Oral administration of liposomal insulin

Liposomes as Multifunctional Nano-Carriers for Medicinal Natural Products

Although medicinal natural products and their derivatives have shown promising effects in disease therapies, they usually suffer the drawbacks in low solubility and stability in the physiological environment, low delivery efficiency, side effects due to multi-targeting, and low site-specific distribution in the lesion. In this review, targeted delivery was well-guided by liposomal formulation in the aspects of preparation of functional liposomes, liposomal medicinal natural products, combined therapies, and image-guided therapy. This review is believed to provide useful guidance to enhance the targeted therapy of medicinal natural products and their derivatives.

Comparison in the Glucose Response of Flexible Liposomes Loaded with Insulin with the Addition of Different Surfactants in an Experimental Diabetes Model

Background:

Insulin has been included in a variety of dosage forms; nevertheless, liposomes have shown protection to degradation and better absorption. The addition of surfactant to liposomes could give the ability to deform and pass through intact membranes, and could increase the stability and the release of the drug.

Introduction:

Due to the limitations of the current treatment of insulin in diabetic patients, investigation in alternatives routes has increased. The oral route is the most convenient because of the similarity with the natural secretion of this hormone. The aim was to evaluate the in-vivo effect of fourteen formulations of Insulin-loaded flexible liposomes with different surfactants by oral and subcutaneous routes.

Methods:

Fourteen formulations of insulin were obtained with the addition of different surfactants. Size distribution, polydispersion index and Z potential were obtained for all formulations. In-vivo tests were performed in rats induced with experimental diabetes with streptozotocin, and glucose curves were obtained during 480 minutes.

Results:

All formulations by the subcutaneous route caused an optimal reduction in glucose levels. However, the addition of Brij L23 produced a better reduction, lasting for 420 minutes. By the oral route, the reduction of glucose did not reach the normal levels, but the addition of Poloxamer 407 and Brij S10 showed the best reduction in the glucose levels by this route.

Conclusion:

The addition of surfactants to the lipid structure can modify the release of the insulin by different routes of administration, but this behavior depends on the characteristics of the surfactant, such as the melting phase transition temperature of the lipid bilayer.

In Vitro and In Vivo Profiles and Characterization of Insulin Nanocarriers Based in Flexible Liposomes Designed for Oral Administration

Background:

Alternatives routes of delivery for Insulin have been evaluated to improve treatment for Diabetes Mellitus. The oral route is the most convenient physiologically; it releases in a similar way to endogenous secretion. Flexible liposomes have deformable abilities to pass through membranes with adequate therapeutic effects, but they have been tested only dermally.

Objective:

Our aim was to develop an oral nanocarrier based on flexible liposomes for insulin with polymer addition to reduce gastrointestinal degradation.

Methods:

Different percentages of polyethylene glycol were added to a conventional formulation of flexible liposomes. The manufacturing procedure was the heating method. Z potential, size particle, polydispersity index and encapsulation percentage were evaluated. A release profile was performed in the stomach and intestinal pH mediums by two-stage reverse dialysis method. The in-vivo test was performed in experimental diabetic rats by oral, transdermal and subcutaneous routes.

Results:

All the formulations showed polydispersity but adequate Z potential. The 10% PEG formulation obtained the best insulin enclosure with 81.9%. The insulin integrity after preparation was confirmed by polyacrylamide gel electrophoresis. PEG and non-PEG formulations showed similar behavior in acid release profile but the release and stability of lipid structures were better and longer in intestinal pH conditions. In vivo tests showed a reduction to normal glucose levels only in subcutaneous route.

Conclusion:

The polymer inclusion in flexible liposomes generates an adequate nanocarrier for proteins in terms of stability and composition; although its in-vivo use reduces glucose levels in subcutaneous route, the effect was not adequate in oral route.

