Thiolated polycarbophil as an adjuvant for permeation enhancement in nasal delivery of antisense oligonucleotides

Development of chitosan based β-carotene mucoadhesive formulation for skin cancer treatment

Mucopermeating nanoformulations can enhance mucosal penetration of poorly soluble drugs at their target site. In this work, thiolated chitosan (TCS)-lithocholic acid (LA) nanomicelles loaded with β-carotene, a safe phytochemical with anticancer properties, were designed to improve the pharmaceutical and pharmacological drug profile. The TCS-LA nanomicelles were characterized by FTIR to confirm the presence of the thiol group that favors skin adhesion, and to corroborate the conjugation of hydrophobic LA with hydrophilic CS to form an amphiphilic polymer derivative. Their crystalline nature and thermal behavior were investigated by XRD and DSC analyses, respectively. According to DLS and TEM, their average size was <300 nm, and their surface charge was +27.0 mV. β-carotene entrapment and loading efficiencies were 64 % and 58 %, respectively. In vitro mucoadhesion and ex vivo mucopenetration analyses further corroborated the potential of the nanoformulation to deliver the drug in a sustained manner under conditions mimicking cancer micro-environment. Anticancer studies in mice demonstrated that the loaded nanomicelles delayed skin cancer growth, as revealed by both morphological and biochemical parameters. Based on the results obtained herein, it can be concluded that drug-loaded TCS-LA is a novel, stable, effective and safe mucoadhesive formulation of β-carotene for the potential treatment of skin cancer.

Nose-to-Brain (N2B) Delivery: An Alternative Route for the Delivery of Biologics in the Management and Treatment of Central Nervous System Disorders

In recent years, there have been a growing number of small and large molecules that could be used to treat diseases of the central nervous system (CNS). Nose-to-brain delivery can be a potential option for the direct transport of molecules from the nasal cavity to different brain areas. This review aims to provide a compilation of current approaches regarding drug delivery to the CNS via the nose, with a focus on biologics. The review also includes a discussion on the key benefits of nasal delivery as a promising alternative route for drug administration and the involved pathways or mechanisms. This article reviews how the application of various auxiliary agents, such as permeation enhancers, mucolytics, in situ gelling/mucoadhesive agents, enzyme inhibitors, and polymeric and lipid-based systems, can promote the delivery of large molecules in the CNS. The article also includes a discussion on the current state of intranasal formulation development and summarizes the biologics currently in clinical trials. It was noted that significant progress has been made in this field, and these are currently being applied to successfully transport large molecules to the CNS via the nose. However, a deep mechanistic understanding of this route, along with the intimate knowledge of various excipients and their interactions with the drug and nasal physiology, is still necessary to bring us one step closer to developing effective formulations for nasal-brain drug delivery.

Challenges and Opportunities in the Oral Delivery of Recombinant Biologics

Recombinant biological molecules are at the cutting-edge of biomedical research thanks to the significant progress made in biotechnology and a better understanding of subcellular processes implicated in several diseases. Given their ability to induce a potent response, these molecules are becoming the drugs of choice for multiple pathologies. However, unlike conventional drugs which are mostly ingested, the majority of biologics are currently administered parenterally. Therefore, to improve their limited bioavailability when delivered orally, the scientific community has devoted tremendous efforts to develop accurate cell- and tissue-based models that allow for the determination of their capacity to cross the intestinal mucosa. Furthermore, several promising approaches have been imagined to enhance the intestinal permeability and stability of recombinant biological molecules. This review summarizes the main physiological barriers to the oral delivery of biologics. Several preclinical in vitro and ex vivo models currently used to assess permeability are also presented. Finally, the multiple strategies explored to address the challenges of administering biotherapeutics orally are described.

