Oral delivery of low molecular weight heparin microspheres prepared using biodegradable polymer matrix system

Nanoparticles: Oral Delivery for Protein and Peptide Drugs

Protein and peptide drugs have many advantages, such as high bioactivity and specificity, strong solubility, and low toxicity. Therefore, the strategies for improving the bioavailability of protein peptides are reviewed, including chemical modification of nanocarriers, absorption enhancers, and mucous adhesion systems. The status, advantages, and disadvantages of various strategies are systematically analyzed. The systematic and personalized design of various factors affecting the release and absorption of drugs based on nanoparticles is pointed out. It is expected to design a protein peptide oral delivery system that can be applied in the clinic.

Low-Molecular-Weight Heparins: Reduced Size Particulate Systems for Improved Therapeutic Outcomes

A wide range of diseases have been treated using low-molecular-weight heparins (LMWHs), the drug of choice for anticoagulation. Owing to their better pharmacokinetic features compared to those of unfractionated heparin (uFH), several systems incorporating LMWHs have been investigated to deliver and improve their therapeutic outcomes, especially through development of their micro- and nano-particles. This review article describes current perspectives on the fabrication, characterization, and application of LMWHs-loaded micro- and nano-particles to achieve ameliorated bioavailability. The valuable applications of LMWH will continue to encourage researchers to identify efficient delivery systems that have specific release characteristics and ameliorated bioavailability, overcoming the challenges presented by biological obstructions and the physicochemical properties of LMWHs.

Passive targeting and lung tolerability of enoxaparin microspheres for a sustained antithrombotic activity in rats

Pulmonary bed can retain microparticles (MP) larger than their capillaries' diameter, hence we offer a promising way for lung passive targeting following intravenous (IV) administration. In this study, enoxaparin (Enox)-albumin microspheres (Enox-Alb MS) were, optimally, developed as lung targeted sustained release MP for IV use. Lung tolerability and targeting efficiency of Enox-Alb MS were tested, and the pharmacokinetic profile following IV administration to albino rats was constructed. In vivo studies confirmed high lung targeting efficiency of Enox-Alb MS with lack of potential tissue toxicity. The anticoagulant activity of the selected Alb MS was significantly sustained for up to 38 h compared to 5 h for the market product. Alb MS are promising delivery carriers for controlled and targeted delivery of Enox to the lungs for prophylaxis and treatment of pulmonary embolism.

Preparation and evaluation of a novel oral delivery system for low molecular weight heparin

OBJECTIVE

The objective of the present work was to prepare and evaluate a novel oral formulation for systemic delivery of low molecular weight heparin (LMWH). The formulation consisted of Eudragit S 100-coated positively charged liposomes encapsulating LMWH and a penetration enhancer.

MATERIALS AND METHODS

Positively charged liposomes were first prepared by the thin film hydration method using lipid (soy phosphotidylcholine and cholesterol) and stearyl amine (SA) in the optimum ratio of 16:1, along with cetylpyridinium chloride (CPC) as a penetration enhancer. Prepared liposomes were coated with negatively charged Eudragit S 100 (0.3% w/v). The formulations were studied for various in vitro and in vivo properties. Differential scanning calorimetry (DSC), x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) studies, and in vitro drug release were used for in vitro characterization of the formulations. Ex vivo permeation studies were performed by using distal small intestine of rat. Oral absorption studies were conducted with the rat model.

RESULTS

Coating of the liposomes was confirmed by SEM and particle size determination studies. In vitro release studies of coated liposomes have demonstrated that the release of LMWH was in the following order: Stomach < small intestine < distal small intestine < colon. Ex vivo permeation studies have shown a fivefold increase in permeation of LMWH with Eudragit S 100-coated liposomes compared to uncoated, uncharged liposomes. Oral absorption studies have showed that with Eudragit-coated liposomes, the oral bioavailability of LMWH was improved, compared to plain LMWH solution. This is revealed by a threefold increase in the area under the curve (AUC) of the plasma concentration time curve.

CONCLUSION

A novel formulation for oral delivery of LMWH was thus successfully prepared and evaluated.

Recent advances in anticoagulant drug delivery

INTRODUCTION

Anticoagulants have been prescribed to patients to prevent deep vein thrombosis or pulmonary embolism. However, because of several problems in anticoagulant therapy, much attention has been directed at developing an ideal anticoagulant, and numerous attempts have been made to develop new anticoagulant delivery systems in recent years.

AREAS COVERED

This review discusses the challenges associated with the recent development of anticoagulants and their delivery systems. Various delivery methods have been developed to improve the use of anticoagulants. Recent advances in anticoagulant delivery and antidote development are also discussed in the context of their current progression states.

