Delivery Of Therapeutic Peptides Research Articles

Enzymatically-responsive poly(ethylene glycol) hydrogels for the controlled delivery of therapeutic peptides

Therapeutic angiogenesis holds great potential for treatment of ischemic tissues and in tissue engineering, where insufficient vascularization limits construct size, complexity, and anastomosis with host vasculature. However, no FDA approved treatments exist to robustly enhance vascularization within ischemic tissue. Many proangiogenic approaches have been developed, often via delivery of angiogenic proteins or peptides. Peptides typically mimic the bioactivity of larger proteins or growth factors, and offer advantages over traditional protein delivery, including more versatile synthesis methods and increased stability in vivo. However, both proteins and peptides suffer from rapid clearance and poor pharmacokinetics when delivered systemically, motivating the development of controlled release systems. Enzymatically-responsive systems where delivery of protein drugs is controlled by the local tissue microenvironment have shown improved tissue healing over bolus protein delivery. Therefore, a hydrogel-based platform technology was developed to control and sustain peptide drug release via matrix metalloproteinase (MMP) activity. Poly(ethylene glycol) (PEG) hydrogels were formed by crosslinking norbornene functionalized multi-arm PEG with peptide drugs flanked by MMP substrates and terminal cysteine residues. In vitro bioactivity testing identified three peptides (Qk (from Vascular Endothelial Growth Factor), SPARC113, and SPARC118 (from Secreted Protein Acidic and Rich in Cysteine)) that retained bioactivity in their expected released forms (e.g., with residual amino acids left by MMP substrates after cleavage). Incorporation of these peptides into hydrogels flanked by MMPdegradable substrates successfully produced hydrogels with enzymatically-responsive hydrogel degradation and peptide release behaviors. Hydrogels degraded via bulk degradation, and peptide release was in close agreement with mass loss. Qk, SPARC113, and SPARC118-releasing hydrogels were confirmed to release bioactive components in vitro after MMP-mediated degradation. Further investigation revealed key peptide drug properties, specifically size and hydrophobicity, control the rate of hydrogel degradation and peptide release. When implanted subcutaneously, SPARC113 and SPARC118-releasing hydrogels both significantly increased vascular ingrowth compared to controls one week after implantation without significantly affecting vessel size. As the longitudinal availability of VEGF has been shown critical for bioactivity, alternate hydrogels were formed to provide temporal control over enzymatically-responsive release of the VEGF peptide mimic, Qk. MMP-degradable linkers with a variety of cleavage kinetics were used to tether Qk to hydrogels formed with non-degradable peptide crosslinks. Hydrogel degradation was successfully uncoupled from peptide release, and three of the linkers provided temporal control over enzymatically-responsive peptide release kinetics in vitro and in vivo. Qk was confirmed to be bioactive as released,…

Cell-Penetrating Peptides as Carriers for Oral Delivery of Biopharmaceuticals.

Oral delivery of biopharmaceuticals, for example peptides and proteins, constitutes a great challenge in drug delivery due to their low chemical stability and poor permeation across the intestinal mucosa, to a large extent limiting the mode of administration to injections, which is not favouring patient compliance. Nevertheless, cell-penetrating peptides (CPPs) have shown promising potential as carriers to overcome the epithelium, and this minireview highlights recent knowledge gained within the field of CPP-mediated transepithelial delivery of therapeutic peptides and proteins from the intestine. Two approaches may be pursued: co-administration of the carrier and therapeutic peptide in the form of complexes obtained by simple bulk mixing, or administration of covalent conjugates demanding more advanced production methodologies. These formulation approaches have their pros and cons, and which is to be preferred depends on the physicochemical properties of both the specific CPP and the specific cargo. In addition to the physical epithelial barrier, a metabolic barrier must be overcome in order to obtain CPP-mediated delivery of a cargo drug from the intestine, and a number of strategies have been employed to delay enzymatic degradation of the CPP. The mechanisms by which CPPs translocate across membranes are not fully understood, but possibly involve endocytosis as well as direct translocation, and the CPP-mediated transepithelial delivery of cargo drugs thus likely involves similar mechanisms for the initial membrane interaction and translocation. However, the mechanisms responsible for transcytosis of the cargo drug, if taken up by an endocytic mechanism, or direct translocation across the epithelium are so far not known.

