Biological activity of insulin in GMO gels and the effect of agitation

Injectable long-acting formulations (ILAFs) and manufacturing techniques

INTRODUCTION

Most therapeutics delivered using short-acting formulations need repeated administration, which can harm patient compliance and raise failure risks related to inconsistent treatment. Injectable long-acting formulations (ILAFs) are controlled/sustained-release formulations fabricated to deliver active pharmaceutical ingredients (APIs) and extend their half-life over days to months. Longer half-lives of ILAFs minimize the necessity for frequent doses, increase patient compliance, and reduce the risk of side effects from intravenous (IV) infusions. Using ILAF technologies, the immediate drug release can also be controlled, thereby minimizing potential adverse effects due to high initial drug blood concentrations.

AREA COVERED

In this review, we have discussed various ILAFs, their physiochemical properties, fabrication technologies, advantages, and practical issues, as well as address some major challenges in their application. Especially, the approved ILAFs are highlighted.

EXPERT OPINION

ILAFs are sustained-release formulations with extended activity, which can improve patient compliance. ILAFs are designed to deliver APIs like proteins and peptides and extend their half-life over days to months. The specific properties of each ILAF preparation, such as extended-release and improved drug targeting capabilities, make them an effective approach for precise and focused therapy. Furthermore, this is especially helpful for biopharmaceuticals with short biological half-lives and low stability since most environmental conditions can protect them from sustained-release delivery methods.

Lipid engineered nanoparticle therapy for burn wound treatment

INTRODUCTION

Skin is the largest organ of the human body protecting the underlying organs and tissues from any foreign attack. Any damage caused in the skin may sometimes result in serious consequences within the internal body tissues. Burn is one such issue that damage the layers of skin and thereby makingthe skin vulnerableand pronefor any foreign matter to enter and cause serious diseases.

METHODS

An online literature assessment was steered for the lipid nanoparticles, burn wound treatments, and different types of nanoformulation. Appropriate information was taken from different electronic scientific databases such as Web of Science, Elsevier, Science Direct, Springer, PubMed, Google Scholar etc.,Additional data was summarized from textbooks, local prints and scripts.

RESULTS

Recent innovations and developments in nanotechnology-based drug delivery systems has shown promising results in minimizing the drawbacks associated with conventional therapies. Lipid based nanoparticles possess capabilities to deliver active agents to their target site without the possibility of degradation. Conventional therapy of burn wound is costly and the treatment is long lasting, making the patient uncomfortable. Moreover, italso doesn't yield satisfactory results or narrow effects.Encapsulation of bioactives inside the lipid core protects the active entity from pH and enzymatic degradations.

CONCLUSION

This review highlights the drawbacks associated with the conventional dosage forms. A lot of consideration is focused on the advancement of nanomaterials using innovative methods in wound care for treating burn wounds with the faster healing effect.This review article highlights recent developments in lipid based nanoformulations for treatment of burn wound injury.

Reduction of enzymatic degradation of insulin via encapsulation in a lipidic bicontinuous cubic phase

Oral delivery of the protein drug insulin is not currently possible due to rapid degradation of the secondary structure in low pH conditions in the stomach and under the influence of digestive enzymes in the gastrointestinal tract. Effective oral delivery of insulin and other protein- or peptide-based drugs will, therefore, require encapsulation in a material or nanoparticle. Herein we investigate the ability of the lipid bicontinuous cubic phase formed by two lipids, monoolein (MO) and phytantriol (PT), to protect encapsulated insulin from degradation by the enzyme chymotrypsin, typically found in the small intestine. High encapsulation efficiency (>80%) was achieved in both lipid cubic phases with retention of the underlying cubic nanostructure. Release of insulin from the cubic matrix was shown to be diffusion-controlled; the release rate was dependent on the cubic nanostructure and consistent with measured diffusion coefficients for encapsulated insulin. Encapsulation was shown to significantly retard enzymatic degradation relative to that in water, with the protective effect lasting up to 2 h, exemplifying the potential of these materials to protect the encapsulated protein payload during oral delivery.

