Porous polystyrene beads as carriers for self-emulsifying system containing loratadine

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

Silane Modification of Mesoporous Materials for the Optimization of Antiviral Drug Adsorption and Release Capabilities in Vaginal Media

Three different functionalities have been incorporated into mesoporous materials by means of a coupling reaction with the siloxanes 3-glycidoxypropyl-trimethoxysilane (GLYMO), 3-methacryloxypropyl-trimethoxysilane (MEMO), and 3-mercaptopropyl-trimethoxysilane (MPTMS). The disposition of the different functional groups, as well as the interaction mechanism, with the mesoporous substrate has been identified. The amount of the antiviral drug acyclovir (ACV) adsorbed depends not only on the available surface area but also on the chemical or physicochemical interactions between functionalities. The drug adsorption isotherm of the materials functionalized with GLYMO and MPTMS follow mechanisms dependent on the different surface coverage and the possibilities to establish physicochemical interactions between the drug molecule and the functionalities. On the contrary, when functionalizing with MEMO, the dominant adsorption mechanism is characteristic of chemically bonded adsorbates. The ACV release kinetics is best fitted to the Weibull model in all the functionalized materials. When the MTPMS is used as a functionalizing agent, the drug diffusion occurs at low kinetics and homogeneously along the mesoporous channels.

Orally administered self-emulsifying drug delivery system in disease management: advancement and patents

Introduction: Oral administration of a drug is the most common, ideal and preferred route of administration. The main problem of oral drug formulations is their low bioavailability arises from poor aqueous solubility of drug. Aqueous solubility of lipophilic drugs can be improved by various techniques like salt formation, complexation, addition of co-solvent etc. but self-emulsifying drug-delivery system (SEDDS) is getting more attention for increasing the solubility of such drugs. The SEDDS is an isotropic mixture of drug, lipids, and emulsifiers, usually with one or more hydrophilic co-solvents/co-emulsifiers. This system is having ability to generate oil-in-water (o/w) emulsions or microemulsions upon gentle agitation followed by dilution with aqueous phase. The SEDDSs are relatively newer, lipid-based technological innovations possessing unparalleled potential in improving oral bioavailability of poorly water-soluble drugs.Areas covered: This review provides updated information regarding the types of SEDDS, their preparation techniques, drug delivery and related recent patents along with marketed formulations.Expert opinion: The SEDDS has been explored for improving bioavailability, rising intra-subject heterogeneity, and increasing solubility. SEDDS offers the benefit of a protective effect against the hostile environment in the gut. The unique fabrication techniques provide specific strategy to overcome the low bioavailability and poor solubility problems.

Amino Functionalized Micro-Mesoporous Hybrid Particles for the Sustained Release of the Antiretroviral Drug Tenofovir

The sustained release of an antiretroviral agent to women mucosa has been proved as an excellent strategy to reduce the sexual transmission of HIV. Hybrid micro-mesoporous particles have been synthesized and functionalized with a silane coupling agent followed by loading the antiretroviral tenofovir. It has been observed that the disposition of the silane molecule on the surface of the particles determines the interaction mechanism with the antiretroviral molecule loaded independently on the surface area of the particles. In this sense, available and free amino groups are required to achieve a smart pH-responsive material, a condition that is only achieved in those materials containing a silane chemisorbed monolayer. Moreover, the modulation of the release kinetics attributed to the presence of the silane monolayer covering the mesopores has been confirmed by fitting the releasing curves to the first order and Weibull models. The developed micro-mesoporous particles have been demonstrated to be excellent smart-release vehicles for antiviral agents and can be safely used in polymer mucoadhesive vaginal gels.

Adaptation of hard gelatin capsules for oral delivery of aqueous radiopharmaceuticals

PURPOSE

Oral administration of Iodine-131 (I-131) solutions causes high risk of contamination for patients and dispensers. The objective of the study was to adapt hard gelatin capsules (HGCs) for filling with radiopharmaceutical solutions without deformation.

METHODS

Polystyrene (PS) internally lining films with different thicknesses were used to protect HGCs. The insulated HGCs were evaluated for their physicochemical characteristics and rupturing time in different dissolution media. HGCs internally lined with PS were examined for withstand loading with different volumes and radioactivities of I-131 solutions. Radioactivity release was studied in deionized water and acidic media. Quality control of released I-131 was inspected for radiochemical purities.

