Oral Peptide Delivery System Research Articles

Assessment of hydrophobic-ion paired insulin incorporated SMEDDS for the treatment of diabetes mellitus

To overcome the low oral bioavailability of insulin, we hypothesized that the insulin-hydrophobic ion pairing (HIP) complex incorporated self-microemulsifying drug delivery system (SMEDDS) would be beneficial. In the present study, an oral insulin delivery system was developed and estimated using the HIP technique and SMEDDS. Further insulin-HIP complexes were characterized using various spectroscopical techniques. Additionally, insulin-HIP complexes were subjected to analysis of complexes' conformational stability in the real physiological solution using computational approaches. On the other hand, in vitro, and in vivo studies were carried out to investigate the permeability and hypoglycemic effect. Subsequently, in an in vitro non-everted gut sac study, the apparent permeability coefficient (Papp) was approximately 8-fold higher in the colon than in the jejunum, and the HIP-incorporated SMEDDS showed an approximately 3-fold higher Papp value than the insulin solution. The hypoglycemic effect after in situ colon instillation, the HIP complex between insulin and sodium docusate-incorporated SMEDDS showed a pharmacological availability of 2.52 ± 0.33 % compared to the subcutaneously administered insulin solution. Thus, based on these outcomes, it can be concluded that the selection of appropriate counterions is important in developing HIP-incorporated SMEDDS, wherein this system shows promise as a tool for oral peptide delivery systems.

Synthesis and In Vivo Evaluation of Insulin-Loaded Whey Beads as an Oral Peptide Delivery System.

For many diabetics, daily, lifelong insulin injections are required to effectively manage blood glucose levels and the complications associated with the disease. This can be a burden and reduces patient quality of life. Our goal was to develop a more convenient oral delivery system that may be suitable for insulin and other peptides. Insulin was entrapped in 1.5-mm beads made from denatured whey protein isolate (dWPI) using gelation. Beads were then air-dried with fumed silica, Aerosil®. The encapsulation efficiency was ~61% and the insulin loading was ~25 µg/mg. Dissolution in simulated gastric-, and simulated intestinal fluids (SGF, SIF) showed that ~50% of the insulin was released from beads in SGF, followed by an additional ~10% release in SIF. The omission of Aerosil® allowed greater insulin release, suggesting that it formed a barrier on the bead surface. Circular dichroism analysis of bead-released insulin revealed an unaltered secondary structure, and insulin bioactivity was retained in HepG2 cells transfected to assess activation of the endogenous insulin receptors. Insulin-entrapped beads were found to provide partial protection against pancreatin for at least 60 min. A prototype bead construct was then synthesised using an encapsulator system and tested in vivo using a rat intestinal instillation bioassay. It was found that 50 IU/kg of entrapped insulin reduced plasma glucose levels by 55% in 60 min, similar to that induced by subcutaneously (s.c.)-administered insulin (1 IU/kg). The instilled insulin-entrapped beads produced a relative bioavailability of 2.2%. In conclusion, when optimised, dWPI-based beads may have potential as an oral peptide delivery system.

Semi-elastic core-shell nanoparticles enhanced the oral bioavailability of peptide drugs

The rigidity of nanoparticles was newly reported to influence their oral delivery. Semi-elastic nanoparticles can enhance the penetration in mucus and uptake by epithelial cells. However, it is still challenging and unclear that the semi-elastic core-shell nanoparticles can enhance the oral bioavailability of peptide drugs. This study was for the first time to validate the semi-elastic core-shell poly(lactic-co-glycolic acid) (PLGA)-lipid nanoparticles (LNPs) as the carrier of the oral peptide drug. The antihypertensive peptide Val-Leu-Pro-Val-Pro (VP5) loaded LNPs (VP5-LNPs) were prepared by a modified thin-film ultrasonic dispersion method. Uptake experiment was performed in Caco-2 and HT-29 cells and monitored by high content screening (HCS) and flow cytometric (FCM). Pharmacokinetics of VP5-LNPs was carried out in Sprague-Dawley (SD) rats and analyzed by DAS 2.0. The optimal VP5-LNPs had an average particle size of 247.3±3.8nm, zeta potential of −6.57±0.45mV and excellent entrapment efficiency (EE) of 89.88%±1.23%. Transmission electron microscope (TEM) and Differential scanning calorimeter (DSC) further confirmed the core-shell structure. VP5-LNPs could increase the cellular uptake in vitro and have a 2.55-fold increase in AUC0-72h, indicating a great promotion of the oral bioavailability. The semi-elastic LNPs remarkably improved the oral availability of peptide and could be a promising oral peptide delivery system for peptide drugs in the future.