Immobilisation of β-galactosidase within a lipid sponge phase: structure, stability and kinetics characterisation

In the formulation of an active enzyme enclosed in a matrix for controlled delivery, it is a challenge to achieve a high protein load and to ensure high activity of the protein. For the first time to our knowledge, we report the use of a highly swollen lipid sponge (L₃) phase for encapsulation of the large active enzyme, β-galactosidase (β-gal, 238 kDa). This enzyme has large relevance for applications in, e.g. the production of lactose free milk products. The formulation consisted of diglycerol monooleate (DGMO), and a mixture of mono-, di- and triglycerides (Capmul GMO-50) stabilised by polysorbate 80 (P80). The advantage of this type of matrix is that it can be produced on a large scale with a fairly simple and mild process as the system is in practice self-dispersing, yet it has a well-defined internal nano-structure. Minor effects on the sponge phase structure due to the inclusion of the enzyme were observed using small angle X-ray scattering (SAXS). The effect of encapsulation on the enzymatic activity and kinetic characteristics of β-galactosidase activity was also investigated and can be related to the enzyme stability and confinement within the lipid matrix. The encapsulated β-galactosidase maintained its activity for a significantly longer time when compared to the free solution at the same temperature. Differences in the particle size and charge of sponge-like nanoparticles (L₃-NPs) with and without the enzyme were analysed by dynamic light scattering (DLS) and zeta-potential measurements. Moreover, all the initial β-galactosidase was encapsulated within L₃-NPs as revealed by size exclusion chromatography.

Nonlamellar liquid crystals: a new paradigm for the delivery of small molecules and bio-macromolecules

The aim of this article is to collate the recent developments in the field of drug delivery, medical therapeutics and diagnostics specifically involving the nonlamellar liquid crystalline (NLC) systems. This review highlights different NLC phases having cubic, hexagonal and sponge internal structures, and their application in the field of drug delivery, such as dose reduction, toxicity reduction and therapeutic efficacy enhancement either in the form of nanoparticles, colloidal dispersion or gels. In addition, application of NLC systems as vehicles for peptides, proteins and as a theranostic system in cancer and other disease conditions is also elaborated, which is a growing platform of interest. Overall, the present review gives us a complete outlook on applications of NLC systems in the field of medicine.

Cubic liquid crystalline nanoparticles containing a polysaccharide from Ulva fasciata with potent antihyperlipidaemic activity

The present study involves the preparation of cubic liquid crystalline nanoparticles (cubsomes) for liver targeting to assess the potential of a formulated bioactive polysaccharide isolated from the hot aqueous extract of Ulva fasciata as an alternative natural agent with anti-hyperlipidaemic activity. Cubosomal nanoparticles were prepared by disrupting the cubic gel phase of the polysaccharide and water in the presence of a surfactant. Different lipid matrices and stabilizers were tested. All the formulations were in the nanosize range and showed sufficient negative charge to inhibit the aggregation of the cubosomes. Drug entrapment efficiencies (EEs%) were determined and in vitro release studies were performed. Transmission electron microscopy (TEM) and differential scanning calorimetry were used to analyze the loaded cubosomal nanoparticles containing glyceryl monostearate (GMO 2.25 g), poloxamer 407 (0.25 g) and 50 mg of the polysaccharide. A preclinical study comparing the cubic liquid crystalline nanoparticles containing polysaccharide to fluvastatin as a reference drug in hyperlipidaemic rats was conducted. The rats treated with the polysaccharide- loaded cubosomes showed significant decreases in total cholesterol (TC), triglycerides (TG) and total lipid (TL) compared to the untreated HL rats. In addition, oxidative stress and antioxidant biomarkers were measured in the HL rats. Compared to the untreated HL rats, the cubosome treated rats showed a significant reduction in malondialdehyde (MDA), whereas insignificant changes were detected in nitric oxide (NO), glutathione (GSH) levels and total antioxidant capacity (TAC). Further, vascular and intercellular adhesion molecules (VCAM, ICAM), and myeloperoxidase were demonstrated. A histopathological examination was conducted to study the alterations in histopathological lesions and to document the biochemical results. In conclusion, this study demonstrates the superiority of using a natural lipid regulator such as polysaccharide loaded cubosomes instead of fluvastatin.