RESULTS

There was a directly proportion between PS lining thickness and stability of HGCs after filling with 500 μl aqueous methylene blue solution. HGCs internally lined with PS 100 μm thickness withstand deformation for ˃ two months; however showed fast in-vitro rupturing time in different dissolution media. Internally lined HGCs loaded with different volumes and radioactivities of I-131 solutions resisted for one week without radioactive leakage. Yet, revealed complete release of I-131 after 20 min in dissolution media with great radiochemical purity.

CONCLUSION

The study promises safely I-131 aqueous solution delivery via adapted HGCs. Graphical abstract Oral administration of radiopharmaceuticals.

Self Emulsifying Drug Delivery System: A Recent Approach

In recent years, nearly 40 % newer drugs compounds are hydrophobic in nature, which is a major challenge now-a-days for oral drug delivering due to low aqueous solubility. Lipid based drug delivery system is one of the favourable approach for poorly soluble compounds which can improve the drug absorption and oral bioavailability. Due to ion-pairing with appropriate surfactant and co-surfactant the macromolecular drug molecular oil droplet being found in the gut flow oral absorption which sufficiently stable towards lipase. Due to the formation of emulsified drug in micron level, it can efficiently endow the oral bioavailability. Several comprehensive papers have been published in the literature illustration diverse type of lipid based formulation with recent advancements. This article is based on an exhaustive and updated review on newer technology which out line an explicit discussion on its formulations and industrial scale up.

Theoretical and Experimental Studies of the Controlled Release of Tetracycline Incorporated into Bioactive Glasses

Several authors have studied the release profile of drugs incorporated in different devices. However, to the best of our knowledge, although many studies have been done on the release of tetracycline, in these release devices, no study has investigated if the released compound is actually the tetracycline, or, instead, a degraded product. This approach is exploited here. In this work, we analyse the influence of two drying methods on the tetracycline delivery behaviour of synthesised glasses using the sol-gel process. We compare the drying methods results using both theoretical models and practical essays, and analyse the chemical characteristic of the released product in order to verify if it remains tetracycline. Samples were freeze-dried or dried in an oven at 37°C and characterised by several methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), differential thermogravimetric analysis (DTG), differential thermal analyses (DTA) and gas adsorption analysis (BET). The released concentration of tetracycline hydrochloride was studied as a function of time, and it was measured by ultraviolet spectrophotometry in the tetracycline wavelength. The drug delivery profiles were reasonably consistent with a diffusion model analysis. In addition, we observed higher release rates for the freeze-dried compared to those dried in an oven at 37°C. This higher release can be attributed to larger pore size for the freeze-dried sample systems with tetracycline, which promoted more water penetration, improving the drug diffusion. The analysis of the solution obtained in the release tests using high-performance liquid chromatography- mass spectrometry (HPLC-MS) confirmed that tetracycline was being released.

Loratadine bioavailability via buccal transferosomal gel: formulation, statistical optimization, in vitro/in vivo characterization, and pharmacokinetics in human volunteers

Loratadine (LTD) is an antihistaminic drug that suffers limited solubility, poor oral bioavailability (owing to extensive first-pass metabolism), and highly variable oral absorption. This study was undertaken to develop and statistically optimize transfersomal gel for transbuccal delivery of LTD. Transfersomes bearing LTD were prepared by conventional thin film hydration method and optimized using sequential Quality-by-Design approach that involved Placket-Burman design for screening followed by constrained simplex-centroid design for optimization of a Tween-80/Span-60/Span-80 mixture. The transferosomes were characterized for entrapment efficiency, particle size, and shape. Optimized transferosomes were incorporated in a mucoadhesive gel. The gel was characterized for rheology, ex vivo permeation across chicken pouch buccal mucosa, in vitro release, and mucoadhesion. Pharmacokinetic behavior of LTD formulations was investigated in healthy volunteers following administration of a single 10-mg dose. Optimal transferosomes characterized by submicron size (380 nm), spherical shape and adequate loading capacity (60%) were obtained by using quasi-equal ratio surfactant mixture. In terms of amount permeated, percentage released, and mucoadhesion time, the transferosomal gel proved superior to control, transferosome-free gel. Bioavailability of the transferosomal gel was comparable to Claritin® oral tablets. However, inter-individual variability in C_max and AUC was reduced by 76 and 90%, respectively, when the buccal gel was used. Linear Correlation of in vitro release with in vivo buccal absorption fractions was established with excellent correlation coefficient (R²>0.97). In summary, a novel buccal delivery system for LTD was developed. However, further clinical investigation is warranted to evaluate its therapeutic effectiveness and utility.