Polymer-based vehicles for therapeutic peptide delivery.

During the last decades increasing attention has been paid to peptides as potential therapeutics. However, clinical applications of peptide drugs suffer from susceptibility to degradation, rather short circulation half-life, limited ability to cross physiological barriers and potential immunogenicity. These challenges can be addressed by using polymeric materials as peptide delivery systems, owing to their versatile structures and properties. A number of polymer-based vehicles have been developed to stabilize the peptides and to control their release rates. Unfortunately, no single polymer or formulation strategy has been considered ideal for all types of peptide drugs. In this review, currently used and potential polymer-based systems for the peptide delivery will be discussed.

Cloning strategies for heterologous expression of the bacteriocin enterocin A by Lactobacillus sakei Lb790, Lb. plantarum NC8 and Lb. casei CECT475.

BackgroundBacteriocins produced by lactic acid bacteria (LAB) attract considerable interest as natural and nontoxic food preservatives and as therapeutics whereas the bacteriocin-producing LAB are considered potential probiotics for food, human and veterinary applications, and in the animal production field. Within LAB the lactobacilli are increasingly used as starter cultures for food preservation and as probiotics. The lactobacilli are also natural inhabitants of the gastrointestinal (GI) tract and attractive vectors for delivery of therapeutic peptides and proteins, and for production of bioactive peptides. Research efforts for production of bacteriocins in heterologous hosts should be performed if the use of bacteriocins and the LAB bacteriocin-producers is ever to meet the high expectations deposited in these antimicrobial peptides. The recombinant production and functional expression of bacteriocins by lactobacilli would have an additive effect on their probiotic functionality.ResultsThe heterologous production of the bacteriocin enterocin A (EntA) was evaluated in different Lactobacillus spp. after fusion of the versatile Sec-dependent signal peptide (SPusp45) to mature EntA plus the EntA immunity gene (entA + entiA) (fragment UAI), and their cloning into plasmid vectors that permitted their inducible (pSIP409 and pSIP411) or constitutive (pMG36c) production. The amount, antimicrobial activity (AA) and specific antimicrobial activity (SAA) of the EntA produced by Lactobacillus sakei Lb790, Lb. plantarum NC8 and Lb. casei CECT475 transformed with the recombinant plasmids pSIP409UAI, pSIP411UAI and pMGUAI varied depending of the expression vector and the host strain. The Lb. casei CECT475 recombinant strains produced the largest amounts of EntA, with the highest AA and SAA. Supernatants from Lb. casei CECT (pSIP411UAI) showed a 4.9-fold higher production of EntA with a 22.8-fold higher AA and 4.7-fold higher SAA than those from Enterococcus faecium T136, the natural producer of EntA. Moreover, supernatants from Lb. casei CECT475 (pSIP411UAI) showed a 15.7- to 59.2-fold higher AA against Listeria spp. than those from E. faecium T136.ConclusionLb. casei CECT457 (pSIP411UAI) may be considered a promising recombinant host and cell factory for the production and functional expression of the antilisterial bacteriocin EntA.

Developing a Dissociative Nanocontainer for Peptide Drug Delivery.

The potency, selectivity, and decreased side effects of bioactive peptides have propelled these agents to the forefront of pharmacological research. Peptides are especially promising for the treatment of neurological disorders and pain. However, delivery of peptide therapeutics often requires invasive techniques, which is a major obstacle to their widespread application. We have developed a tailored peptide drug delivery system in which the viral capsid of P22 bacteriophage is modified to serve as a tunable nanocontainer for the packaging and controlled release of bioactive peptides. Recent efforts have demonstrated that P22 nanocontainers can effectively encapsulate analgesic peptides and translocate them across blood-brain-barrier (BBB) models. However, release of encapsulated peptides at their target site remains a challenge. Here a Ring Opening Metathesis Polymerization (ROMP) reaction is applied to trigger P22 nanocontainer disassembly under physiological conditions. Specifically, the ROMP substrate norbornene (5-Norbornene-2-carboxylic acid) is conjugated to the exterior of a loaded P22 nanocontainer and Grubbs II Catalyst is used to trigger the polymerization reaction leading to nanocontainer disassembly. Our results demonstrate initial attempts to characterize the ROMP-triggered release of cargo peptides from P22 nanocontainers. This work provides proof-of-concept for the construction of a triggerable peptide drug delivery system using viral nanocontainers.

