Polymeric particulates to improve oral bioavailability of peptide drugs

In Vitro Release and In Vivo Pharmacokinetics of Praziquantel Loaded in Different Polymer Particles

Approximately 1 billion people are affected by neglected diseases around the world. Among these diseases, schistosomiasis constitutes one of the most important public health problems, being caused by Schistosoma mansoni and treated through the oral administration of praziquantel (PZQ). Despite being a common disease in children, the medication is delivered in the form of large, bitter-tasting tablets, which makes it difficult for patients to comply with the treatment. In order to mask the taste of the drug, allow more appropriate doses for children, and enhance the absorption by the body, different polymer matrices based on poly(methyl methacrylate) (PMMA) were developed and used to encapsulate PZQ. Polymer matrices included PMMA nano- and microparticles, PMMA-co-DEAEMA (2-(diethylamino)ethyl methacrylate), and PMMA-co-DMAEMA (2-(dimethylamino)ethyl methacrylate) microparticles. The performances of the drug-loaded particles were characterized in vitro through dissolution tests and in vivo through pharmacokinetic analyses in rats for the first time. The in vitro dissolution studies were carried out in accordance with the Brazilian Pharmacopeia and revealed a good PZQ release profile in an acidic medium for the PMMA-DEAEMA copolymer, reaching values close to 100 % in less than 3 h. The in vivo pharmacokinetic analyses were conducted using free PZQ as the control group that was compared with the investigated matrices. The drug was administered orally at doses of 60 mg/kg, and the PMMA-co-DEAEMA copolymer microparticles were found to be the most efficient release system among the investigated ones, reaching a Cmax value of 1007 ± 83 ng/mL, even higher than that observed for free PZQ, which displayed a Cmax value of 432 ± 98 ng/mL.

Advances in microneedle-based transdermal delivery for drugs and peptides

Transdermal drug delivery is a viable and clinically proven route of administration. This route specifically requires overcoming the mechanical barrier provided by the Stratum Corneum of epidermis and vascular and nervous networks within the dermis. First-generation Transdermal patches and second-generation iontophoretic patches have been translated into commercial clinical products successfully. The current review reports different studies that aim to enhance the transdermal delivery of biopharmaceutical using microneedles and their effect on drug delivery. Microneedles (MN) are the micron-scale hybrid between transdermal patches and hypodermic syringes. Microneedles are tested and proven to show better delivery of the drugs, overcoming the drawbacks of hypodermic syringes. Multiple microneedles designs have been fabricated i.e. solid, coated, hollow, and polymer microneedles. Hollow microneedles are shorter in length but similar to hypodermic needles and have pore for infusion of liquid formulation of the drug. Solid microneedles a patch is applied after creating a hole in the skin; Drugs are coated on the surface of Coated microneedles; Polymer microneedles can be of different types like dissolving, non-dissolving or hydrogel-forming made up of polymers. Various advantages and limitations associated with the use of these techniques are discussed. Delivery of peptide and protein molecules with microneedles represents a significant opportunity for a better clinical outcome and hence value creation compared to standard injectable routes of administration. The advancement in various formulation and microfabrication techniques are currently being focused to aid the delivery of protein drugs via microneedles. The most recent advances and limitations in Microneedles -mediated protein and peptide delivery were discussed.

The role of polysaccharides from natural resources to design oral insulin micro- and nanoparticles intended for the treatment of Diabetes mellitus: A review

Oral administration of insulin (INS) would represent a revolution in the treatment of diabetes, considering that this route mimics the physiological dynamics of endogenous INS. Nano- and microencapsulation exploiting the advantageous polysaccharides properties has been considered an important technological strategy to protect INS against harsh conditions of gastrointestinal tract, in the same time that improve the permeability via transcellular and/or paracellular pathways, safety and in some cases even selectivity for targeting delivery of INS. In fact, some polysaccharides also give to the systems functional properties such as pH-responsiveness, mucoadhesiveness under specific physiological conditions and increased intestinal permeability. In general, all polysaccharides can be functionalized with specific molecules becoming more selective to the cells to which INS is delivered. The present review highlights the advances in the past 10 years on micro- and nanoencapsulation of INS exploiting the unique natural properties of polysaccharides, including chitosan, starch, alginate, pectin, and dextran, among others.

Enhanced Oral Bioavailability of Ibrutinib Encapsulated Poly (Lactic-co- Glycolic Acid) Nanoparticles: Pharmacokinetic Evaluation in Rats

Background:

The poor oral bioavailability of newly discovered chemical entities and marketed formulations are usually related to poor aqueous solubility or poor permeability, leading to drug failure in the development phases or therapeutic failure in a clinical setting. However, advancement in drug formulations and delivery technologies have enabled scientists to improve the bioavailability of formulations by enhancing solubility or permeability.