Lipid Nanoparticles-Encapsulated YF4: A Potential Therapeutic Oral Peptide Delivery System for Hypertension Treatment.

Drugs are administered orally in the clinical treatment of hypertension. Antihypertensive peptides have excellent angiotensin converting enzyme inhibitors activity in vitro. However, the poor oral bioavailability and therapeutic effect of antihypertensive peptides were mainly caused by rapid degradation in gastrointestinal and the short circulation time in blood, which remain to be further optimized. Therefore, the novel oral peptide delivery system is urged to improve the oral absorption and efficacy of peptide drugs. In this work, Tyr-Gly-Leu-Phe (YF4)-loaded lipid nanoparticles (YF4-LNPs) combined the advantages of polymer nanoparticles and liposomes were developed, which could greatly enhance the oral bioavailability and ameliorate the sustained release of peptide drug. YF4 loaded nanoparticles (YF4-NPs) were firstly prepared by a double-emulsion internal phase/organic phase/external phase (W1/O/W2) solvent evaporation method. YF4-NPs were further coated by membrane hydration-ultrasonic dispersion method to obtain the YF4-LNPs. The optimal YF4-LNPs showed a small particle size of 227.3 ± 3.8 nm, zeta potential of -7.27 ± 0.85 mV and high entrapment efficiency of 90.28 ± 1.23%. Transmission electronic microscopy analysis showed that the core-shell lipid nanoparticles were spherical shapes with an apparent lipid bilayer on the surface. Differential scanning calorimetry further proved that YF4 was successfully entrapped into YF4-LNPs. The optimal preparation of YF4-LNPs exhibited sustained release of YF4 in vitro and a 5 days long-term antihypertensive effect in vivo. In summary, the lipid nanoparticles for oral antihypertensive peptide delivery were successfully constructed, which might have a promising future for hypertension treatment.

Initial Risk Assessment as part of the Quality by Design in peptide drug containing formulation development

Risk Assessment (RA) is the key element of the Quality by Design (QbD) approach recommended by the pharmaceutical regulatory bodies. This research paper aimed to implement the regulatory requirements, the QbD thinking and the RA from the first steps of the oral peptide formulation development. The authors intended to give a general recommendation about the application possibilities of this methodology, to demonstrate the risk factors and the required decision points. Later, this paper presents a concrete development in practice. This case study shows the QbD and RA based early phase development of the GLP 1 analog, Liraglutide, an antidiabetic peptide drug mainly used in the treatment of type 2 Diabetes Mellitus. The objective here was to design Liraglutide encapsulated polymeric nanoparticles for oral delivery and the progress of their RA based development is presented. In this case, the particle size, the encapsulation efficiency, and the drug loading were found as the most critical quality attributes, the polymer concentration, the drug concentration, the w2/o ratio, the stabilizer concentration and polymer type were identified by the criticality rating as having the greatest impact on the product quality among the critical material attributes, finally the sonication time and sonication power were selected as the most critical elements of the production process. The results showed the importance of the risk factor-focused development in the oral peptide pharmaceutical formulations, and underlined the importance of the profound planning phase even in such cases. The formulation of an oral peptide delivery system is associated with several risks, but their priority ranking helps to focus on the resources (human, financial, time) related to the final product quality aimed at.