Liquid Crystal Systems in Drug Delivery

Liquid crystals have been recently studied as novel drug delivery system. The reason behind this is their similarity to colloidal systems in living organisms. They have proven to be advantageous over Traditional, Dermal, Parentral and Oral Dosage forms. Liquid crystals are thermodynamically stable and possess long shelf life. Liquid crystals show bio adhesive properties and sustained release effects. Objective of this book chapter is to provide in-depth information of Pharmaceutical crystal technology. It shall deal with cubic and hexagonal liquid crystal and their applications in Drug delivery system.

Lipid-based nanocarriers for oral peptide delivery

This article is aimed to overview the lipid-based nanostructures designed so far for the oral administration of peptides and proteins, and to analyze the influence of their composition and physicochemical (particle size, zeta potential) and pharmaceutical (drug loading and release) properties, on their interaction with the gastro-intestinal environment, and the subsequent PK/PD profile of the associated drugs. The ultimate goal has been to highlight and comparatively analyze the key factors that may be determinant of the success of these nanocarriers for oral peptide delivery. The article ends with some prospects on the challenges to be addressed for the intended commercial success of these delivery vehicles.

Development and characterization of novel hydrogel containing antimicrobial drug for treatment of burns

INTRODUCTION

The aim of burn management and therapy is fast healing and epithelisation to prevent infection. The present study is concerned with the development and characterization of a novel nanaoparticulate system; cubosomes, loaded with silver sulfadiazine (SSD) and Aloe vera for topical treatment of infected burns.

METHODS

Cubosome dispersions were formulated by an emulsification technique using different concentrations of a lipid phase Glyceryl Monooleate (GMO) and Poloxamer 407. The optimum formulae were incorporated in an aloe vera gel containing carbopol 934, to form cubosomal hydrogels (cubogels). The cubogels were characterized by in vitro release of SSD, rheological properties, pH, bioadhesion, Transmission Electron Microscopy and in-vivo Wound Healing Study.

RESULTS

The results show that the different concentration of GMO had significant effect on particle size, % EE and in vitro drug release. From the in-vitro drug release pattern and similarity factor (f2), it was concluded that batch CG3 (15% GMO and 1% P407) exhibited complete and controlled drug release within 12 hour (i.e. 98.25%), better bio adhesion and superior burn healing as compared to the marketed product.

CONCLUSION

The in vivo burns healing study in rats revealed that the prepared optimized cubogel containing SSD and aloe vera has superior burns healing rate than cubogel with only SSD and marketed preparation so, it may be successfully used in the treatment of deep second degree burn.

In vitro and in vivo evaluation of cubosomes containing 5-fluorouracil for liver targeting

The objective of this study was to prepare cubosomal nanoparticles containing a hydrophilic anticancer drug 5-fluorouracil (5-FU) for liver targeting. Cubosomal dispersions were prepared by disrupting a cubic gel phase of monoolein and water in the presence of Poloxamer 407 as a stabilizer. Cubosomes loaded with 5-FU were characterized in vitro and in vivo. In vitro, 5-FU-loaded cubosomes entrapped 31.21% drug and revealed nanometer-sized particles with a narrow particle size distribution. In vitro 5-FU release from cubosomes exhibited a phase of rapid release of about half of the entrapped drug during the first hour, followed by a relatively slower drug release as compared to 5-FU solution. In vivo biodistribution experiments indicated that the cubosomal formulation significantly (P<0.05) increased 5-FU liver concentration, a value approximately 5-fold greater than that observed with a 5-FU solution. However, serum serological results and histopathological findings revealed greater hepatocellular damage in rats treated with cubosomal formulation. These results demonstrate the successful development of cubosomal nanoparticles containing 5-FU for liver targeting. However, further studies are required to evaluate hepatotoxicity and in vivo antitumor activity of lower doses of 5-FU cubosomal formulation in treatment of liver cancer.