Objective:

This study reports the enhancement of the oral bioavailability of ibrutinib (IBR), a poorly soluble anticancer drug in Wistar albino rats.

Methods:

IBR loaded nanoparticles were formulated through the nanoprecipitation method by utilizing poly lactide-co-glycolide (PLGA) as a safe, biodegradable and biocompatible polymer, and poloxamer or pluronic 127 as a stabilizer. Animals were administered with a dose of 10 mg/kg of IBR suspension or an equivalent amount of IBR loaded nanoparticles. Plasma samples were extracted and analyzed by state of the art UPLC-MS/MS technique. Pharmacokinetic (PK) parameters and bioavailability were calculated by non-compartmental analysis.

Results:

There was an approximately 4.2-fold enhancement in the oral bioavailability of IBR-loaded nanoparticles, as compared to the pure IBR suspension. The maximum plasma concentration (Cmax; 574.31 ± 56.20 Vs 146.34 ± 5.37 ng/mL) and exposure (AUC; 2291.65 ± 263.83 vs 544.75 ± 48.33 ng* h/mL) of IBR loaded nanoparticles were significantly higher than those exhibited through pure IBR suspension.

Conclusion:

The outcomes of the present study suggested the potential of PLGA nanoparticles in the enhancement of bioavailability and the therapeutic efficacy of IBR.

Targeting the intestinal lymphatic system: a versatile path for enhanced oral bioavailability of drugs

INTRODUCTION

The major challenge of first pass metabolism in oral drug delivery can be surmounted by directing delivery toward intestinal lymphatic system (ILS). ILS circumvents the liver and transports drug directly into systemic circulation via thoracic duct. Lipid and polymeric nanoparticles are transported into ILS through lacteal and Peyer's patches. Moreover, surface modification of nanoparticles with ligand which is specific for Peyer's patches enhances the uptake of drugs into ILS. Bioavailability enhancement by lymphatic uptake is an advantageous approach adopted by scientists today. Therefore, it is important to understand clear insight of ILS in targeted drug delivery and challenges involved in it.

AREAS COVERED

Current review includes an overview of ILS, factors governing lymphatic transport of nanoparticles and absorption mechanism of lipid and polymeric nanoparticles into ILS. Various ligands used to target Peyer's patch and their conjugation strategies to nanoparticles are explained in detail. In vitro and in vivo models used to assess intestinal lymphatic transport of molecules are discussed further.

EXPERT OPINION

Although ILS offers a versatile pathway for nanotechnology based targeted drug delivery, extensive investigations on validation of the lymphatic transport models and on the strategies for gastric protection of targeted nanocarriers have to be perceived in for excellent performance of ILS in oral drug delivery.

Targeted release of stromal cell-derived factor-1α by reactive oxygen species-sensitive nanoparticles results in bone marrow stromal cell chemotaxis and homing, and repair of vascular injury caused by electrical burns

Rapid repair of vascular injury is an important prognostic factor for electrical burns. This repair is achieved mainly via stromal cell-derived factor (SDF)-1α promoting the mobilization, chemotaxis, homing, and targeted differentiation of bone marrow mesenchymal stem cells (BMSCs) into endothelial cells. Forming a concentration gradient from the site of local damage in the circulation is essential to the role of SDF-1α. In a previous study, we developed reactive oxygen species (ROS)-sensitive PPADT nanoparticles containing SDF-1α that could degrade in response to high concentration of ROS in tissue lesions, achieving the goal of targeted SDF-1α release. In the current study, a rat vascular injury model of electrical burns was used to evaluate the effects of targeted release of SDF-1α using PPADT nanoparticles on the chemotaxis of BMSCs and the repair of vascular injury. Continuous exposure to 220 V for 6 s could damage rat vascular endothelial cells, strip off the inner layer, significantly elevate the local level of ROS, and decrease the level of SDF-1α. After injection of Cy5-labeled SDF-1α-PPADT nanoparticles, the distribution of Cy5 fluorescence suggested that SDF-1α was distributed primarily at the injury site, and the local SDF-1α levels increased significantly. Seven days after injury with nanoparticles injection, aggregation of exogenous green fluorescent protein-labeled BMSCs at the injury site was observed. Ten days after injury, the endothelial cell arrangement was better organized and continuous, with relatively intact vascular morphology and more blood vessels. These results showed that SDF-1α-PPADT nanoparticles targeted the SDF-1α release at the site of injury, directing BMSC chemotaxis and homing, thereby promoting vascular repair in response to electrical burns.