Development, stability and in vitro delivery profile of new loratadine-loaded nanoparticles

Purpose: Loratadine is used as antihistaminic without side effects in nervous systems. This drug is a weak base and it is absorbed from the intestine. The nitrogen of the pyridine ring is protonated in the stomach affecting the oral bioavailability. The aim of this paper was obtaining, characterize and evaluate the release profiles and the stability of a gastroresistant loratadine nanosuspension. Methods: The nanosuspension was prepared by the solvent displacement evaporation method, using three different polymers (Eudragit® L 100 55, Kollicoat® MAE 100P and PEG 4000) and Polysorbate 80. Dynamic Light Scattering was used for evaluating the particle size (PS), zeta potential, and conductivity of the nanosuspension. Loratadine release profiles were evaluated in simulated gastrointestinal fluids. The shelf and accelerated stability were assessed during three months. Results: Nanosuspension particle size was 45.94 ± 0.50 nm, with a low polydispersion index (PdI, 0.300). Kollicoat® MAE 100P produced a hard and flexible coating layer. In simulated intestinal fluids, the 100 percent of loratadine was released in 40 min, while in simulated stomach fluids the release was lesser than 5%. Nanosuspension presented a good physicochemical stability showing a reduction in PS and PdI after three months (43.29 ± 0.16 and 0.250; respectively). Conclusions: A promissory loratadine nanosuspension for loratadine intestinal delivery was obtained, by using a low energy method, which is an advantage for a possible scale up for practical purpose.

Solidified SNEDDS of loratadine: formulation using hydrophilic and hydrophobic grades of Aerosil®, pharmacokinetic evaluations and in vivo–in silico predictions using GastroPlus™

Hydrophilic and hydrophobic grades of Aerosil® were employed to develop solid-SNEDDS of loratadine and evaluated for their influence on powder, physicochemical and biopharmaceutical properties.

Sonication-Assisted Layer-by-Layer Assembly for Low Solubility Drug Nanoformulation

Sonication-assisted layer-by-layer (LbL) self-assembly is a nanoencapsulation technique based on the alternate adsorption of oppositely charged polyelectrolytes, enabling the encapsulation of low solubility drugs. In this work, a top-down LbL technique was performed using a washless approach and ibuprofen (IBF) as a model class II drug. For each saturated layer deposition, polyelectrolyte concentration was determined by titration curves. The first layer was constituted by cationic poly(allylamine hydrochloride) (PAH), given the IBF negative surface charge, followed by anionic polystyrenesulfonate (PSS). This polyelectrolyte sequence was made up with 2.5, 5.5, and 7.5 bilayer nanoshells. IBF nanoparticles (NPs) coated with 7.5 bilayers of PAH/PSS showed 127.5 ± 38.0 nm of particle size, a PDI of 0.24, and a high zeta potential (+32.7 ± 0.6 mV), allowing for a stable aqueous nanocolloid of the drug. IBF entrapment efficiency of 72.1 ± 5.8% was determined by HPLC quantification. In vitro MTT assay showed that LbL NPs were biocompatible. According to the number of coating layers, a controlled release of IBF from LbL NPs was achieved under simulated intestinal conditions (from 5 h up to 7 days). PAH/PSS-LbL NPs constitute a potential delivery system to improve biopharmaceutical parameters of water low solubility drugs.

Porous polystyrene spheres loaded self nano-emulsifying systems of rosuvastatin calcium

The aim of the study was to investigate potential of Solid Self Nano-Emulsifying Drug Delivery System (SNEDDS) for enhancing solubility and oral bioavailability of Rosuvastatin Calcium (RC).

Development of self-microemulsifying drug delivery system and solid-self-microemulsifying drug delivery system of telmisartan

OBJECTIVE

Self-microemulsifying drug delivery system (SMEDDS) and solid-SMEDDS of telmisartan was aimed at overcoming the problems of poor solubility and bioavailability.