EXPERT OPINION

There have been many different approaches to developing the delivery system of anticoagulants. One approach has been to expand the use of new oral agents and develop their antidotes. Reducing the size of heparins to use smaller heparins for delivery, and developing oral or topical heparins are also some of the approaches used. Various physical formulations or chemical modifications are other ways that have enhanced the therapeutic potential of anticoagulant agents. On the whole, recent advances have contributed to increasing the efficacy and safety of anticoagulant clinically and have benefited the field of anticoagulant delivery.

Development of subcutaneous sustained release nanoparticles encapsulating low molecular weight heparin

The objective of the present research work was to prepare and evaluate sustained release subcutaneous (s.c.) nanoparticles of low molecular weight heparin (LMWH). The nanoparticles were prepared by water–in-oil in-water (w/o/w) emulsion and evaporation method using different grades of polylactide co-glycolide (50:50, 85:15), and different concentrations of polyvinyl alcohol (0.1%, 0.5%, 1%) aqueous solution as surfactant. The fabricated nanoparticles were evaluated for size, shape, zeta potential, encapsulation efficiency, in vitro drug release, and in vivo biological activity (anti-factor Xa activity) using the standard kit. The drug and excipient compatibility was analyzed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The formation of nanoparticles was confirmed by scanning electron microscopy; nanoparticles were spherical in shape. The size of prepared nanoparticles was found between 195 nm and 251 nm. The encapsulation efficiency of the nanoparticles was found between 46% and 70%. In vitro drug, release was about 16–38% for 10 days. In vivo drug, release shows the sustained release of drug for 10 days in rats. FTIR studies indicated that there was no loss in chemical integrity of the drug upon fabrication into nanoparticles. DSC and XRD results demonstrated that the drug was changed from the crystalline form to the amorphous form in the formulation during the fabrication process. The results of this study revealed that the s.c. nanoparticles were suitable candidates for sustained delivery of LMWH.

Unique insights into the intestinal absorption, transit, and subsequent biodistribution of polymer-derived microspheres

Polymeric microspheres (MSs) have received attention for their potential to improve the delivery of drugs with poor oral bioavailability. Although MSs can be absorbed into the absorptive epithelium of the small intestine, little is known about the physiologic mechanisms that are responsible for their cellular trafficking. In these experiments, nonbiodegradable polystyrene MSs (diameter range: 500 nm to 5 µm) were delivered locally to the jejunum or ileum or by oral administration to young male rats. Following administration, MSs were taken up rapidly (≤ 5 min) by the small intestine and were detected by transmission electron microscopy and confocal laser scanning microscopy. Gel permeation chromatography confirmed that polymer was present in all tissue samples, including the brain. These results confirm that MSs (diameter range: 500 nm to 5 µm) were absorbed by the small intestine and distributed throughout the rat. After delivering MSs to the jejunum or ileum, high concentrations of polystyrene were detected in the liver, kidneys, and lungs. The pharmacologic inhibitors chlorpromazine, phorbol 12-myristate 13-acetate, and cytochalasin D caused a reduction in the total number of MSs absorbed in the jejunum and ileum, demonstrating that nonphagocytic processes (including endocytosis) direct the uptake of MSs in the small intestine. These results challenge the convention that phagocytic cells such as the microfold cells solely facilitate MS absorption in the small intestine.

Synthesis of a targeted library of heparan sulfate hexa- to dodecasaccharides as inhibitors of β-secretase: potential therapeutics for Alzheimer's disease

Heparan sulfates (HS) are a class of sulfated polysaccharides that function as dynamic biological regulators of the functions of diverse proteins. The structural basis of these interactions, however, remains elusive, and chemical synthesis of defined structures represents a challenging but powerful approach for unravelling the structure-activity relationships of their complex sulfation patterns. HS has been shown to function as an inhibitor of the β-site cleaving enzyme β-secretase (BACE1), a protease responsible for generating the toxic Aβ peptides that accumulate in Alzheimer's disease (AD), with 6-O-sulfation identified as a key requirement. Here, we demonstrate a novel generic synthetic approach to HS oligosaccharides applied to production of a library of 16 hexa- to dodecasaccharides targeted at BACE1 inhibition. Screening of this library provided new insights into structure-activity relationships for optimal BACE1 inhibition, and yielded a number of potent non-anticoagulant BACE1 inhibitors with potential for development as leads for treatment of AD through lowering of Aβ peptide levels.