Diblock Terpolymers Are Tunable and pH Responsive Vehicles To Increase Hydrophobic Drug Solubility for Oral Administration

Synthetic polymers offer tunable platforms to create new oral drug delivery vehicles (excipients) to increase solubility, supersaturation maintenance, and bioavailability of poorly aqueous soluble pharmaceutical candidates. Five well-defined diblock terpolymers were synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT) and consist of a first block of either poly(ethylene-alt-propylene) (PEP), poly(N-isopropylacrylamide) (PNIPAm), or poly(N,N-diethylaminoethyl methacrylate) (PDEAEMA) and a second hydrophilic block consisting of a gradient copolymer of N,N-dimethylacrylamide (DMA) and 2-methacrylamidotrehalose (MAT). This family of diblock terpolymers offers hydrophobic, hydrophilic, or H-bonding functionalities to serve as noncovalent sites of drug binding. Drug-polymer spray dried dispersions (SDDs) were created with a model drug, probucol, and characterized by differential scanning calorimetry (DSC). These studies revealed that probucol crystallinity decreased with increasing H-bonding sites available in the polymer. The PNIPAm-b-P(DMA-grad-MAT) systems revealed the best performance at pH 6.5, where immediate probucol release and effective maintenance of 100% supersaturation was found, which is important for facilitating drug solubility in more neutral conditions (intestinal environment). However, the PDEAEMA-b-P(DMA-grad-MAT) system revealed poor probucol dissolution at pH 6.5 and 5.1. Alternatively, at an acidic pH of 3.1, a rapid and high dissolution profile and effective supersaturation maintenance of up to 90% of the drug was found, which could be useful for triggering drug release in acidic environments (stomach). The PEP-b-P(DMA-grad-MAT) system showed poor performance (only ∼20% of drug solubility at pH 6.5), which was attributed to the low solubility of the polymers in the dissolution media. This work demonstrates the utility of diblock terpolymers as a potential new excipient platform to optimize design parameters for triggered release and solubilizing hydrophobic drug candidates for oral delivery.

Lysosomal enzyme replacement therapies: Historical development, clinical outcomes, and future perspectives

Lysosomes and lysosomal enzymes play a central role in numerous cellular processes, including cellular nutrition, recycling, signaling, defense, and cell death. Genetic deficiencies of lysosomal components, most commonly enzymes, are known as "lysosomal storage disorders" or "lysosomal diseases" (LDs) and lead to lysosomal dysfunction. LDs broadly affect peripheral organs and the central nervous system (CNS), debilitating patients and frequently causing fatality. Among other approaches, enzyme replacement therapy (ERT) has advanced to the clinic and represents a beneficial strategy for 8 out of the 50-60 known LDs. However, despite its value, current ERT suffers from several shortcomings, including various side effects, development of "resistance", and suboptimal delivery throughout the body, particularly to the CNS, lowering the therapeutic outcome and precluding the use of this strategy for a majority of LDs. This review offers an overview of the biomedical causes of LDs, their socio-medical relevance, treatment modalities and caveats, experimental alternatives, and future treatment perspectives.

Therapeutic Potential of Epigallocatechin Gallate Nanodelivery Systems

Nowadays, the society is facing a large health problem with the rising of new diseases, including cancer, heart diseases, diabetes, neurodegenerative diseases, and obesity. Thus, it is important to invest in substances that enhance the health of the population. In this context, epigallocatechin gallate (EGCG) is a flavonoid found in many plants, especially in tea. Several studies support the notion that EGCG has several benefits in fighting cancer, heart diseases, diabetes, and obesity, among others. Nevertheless, the poor intestinal absorbance and instability of EGCG constitute the main drawback to use this molecule in prevention and therapy. The encapsulation of EGCG in nanocarriers leads to its enhanced stability and higher therapeutic effects. A comprehensive review of studies currently available on the encapsulation of EGCG by means of nanocarriers will be addressed.

Opioid Addiction: Social Problems Associated and Implications of Both Current and Possible Future Treatments, including Polymeric Therapeutics for Giving Up the Habit of Opioid Consumption

BACKGROUND

Detoxification programmes seek to implement the most secure and compassionate ways of withdrawing from opiates so that the inevitable withdrawal symptoms and other complications are minimized. Once detoxification has been achieved, the next stage is to enable the patient to overcome his or her drug addiction by ensuring consumption is permanently and completely abandoned, only after which can the subject be regarded as fully recovered.

METHODS

A systematic search on the common databases of relevant papers published until 2016 inclusive.

RESULTS AND CONCLUSION

Our study of the available oral treatments for opioid dependence has revealed that no current treatment can actually claim to be fully effective. These treatments require daily oral administration and, consequently, regular visits to dispensaries, which in most cases results in a lack of patient compliance, which causes fluctuations in drug plasma levels. We then reviewed alternative treatments in the available scientific literature on polymeric sustained release formulations. Research has been done not only on release systems for detoxification but also on release systems for giving up the habit of taking opioids. These efforts have obtained the recent authorization of polymeric systems for use in patients that could help them to reduce their craving for drugs.