Cubic and hexagonal liquid crystals as drug delivery systems

Lipids have been widely used as main constituents in various drug delivery systems, such as liposomes, solid lipid nanoparticles, nanostructured lipid carriers, and lipid-based lyotropic liquid crystals. Among them, lipid-based lyotropic liquid crystals have highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix. The intricate nanostructures of the cubic phase and hexagonal phase have been shown to provide diffusion controlled release of active pharmaceutical ingredients with a wide range of molecular weights and polarities. In addition, the biodegradable and biocompatible nature of lipids demonstrates the minimum toxicity and thus they are used for various routes of administration. Therefore, the research on lipid-based lyotropic liquid crystalline phases has attracted a lot of attention in recent years. This review will provide an overview of the lipids used to prepare cubic phase and hexagonal phase at physiological temperature, as well as the influencing factors on the phase transition of liquid crystals. In particular, the most current research progresses on cubic and hexagonal phases as drug delivery systems will be discussed.

Optimized loading and sustained release of hydrophilic proteins from internally nanostructured particles

In this study, we demonstrate that emulsified microemulsions and micellar cubosomes are suitable as sustained delivery vehicles for water-soluble proteins. Through structural modifications, the loading efficiency of two model proteins, namely bovine serum albumin (BSA) and cytochrome c could be remarkably increased. A procedure for preparing these particles loaded with optimized amounts of sensitive substances is presented. Loading and dispersion at low temperatures is performed in two successive steps. First, a water-in-oil microemulsion is loaded with the proteins. Subsequently, this phase is dispersed in water resulting in particles with microemulsion and micellar cubic internal structure and a size of approximately 620 nm. This two-step method ensures optimal loading of the particles with the proteins. These nanostructured particles are able to sustain the release of the water-soluble BSA and cytochrome c. Within one day, less than 10% of BSA and 15% of cytochrome c are released. The release rate of cytochrome c is influenced by the nanostructure of the particles.

Hydrogel-Forming Microneedle Arrays for Enhanced Transdermal Drug Delivery

Unique microneedle arrays prepared from crosslinked polymers, which contain no drug themselves, are described. They rapidly take up skin interstitial fluid upon skin insertion to form continuous, unblockable, hydrogel conduits from attached patch-type drug reservoirs to the dermal microcirculation. Importantly, such microneedles, which can be fabricated in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves and transdermal drug delivery is now controlled by the crosslink density of the hydrogel system rather than the stratum corneum, while electrically modulated delivery is also a unique feature. This technology has the potential to overcome the limitations of conventional microneedle designs and greatly increase the range of the type of drug that is deliverable transdermally, with ensuing benefits for industry, healthcare providers and, ultimately, patients.

Nanostructured self assembled lipid materials for drug delivery and tissue engineering

Every living organism comprises of lipids as basic building blocks in addition to other components. Utilizing these lipids for pharmaceutical and biomedical applications can overcome biocompatibility and biodegradability issues. A well known example is liposomes (lipids arranged in lamellar structures), but other than that there are additional unique mesophasic structures of lipids formed as a result of lipid polymorphisms, which include cubic-, hexagonal- or sponge-phase structures. These structures provide the advantages of stability and production feasibility compared with liposomes. Cubosomes, which exist in a cubic structure, have improved stability, bioadhesivity and biocompatibility. Hexagonal phases or hexosomes exhibit hexagonal arrangements and can encapsulate different drugs with high stability. Lipids also forms tube-like structures known as tubules and ribbons that are also utilized in different biomedical applications, especially in tissue engineering. Immune stimulating complexes are nanocage-like structures formed as a result of interactions of lipid, antigen and Quillaja saponin. These lipidic mesophasic structures have been utilized for gene, vaccine and drug delivery. This article addresses lipid self-assembled supramolecular nanostructures, including cubosomes, hexosomes, tubules, ribbons, cochleates, lipoplexes and immune stimulating complexes and their biomedical applications.