METHODOLOGY

The formulation strategy included selection of oil phase based on saturated solubility studies and surfactant and co-surfactant screening on the basis of their emulsification ability. Ternary phase diagrams were constructed to identify the self-emulsifying region using a dilution method. The prepared formulations of SMEDDS were evaluated for their drug content, loading efficiency, morphology, globule size determination. Solid-SMEDDS were prepared by adsorption technique using microcrystalline cellulose (1% w/w) and were evaluated for micromeritic properties, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction.

RESULTS

The formulation containing telmisartan (20 mg), castor oil (30% w/w), tween 20 (55% w/w), propylene glycol (15% w/w) was concluded to be optimized. The optimized SMEDDS and solid-SMEDDS exhibited 100% in vitro drug release up to 120 min, which was significantly higher (P < 0.05, t-test) than that of the pure drug. Solid-SMEDDS may be considered as a better solid dosage form as solidified formulations are more ideal than liquid ones in terms of its stability.

CONCLUSION

These results suggest the potential use of SMEDDS and solid-SMEDDS to improve the dissolution and hence oral bioavailability of poorly water-soluble drugs like telmisartan through oral route.

Dissolution evaluation in vitro and bioavailability in vivo of self-microemulsifying drug delivery systems for pH-sensitive drug loratadine

The aim of this study was to improve the oral absorption of loratadine, a pH-sensitive drug, by self-microemulsifying drug delivery systems (SMEDDSs). The optimal SMEDDS was analysed and evaluated after emulsification in distilled water with diameter of 26.57 ± 0.71 nm and zeta potential of -30.5 ± 4.5 mV. Dissolution experiments in vitro were carried out in different released media of pH values and the SMEDDS formulations were able to release loratadine completely in different media while market tablets just performed similarly in the media of pH 1.2. Furthermore, the oral bioavailability and the pharmacokinetic behaviour of loratadine formulations in vivo were studied after a single dose of 1 mg/kg loratadine in beagle dogs. The SMEDDS formulations displayed higher Cmax and AUC, approximately 9 and 5 times increase than those of market tablets (p < 0.01) respectively. These results demonstrated that SMEDDS formulations had significantly increased the oral absorption of loratadine in beagle dogs.

Enhanced transdermal permeability of piroxicam through novel nanoemulgel formulation

BACKGROUND

Piroxicam is a non-steroidal anti-inflammatory drug belongs to BCS class II drugs having poor solubility and is associated with a number of undesirable side-effects on the stomach and kidneys in addition to gastric mucosal damage.

AIM

The present work was to develop and characterize nanoemulgel formulation as transdermal delivery system for poorly water soluble drug, in order to overcome the troubles associated with its oral delivery and to circumvent the need of chemical penetration enhancers, which are responsible for causing skin irritation in transdermal drug delivery.

MATERIALS AND METHODS

Different nanoemulsion components (oil, surfactant and co-surfactant) were selected on the basis of solubility and emulsification ability. Pseudoternary phase diagrams were constructed using aqueous titration method to figure out the concentration range of components. Carbopol 934 was added as gel matrix to convert nanoemulsion into nanoemulgel. Drug loaded nanoemulsions and nanoemulgels were characterized for particle size, transmission electron microscopy, viscosity, conductivity, spreadability, rheological behavior, permeation studies using Wistar rat skin and stability studies. Transdermal permeation of piroxicam from nanoemulgels was determined by using Franz Diffusion cell.

RESULTS

The optimized nanoemulgel (BG6) contained 10% oleic acid as oil, 35% tween 80 and ethanol as surfactant co-surfactant mixture, 55% water, 0.5% drug and 0.5% w/w carbopol. The ex vivo permeation profile of optimized formulation was compared with nanoemulsion and marketed formulation (Feldene(®)). Nanoemulgel showed higher (P < 0.05) cumulative amount of drug permeated and flux and significantly less drug retained along with less lag time than marketed formulation.

CONCLUSION

The results indicate that nanoemulgel formulation can be used as a feasible alternative to conventional formulations of piroxicam with advanced permeation characteristics for transdermal application.