The transport mechanism of integrin αvβ3 receptor targeting nanoparticles in Caco-2 cells

As for the existence of epithelium barrier, accelerating the transport remains huge challenges for orally delivered protein and peptide drugs into blood circulation. Modifying nanopaticles (NPs) with targeting peptides can enhance the intestinal absorption of loaded macromolecular drugs. However, the transport process, which mainly means how the NPs pass through the apical membrane and the basolateral side and then enter into blood circulation, is needed comprehensive investigation. In this study, we systemically studied the transport mechanisms in Caco-2 cell model of trimethyl chitosan based NPs (TMC NPs) before and after modification of FQS, an integrin αvβ3 receptor targeting peptide. Our results showed FQS peptide mediated multiple endocytosis pathways and could activate integrin αvβ3 receptor by interacting with FAK and Src-family kinases to induce receptor-mediated endocytosis of the NPs. Then, both endocytosed NPs could transport from early endosome to lysososmes via late endosomes/lysosome pathway, as well as to recycling endosomes and Golgi apparatus through early endosome/recycling endosomes and Golgi apparatus/recycling endosomes/plasma membrane pathways, respectively. After FQS peptide modification, the endocytosis subpathways of NPs have been changed, and more pathways are involved in exocytosis process for FQS-modified NPs compared with non-modified NPs. Our study indicated the ligand modification could enhance the uptake and transport by altering some pathways in whole transport process of NPs.

A new method of wound treatment: targeted therapy of skin wounds with reactive oxygen species-responsive nanoparticles containing SDF-1α

Objective

To accelerate wound healing through promoting vascularization by using reactive oxygen species (ROS)-responsive nanoparticles loaded with stromal cell-derived factor-1α(SDF-1α).

Methods

The ROS-reactive nanomaterial poly-(1,4-phenyleneacetone dimethylene thioketal) was synthesized, and its physical and chemical properties were characterized. ROS-responsive nanoparticles containing SDF-1α were prepared through a multiple emulsion solvent evaporation method. The loading capacity, stability, activity of the encapsulated protein, toxicity, and in vivo distribution of these nanoparticles were determined. These nanoparticles were administered by intravenous infusion to mice with full-thickness skin defects to study their effects on the directed chemotaxis of bone marrow mesenchymal stem cells, wound vascularization, and wound healing.

Results

The synthesized ROS-reactive organic polymer poly-(1,4-phenyleneacetone dimethylene thioketal) possessed a molecular weight of approximately 11.5 kDa with a dispersity of 1.97. ROS-responsive nanoparticles containing SDF-1α were prepared with an average diameter of 110 nm and a drug loading capacity of 1.8%. The encapsulation process showed minimal effects on the activity of SDF-1α, and it could be effectively released from the nanoparticles in the presence of ROS. Encapsulated SDF-1α could exist for a long time in blood. In mice with full-thickness skin defects, SDF-1α was effectively released and targeted to the wounds, thus promoting the chemotaxis of bone marrow mesenchymal stem cells toward the wound and its periphery, inducing wound vascularization, and accelerating wound healing.

Self-emulsifying drug delivery systems in oral (poly)peptide drug delivery

INTRODUCTION

Oral administration of most therapeutic peptides and proteins is mainly restricted due to the enzymatic and absorption membrane barrier of the GI tract. In order to overcome these barriers, various technologies have been explored. Among them, self-emulsifying drug delivery systems (SEDDS) received considerable attention as potential carriers to facilitate oral peptide and protein delivery in recent years.

AREAS COVERED

This review article intends to summarize physiological barriers which limit the bioavailability of orally administrated peptide and protein drugs. Furthermore, the potential of SEDDS to protect incorporated peptides and proteins towards peptidases and proteases and to penetrate the mucus layer is reviewed. Their permeation-enhancing properties and their ability to release the drug in a controlled way are described. Moreover, this review covers the results of in vivo studies providing evidence for this promising approach.

EXPERT OPINION

As SEDDS can: i) provide a protective effect towards a presystemic metabolism; ii) efficiently permeate the intestinal mucus gel layer in order to reach the absorption membrane; and iii) be produced in a very simple and cost-effective manner, they are a promising tool for oral peptide and protein drug delivery.