Intranasal delivery: An attractive route for the administration of nucleic acid based therapeutics for CNS disorders

The etiologies of several cardiovascular, inflammatory, neurological, hereditary disorders, cancer, and infectious diseases have implicated changes in the genetic set up or genetic mutations as the root cause. Nucleic acid based therapeutics (NBTs) is a new class of biologics that are known to regulate gene expression at the transcriptional and post-transcriptional level. The NBTs include oligonucleotides, nucleosides, antisense RNA, small interfering RNAs, micro RNA etc. In recent times, this new category of biologics has found enormous potential in the management of cardiovascular, inflammatory, neurological disorders, cancer, infectious diseases and organ transplantation. However, the delivery of NBTs is highly challenging in terms of target specificity (intracellular delivery), mononuclear phagocyte system uptake, stability and biodistribution. Additionally, management of the above mentioned disorders require regular and intrusive therapy making non-invasive routes preferable in comparison to invasive routes like parenteral. The nasal route is garnering focus in delivery of NBTs to the brain in the management of several CNS disorders due to the associated merits such as non-invasiveness, possibility of chronic delivery, improved patient compliance, avoidance of hepatic and gastrointestinal metabolism as well as ability to bypass the BBB. Hence in recent times, this route has been sought by the reserachers as an alternative to parenteral therapy for the delivery of several NBTs. This review shall focus on an array of NBTs delivered through nasal route, their challenges, applications and opportunities. The novel delivery systems for incorporating NBTs; their targeting strategies shall be critically reviewed. The challenges towards regulatory approvals and commercialization shall also be discussed at large. Comparison of learnings derived from the success and barriers in nasal delivery of NBTs will help in identification of futuristic opportunities for their translation from bench to bedside.

Design and Efficacy of Nanogels Formulations for Intranasal Administration

Nanogels are drug delivery systems that can bypass the blood-brain barrier and deliver drugs to the desired site when administered intranasally. They have been used as a drug delivery platform for the management of brain diseases such as Alzheimer disease, migraine, schizophrenia and depression. nanogels have also been developed as vaccine carriers for the protection of bacterial infections such as influenza, meningitis, pneumonia and as veterinary vaccine carriers for the protection of animals from encephalomyelitis and mouth to foot disease. It has been developed as vaccine carriers for the prevention of lifestyle disease such as obesity. Intranasal administration of therapeutics using nanogels for the management of brain diseases revealed that the drug transportation was via the olfactory nerve pathway resulting in rapid drug delivery to the brain with excellent neuroprotective effect. The application of nanogels as vaccine carriers also induced significant responses associated with protective immunity against selected bacterial and viral infections. This review provides a detailed information on the enhanced therapeutic effects, mechanisms and biological efficacy of nanogels for intranasal administration.

Screening of anionic-modified polymers in terms of stability, disintegration, and swelling behavior

This study aimed to screen the stability, disintegration, and swelling behavior of chemically modified anionic polymers. Investigated polymers were well-known and widely used staples of the pharmaceutical and medical field, namely, alginate (AL), carboxymethyl cellulose (CMC), polycarbophil (PC), and hyaluronic acid (HA). On the basis of amide bond formation between the carboxylic acid moieties of anionic polymers and the primary amino group of the modification ligand cysteine (CYS), the modified polymers were obtained. Unmodified polymers served as controls throughout all studies. With the Ellman's assay, modification degrees were determined of synthesized polymeric excipients. Stability assay in terms of erosion study at physiological conditions were performed. Moreover, water uptake of compressed polymeric discs were evaluated and further disintegration studies according to the USP were carried out to define the potential ranking. Results ranking figured out PCCYS > CMCCYS > HACYS > ALCYS in terms of water uptake capacity compared to respective controls. Cell viability assays on Caco-2 cell line as well as on RPMI 2650 (ATTC CCL30) proved modification not being harmful to those. Due to the results of this study, an intense screening of prominent anionic polymer derivate was performed in order to help the pharmaceutical research for the best choice of polymeric excipients for developments of controlled drug release systems.

Novel delivery systems for improving the clinical use of peptides

Peptides have long been recognized as a promising group of therapeutic substances to treat various diseases. Delivery systems for peptides have been under development since the discovery of insulin for the treatment of diabetes. The challenge of using peptides as drugs arises from their poor bioavailability resulting from the low permeability of biological membranes and their instability. Currently, subcutaneous injection is clinically the most common administration route for peptides. This route is cost-effective and suitable for self-administration, and the development of appropriate dosing equipment has made performing the repeated injections relatively easy; however, only few clinical subcutaneous peptide delivery systems provide sustained peptide release. As a result, frequent injections are needed, which may cause discomfort and additional risks resulting from a poor administration technique. Controlled peptide delivery systems, able to provide required therapeutic plasma concentrations over an extended period, are needed to increase peptide safety and patient compliancy. In this review, we summarize the current peptidergic drugs, future developments, and parenteral peptide delivery systems. Special emphasis is given to porous silicon, a novel material in peptide delivery. Biodegradable and biocompatible porous silicon possesses some unique properties, such as the ability to carry exceptional high peptide payloads and to modify peptide release extensively. We have successfully developed porous silicon as a carrier material for improved parenteral peptide delivery. Nanotechnology, with its different delivery systems, will enable better use of peptides in several therapeutic applications in the near future.