In vitro and in vivo preclinical evaluation of a minisphere emulsion-based formulation (SmPill®) of salmon calcitonin

Salmon calcitonin (sCT, MW 3432Da) is a benchmark molecule for an oral peptide delivery system because it is degraded and has low intestinal epithelial permeability. Four dry emulsion minisphere prototypes (SmPill®) containing sCT were co-formulated with permeation enhancers (PEs): sodium taurodeoxycholate (NaTDC), sodium caprate (C10) or coco-glucoside (CG), or with a pH acidifier, citric acid (CA). Minispheres protected sCT from thermal degradation and the released sCT retained high bioactivity, as determined by cyclic AMP generation in T47D cells. Pre-minisphere emulsions of PEs combined with sCT increased absolute bioavailability (F) compared to native sCT following rat intra-jejunal (i.j.) and intra-colonic (i.c.) loop instillations, an effect that was more pronounced in colon. Minispheres corresponding to ~2000I.U. (~390μg) sCT/kg were instilled by i.j. or i.c. instillations and hypocalcaemia resulted from all prototypes. The absolute F (i.j.) of sCT was 11.0, 4.8, and 1.4% for minispheres containing NaTDC (10μmol/kg), CG (12μmol/kg) or CA (32μmol/kg) respectively. For i.c. instillations, the largest absolute F (22% in each case) was achieved for minispheres containing either C10 (284μmol/kg) or CG (12μmol/kg), whilst the absolute F was 8.2% for minispheres loaded with CA (32μmol/kg). In terms of relative F, the best data were obtained for minispheres containing NaTDC (i.j.), a 4-fold increase over sCT solution, and also for either C10 or CG (i.c.), where there was a 3-fold increase over sCT solution. Histology of instilled intestinal loops indicated that neither the minispheres nor components thereof caused major perturbation. In conclusion, selected SmPill® minisphere formulations may have the potential to be used as oral peptide delivery systems when delivered to jejunum or colon.

Recent advances in the oral delivery of insulin.

Insulin was discovered over 90 years ago. However oral insulin still remains a challenging and elusive goal. Extensive efforts are being made worldwide for developing noninvasive drug delivery systems, mainly via oral route as it is the most widely accepted means of administration. The main barriers faced in oral protein delivery are the enzymatic degradation and poor permeability across the intestinal wall. The approaches for developing an oral insulin delivery system mainly focus on overcoming these barriers. To overcome the gastro-intestinal barriers various types of formulations such as insulin conjugates, permeation enhancers, micro/nanoparticles, liposomes etc. are investigated. In the recent years a number of advances have taken place in understanding the needs and workable mechanisms of improved oral peptide delivery systems. In this review the recent patents on oral insulin is focused. Emphasis is on the technologies based on permeation enhancers and nanoparticle based carrier systems.

Oral delivery of therapeutic protein/peptide for diabetes – Future perspectives

Diabetes is a metabolic disease and is a major cause of mortality and morbidity in epidemic proportions. A type I diabetic patient is dependent on daily injections of insulin, for survival and also to maintain a normal life, which is uncomfortable, painful and also has deleterious effects. Extensive efforts are being made worldwide for developing noninvasive drug delivery systems, especially via oral route. Oral route is the most widely accepted means of administration. However it is not feasible for direct delivery of peptide and protein drugs. To overcome the gastro-intestinal barriers various types of formulations such as polymeric micro/nanoparticles, liposomes, etc. are investigated. In the recent years lot of advances have taken place in developing and understanding the oral peptide delivery systems. Simultaneously, the development and usage of other peptides having anti-diabetic potentials are also considered for diabetes therapy. In this review we are focusing on the advances reported during the past decade in the field of oral insulin delivery along with the possibility of other peptidic incretin hormones such as GLP-1, exendin-4, for diabetes therapy.

Carbopol-Lectin Conjugate Coated Liposomes for Oral Peptide Delivery

Within the current study, a delivery system based on a novel polymer-lectin conjugate (carbopol-lectin) was evaluated for the oral delivery of therapeutic peptides and proteins. It was demonstrated that covalent attachment of lectin to carbopol does neither decrease nor abolish the specific binding properties of lectin. Bioadhesion studies revealed that liposomes coated with carbopol lectin are more bioadhesive than liposomes coated with unmodified carbopol. Finally, the in vivo data suggest that carbopol-lectin conjugate coated liposomes are effective oral peptide delivery systems which are capable of increasing the pharmacological effect of orally administered calcitonin.