Atorvastatin calcium loaded chitosan nanoparticles: in vitro evaluation and in vivo pharmacokinetic studies in rabbits

<p>In this study, we prepared atorvastatin calcium (AVST) loaded chitosan nanoparticles to improve the oral bioavailability of the drug. Nanoparticles were prepared by solvent evaporation technique and evaluated for its particle size, entrapment efficiency, zeta potential, <italic>in vitro</italic> release and surface morphology by scanning electron microscopy (SEM). In addition, the pharmacokinetics of AVST from the optimized formulation (FT5) was compared with marketed immediate release formulation (Atorva^(r)) in rabbits. Particle size of prepared nanoparticles was ranged between 179.3 ± 7.12 to 256.8 ± 8.24 nm with a low polydispersity index (PI) value. Zeta potential study showed that the particles are stable with positive values between 13.03 ± 0.32 to 46.90 ± 0.49 mV. FT-IR studies confirmed the absence of incompatibility of AVST with excipient used in the formulations. <italic>In vitro</italic> release study showed that the drug release was sustained for 48 h. Results of pharmacokinetics study showed significant changes in the pharmacokinetic parameter (2.2 fold increase in AUC) of the optimized formulation as compared to marketed formulation (Atorva^(r)). Thus, the developed nanoparticles evidenced the improvement of oral bioavailability of AVST in rabbit model.</p>

Mucosal vaccines: a paradigm shift in the development of mucosal adjuvants and delivery vehicles

Mucosal immune responses are the first-line defensive mechanisms against a variety of infections. Therefore, immunizations of mucosal surfaces from which majority of infectious agents make their entry, helps to protect the body against infections. Hence, vaccinization of mucosal surfaces by using mucosal vaccines provides the basis for generating protective immunity both in the mucosal and systemic immune compartments. Mucosal vaccines offer several advantages over parenteral immunization. For example, (i) ease of administration; (ii) non-invasiveness; (iii) high-patient compliance; and (iv) suitability for mass vaccination. Despite these benefits, to date, only very few mucosal vaccines have been developed using whole microorganisms and approved for use in humans. This is due to various challenges associated with the development of an effective mucosal vaccine that can work against a variety of infections, and various problems concerned with the safe delivery of developed vaccine. For instance, protein antigen alone is not just sufficient enough for the optimal delivery of antigen(s) mucosally. Hence, efforts have been made to develop better prophylactic and therapeutic vaccines for improved mucosal Th1 and Th2 immune responses using an efficient and safe immunostimulatory molecule and novel delivery carriers. Therefore, in this review, we have made an attempt to cover the recent advancements in the development of adjuvants and delivery carriers for safe and effective mucosal vaccine production.

Nanomedical engineering: shaping future nanomedicines

Preclinical research in the field of nanomedicine continues to produce a steady stream of new nanoparticles with unique capabilities and complex properties. With improvements come promising treatments for diseases, with the ultimate goal of clinical translation and better patient outcomes compared with current standards of care. Here, we outline engineering considerations for nanomedicines, with respect to design criteria, targeting, and stimuli-triggered drug release strategies. General properties, clinical relevance, and current research advances of various nanomedicines are discussed in light of how these will realize their potential and shape the future of the field.

Preparation of risedronate nanoparticles by solvent evaporation technique

One approach for the enhancement of oral drug bioavailability is the technique of nanoparticle preparation. Risedronate sodium (Biopharmaceutical Classification System Class III) was chosen as a model compound with high water solubility and low intestinal permeability. Eighteen samples of risedronate sodium were prepared by the solvent evaporation technique with sodium dodecyl sulfate, polysorbate, macrogol, sodium carboxymethyl cellulose and sodium carboxymethyl dextran as nanoparticle stabilizers applied in three concentrations. The prepared samples were characterized by dynamic light scattering and scanning electron microscopy. Fourier transform mid-infrared spectroscopy was used for verification of the composition of the samples. The particle size of sixteen samples was less than 200 nm. Polysorbate, sodium carboxymethyl dextran and macrogol were determined as the most favourable excipients; the particle size of the samples of risedronate with these excipients ranged from 2.8 to 10.5 nm.

Molecular imprinted polymers as drug delivery vehicles

This review is aimed to discuss the molecular imprinted polymer (MIP)-based drug delivery systems (DDS). Molecular imprinted polymers have proved to possess the potential and also as a suitable material in several areas over a long period of time. However, only recently it has been employed for pharmaceuticals and biomedical applications, particularly as drug delivery vehicles due to properties including selective recognition generated from imprinting the desired analyte, favorable in harsh experimental conditions, and feedback-controlled recognitive drug release. Hence, this review will discuss their synthesis, the reason they are selected as drug delivery vehicles and for their applications in several drug administration routes (i.e. transdermal, ocular and gastrointestinal or stimuli-reactive routes).