Efficacy of targeted liposomes and nanocochleates containing imatinib plus dexketoprofen against fibrosarcoma

The main challenges in treating cancer using chemotherapeutics are insufficient dose at the target site and the development of drug resistance, while higher doses can induce side effects by damaging nontarget tissues. Combinatorial drug therapy may overcome these limitations by permitting lower doses and more specific targeting, thereby mitigating drug resistance and nontarget side effects. Recent reports indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) have anticancer potential and can be used together with conventional chemotherapeutics to improve efficacy and safety. In the present study, imatinib mesylate and dexketoprofen trometamol were selected as model drugs to develop targeted surface-modified liposome and nanocochleate formulations for fibrosarcoma treatment. The physicochemical properties and in vitro efficacy of various formulations were evaluated by measurement of particle size distribution, polydispersity index, zeta potential, encapsulation efficiency, diffusion through Caco-2 cells, and toxicity in culture. Selected formulations were then evaluated in fibrosarcoma-bearing model mice by histopathological observations and tyrosine kinase receptor inhibition assays. The most effective formulation on the fibrosarcoma model was a PEGylated nanocochleate formulation. These findings provide a foundation for developing more effective formulations and chemotherapeutic strategies for the treatment of fibrosarcoma and other types of cancer.

Antinociceptive Effect of Liposomal Bupivacaine Formulations After Intrathecal Administration in Rats

Background/aim

Based on our previous in vitro study with multilamellar liposomal bupivacaine (MLB) versus bupivacaine alone in artificial cerebrospinal fluid, we aimed to investigate in vivo antinociceptive effect of intrathecal MLB by determining tail flick latency (TFL) time after thermal stimulation in rats.

Materials and methods

After preparing MLB and high-yield drug entrapment in liposome (HYDEL) bupivacaine, 18 female Wistar rats were assigned to 3 groups as control (bupivacaine) and study groups (MLB and HYDEL bupivacaine) including 6 rats in each group to administer these drugs intrathecally. Antinociceptive activity was determined in terms of TFL time after thermal stimulation. Maximum possible effect (MPE) calculated from TFL times and rats with motor block were documented.

Results

TFL times after intrathecal injection of HYDEL bupivacaine were significantly longer than that of the control and MLB groups (P < 0.05) and returned to baseline 180 min after intrathecal injection. MPE (100%) with intrathecal HYDEL bupivacaine occurred between 10 to 45 min. Afterwards, MPEs were 70% and 50% for the control and MLB groups, respectively. Motor block disappeared after 20 min in the study groups while it lasted 75 min in the control.

Conclusion

Intrathecal administration of MLB and HYDEL bupivacaine in rats resulted in longer duration of antinociceptive activity with shorter motor block duration.

The Effectiveness of Raloxifene-Loaded Liposomes and Cochleates in Breast Cancer Therapy

Liposome (spherical vesicles) and cochleate (multilayer crystalline, spiral structure) formulations containing raloxifene have been developed having dimethyl-β-cyclodextrin (DM-β-CD) or sodium taurocholate (NaTC). Raloxifene was approved initially for the treatment of osteoporosis but it is also effective on breast tissue and endometrial cells. Raloxifene inhibits matrix metalloproteinase-2 (MMP-2) enzyme, which is known to be responsible for tumor invasion and the initiation of angiogenesis during the tumor growth. Therefore, raloxifene was selected as a model drug. A series of raloxifene-loaded liposome and cochleate formulations were prepared. In vitro release studies and in vivo tests were performed. Breast cancer cell lines (MCF-7) were also used to find the most effective formulation. Highest antitumor activity was observed, and MMP-2 enzyme was also found to be inhibited with raloxifene-loaded cochleates containing DM-β-CD. These developed formulations can be helpful for further treatment alternatives and new strategies for cancer therapy.

Release Pattern of Liposomal Bupivacaine in Artificial Cerebrospinal Fluid

OBJECTIVE

We aimed to compare the possible controlled release profile of multilamellar liposomal bupivacaine formulations with non-liposomal forms in artificial cerebrospinal fluid (CSF) under in vitro conditions.

METHODS

Liposome formulations were prepared using a dry-film hydration method. Then, an artificial CSF-buffered solution was prepared. Bupivacaine base with liposomal bupivacaine base, bupivacaine HCl with liposomal bupivacaine HCl and bupivacaine HCl were added in a Franz diffusion cell. These solutions were kept in a hot water bath for 24 h. The samples were taken at 0.5, 1, 3, 6, 12 and 24 h (1st series of experiment). Solutions of bupivacaine base with liposomal bupivacaine base and bupivacaine HCl with liposomal bupivacaine HCl were centrifuged to obtain liposomal bupivacaine base and liposomal bupivacaine HCl. Afterwards, liposomal bupivacaine base and liposomal bupivacaine HCl were added in a Franz diffusion cell. After keeping these solutions in a hot water bath for 24 h as well, the samples were taken at the same time intervals (2(nd) series of experiment). All samples (54 from the 1st experiment and 36 from the 2(nd) experiment) were analysed with high-performance liquid chromatography and ultra-performance liquid chromatography and their chromatograms were obtained.