Phosphorothioate oligonucleotide quantification by μ-liquid chromatography-mass spectrometry

Phosporothioate oligonucleotides represent an important class of therapeutic oligonucleotides, in which none-bridging oxygen atoms of the phosphate groups are replaced by sulfur. These oligonucleotides are designed to treat disease by modulating gene expression of an affected individual. As the development and application of these therapeutical oligonucleotides require analytical support, the development, validation, and application of an assay for the quantitative analysis of a phosporothioate oligonucleotide in rat plasma is described. The method employs ion-pair reversed-phase chromatography on a monolithic capillary column with acetonitrile gradients in cyclohexyldimethylammonium acetate for separation and high-resolution tandem mass spectrometry for detection of nucleic acids. Chromatographic parameters (i.e. column temperature, mobile phase composition) as well as mass spectrometric parameters (i.e. spray voltage, gas flow, and capillary position, scan mode) have been optimized for sensitive oligonucleotide quantification. Furthermore, a solid-phase extraction method was developed which enabled processing of 10 μl of plasma. The five-point calibration curve showed linearity over the range of concentrations from 100 to 1,000 nM of the oligonucleotide. The limit of detection was 50 nM. The intra- and inter-day precision and accuracies were always better than 10.2 %. Using this assay, we performed a pharmacokinetic study of the phosporothioate oligonucleotide in rat treated with a single intravenous dose of 0.39 μmol/kg. The assay sensitivity was sufficient to study the early phase elimination of the oligonucleotide. Small amounts of the oligonucleotide were detectable up to 3 h after dosing.

Thiolated chitosan nanoparticles for the nasal administration of leuprolide: bioavailability and pharmacokinetic characterization

The purpose of this study was to develop thiolated nanoparticles to enhance the bioavailability for the nasal application of leuprolide. Thiolated chitosan-thioglycolic acid (chitosan-TGA) and unmodified chitosan nanoparticles (NPs) were developed via ionic gelation with tripolyphosphate (TPP). Leuprolide was incorporated during the formulation process of NPs. The thiolated (chitosan-TGA) NPs had a mean size of 252 ± 82 nm, a zeta potential of +10.9 ± 4 mV, and payload of leuprolide was 12 ± 2.8. Sustained release of leuprolide from thiolated NPs was demonstrated over 6h, which might be attributed to inter- and/or intramolecular disulfide formation within the NPs network. Ciliary beat frequency (CBF) study demonstrated that thiolated NPs can be considered as suitable additives for nasal drug delivery systems. Compared to leuprolide solution, unmodified NPs and thiolated NPs provoked increased leuprolide transport through porcine nasal mucosa by 2.0 and 5.2 folds, respectively. The results of a pharmacokinetic study in male Sprague-Dawley rats showed improved transport of leuprolide from thiolated NPs as compared to leuprolide solution. Thiolated NPs had a 6.9-fold increase in area under the curve, more than 4-fold increase in elimination half-life, and a ∼3.8-fold increase in maximum plasma concentration compared to nasal solution alone. The relative nasal bioavailability (versus s.c. injection) of leuprolide thiolated NPs calculated on the basis of AUC((0-6)) was about 19.6% as compared to leuprolide solution 2.8%. The enhanced bioavailability of leuprolide is likely due to facilitated transport by thiolated NPs rather than improved release.