Challenges and advances in nanoparticle-based oral insulin delivery

For many decades, rigorous efforts have been made worldwide to develop a successful oral insulin-delivery system, which still remains an elusive goal. However, over the past few years, tremendous understanding has evolved in the development of biocompatible and biodegradable polymers, synthesis of nanopeptide delivery systems, bicompatibility and its cellular uptake mechanisms. With these advancements, efforts are being directed toward nanoparticle-based oral peptide-delivery systems. It is established that nanoparticles enhance oral bioavailability by facilitating insulin uptake via a transcellular or paracellular pathway. In this process, the particle also reaches the systemic circulation. Hence, biocompatibility and the half-life of the particles in the systemic circulation is an important aspect that needs to be looked into. In this review, the various approaches adopted for nanoparticle-based oral insulin delivery, uptake mechanisms, biocompatibility and bioavailability of the nanoparticle are discussed.

Synthesis and evaluation of lauryl succinyl chitosan particles towards oral insulin delivery and absorption

In this work a novel chitosan derivative, lauryl succinyl chitosan (LSC) was developed for the purpose of evaluating its applications towards oral peptide delivery system. Nano/microparticles were developed from this derivative by sodium tripolyphosphate (TPP) cross linking. Human insulin was used as the model protein drug and the release kinetics was studied at gastrointestinal pH. The presence of succinyl carboxyl groups had inhibitory effect on the release kinetics of insulin at pH 1.2 minimizing up to about 8.5 ± 0.45% in two hours. Results showed that the presence of hydrophobic moieties controlled the release of the loaded insulin from the particles at intestinal pH. The particles were negatively charged with size ranging from 315 nm to 1.090 μm. The mucoadhesive capacity was established ex vivo using the jejunum of rat intestine. Confocal microscopy studies proved the tight junction permeability in Caco 2 cells and in vivo uptake of the FITC-insulin from loaded nanoparticles by the rat intestinal epithelium. The results demonstrated that the modified chitosan with both hydrophilic (succinyl) and hydrophobic (lauryl) moieties had improved the release characteristics, mucoadhesivity as well as the permeability of the insulin compared to the native chitosan particles. The LSC2 particles were capable of reducing blood glucose levels in diabetic rats for the duration of about 6 h. This indicated that this novel derivative could be a promising candidate for oral peptide delivery.

Biopharmaceutical approaches for developing and assessing oral peptide delivery strategies and systems: in vitro permeability and in vivo oral absorption of salmon calcitonin (sCT).

To evaluate a biopharmaceutical approach for selecting formulation additives and establishing the performance specifications of an oral peptide delivery system using sCT as a model peptide. The effect of formulation additives on sCT effective permeability and transepithelial electrical resistance (TEER) was evaluated in side-by-side diffusion chambers using rat intestinal segments. Baseline regional oral absorption of sCT was evaluated in an Intestinal and Vascular Access Port (IVAP) dog model by administration directly into the duodenum, ileum, and colon by means of surgically implanted, chronic catheters. The effect of varying the input rate and volume of the administered solution on the extent of sCT absorption was also evaluated. Citric acid (CA) was utilized in all studies to cause a transient reduction in local pH. In vitro samples and plasma samples were analyzed by radioimmunoassay (RIA). Two oral delivery systems were prepared based on the results of the in vitro and IVAP studies, and evaluated in normal dogs. Maximal permeability enhancement of sCT was observed using taurodeoxycholate (TDC) or lauroyl carnitine (LC) in vitro. Ileal absorption of sCT was higher than in other regions of the intestine. Low volume and bolus input of solution formulations was selected as the optimal condition for the IVAP studies since larger volumes or slower input rates resulted in significantly lower sCT bioavailability (BA). Much lower BA of sCT was observed when CA was not used in the formulation. The absolute oral bioavailability (mean+/-SD) in dogs for the control (sCT + CA) and two proprietary sCT delivery systems was 0.30%+/-0.05%, 1.10+/-0.18%, and 1.31+/-0.56%, respectively. These studies demonstrate the utility of in vitro evaluation and controlled in vivo studies for developing oral peptide delivery strategies. Formulation additives were selected, the optimal intestinal region for delivery identified, and the optimal release kinetics of additives and actives from the delivery system were characterized. These methods were successfully used for devising delivery strategies and fabricating and evaluating oral sCT delivery systems in animals. Based on these studies, sCT delivery systems have been fabricated and tested in humans with favorable results.