Formulation Approaches to Overcome Biopharmaceutical Limitations of Inhaled Peptides/Proteins.

The pulmonary dosing route has been advocated as an attractive alternative to injection and oral administration for the systemic delivery of therapeutic peptides and proteins. The lung possesses many favorable physiological characteristics for systemic absorption of inhaled peptides/proteins, so inhalable formulation systems of these drugs have generated considerable interest as a valid and non-invasive dosing approach. A major obstacle to the widespread use of inhalation therapies for many peptides/proteins is the limited bioavailability and thereby insufficient therapeutic outcomes because of biopharmaceutical challenges such as rapid pulmonary clearance, limited pulmonary deposition, delayed dissolution in lung environment, poor membrane permeability, and low metabolic stability. A better understanding of the biopharmaceutical properties of inhaled peptides/proteins would be indispensable to overcome these drawbacks with the aid of strategic drug delivery systems and chemical synthesis of new derivatives based on structure-activity relationship information, possibly leading to improved therapeutic potential of pharmaceutical products. The present paper reviews biopharmaceutical properties of inhaled peptides/proteins, with a focus on the pharmacokinetic fate of inhaled peptides/proteins and critical determinants of therapeutic potential. The emphasis in this mini-review will also be on viable formulation approaches for breakthroughs beyond the biopharmaceutical limitations of inhalation therapy with peptides/proteins.

Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement

Acylation of peptide drugs with fatty acid chains has proven beneficial for prolonging systemic circulation, as well as increasing enzymatic stability and interactions with lipid cell membranes. Thus, acylation offers several potential benefits for oral delivery of therapeutic peptides, and we hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate its influence on intestinal cell translocation and membrane interaction.We find that acylation drastically increases in vitro intestinal peptide flux and confers a transient permeability enhancing effect on the cell layer. The analogues permeabilize model lipid membranes, indicating that the effect is due to a solubilization of the cell membrane, similar to transcellular oral permeation enhancers. The effect is dependent on pH, with larger effect at lower pH, and is impacted by acylation chain length and position. Compared to the unacylated peptide backbone, N-terminal acylation with a short chain provides 6- or 9-fold increase in peptide translocation at pH 7.4 and 5.5, respectively. Prolonging the chain length appears to hamper translocation, possibly due to self-association or aggregation, although the long chain acylated analogues remain superior to the unacylated peptide. For K18-acylation a short chain provides a moderate improvement, whereas medium and long chain analogues are highly efficient, with a 12-fold increase in permeability compared to the unacylated peptide backbone, on par with currently employed oral permeation enhancers. For K18-acylation the medium chain acylation appears to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may decrease the permeability.In conclusion, acylated sCT acts as its own in vitro intestinal permeation enhancer, with reversible effects on Caco-2 cells, indicating that acylation of sCT may represent a promising tool to increase intestinal permeability without adding oral permeation enhancers.

Abstract 4538: Multivalent targeting based delivery of therapeutic peptide using AP1-ELP carrier for effective cancer therapy