Novel formulations for antimicrobial peptides

Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

Evaluations of therapeutic efficacy of intravitreal injected polylactic-glycolic acid microspheres loaded with triamcinolone acetonide on a rabbit model of uveitis

Conventional treatments of uveitis are not ideal because of the short period of therapeutic efficacy. In the present study, biodegradable polylactic-glycolic acid microspheres loaded with triamcinolone acetonide (TA) were prepared to achieve sustained drug release and their therapeutic efficacy was investigated on a rabbit model of uveitis. TA-loaded microspheres (TA-MS) were prepared by the solvent evaporation method and characterized for encapsulation efficiency, particle size, morphology and in vitro release. The therapeutic efficacy was studied on the rabbit experimental uveitis model based on scoring of the inflammation, aqueous leukocyte counting, aqueous protein determination and histological examination. The TA-MS exhibited smooth and intact surfaces with an average diameter of 50.87 μm. The drug-loading coefficient and encapsulation efficiency were 15.2 ± 0.6 % and 91.24 ± 3.77 %, respectively. The drug release from TA-MS lasted up to 87 days, but only 46 days for TA suspension. The change in surface morphology also showed sustained drug release from TA-MS. TA-MS exhibited improved therapeutic efficacy in lipopolysaccharide -induced uveitis compared to TA suspension, especially in regard to the inhibition of inflammation. The TA-MS had a longer-term therapeutic effect on intraocular inflammation in LPS-induced uveitis in rabbits compared to TA suspension. The results suggested that TA-MS can be developed as a potential sustained-release system for the treatment of uveitis.

Oral delivery of peptides and proteins using lipid-based drug delivery systems

INTRODUCTION

In order to successfully develop lipid-based drug delivery systems (DDS) for oral administration of peptides and proteins, it is important to gain an understanding of the colloid structures formed by these DDS, the mode of peptide and protein incorporation as well as the mechanism by which intestinal absorption of peptides and proteins is promoted.

AREAS COVERED

The present paper reviews the literature on lipid-based DDS, employed for oral delivery of peptides and proteins and highlights the mechanisms by which the different lipid-based carriers are expected to overcome the two most important barriers (extensive enzymatic degradation and poor transmucosal permeability). This paper also gives a clear-cut idea about advantages and drawbacks of using different lipidic colloidal carriers ((micro)emulsions, solid lipid core particles and liposomes) for oral delivery of peptides and proteins.

EXPERT OPINION

Lipid-based DDS are safe and suitable for oral delivery of peptides and proteins. Significant progress has been made in this area with several technologies on clinical trials. However, a better understanding of the mechanism of action in vivo is needed in order to improve the design and development of lipid-based DDS with the desired bioavailability and therapeutic profile.

Polymeric particulate technologies for oral drug delivery and targeting: a pathophysiological perspective

The oral route for delivery of pharmaceuticals is the most widely used and accepted. Nanoparticles and microparticles are increasingly being applied within this arena to optimize drug targeting and bioavailability. Frequently the carrier systems used are either constructed from or contain polymeric materials. Examples of these nanocarriers include polymeric nanoparticles, solid lipid nanocarriers, self-nanoemulsifying drug delivery systems and nanocrystals. It is the purpose of this review to describe these cutting edge technologies and specifically focus on the interaction and fate of these polymers within the gastrointestinal system.

Preparation, characterization, and in vivo evaluation of triamcinolone acetonide microspheres after intravitreal administration

PURPOSE

The aim of this study was to evaluate the intraocular pressure (IOP) increasing effect and bioavailability of triamcinolone acetonide (TA) microspheres, as a novel drug delivery system, after intravitreal administration.

METHODS

Microspheres loaded by TA were prepared by the solvent evaporation method. After encapsulation, the final microspherical formulation was tested in an animal model. The left eyes of rabbits received microspherical TA and the right eyes were injected with conventional TA suspension. The drug concentration in the vitreous samples at days 7, 14, 28, and 56 after the injection was determined by high-performance liquid chromatography. The IOP was also checked at the same days with the Schiotz tonometer.

RESULTS

There was no statistically significant (P>0.05) difference between mean concentration of TA in the vitreous of right and left eyes at the different sampling times except day 56. Mean IOP of eyes that received microspherical TA was increased less than that of the eyes injected with TA suspension, and the difference was statistically significant (P<0.05) for each measurement day. TA was detectable in both eyes after 8 weeks. Both TA microsphere and suspension showed the sustained release profile.