Absorption enhancers: applications and advances

Absorption enhancers are functional excipients included in formulations to improve the absorption of a pharmacologically active drug. The term absorption enhancer usually refers to an agent whose function is to increase absorption by enhancing membrane permeation, rather than increasing solubility, so such agents are sometimes more specifically termed permeation enhancers. Absorption enhancers have been investigated for at least two decades, particularly in efforts to develop non-injection formulations for peptides, proteins, and other pharmacologically active compounds that have poor membrane permeability. While at least one product utilizing an absorption enhancer for transdermal use has reached the market, quite a few more appear to be at the threshold of becoming products, and these include oral and transmucosal applications. This paper will review some of the most advanced absorption enhancers currently in development and the formulation technologies employed that have led to their success. In addition, a more basic review of the barriers to absorption and the mechanisms by which those barriers can be surmounted is presented. Factors influencing the success of absorption-enhancing formulations are discussed. If ultimately successful, the products now in development should offer non-injection alternatives for several peptide or protein drugs currently only administered by injection. The introduction of new absorption enhancers as accepted pharmaceutical excipients, and the development of formulation technologies that afford the greatest benefit/risk ratio for their use, may create opportunities to apply these enabling technologies more broadly to existing drugs with non-optimal delivery properties.

Safety assessment of thiolated polymers: effect on ciliary beat frequency in human nasal epithelial cells

OBJECTIVE

The aim of this study was to investigate the nasal safety of gel formulations of thiolated polymers (thiomers) by assessing their effect on ciliary beat frequency (CBF) in human nasal epithelial cells.

METHODS

Poly(acrylic acid) 450 kDa-cysteine (PAA-cys) and alginate-cysteine (alg-cys) were synthesized by covalent attachment of L-cysteine to the polymeric backbone. The cationic polymer chitosan-thiobutylamidine (chito-TBA) was synthesized by attaching iminothiolane to chitosan. CBF using was measured by a photometric system. CBF was measured before incubating the cells with test gels, during incubation and after washing out the polymeric test gels to evaluate reversibility of cilio-inhibition. The influence of viscosity on CBF was determined by using hydroxyethylcellulose (HEC)-gels of various concentrations.

RESULTS

Ciliary beating was observed to be affected by viscosity, but cilia were still beating in the presence of a HEC-gel displaying an apparent viscosity of 25 Pa.s. In case of thiolated polymers and their unmodified control, a concentration-dependent decrease in CBF could be observed. PAA-cys, alg-cys, chito-TBA and their corresponding unmodified controls exhibited a moderate cilio-inhibitory effect, followed by a partial recovery of CBF when used at a concentration of 1%. Alg-cys 2% and chito-TBA 2% (m/v) gels exhibited severe cilio-inhibition, which was partially reversible. L-cysteine and reduced glutathione led to mild cilio-inhibition at concentrations of 3% (m/v).

CONCLUSIONS

Taking into account that dilution after application and cilio-modifying effects is usually more pronounced under in vitro conditions, thiomers can be considered as suitable excipients for nasal drug delivery systems.

Thiolated polycarbophil/glutathione: defining its potential as a permeation enhancer for oral drug administration in comparison to sodium caprate

Thiolated polyacrylates were shown to be permeation enhancers with notable potential. The aim of this study was to evaluate the permeation enhancing properties of a thiolated polycarbophil/glutathione (PCP-Cys/GSH) system for oral drug application in comparison to a well-established permeation enhancer, namely sodium caprate. In vitro permeation studies were conducted in Ussing-type chambers with sodium fluoresceine (NaFlu) and fluoresceine isothiocyanate labeled dextran (molecular mass 4 kDa; FD4) as model compounds. Bioavailability studies were carried out in Sprague Dawley rats with various formulations. Moreover, cytotoxic effects of both permeation enhancers were compared. Permeation enhancement ratios of 1% sodium caprate were found to be 3.0 (FD4) and 2.3 (NaFlu), whereas 1% PCP-Cys/0.5% GSH displayed enhancement ratios of 2.4 and 2.2. Both excipients performed at a similar level in vivo. Sodium caprate solutions increased oral bioavailability 2.2-fold (FD4) and 2.3-fold (NaFlu), while PCP-Cys hydrogels led to a 3.2-fold and 2.2-fold enhancement. Cell viability experiments revealed a significantly higher tolerance of Caco-2 cells towards 0.5% PCP-Cys (81% survival) compared to 0.5% sodium caprate (5%). As PCP-Cys is not absorbed from mucosal membranes due to its comparatively high molecular mass, systemic side-effects can be excluded. In conclusion, both systems displayed a similar potency for permeation enhancement of hydrophilic compounds. However, PCP-Cys seems to be less harmful to cultured cells.