Abstract The main objectives of drug delivery for almost all cancer therapies are to improve the therapeutic index of anticancer drugs by increasing the amount of drug delivered to the specific tumor site and decreasing its exposure to healthy tissues. Elastin like Polypeptides (ELPs) retain all the advantages of polymeric drug delivery systems, as they are composed of non-toxic and biodegradable amino acid, derived from mammalian tropoelastin. IL-4 receptors (IL-4R) are found to be highly expressed in a wide variety of human tumors and studies have reported that IL-4/IL-4R interactions amplify the expression of some anti-apoptotic proteins, so prevent drug-induced cancer cell death. Thus we have designed multivalent IL-4R targeted based macromolecular carriers, AP1-ELP polymers, in order to examine the therapeutic efficacy in delivering the therapeutic peptide (KLAKLAK)2 to tumor cells. As for the study AP1-ELP polymer, containing six IL-4R binding peptide (AP1) was conjugated with proapoptotic peptide (KLAKLAK)2 on the C-terminal site by cloning. The resultant AP1-ELP-(KLAKLAK)2 construct was successfully expressed and purified from E coli using inverse temperature cycling method. Confocal imaging verified the better cellular accumulation of AP1-ELP-(KLAKLAK)2 in IL-4R highly expressing cancer cells. The cytotoxic effect towards IL-4R highly expressing tumor cells were highly enhanced when treated with AP1-ELP-(KLAKLAK)2 compared to control. FACS analysis data confirmed the significant increase of apoptotic cells when treated with AP1-ELP-(KLAKLAK)2 compared to ELP-(KLAKLAK)2 in dose dependent manner. Ex vivo biodistridution study displayed an increase in intra-tumoral uptake and localization of FNR-675 labeled AP1-ELP-(KLAKLAK)2 than ELP-(KLAKLAK)2. Additionally, AP1-ELP-(KLAKLAK)2 significantly inhibit the tumor growth when injected intravenously in MDA-MB 231 xenograft mouse model. Thus AP1-ELP-(KLAKLAK)2 polymer enhanced apoptotic and antitumor activity against IL-4R highly expressing tumor cells suggesting the clinical potential of our polymer. Citation Format: Sarangthem V. Devi, Yun Jae Kim, Young-Jin Lee, Kuen Hur, Byung-Heon Lee, Rang Woon Park. Multivalent targeting based delivery of therapeutic peptide using AP1-ELP carrier for effective cancer therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4538. doi:10.1158/1538-7445.AM2015-4538

Challenges and new strategies for therapeutic peptide delivery to the CNS.

Therapeutic peptides represent a largely untapped resource in medicine today, especially in the central nervous system. Despite their ease of design and remarkably high target specificity, it is difficult to deliver them beyond the blood-brain barrier or into the required intracellular compartments. In addition, the instability of these peptides in vivo precludes their use to combat the symptoms of numerous neurological disorders including Alzheimer's disease and spinocerebellar ataxia. In this review, we aim to characterize recent advances in the delivery of therapeutic peptides to the central nervous system past the blood-brain barrier and discuss the advantages and disadvantages of the examined methods as well as explore new potential directions.

654. Recombinant Gene and Cell Therapy With Serine-Histogranin and Endomorphin-1 for the Experimental Treatment of Chronic Neuropathic Pain

The insufficient pain relief provided by current pharmacotherapy for chronic neuropathic pain represents a serious medical problem. The development of new treatment strategies is therefore of a high clinical interest. The mechanisms underlying development of chronic pain include decrease in spinal tonic inhibition due to the dysfunction of GABA signaling and increase in excitatory signaling through glutamate NMDA receptors. Previous studies showed beneficial effect of the intraspinal transplantation of GABAergic neuronal precursor cells (NPCs) and of the intraspinal delivery of serine histogranin (SHG), an NMDA receptor antagonist. Moreover, our studies showed that combined injection of SHG with another analgesic peptide, endomorphin-1 (EM-1), potentiated analgesic effect of SHG. Endomorphins are highly selective for μ-opioid receptors and have been shown to decrease neuropathic pain in previous studies.Cells and gene therapy provides suitable tools for targeted delivery of therapeutic peptides thus minimizing adverse effect of systemic delivery. Here we attempted to simultaneously target inhibitory and excitatory pathways in the spinal cord of injured animals by using either recombinant cells or recombinant AAV vectors. Recombinant plasmid encoding single- and multi-SHG and EM-1 was engineered and successful production of recombinant peptides by transduced HEK 293 cells was analyzed by immunocytochemistry and FLISA. AAV vectors were used as carriers of recombinant cDNA and used for either transduction of NPC or for direct spinal injection. Clip compression injury of the spinal cord was use as a model of central neuropathic pain. Animals showing clear sign of pain-related behavior were used for intraspinal injection of either recombinant NPCs or recombinant AAVs. Animals were tested weekly to evaluate analgesic effect of the treatment. Two week post injection animals treated with rAAVs showed significant attenuation of tactile sensitivity compared to controls and the antinociceptive effect sustained up to 6 weeks post injection. Enhanced analgesic effect was observed in the group with 6SHG-EM1 construct compared to 1SHG-EM1. Animals treated with rNPCs did not display significant pain relief compared to nonrecombinant NPCs group. However, these results may be masked by a low survival rate of the transplanted cells. Better strategies for rNPC engineering are currently examined. The presence of SHG and EM (above the levels of controls animals) was detected by FLISA methods and by immunohistochemistry in the spinal cord of treated animals suggesting successful production of recombinant peptides.This study demonstrates that the beneficial effect of combined therapy in the management of chronic pain may be enhanced by using gene engineering tools to deliver therapeutic substances into CNS in a single step and minimize the need for extensive surgical interventions.