RESULTS

After obtaining calibration curves for bupivacaine base and HCl, release patterns of these formulations were plotted. A markedly controlled slow-release pattern was observed for multilamellar liposomal bupivacaine than for non-liposomal bupivacaine in artificial CSF.

CONCLUSION

Demonstration of controlled slow-release profile for mutilamellar liposomal bupivacaine in artificial CSF in vitro might support intrathecal use of liposomal bupivacaine in vivo in animal studies.

Enhanced hypoglycemic effect of biotin-modified liposomes loading insulin: effect of formulation variables, intracellular trafficking, and cytotoxicity

Peroral protein/peptide delivery has been one of the most challenging, but encouraging topics in pharmaceutics. This article was intended to explore the potential of biotin-modified liposomes (BLPs) as oral insulin delivery carriers. By incorporating biotin-DSPE into the lipid bilayer, we prepared BLPs using reverse evaporation/sonication method. We investigated hypoglycemic effects in normal rats after oral administration of BLPs, and the possible absorption mechanism by a series of in vitro tests. The relative pharmacological bioavailability of BLPs was up to 11.04% that was as much as 5.28 folds of conventional liposomes (CLPs). The results showed that the enhanced oral absorption of insulin mainly attributed to biotin ligand-mediated endocytosis. The results provided proof of BLPs as effective carriers for oral insulin delivery.

Oral insulin delivery: how far are we?

Oral delivery of insulin may significantly improve the quality of life of diabetes patients who routinely receive insulin by the subcutaneous route. In fact, compared with this administration route, oral delivery of insulin in diabetes treatment offers many advantages: higher patient compliance, rapid hepatic insulinization, and avoidance of peripheral hyperinsulinemia and other adverse effects such as possible hypoglycemia and weight gain. However, the oral delivery of insulin remains a challenge because its oral absorption is limited. The mainbarriers faced by insulin in the gastrointestinal tract are degradation by proteolytic enzymes and lack of transport across the intestinal epithelium. Several strategies to deliver insulin orally have been proposed, but without much clinical or commercial success. Protein encapsulation into nanoparticles is regarded as a promising alternative to administer insulin orally because they have the ability to promote insulin paracellular or transcellular transport across the intestinal mucosa. In this review, different delivery systems intended to increase the oral bioavailability of insulin will be discussed, with a special focus on nanoparticulate carrier systems, as well as the efforts that pharmaceutical companies are making to bring to the market the first oral delivery system of insulin. The toxicological and safety data of delivery systems, the clinical value and progress of oral insulin delivery, and the future prospects in this research field will be also scrutinized.

Liposomal delivery of proteins and peptides

INTRODUCTION

A number of delivery issues exist for biotech molecules including peptides, proteins and gene-based medicines that now make up over 60% of the drug pipeline. The problems comprise pharmaceutical ad biopharmaceutical issues. One of the common approaches to overcome these issues is the use of a carrier and liposomes as carriers have been investigated extensively over the last decade.

AREAS COVERED

The review has been discussed in terms of formulation and preclinical development studies and in vivo studies encompassing different delivery routes including parenteral, oral, buccal, pulmonary, intranasal, ocular and transdermal involving liposomes as carriers. Important research findings have been tabulated under each side heading and an expert opinion has been summarised for each delivery route.

EXPERT OPINION

The conclusion and expert opinion - conclusion sections discuss in detail troubleshooting aspects related to the use of liposomes as carriers for delivery of biopharmaceutical moieties and scrutinises the aspects behind the absence of a protein/peptide-containing liposome in market.