Enhanced bioavailability of orally administered antisense oligonucleotide to nuclear factor kappa B mRNA after microencapsulation with albumin

Antisense molecules that pertain to ribonucleic acid (RNA) and complementary to the messenger RNA (mRNA) are produced by transcription of a given gene. Antisense oligonucleotides have emerged as potential gene-specific therapeutic agents that are currently undergoing evaluation in clinical trials for a variety of diseases. When administered orally, antisense oligionucleotides have poor bioavailability as they are rapidly degraded by the acid in the stomach and by the enzymes in the intestine. Therefore, the enhancement of bioavailability after oral administration is highly desirable. This article shows the enhanced bioavailability of antisense oligonucleotides that targets nuclear factor kappa B (NF-κB) mRNA after encapsulating in an inert, biodegradable albumin polymer matrix that was administered via the oral route into a rat model. The bioavailability of the antisense oligonucleotides to NF-κB in microencapsulated form was compared to the solution form of the drug upon oral administration. The solution form had a low bioavailability of 9%, whereas the bioavailability for the microencapsulated form of the drug increased up to 70%. Moreover, the other pharmacokinetic parameters including half-life (t1/2) and volume of distribution (Vd) increased for the microencapsulated form compared to the solution form of the drug.

NANO/MICROSCALE TECHNOLOGIES FOR DRUG DELIVERY

Nano- and microscale technologies have made a marked impact on the development of drug delivery systems. The loading efficiency and particle size of nano/micro particles can be better controlled with these new technologies than conventional methods. Moreover, drug delivery systems are moving from simple particles to smart particles and devices with programmable functions. These technologies are also contributing to in vitro and in vivo drug testing, which are important to evaluate drug delivery systems. For in vitro tests, lab-on-a-chip models are potentially useful as alternatives to animal models. For in vivo test, nano/micro-biosensors are developed for testing chemicals and biologics with high sensitivity and selectivity. Here, we review the recent development of nanoscale and microscale technologies in drug delivery including drug delivery systems, in vitro and in vivo tests.

Formulation, biological and pharmacokinetic studies of sucrose ester-stabilized nanosuspensions of oleanolic Acid

PURPOSE

The aim of this study was to develop sucrose ester (SE)-stabilized oleanolic acid (OA) nanosuspensions (NS) for enhanced delivery.

METHODS

SEOA NS were prepared via O/W emulsion and organic solvent evaporation methods. The particles' size and polydispersity index were measured by nanosizer. Their percent encapsulation efficiency, saturation solubility and in vitro dissolution rate were obtained via HPLC. The in vitro bioefficacy was analyzed by MTT measurements in A549 human non-small-cell lung cancer cell line. The cellular uptake of OA and in vivo pharmacokinetics profile were determined using LC-ESI-MS/MS.

RESULTS

Spherical SEOA NS particles (~100 nm in diameter) were produced and found to be physicochemically stable over a month at 4°C. In particular, SEOA 4121 NS (SEL: SEP at 4:1 w/w; SE: OA at 2:1 w/w) produced the greatest increase in saturation solubility (1.89 mg/mL vs. 3.43 μg/mL), dissolution rate, cytotoxicity and bioavailability. Preliminary studies indicated that cellular uptake of SEOA NS by A549 cells was temperature-, concentration- and time-dependent.

CONCLUSION

Preparing OA as SE-stabilized NS particles provides a novel method to enhance saturation solubility, in vitro dissolution rate, bioefficacy and in vivo bioavailability of free OA and/or other potentially useful hydrophobic drugs.

New challenges for a second-generation low-molecular-weight heparin: focus on bemiparin

Bemiparin is a second-generation low-molecular-weight heparin (LMWH) that has the lowest molecular weight, the longest half-life and the highest anti-Factor Xa/anti-Factor IIa activity ratio. The safety and efficacy of bemiparin has been demonstrated in several studies and currently it is licensed for the treatment and prophylaxis of venous thromboembolism (VTE), as well as for the prevention of clotting in the extracorporeal circuit during hemodialysis. Multicenter pharmacoeconomic studies carried out in the Spanish National Health system indicate that bemiparin is more cost effective than enoxaparin for the prevention of VTE in total knee replacement. Interestingly, recent results suggest that bemiparin could be useful as an adjuvant treatment in the management of lower-extremity diabetic ulcers. Since international guidelines recommend LMWHs for initial and continuous anticoagulant treatment in cancer patients with VTE, as well as for its prevention, results from ongoing trials could be critical to establish the potential of bemiparin in oncological patients. Finally, the pharmacokinetics of two oral bemiparin formulations are currently being analyzed in a Phase I trial.