Conjugation of cell-penetrating peptides to parathyroid hormone affects its structure, potency, and transepithelial permeation.

Delivery of therapeutic peptides and proteins by the use of cell-penetrating peptides (CPPs) as carriers has been suggested as a feasible strategy. The aim of the present study was to investigate the effect of conjugating a series of well-known CPPs to the biologically active part of parathyroid hormone, i.e., PTH(1-34), and to evaluate the effect with regard to secondary structure, potency in Saos-2 cells, immunogenicity, safety, as well as the transepithelial permeation across monolayers by using the Caco-2 cell culture model. Further, co-administration of CPP and PTH(1-34) as an alternative to covalent conjugation was compared with regard to the transepithelial permeation. CPP-conjugated PTH(1-34) fusion peptides were successfully expressed in Escherichia coli and purified from inclusion bodies. No clear correlation between the degree of secondary structure of the CPP-conjugated PTH(1-34) fusion peptides and their potency was found, albeit a general decrease in permeation was observed for both N- and C-terminally CPP-conjugated PTH(1-34) as compared to native PTH(1-34). However, attachment of CPP to the N-terminus significantly increased permeation across Caco-2 cell monolayers as compared to the corresponding C-terminally CPP-conjugated PTH(1-34). In addition, the nonaarginine sequence proved to be the only CPP capable of increasing permeation when conjugated to PTH(1-34) as compared to co-administration of CPP and PTH(1-34). This enhancement effect was, however, associated with an unacceptably low level of cell viability. In conclusion, covalent conjugation of CPPs to PTH(1-34) influenced the secondary structure, potency, and transepithelial permeation efficiency of the resulting conjugate, and hence this approach appears not to be favorable as compared to co-administration when optimizing CPP-mediated permeation of PTH(1-34) across an intestinal epithelium.

Development and in vitro assessment of enzymatically-responsive poly(ethylene glycol) hydrogels for the delivery of therapeutic peptides

Despite the recent expansion of peptide drugs, delivery remains a challenge due to poor localization and rapid clearance. Therefore, a hydrogel-based platform technology was developed to control and sustain peptide drug release via matrix metalloproteinase (MMP) activity. Specifically, hydrogels were composed of poly(ethylene glycol) and peptide drugs flanked by MMP substrates and terminal cysteine residues as crosslinkers. First, peptide drug bioactivity was investigated in expected released forms (e.g., with MMP substrate residues) in vitro prior to incorporation into hydrogels. Three peptides (Qk (from Vascular Endothelial Growth Factor), SPARC113, and SPARC118 (from Secreted Protein Acidic and Rich in Cysteine)) retained bioactivity and were used as hydrogel crosslinkers in full MMP degradable forms. Upon treatment with MMP2, hydrogels containing Qk, SPARC113, and SPARC118 degraded in 6.7, 6, and 1 days, and released 5, 8, and, 19% of peptide, respectively. Further investigation revealed peptide drug size controlled hydrogel swelling and degradation rate, while hydrophobicity impacted peptide release. Additionally, Qk, SPARC113, and SPARC118 releasing hydrogels increased endothelial cell tube formation 3.1, 1.7, and 2.8-fold, respectively. While pro-angiogenic peptides were the focus of this study, the design parameters detailed allow for adaptation of hydrogels to control peptide release for a variety of therapeutic applications.