CONCLUSION

The results of this study showed less IOP increasing effect of triamcinolone microspheres in comparison with suspension form.

pH-responsive microspheres encapsulated with iron oxide nanoaggregates for gastrointestinal delivery

Block copolymer-stabilized iron oxide nanoaggregates were fabricated into pH-responsive polymeric microspheres for intestinal delivery of the magnetic nanoaggregates. A diblock copolymer consisted of methoxy poly(ethylene glycol) (mPEG) and poly(e-caprolactone) (PCL) was synthesized by ring-opening polymerization. Microspheres, consisted of Eudragit L100-55 encapsulate and stabilized magnetic nanoaggregates, were prepared by an oil-in-oil emulsification technique. The magnetization of the microspheres decreased, and the stability of the magnetic nanoaggregates in aqueous solutions increased as the amount of block copolymers in the microspheres increased. The encapsulated magnetic nanoaggregates were visualized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The encapsulation efficiency of nanoaggregates of the microspheres increased as the amount of diblock copolymer in the nanoaggregates was increased. The in vitro experiments confirmed the pH-dependent release of the nanoaggregates from the microspheres. The microspheres were administered to the animals by oral gavages, and the nanoaggregates in small intestines were visualized by histological examination of intestinal inner walls. Higher amounts of the block copolymer in the nanoaggregates increased the uptake efficiency in the intestinal tissues. Thus, the incorporation of the block copolymers in the magnetic nanoaggregates increased the intestinal absorption of the aggregates and Eudragit microspheres and effectively protected the nanoaggregates at low pH conditions of the stomach area.

Nanotechnology as a promising strategy for alternative routes of insulin delivery

Since its discovery, insulin has been used as highly specific and effective therapeutic protein to treat type 1 diabetes and later was associated to oral antidiabetic agents in the treatment of type 2 diabetes. Generally, insulin is administered parenterally. Although this route is successful, it still has several limitations, such as discomfort, pain, lipodystrophy at the injection sites and peripheral hyperinsulinemia, which may be the cause of side effects and some complications. Thus, alternative routes of administration have been developed, namely, those based on nanotechnologies. Nanoparticles, made of synthetic or natural materials, have been shown to successfully overcome the inherent barriers for insulin stability, degradation, and uptake across the gastrointestinal tract and other mucosal membranes. This review describes some of the many attempts made to develop alternative and more convenient routes for insulin delivery.

Statistical Optimization of Oral Vancomycin-Eudragit RS Nanoparticles Using Response Surface Methodology

A Box-Behnken design with three replicates was used for preparation and evaluation of Eudragit vancomycin (VCM) nanoparticles prepared by double emulsion. The purpose of this work was to optimize VCM nanoparticles to improve the physicochemical properties. Nanoparticles were formed by using W1/O/W2 double-emulsion solvent evaporation method using Eudragit RS as a retardant material. Full factorial design was employed to study the effect of independent variables, RPM (X1), amount of emulsifier (X2), stirring rate (X3), volume of organic phase (X4) and volume of aqueous phase (X5), on the dependent variables as production yield, encapsulation efficiency and particle size. The optimum condition for VCM nanoparticles preparation was 1:2 drug to polymer ratio, 0.2 (%w/w) amount of emulsifier , 25 mL (volume of organic phase), 25 mL (volume of aqueous phase), 3 min (time of stirring) and 26000 RPM. RPM and emulsifier concentrations were the effective factors on the drug loading (R2 = 90.82). The highest entrapment efficiency was obtained when the ratio of drug to polymer was 1:3. Zeta (ζ) potential of the nanoparticles was fairly positive in molecular level. In vitro release study showed two phases: an initial burst for 0.5 h followed by a very slow release pattern during a period of 24 h. The release of VCM was influenced by the drug to polymer ratio and particle size and was found to be diffusion controlled. The best-fit release kinetic was achieved with Peppas model. In conclusion, the VCM nanoparticle preparations showed optimize formulation, which can be useful for oral administrations.

Formulation and evaluation of solid lipid nanoparticles of ramipril

Solid lipid nanoparticles are typically spherical with an average diameter between 1 and 1000 nm. It is an alternative carrier system to tradition colloidal carriers, such as, emulsions, liposomes, and polymeric micro and nanoparticles. Ramipril is an antihypertensive agent used in the treatment of hypertension. Its oral bioavailability is 28% and it is rapidly excreted through the renal route. This drug has many side effects such as, postural hypotension, hyperkalemia, and angioedema, when given as an immediate dosage form. To overcome the side effects and to increase the bioavailability of ramipril, solid lipid nanoparticles of ramipril are prepared by using lipids (glyceryl monostearate and glyceryl monooleate) with stabilizers (tween 80, poloxamer 188, and span 20). The prepared formulations have been evaluated for entrapment efficiency, drug content, in-vitro drug release, particle size analysis, scanning electron spectroscopy, Fourier transform-infrared studies, and stability. A formulation containing glyceryl monooleate, stabilized with span 20 as surfactant showed prolonged drug release, smaller particle size, and narrow particle size distribution, as compared to other formulations with different surfactants and lipids.