Adsorption behaviors of DPPC/MO aggregates on SiO2 surfaces

The adsorption kinetics of extruded 1,2-dipalmitoyl- sn-glycero-3-phosphatidylcholine (DPPC)/1-(cis-9-octadecenoyl)- rac-glycerol (monoolein, MO) aggregates on SiO 2 surface at 25 degrees C is investigated in real time, using the dissipative quartz crystal microbalance (QCM) technique. Four adsorption pathways have been identified depending on the molar fraction of MO in the DPPC/MO system: (I) intact vesicle adsorption, (II) vesicle reorganization on a SiO 2 surface, (III) supported lipid bilayer (SLB) formation, and (IV) cubosome adsorption. The results can be understood by the fact that DPPC is a lamellar phase-forming lipid, whereas MO prefers the cubic phase. Therefore, the incorporation of MO in DPPC increases the packing parameter. Equally important, MO also increases the mobility of lipid molecules and lateral pressure in the bilayers as a result of the presence of a unique cis- double bond. Before extrusion, the vesicles size increases with the MO content when X MO <or= 0.7 and cubosomes are formed for X MO >or= 0.8. The extruded DPPC/MO suspensions consist of reformed vesicles for X MO <or= 0.7 and filtered cubosomes for X MO >or= 0.8, all with a uniform diameter of approximately 100 nm. Differential scanning calorimetry (DSC) further indicates that the addition of MO lowers the main phase transition temperature of DPPC and thus makes the hydrophobic interior more fluid.

Preparation and characterization of uniform-sized chitosan microspheres containing insulin by membrane emulsification and a two-step solidification process

Chitosan microsphere has important application in controlled release of protein and peptide drug, because it shows excellent mucoadhesive and permeation enhancing effect across the biological surfaces. In the conventional preparation methods of chitosan microsphere, the W/O emulsion was usually prepared by mechanical stirring method, and then the droplets were solidified by glutaraldehyde. There existed limitation and shortage such as broad size distribution, de-activity of bio-drug and difficulty in drug release because protein and peptide drug have the same amino group as chitosan. In this study, we established a method to prepare uniform-sized microsphere, and solve above problems by combining a special membrane emulsification technique and a step-wise crosslinking method. That is, the chitosan/acetic acid aqueous solution was pressed through the uniform pores of a porous glass membrane into a paraffin/petroleum ether mixture containing PO-500 emulsifier, to form a W/O emulsion with uniform droplet size. Then, the uniform droplets were solidified by a two-step crosslinking method. At the first step, tripolyphosphate (TPP) solution was dropped gradually in the emulsion, TPP diffused into the droplet to crosslink chitosan by an ionic linkage, generating a microgel. At the second step, an adequate amount of glutaraldehyde was added. The solidification conditions of the two-step process were optimized by investigating the effects of solidification conditions on morphology of microspheres, encapsulation efficiency (EE), drug activity and release profile in vitro. The suitable preparative conditions were determined as follows: pH value of aqueous phase and TPP solution was 3.5-4.0, the molar ratio of amino group of chitosan to aldehyde group of glutaraldehyde was 1:1 and the crosslinking time of glutaraldehyde was 60 min.