Controlled transdermal delivery of leuprorelin by pulsed iontophoresis and ion-exchange fiber

Poor transport efficacy and issues related to biological variation are major concerns in the development of novel iontophoretic devices for the transdermal delivery of therapeutic peptides. The objective of this study was to examine the impact of constant and pulsed current on the transport of nonapeptide leuprorelin acetate across porcine epidermis. Also, the potential of drug delivery system combining iontophoresis and ion-exchange fibers as drug matrices for the delivery of the same peptide was tested. The present study demonstrated the benefit of pulsed current (Tn=2.59×10−4) over constant current (Tn=1.7×10−4) in terms of more efficient transdermal peptide transport. An increase in the delivery of electroosmotic marker by pulsed current was due to the combined effect of more pronounced electroosmotic transport and reduced inhibition of passive transport. We also showed a promising approach using ion-exchange fibers for controlling the release and iontophoretic transdermal delivery of peptides. Positively charged leuprorelin acetate was bound to the ion-exchange groups of cation-exchange fibers until it was gradually released by mobile counter ions in the external solution. Transdermal flux from acrylic acid grafted Smopex®-102 fibers remained higher (Jss=0.71μg/hcm2) than from sulfonic acid grafted Smopex®-101 fibers (Jss=0.31μg/hcm2) due to better drug release.

Enhanced Transdermal Peptide Delivery and Stability by Lipid Conjugation: Epidermal Permeation, Stereoselectivity and Mechanistic Insights

Efficient delivery of therapeutic peptides to the skin will facilitate better outcomes in dermatology. The tetrapeptide AAPV, an elastase inhibitor with potential utility in the management of psoriasis was coupled to short chain lipoamino acids (Laa: C6-C10) to enhance the peptide permeation into and through human epidermis. AAPV was conjugated to Laas by solid phase synthesis. Peptide stability, skin distribution and permeation, elastase activity and surface activity were determined. Laas increased peptide permeation into the skin. The permeation lag time and amount of peptide remaining in the skin increased with the carbon chain length of the Laa conjugate. We also demonstrated stereoselective permeation enhancement in favour of the D-diastereomer. Importantly, the elastase inhibition activity of the peptide was largely retained after coupling to the Laa conjugates, showing potential therapeutic utility. The Laa-peptide structures were shown to be surface active, suggesting that this surfactant-like activity coupled with enhanced lipophilicity may contribute to their interaction with and permeation through the lipid domains of the stratum corneum. This study suggests that the Laa conjugation approach may be useful for enhancing the permeation of moderately sized peptide drugs with potential application in the treatment of skin disorders.

Penetrating the cell membrane, thermal targeting and novel anticancer drugs: the development of thermally targeted, elastin-like polypeptide cancer therapeutics.

Therapeutic peptides offer important cancer treatment approaches. Designed to inhibit oncogenes and other oncoproteins, early therapeutic peptides applications were hampered by pharmacokinetic properties now addressed through tumor targeting strategies. Active targeting with environmentally responsive biopolymers or macromolecules enhances therapeutics accumulation at tumor sites; passive targeting with macromolecules, or liposomes, exploits angiogenesis and poor lymphatic drainage to preferentially accumulate therapeutics within tumors. Genetically engineered, thermally-responsive, elastin-like polypeptides use both strategies and cell-penetrating peptides to further intratumoral cell uptake. This review describes the development and application of cell-penetrating peptide-elastin-like polypeptide therapeutics for the thermally targeted delivery of therapeutic peptides.