Formulation strategies to improve the bioavailability of poorly absorbed drugs with special emphasis on self-emulsifying systems

Poorly water-soluble drug candidates are becoming more prevalent. It has been estimated that approximately 60–70% of the drug molecules are insufficiently soluble in aqueous media and/or have very low permeability to allow for their adequate and reproducible absorption from the gastrointestinal tract (GIT) following oral administration. Formulation scientists have to adopt various strategies to enhance their absorption. Lipidic formulations are found to be a promising approach to combat the challenges. In this review article, potential advantages and drawbacks of various conventional techniques and the newer approaches specifically the self-emulsifying systems are discussed. Various components of the self-emulsifying systems and their selection criteria are critically reviewed. The attempts of various scientists to transform the liquid self-emulsifying drug delivery systems (SEDDS) to solid-SEDDS by adsorption, spray drying, lyophilization, melt granulation, extrusion, and so forth to formulate various dosage forms like self emulsifying capsules, tablets, controlled release pellets, beads, microspheres, nanoparticles, suppositories, implants, and so forth have also been included. Formulation of SEDDS is a potential strategy to deliver new drug molecules with enhanced bioavailability mostly exhibiting poor aqueous solubility. The self-emulsifying system offers various advantages over other drug delivery systems having potential to solve various problems associated with drugs of all the classes of biopharmaceutical classification system (BCS).

Development of Solid SEDDS, IV: Effect of Adsorbed Lipid and Surfactant on Tableting Properties and Surface Structures of Different Silicates

PURPOSE

To compare six commonly available silicates for their suitability to develop tablets by adsorbing components of liquid lipid-based drug delivery systems.

METHODS

The tabletability of Aerosil® 200, Sipernat® 22, Sylysia® 350, Zeopharm® 600, Neusilin® US2 and Neusilin® UFL2 were studied by compressing each silicate into tablets in the presence of 20% microcrystalline cellulose and measuring the tensile strength of tablets produced. Three components of lipid based formulations, namely, Capmul® MCM EP (glycerol monocaprylocaprate), Captex® 355 EP/NF (caprylic/capric triglycerides) and Cremophor® EL (PEG-35 castor oil), were adsorbed individually onto the silicates at 1:1 w/w, and the mixtures were then compressed into tablets. The SEM photomicrographs of neat silicates and their 1:1 w/w mixtures (also 1:2 and 1:3 for Neusilin® US2 and Neusilin® UFL2) with one of the liquids (Cremophor® EL) were recorded.

RESULTS

Neat Aerosil® 200, Sipernat® 22 and Sylysia® 350 were non-tabletable to the minimum acceptable tensile strength of 1 MPa, and they were also non-tabletable in presence of liquid. While Zeopharm® 600, Neusilin® US2 and Neusilin® UFL2 were tabletable without the addition of liquids, only Neusilin® US2 retained acceptable tabletability with 1:1 liquid. The SEM images of silicate-liquid mixtures indicated that, except for Neusilin® US2, much of the adsorbed liquid distributed primarily at the surface of particles rather than inside pores, which hindered their compaction into tablets.

CONCLUSION

Among the six silicates studied, Neusilin® US2 was the only silicate able to produce tablets with acceptable tensile strength in presence of a lipid component at 1:1 w/w ratio due to the fact that the liquid was mostly adsorbed into the pores of the silicate rather than at the surface.

Development of Solid SEDDS, V: Compaction and Drug Release Properties of Tablets Prepared by Adsorbing Lipid-Based Formulations onto Neusilin® US2

PURPOSE

To develop tablet formulations by adsorbing liquid self-emulsifying drug delivery systems (SEDDS) onto Neusilin®US2, a porous silicate.

METHODS

Nine SEDDS were prepared by combining a medium chain monoglyceride, Capmul MCM EP, a medium chain triglyceride, Captex 355 EP/NF, or their mixtures with a surfactant Cremophor EL, and a model drug, probucol, was then dissolved. The solutions were directly adsorbed onto Neusilin®US2 at 1:1 w/w ratio. Content uniformity, bulk and tap density, compressibility index, Hausner ratio and angle of repose of the powders formed were determined. The powders were then compressed into tablets. The dispersion of SEDDS from tablets was studied in 250 mL of 0.01NHCl (USP dissolution apparatus; 50 RPM; 37°C) and compared with that of liquid SEDDS.