Polímeros sintéticos biodegradáveis: matérias-primas e métodos de produção de micropartículas para uso em drug delivery e liberação controlada

Micropartículas produzidas a partir de polímeros sintéticos têm sido amplamente utilizadas na área farmacêutica para encapsulação de princípios ativos. Essas micropartículas apresentam as vantagens de proteção do princípio ativo, mucoadesão e gastrorresistência, melhor biodisponibilidade e maior adesão do paciente ao tratamento. Além disso, utiliza menores quantidade de princípio ativo para obtenção do efeito terapêutico proporcionando diminuição dos efeitos adversos locais, sistêmicos e menor toxidade. Os polímeros sintéticos empregados na produção das micropartículas são classificados biodegradáveis ou não biodegradáveis, sendo os biodegradáveis mais utilizados por não necessitam ser removidos cirurgicamente após o término de sua ação. A produção das micropartículas poliméricas sintéticas para encapsulação tanto de ativos hidrofílicos quanto hidrofóbicos pode ser emulsificação por extração e/ou evaporação do solvente; coacervação; métodos mecânicos e estão revisados neste artigo evidenciando as vantagens, desvantagens e viabilidade de cada metodologia. A escolha da metodologia e do polímero sintético a serem empregados na produção desse sistema dependem da aplicação terapêutica requerida, bem como a simplicidade, reprodutibilidade e factibilidade do aumento de escala da produção.

Novel technologies: A weapon against tuberculosis

Tuberculosis (TB) is a leading chronic bacterial infection. Despite potentially curative pharmacotherapies being available for over 50 years, the length of the treatment and the pill burden can hamper patient lifestyle. Low compliance and adherence to administration schedules remain the main reasons for therapeutic failure and contribute to the development of multidrug-resistant strains. The design of novel antibiotics attempts to overcome drug resistance, to shorten the treatment course, and to reduce drug interactions. In this framework, nanotechnology appears as one of the promising approaches for the development of more effective medicines. The present review thoroughly overviews the development of novel microparticulate, encapsulation, and various other carrier-based drug delivery systems for incorporating the principal anti-TB agents. Drug delivery systems have been designed that either target the site of TB or reduce the dosing frequency with the aim of improving patient healthcare.

Fabrication and characterization of porous EH scaffolds and EH-PEG bilayers

Biomaterials made from synthetic polymers are becoming more pervasive in the medical field. Synthetic polymers are particularly advantageous as their chemical and mechanical properties can be easily tailored to a specific application. This work characterizes polymer scaffolds derived from the cyclic acetal monomer 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD). Both porous scaffolds and bilayer scaffolds based upon the EHD monomer were fabricated, and the resulting scaffolds' degradation and mechanical properties were studied. The results showed that by modifying the architecture of an EH scaffold, either by adding a porous network or a poly(ethylene glycol) (PEG) coating, the degradation and Young's modulus of the biomaterial can be significant altered. However, results also indicated that these architectural modifications can be accomplished without a significant loss in the flexural strength of the scaffold. Therefore, we suggest that porous EH scaffolds, and particularly porous EH-PEG bilayers, may be especially useful in dynamic tissue environments due to their advantageous architectural and mechanical properties.

Systemic and mucosal delivery of drugs within polymeric microparticles produced by spray drying

Encapsulation of therapeutic and diagnostic materials into polymeric particles is a means to protect and control or target the release of active substances such as drugs, vaccines, and genetic material. In terms of mucosal delivery, polymeric encapsulation can be used to promote absorption of the active substance, while particles can improve the half-life of drugs administered systemically. Spray drying is an attractive technology used to produce such microparticles, because it combines both the encapsulation and drying steps in a rapid, single-step operation. Even so, spray drying is not classically associated with processes used for drug and therapeutic material encapsulation, since elevated temperatures could potentially denature the active substance. However, a comprehensive review of the literature revealed a number of studies demonstrating that spray drying can be used to produce microparticulate formulations with labile therapeutics. Polymers commonly employed include synthetics such as methacrylic copolymers and polyesters, and natural materials including chitosan and alginate. Drugs and active substances are diverse and included antibiotics, anti-inflammatory agents, and chemotherapeutics. Regarding the delivery of spray-dried particles, the pulmonary, oral, colonic, and nasal mucosal routes are often investigated because they offer a convenient means of administration, which promotes physician and patient compliance. In addition, spray drying has been widely used to produce polymeric microparticles for systemic delivery in order to control the delivery of drugs, vaccines, or genetic material that may exhibit poor pharmacokinetic profiles or pose toxicity concerns. This review presents a brief introduction to the technology of spray drying and outlines the delivery routes and the applications of spray-dried polymeric microparticles.