Cubic liquid crystalline glyceryl monooleate matrices for oral delivery of enzyme

In situ cubic phase transforming system of glyceryl monooleate (GMO) has been prepared which offers protection to the metaloenzyme, seratiopeptidase (STP), in gastric environment and provides delayed and controlled release with no initial burst after oral administration. Effect of magnesium trisilicate (MTS) on floating, proteolytic activity and drug release was studied. Gelucire 43/01 was incorporated in the system to provide prolonged lag time. The drug-loaded matrices required 100 mg of MTS to overcome floatability of GMO matrix. Plain GMO matrices showed 85.3% loss of proteolytic activity in acidic medium, whereas matrices containing MTS showed retention of activity (111.6%). The hydrophobic nature of MTS induced formation of cubic phase at faster rate and the existence of cubic phase was confirmed by polarizing light microscopy. Furthermore, MTS provided alkaline microenvironment, which prevented acid-catalyzed hydrolysis and protein unfolding. The magnesium ions restored the activity of STP. The release of STP was decreased with increasing amount of MTS in the matrix. Gelucire did not affect proteolytic activity. The water uptake of matrices with gelucire was decelerated due to formation of hexagonal phase. However, the rate of STP release from these matrices was very slow due to incorporation of gelucire into lipid bilayers, which provided resistance to movement of STP. Thus, microenvironment-controlled in situ cubic phase transforming GMO matrices provided protection to STP and controlled release.

Particulate and Bulk Bicontinuous Cubic Phases Obtained from Mixtures of Glyceryl Monooleate and Copolymers Bearing Blocks of Lipid−Mimetic Anchors in Water

Copolymers based on poly(ethylene glycol) bearing one or more lipid-mimetic anchors were mixed with glycerylmonooleate (GMO)-a lipid with nonlamellar propensity-to form bulk and particulate bicontinuous cubic phases in water. The particulate phase was obtained via a liquid precursor method. Three forms of copolymer/GMO mixtures were investigated-precursor dispersions in glycerol and bulk and particulate phases in water-by visual observations, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The bulk phases were found to very slowly develop a macroscopic appearance that can be associated with the bicontinuous cubic phase. They were prepared in a slight excess of water, which became opalescent in some of the preparations. Cryo-TEM investigation of the excess showed that vesicles and particles with a dense interior coexisted. The precursors were prepared as solutions in glycerol. The viscous liquid material was investigated by DLS. Diffusion coefficients and the corresponding hydrodynamic radii, ranging from about 10 to 30 nm, were calculated. The particles are presumably of a structure similar to that of conventional emulsion droplets with GMO in the interior and copolymer molecules in the outer regions. The particulate phase in water was obtained upon hydration of the liquid precursors. The dispersions were investigated by DLS and cryo-TEM. DLS revealed the formation of nanosized particles. The size was found to increase with increasing copolymer content for copolymers with only one lipid-mimetic anchor, whereas the opposite trend was observed for the formulations with copolymers bearing more than one lipid-mimetic anchor. The shape and interior of the particles were studied by cryo-TEM. It was found that most particles were globular. For some of the compositions, particles with a dense internal structure dominated. The texture of the internal structures was assigned to dispersed bicontinuous cubic or L3 phases. In other compositions, the interior seemingly consists of arrays of interlamellar attachments.

A novel in situ gel for sustained drug delivery and targeting

The objective of this study was to develop a novel chitosan-glyceryl monooleate (GMO) in situ gel system for sustained drug delivery and targeting. The delivery system consisted of 3% (w/v) chitosan and 3% (w/v) GMO in 0.33M citric acid. In situ gel was formed at a biological pH. In vitro release studies were conducted in Sorensen's phosphate buffer (pH 7.4) and drugs were analyzed either by HPLC or spectrophotometry. Characterization of the gel included the effect of cross-linker, determination of diffusion coefficient and water uptake by thermogravimetric analysis (TGA). Mucoadhesive property of the gel was evaluated in vitro using an EZ-Tester. Incorporation of a cross-linker (glutaraldehyde) retarded the rate and extent of drug release. The in vitro release can further be sustained by replacing the free drug with drug-encapsulated microspheres. Drug release from the gel followed a matrix diffusion controlled mechanism. Inclusion of GMO enhanced the mucoadhesive property of chitosan by three- to sevenfold. This novel in situ gel system can be useful in the sustained delivery of drugs via oral as well as parenteral routes.