Novel asparagine-derived lipid enhances distearoylphosphatidylcholine bilayer resistance to acidic conditions

A novel asparagine-derived lipid analogue (ALA(11,17)) bearing a tetrahydropyrimidinone headgroup and two fatty chains (11 and 17 indicate the lengths of linear alkyl groups) was synthesized in high yield and purity. The thin film hydration of formulations containing 5 mol % or greater ALA(11,17) in distearoylphosphatidylcholine (DSPC) generated multilamellar vesicles (MLVs) that remained unaggregated according to optical microscopy, while those formed from DSPC only were highly clustered. The MLVs were processed into unilamellar liposomes via extrusion and were characterized by dynamic light scattering (DLS), zeta potential, turbidity, and scanning electron microscopy (SEM) analysis. Results show that the presence of ALA(11,17) in DSPC liposomes significantly alters the morphology, colloidal stability, and retention of encapsulated materials in both acidic and neutral conditions. The ability of ALA(11,17)-hybrid liposomes to encapsulate and retain inclusions under neutral and acidic conditions (pH < 2) was demonstrated by calcein dequenching experiments. DLS and SEM confirmed that ALA(11,17)/DSPC liposomes remained intact under these conditions. The bilayer integrity observed under neutral and acidic conditions and the likely biocompatibility of these fatty amino acid analogues suggest that ALA(11,17) is a promising additive for modulating phosphatidylcholine lipid bilayer properties.

New perspective for the treatment of Alzheimer diseases: liposomal rivastigmine formulations

The aim of this study was to determine the transportations of rivastigmine containing from various liposome formulations through Madin Darby Canine Kidney (MDCK) cells monolayer and to compare the in vitro test results with in vivo. There is no other liposome formulation of rivastigmine and the transportations of rivastigmine through MDCK cell monolayers or related study available in the literature. Cytotoxicity (MTT) test was used to determine cell viabilities. The effect of sodium-taurocholate or dimethyl-beta-cyclodextrine as penetration enhancer was also investigated. Characterization and stability studies for liposome formulations were performed. Permeation experiments of rivastigmine were performed through MDCK cells and dialysis membrane. The kinetic of release from liposomes was also investigated. The highest apparent permeability coefficient (log. values) was obtained with sodium-taurocholate liposomes for -1.15 ± 0.16 for MDCK cell. Rivastigmine liposomes and solutions were also administered to mice orally and intraperitonally. Acetylcholinesterase (AChE) activity was determined by Ellman method. AChE% inhibition values were calculated for both blood and brain after administration of rivastigmine solution and liposomes. The highest AChE inhibition was observed for rivastigmine-sodium-taurocholate liposomes. Histological observations of the mice' brains were performed under transmission electron microscope (TEM). The histological results were also indicated and supported all these findings.

Phospholipids and lipid-based formulations in oral drug delivery

Phospholipids become increasingly important as formulation excipients and as active ingredients per se. The present article summarizes particular features of commonly used phospholipids and their application spectrum within oral drug formulation and elucidates current strategies to improve bioavailability and disposition of orally administered drugs. Advantages of phospholipids formulations not only comprise enhanced bioavailability of drugs with low aqueous solubility or low membrane penetration potential, but also improvement or alteration of uptake and release of drugs, protection of sensitive active agents from degradation in the gastrointestinal tract, reduction of gastrointestinal side effects of non-steroidal anti-inflammatory drugs and even masking of bitter taste of orally applied drugs. Technological strategies to achieve these effects are highly diverse and offer various possibilities of liquid, semi-liquid and solid lipid-based formulations for drug delivery optimization.

Vesicles from Pluronic/poly(lactic acid) block copolymers as new carriers for oral insulin delivery

The morphologies of poly(lactic acid)-b-Pluronic-b-poly(lactic acid) (PLA-F127-PLA) aggregates in aqueous solutions were reported previously to be vesicular nano-particles by our group. In the present study, we seek to investigate the feasibility of using PLA-F127-PLA vesicles as oral delivery carrier for insulin. Both in vitro and in vivo release behavior of insulin loaded in PLA-F127-PLA vesicles were studied. A biphasic release behavior was observed for the in vitro release of insulin from PLAF127-29 vesicles. More importantly, it was found in the diabetic mice tests that the blood glucose concentration of oral insulin-loaded PLAF127-29 vesicles decreased from 18.5 to 5.3 mmol/L within 4.5 h and the minimum blood glucose concentration (about 4.5 mmol/L) was achieved after about 5 h. Furthermore, the blood glucose concentration was maintained at this level for at least an additional 18.5 h. These results proved that PLA-F127-PLA vesicles could be promising polymeric carriers for oral insulin delivery application due to their prolonged hypoglycemic effect.