RESULTS

After adsorption of liquid SEDDS onto Neusilin®US2, all powders demonstrated acceptable flow properties and content uniformity for development into tablet. Tablets with good tensile strength (>1 MPa) at the compression pressure of 45 to 135 MPa were obtained. Complete drug release from tablets was observed if the SEDDS did not form gels in contact with water; the gel formation clogged pores of the silicate and trapped the liquid inside pores.

CONCLUSION

Liquid SEDDS were successfully developed into tablets by adsorbing them onto Neusilin®US2. Complete drug release from tablets could be obtained.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Self-emulsifying therapeutic system: a potential approach for delivery of lipophilic drugs

Self-emulsifying therapeutic system (SETs) provide an effective and intelligent solution to the various issues related to the formulation of hydrophobic drugs with limited solubility in gastrointestinal fluid. Although the potential utility of SETs is well known, only in recent years has a mechanistic understanding of the impact of these systems on drug disposition emerged. These in situ emulsion-forming systems have a high stability when incorporated in various dosage forms. SETs are being looked upon as systems which can overcome the problems associated with delivery of poorly water soluble drugs. An in-depth knowledge about lipids and surfactants that can contribute to these systems, criterion for their selection and the proportion in which they can be used, represent some crucial factors determining the in vivo performance of these systems. This article presents a comprehensive account of various types of self-emulsifying formulations with emphasis on their composition and examples of currently marketed preparations.

Porous carriers for controlled/modulated drug delivery

Considerable research efforts have been directed in recent years towards the development of porous carriers as controlled drug delivery matrices because of possessing several features such as stable uniform porous structure, high surface area, tunable pore size and well-defined surface properties. Owing to wide range of useful properties porous carriers have been used in pharmaceuticals for many purposes including development of floating drug delivery systems, sustained drug delivery systems. Various types of pores like open, closed, transport and blind pores in the porous solid allow them to adsorb drugs and release them in a more reproducible and predictable manner. Pharmaceutically exploited porous adsorbents includes, silica (mesoporous), ethylene vinyl acetate (macroporous), polypropylene foam powder (microporous), titanium dioxide (nanoporous). When porous polymeric drug delivery system is placed in contact with appropriate dissolution medium, release of drug to medium must be preceded by the drug dissolution in the water filled pores or from surface and by diffusion through the water filled channels. The porous carriers are used to improve the oral bioavailability of poorly water soluble drugs, to increase the dissolution of relatively insoluble powders and conversion of crystalline state to amorphous state.

Self-nanoemulsifying drug delivery systems: formulation insights, applications and advances

There has been a resurgence of interest in nanoemulsions for various pharmaceutical applications since low-energy emulsification methods, such as spontaneous or self-nanoemulsification, have been described. Self-nanoemulsifying drug delivery systems (SNEDDS) are anhydrous homogenous liquid mixtures consisting of oil, surfactant, drug and coemulsifier or solubilizer, which spontaneously form oil-in-water nanoemulsion of approximately 200 nm or less in size upon dilution with water under gentle stirring. The physicochemical properties, drug solubilization capacity and physiological fate considerably govern the selection of the SNEDDS components. The composition of the SNEDDS can be optimized with the help of phase diagrams, whereas statistical experimental design can be used to further optimize SNEDDS. SNEDDS can improve oral bioavailability of hydrophobic drugs by several mechanisms. The conversion of liquid SNEDDS to solid oral dosage forms or solid SNEDDS has also been achieved by researchers. Solid SNEDDS can offer better patient compliance and minimize problems associated with capsules filled with liquid SNEDDS.

Curve-fitting FTIR studies of loratadine/hydroxypropyl-beta-cyclodextrin inclusion complex induced by co-grinding process