Formulation and evaluation of novel reverse microemulsions containing salmon calcitonin in hydrofluoroalkane propellants

To develop reverse microemulsion as a potential strategy for pulmonary delivery of salmon calcitonin (sCT) in HFA134a propellant of pressurized metered dose inhalers (pMDIs), pluronic P85 (P85) was chosen as the most appropriate surfactant to form microemulsions containing sCT. Formulation parameters, including the surfactant and ethanol content, water content, and sCT loading, were optimized to obtain two desired pMDI formulations A and B with clear and transparent appearance, Tyndall effect, good physical stability and aerosolization properties. Aerosolization properties of the optimized pMDIs were assessed by next generation impactor (NGI) and twin-stage impactor (TSI), and the dose of sCT in each stage was assayed by HPLC. The fine particle fraction (FPF) of formulations A and B were both at the range of approximately 28.0-36.0%. Cytotoxicity studies indicated the cell viability determined by MTT assay only slightly dropped when the A549 cells were exposed to the pMDI formulations. Pharmacological study performed on the male Wistar rats showed the intratracheal administration of the microemulsion pMDIs containing sCT exhibited similar but prolonged hypocalcemic activity compared with the intravenous injection of sCT solution. Therefore, such reverse microemulsions are potential for pulmonary delivery of therapeutic peptides using HFA-pMDIs.

Delivery of therapeutic peptides and proteins to the CNS.

Peptides and proteins have potent effects on the brain after their peripheral administration, suggesting that they may be good substrates for the development of CNS therapeutics. Major hurdles to such development include their relation to the blood-brain barrier (BBB) and poor pharmacokinetics. Some peptides cross the BBB by transendothelial diffusion and others cross in the blood-to-brain direction by saturable transporters. Some regulatory proteins are also transported across the BBB and antibodies can enter the CNS via the extracellular pathways. Glycoproteins and some antibody fragments can be taken up and cross the BBB by mechanisms related to adsorptive endocytosis/transcytosis. Many peptides and proteins are transported out of the CNS by saturable efflux systems and enzymatic activity in the blood, CNS, or BBB are substantial barriers to others. Both influx and efflux transporters are altered by various substances and in disease states. Strategies that manipulate these interactions between the BBB and peptides and proteins provide many opportunities for the development of therapeutics. Such strategies include increasing transendothelial diffusion of small peptides, upregulation of saturable influx transporters with allosteric regulators and other posttranslational means, use of vectors and other Trojan horse strategies, inhibition of efflux transporters including with antisense molecules, and improvement in pharmacokinetic parameters to overcome short half-lives, tissue sequestration, and enzymatic degradation.

Noninvasive Delivery of Therapeutic Peptides and Proteins

Noninvasive Delivery of Therapeutic Peptides and Proteins

Unsaturated glycoceramides as molecular carriers for mucosal drug delivery of GLP-1

The incretin hormone Glucagon-like peptide 1 (GLP-1) requires delivery by injection for the treatment of Type 2 diabetes mellitus. Here, we test if the properties of glycosphingolipid trafficking in epithelial cells can be applied to convert GLP-1 into a molecule suitable for mucosal absorption. GLP-1 was coupled to the extracellular oligosaccharide domain of GM1 species containing ceramides with different fatty acids and with minimal loss of incretin bioactivity. When applied to apical surfaces of polarized epithelial cells in monolayer culture, only GLP-1 coupled to GM1-ceramides with short- or cis-unsaturated fatty acids trafficked efficiently across the cell to the basolateral membrane by transcytosis. In vivo studies showed mucosal absorption after nasal administration. The results substantiate our recently reported dependence on ceramide structure for trafficking the GM1 across polarized epithelial cells and support the idea that specific glycosphingolipids can be harnessed as molecular vehicles for mucosal delivery of therapeutic peptides.

Recent Trend In Oral Local Drug Delivery Using Buccal Mucoadhesive Formulation: A Review

In this 21st century pharmaceutical science has been focused on the delivery of drugs through the oral mucosa. The buccal mucosa has been investigated for mucoadhesive local drug therapy and the systemic delivery of therapeutic peptides and other drugs that are subjected to first-pass metabolism or are unstable within the rest of the gastrointestinal tract. This review focuses on the permeability features of oral mucosa and new potential mucoadhesive local delivery systems to treat oral diseases. DOI: http://dx.doi.org/10.3329/bjdre.v3i2.16612 Bangladesh Journal of Dental Research & Education Vol.3(2) 2013: 41-44