-ionic gelation method with calcium chloride as hardening agent and Tween®20 as emulsifier. The beads exhibited a good spherical shape and good hardness and flexibility with an average size of 1.49 ± 1.36 mm. The oil content, the yield percentage, and the entrapping efficiency were also examined. The beads (formulation code, F2) could prolong the essential oil release until the 10^th d. This beads provided a remarkably longer oviposition deterrence activity against gravid Ae. aegypti with high percentage for 27 d, whereas free O. gratissimum oil showed a short period of time (8 d) in this activity. The stability study showed the stability of oil content and its compositions in storage condition. These results are very affordable approaches to control the dengue fever.

Designing polymeric microparticulate drug delivery system for hydrophobic drug quercetin

The aim of this study was to investigate pharmaceutical potentialities of a polymeric microparticulate drug delivery system for modulating the drug profile of poorly water-soluble quercetin. In this research work two cost effective polymers sodium alginate and chitosan were used for entrapping the model drug quercetin through ionic cross linking method. In vitro drug release, swelling index, drug entrapment efficiency, Fourier Transforms Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Differential Scanning Calorimetric (DSC) studies were also done for physicochemical characterization of the formulations. Swelling index and drug release study were done at a pH of 1.2, 6.8 and 7.4 to evaluate the GI mimetic action which entails that the swelling and release of the all the Formulation1 (F1), Formulation2 (F2) and Formulation3 (F3) at pH 1.2 were minimal confirming the prevention of drug release in the acidic environment of stomach. Comparatively more sustained release was seen from the formulations F2 & F3 at pH 6.8 and pH 7.4 after 7 h of drug release profiling. Drug entrapment efficiency of the formulations shows in F1 (D:C:A = 2:5:30) was approximately 70% whereas the increase in chitosan concentration in F2 (D:C:A = 2:10:30) has shown an entrapment efficiency of 81%. But the comparative further increase of chitosan concentration in F3 (D:C:A = 2:15:30) has shown a entrapment of 80% which is not having any remarkable difference from F2. The FTIR analysis of drug, polymers and the formulations indicated the compatibility of the drug with the polymers. The smoothness of microspheres in F2 & F3 was confirmed by Scanning Electron Microscopy (SEM). However F1 microsphere has shown more irregular shape comparatively. The DSC studies indicated the absence of drug-polymer interaction in the microspheres. Our XRD studies have revealed that when pure drug exhibits crystalline structure with less dissolution profile, formulated microparticles can help us to obtain amorphous form of the same drug that is likely to have more dissolution property. The findings of the study suggest that the microsphere formulations were a promising carrier for quercetin delivery and can be considered as a favorable oral controlled release dosage form for hydrophobic drug quercetin.

Gellan gum-based mucoadhesive microspheres of almotriptan for nasal administration: Formulation optimization using factorial design, characterization, and in vitro evaluation

Background:

Almotriptan malate (ALM), indicated for the treatment of migraine in adults is not a drug candidate feasible to be administered through the oral route during the attack due to its associated symptoms such as nausea and vomiting. This obviates an alternative dosage form and nasal drug delivery is a good substitute to oral and parenteral administration.

Materials and Methods:

Gellan gum (GG) microspheres of ALM, for intranasal administration were prepared by water-in-oil emulsification cross-linking technique employing a 2³ factorial design. Drug to polymer ratio, calcium chloride concentration and cross-linking time were selected as independent variables, while particle size and in vitro mucoadhesion of the microspheres were investigated as dependent variables. Regression analysis was performed to identify the best formulation conditions. The microspheres were evaluated for characteristics such as practical percentage yield, particle size, percentage incorporation efficiency, swellability, zeta potential, in vitro mucoadhesion, thermal analysis, X-ray diffraction study, and in vitro drug diffusion studies.

Results:

The shape and surface characteristics of the microspheres were determined by scanning electron microscopy, which revealed spherical nature and nearly smooth surface with drug incorporation efficiency in the range of 71.65 ± 1.09% – 91.65 ± 1.13%. In vitro mucoadhesion was observed the range of 79.45 ± 1.69% – 95.48 ± 1.27%. Differential scanning calorimetry and X-ray diffraction results indicated a molecular level dispersion of drug in the microspheres. In vitro drug diffusion was Higuchi matrix controlled and the release mechanism was found to be non-Fickian. Stability studies indicated that there were no significant deviations in the drug content, in vitro mucoadhesion and in vitro drug diffusion characteristics.

Conclusion:

The investigation revealed promising potential of GG microspheres for delivering ALM intranasally for the treatment of migraine.

Preparation and Evaluation of Mixture of Eudragit and Ethylcellulose Microparticles Loaded with Ranolazine for Controlled Release

To minimize the unwanted toxic effects of anti-anginal ranolazine by kinetic control of drug release, it was entrapped into gastro-resistant, biodegradable eudragit (EU) and ethyl cellulose (EC) binary blend using phase separation method. Ten formulations were prepared using different polymer blend ratios and solvent. The prepared microparticles were characterized for micromeritic properties, polymer drug compatibility by Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scannibg Calorimetry (DSC), and surface morphology by Scanning Electron Micrography (SEM). The yield of microparticles was up to 90% and more than 98% of the isolated microparticles are having volume mean diameter of 285 μm. The obtained angle of repose, percentage Carr's index and tapped density values were within the limits indicating good flow properties. The surface morphology revealed that particles were free-flowing, spherical, with minute pores and invert dents on the surface. The prepared microparticles were evaluated for percentage yield, encapsulation efficiency and in vitro release studies. FT-IR and DSC studies showed no chemical interaction between the drug and used polymers The in vitro drug release studies were carried out using pH 1.2 acid buffer and pH 7.4 phosphate buffer. EU acts as an excellent pH-dependent binder and helps to release the drug in the intestine. The drug release kinetics followed different transport mechanisms. Increasing the weight fractions of EU and decreased EC helps to control the drug release from the particles. From the differential (f₁) and similarity factor (f₂), Formulation F5 was the formulation most similar to the commercially available oral formulation as reference standard. The drug release performance was greatly affected by the materials used in microparticle preparations, which allow absorption in the intestinal tract.

Impact of crystalline form changing on behavior of microcapsules prepared from three-component gel system

In this paper, the effect of anhydrous-monohydrate process-induced transformation of theophylline was examined in microcapsules produced by in situ gelation method using sodium alginate, hydroxypropylmethylcellulose and hydroxyethylcellulose. Films produced from gel were applied to characterize the changes by NIR spectroscopy, X-ray, DSC method and stereomicroscopy because it is easier to study that in films in the case of gel systems used in situ gelation process. The properties of end-product are influenced by the swelling ability, equilibrium water uptake, release profile and encapsulation efficiency. Water penetration and drug release were evaluated by Davidson-Peppas and Korsmeyer-Peppas models. The ex tempore formed monohydrate crystals were smaller and built into the matrix structure in a greater extent. Increased drug release, matrix erosion and diffuse reflectance values at 1470 and 1950 nm were observed added theophylline later into the gel because of developing a denser structure.