The formation steps of inclusion complex caused by co-grinding loratadine (LOR) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) with a molar ratio of 1:1 or 1:2 were quantitatively investigated by Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis and differential scanning calorimetry (DSC). The phase solubility study and the co-evaporated solid products of the mixture of LOR and HP-beta-CD were also examined. The result indicates that the aqueous solubility of LOR was linearly increased with the increase of HP-beta-CD concentrations, in which the phase solubility diagram was classified as A(L) type. The higher apparent stability constant (2.22 x 10(4)M(-1)) reveals that the inclusion complex formed between LOR and HP-beta-CD was quite stable. The endothermic peak at 134.6 degrees C for the melting point of LOR gradually disappeared from DSC curves of LOR/HP-beta-CD coground mixtures by increasing the cogrinding time, as the disappearance of the co-evaporated solid products. The disappearance of this endothermic peak from LOR/HP-beta-CD coground mixture or the co-evaporated solid products was due to the inclusion complex formation between LOR and HP-beta-CD after cogrinding process or evaporation. Moreover, IR peaks at 1676 cm(-1) down-shifted from 1703 cm(-1) (CO stretching) and at 1235 cm(-1) upper-shifted from 1227 cm(-1) (C-O stretching) related to LOR in the inclusion complex were observed with the increase of cogrinding time, but the peak at 1646 cm(-1) due to O-H stretching of HP-beta-CD was shifted to 1640 cm(-1). The IR spectrum of 15 min-coground mixture was the same as the IR spectrum of the co-evaporated solid product, strongly indicating that the grinding process could cause the inclusion complex formation between LOR and HP-beta-CD. Three components (1700, 1676, and 1640 cm(-1)) and their compositions were certainly obtained in the 1740-1600 cm(-1) region of FTIR spectra for the LOR/HP-beta-CD coground mixture and the co-evaporated solid products by curve-fitting analysis. The component of 1700 cm(-1) detected was due to the un-included LOR in the inclusion complex. This implies that FTIR spectroscopy with curve-fitting analysis might be useful for discriminating the components and compositions in the inclusion complex.

Porous magnesium aluminometasilicate tablets as carrier of a cyclosporine self-emulsifying formulation

The aim of this study was to investigate the ability of liquid loadable tablets (LLT) to be loaded with a self-microemulsifying drug delivery system (SMEDDS) containing cyclosporine (CyA). LLT were prepared by direct compression of the porous carrier magnesium aluminometasilicate and subsequently loaded with SMEDDS by a simple absorption method. SMEDDS was evaluated regarding visual appearance and droplet size distribution after dispersion in aqueous media. The developed SMEDDS was found to be similar to Neoral. LLT were characterized before and after loading regarding weight variation, tablet hardness, disintegration time, and in vitro drug release. It was found that LLT with high porosities suitable for liquid loading and further processing could be prepared. Adding a tablet disintegrant was found to improve in vitro drug release. Additionally, the volume-based loading capacity of LLT was evaluated and found to be comparable to soft gelatin and hard two-piece capsules. Furthermore, the pharmacokinetic performance of CyA from loaded LLT was tested in two PK-studies in dogs. Absorption of CyA from SMEDDS loaded into LLT was found in the first study to be significantly lower than the absorption of CyA from SMEDDS filled into a capsule. However, addition of a superdisintegrant improved the absorption markedly. The bioavailability of CyA from SMEDDS loaded into disintegrating LLT was found in the second study to be at the same level as from capsule formulation. In conclusion, the LLT technology is therefore seen as a promising alternative way of achieving a solid dosage form from liquid drug delivery systems.

Porous magnesium aluminometasilicate tablets as carrier of a cyclosporine self-emulsifying formulation

The aim of this study was to investigate the ability of liquid loadable tablets (LLT) to be loaded with a self-microemulsifying drug delivery system (SMEDDS) containing cyclosporine (CyA). LLT were prepared by direct compression of the porous carrier magnesium aluminometasilicate and subsequently loaded with SMEDDS by a simple absorption method. SMEDDS was evaluated regarding visual appearance and droplet size distribution after dispersion in aqueous media. The developed SMEDDS was found to be similar to Neoral. LLT were characterized before and after loading regarding weight variation, tablet hardness, disintegration time, and in vitro drug release. It was found that LLT with high porosities suitable for liquid loading and further processing could be prepared. Adding a tablet disintegrant was found to improve in vitro drug release. Additionally, the volume-based loading capacity of LLT was evaluated and found to be comparable to soft gelatin and hard two-piece capsules. Furthermore, the pharmacokinetic performance of CyA from loaded LLT was tested in two PK-studies in dogs. Absorption of CyA from SMEDDS loaded into LLT was found in the first study to be significantly lower than the absorption of CyA from SMEDDS filled into a capsule. However, addition of a superdisintegrant improved the absorption markedly. The bioavailability of CyA from SMEDDS loaded into disintegrating LLT was found in the second study to be at the same level as from capsule formulation. In conclusion, the LLT technology is therefore seen as a promising alternative way of achieving a solid dosage form from liquid drug delivery systems.