Nasal administration of glucagon combined with dimethyl-β-cyclodextrin: Comparison of pharmacokinetics and pharmacodynamics of spray and powder formulations

In vivo systemic evaluation of nasal drug absorption from powder formulations in rats

Despite the potential benefits of nasal drug delivery, there is a need for a systematic evaluation of the efficacy of powder formulations adhering to the nasal mucosa. This study aims to establish a systematic evaluation method for nasal drug absorption from powder formulations. We selected three model compounds-antipyrine, griseofulvin, and acyclovir-and analyzed their pharmacokinetics following nasal administration of powder formulations under physiological conditions. Our experimental design incorporated assessments of the drug absorption patterns. Antipyrine demonstrated rapid absorption exclusively from the nasal cavity. In contrast, griseofulvin exhibited absorption from the nasal cavity and the gastrointestinal tract. This phenomenon could be attributed to the rapid nasal clearance of the drug with an initial half-life of 5 min. To further establish the physiological validity of our method, we conducted an experiment to investigate the impact of changing the mucociliary clearance (MC) on nasal absorption that resulted in a 1.2-fold increase in the bioavailability of acyclovir upon prolonged MC. Our findings support the utility of established methods in evaluating nasal absorption and their behavior in the nasal cavity. This study holds a promising advancement toward effective drug delivery via nasal administration, potentially leading to targeted delivery and improved therapeutic outcomes.

Advancements in cyclodextrin-based controlled drug delivery: Insights into pharmacokinetic and pharmacodynamic profiles

This article discusses and summarizes some fascinating outcomes and applications of cyclodextrins (CDs) and their derivatives in drug delivery. These applications include the administration of protein, peptide medications, and gene delivery. Several innovative drug delivery systems, including NPs, microspheres, microcapsules, and liposomes, are designed with the help of CD, which is highlighted in this article. The use of these compounds as excipients in medicine formulation is reviewed, in addition to their well-known effects on drug solubility and dissolution, as well as their bioavailability, safety, and stability. Furthermore, the article focuses on many factors that influence the development of inclusion complexes, as having this information is necessary to manage these diverse materials effectively. An overview of the commercial availability, regulatory status, and patent status of CDs for pharmaceutical formulation is also presented. Due to the fact that CDs can discover new uses in drug delivery consistently, it is predicted that they will solve a wide range of issues related to the distribution of a variety of unique medications through various delivery channels.

Topological Aspects of the Design of Nanocarriers for Therapeutic Peptides and Proteins

Supramolecular chemistry holds great potential for the design of versatile and safe carriers for therapeutic proteins and peptides. Nanocarriers can be designed to meet specific criteria for given application (exact drug, administration route, target tissue, etc.). However, alterations in the topology of formulation components can drastically change their activity. This is why the supramolecular topology of therapeutic nanoconstructions has to be considered. Herein, we discuss several topological groups used for the design of nanoformulations for peptide and protein delivery: modification of polypeptide chains by host-guest interactions; packaging of proteins and peptides into liposomes; complexation and conjugation with dendrimers. Each topological type has its own advantages and disadvantages, so careful design of nanoformulations is needed. Ideally, each case where nanomedicine is needed requires a therapeutic construction specially created for that taking into account features of the administration route, target tissue, or organ, properties of a drug, its bioavailability, etc. The wide number of studies in the field of protein delivery by supramolecular and nanocarriers for proteins and peptides evidence their increasing potential for different aspects of the innovative medicine. Although significant progress has been achieved in the field, there are several remaining challenges to be overcome in future.

Overview of intranasally delivered peptides: key considerations for pharmaceutical development

INTRODUCTION

Intranasal (IN) delivery for peptides provides unique advantages compared to other invasive systemic delivery routes. However, there still lacks a clear understanding on how to evaluate the potential of the peptides for nasal delivery and key considerations for the nasal formulation development.

AREAS COVERED

A retrospective analysis of intranasally delivered peptides was conducted. The goals of this undertaking were 1) to build a database of the key physicochemical and pharmacokinetic properties of peptides delivered by the nasal route, 2) to evaluate formulation attributes applied to IN peptide delivery systems, and 3) to provide key considerations for IN delivery of peptides.

EXPERT OPINION/COMMENTARY

Extensive data mining showed that peptides with molecular weights up to 6000 Da have been delivered intranasally. The high solubility of some peptides highlighted the possibility of delivering sufficient amounts of peptide in the limited volume available for nasal sprays. Permeation enhancers and mucoadhesives have shown promise in improving the IN bioavailability of peptides. Other formulation considerations, such as the type of formulation, pH, osmolality, as well as drug deposition, are reviewed herein. Based on this retrospective analysis, key considerations for nasal peptides formulations were proposed to guide drug discovery and development for IN delivery of peptides.

The nature of amyloid-like glucagon fibrils

Protein aggregation and formation of amyloid fibrils is a phenomenon usually associated with proteotoxicity and degenerative diseases, such as type 2 diabetes, Alzheimer's disease, and prion diseases. However, several protein and peptide hormones are known to have a high propensity to form amyloid-like fibrils in vitro raising concerns about safety and stability of pharmaceutical protein solutions. Comprehensive understanding of the aggregation mechanisms is an important prerequisite to the design of strategies to prevent fibril formation. Detailed kinetic, spectroscopic, and morphological studies have revealed that glucagon can form several types of fibrils that differ at the level of molecular packing of the peptide. Each type forms through distinct nucleation-dependent aggregation pathways influenced by solution conditions and can be self-propagated by seeding. An increasing number of functional amyloid-like structures have been discovered in nature, and it has recently been proposed that an amyloid-like state of glucagon may be utilized by the pancreatic α-cells as in vivo storage form. This article reviews the current state of our knowledge about the nature of the different types of amyloid-like glucagon fibrils, the mechanisms by which they form, and discusses implications for formulation strategies and the safety of glucagon pharmaceuticals.

The effect of cyclodextrins on chemical and physical stability of glucagon and characterization of glucagon/gamma-CD inclusion complexes

The purpose of the study was to evaluate the effect of cyclodextrin (CD) complexation on the chemical and physical stability of a polypeptide hormone glucagon and to study the interactions between glucagon and gamma-cyclodextrin molecules in inclusion complexes. The chemical stability of glucagon at pH 2.0 was studied with HPLC-UV and HPLC-MS/MS. The physical stability of glucagon at pH 2.5 was studied by measuring the turbidity (A(405 nm)) and viscosity (Ostwald capillary viscosimeter) of the samples. The structure of glucagon/gamma-CD complexes at pH 2.5 was studied with 2D-NMR. The presence of various CDs increased the chemical half-life of glucagon at pH 2.0 (37 degrees C, 0.01 M HCl, ionic strength 0.15) and prolonged the lag-time before aggregation at pH 2.5 (0.9% (w/v) NaCl in 3.2 mM HCl). The NMR studies showed that the side chains of all the aromatic amino acid residues (Phe6, Tyr10, Tyr13, Phe22, Trp25) and leucines (Leu14 and Leu26) of glucagon interacted with the cavities of the gamma-CD molecules. The present study shows that glucagon forms inclusion complexes with cyclodextrins in acidic solution, resulting in an improvement in its chemical and physical stability.

Nasal clearance in health and disease

This paper reviews the anatomical and physiological factors of importance for nasal drug delivery and discusses in particular the influence of the nasal mucociliary clearance mechanism on the nasal absorption of drugs. The effect of nasal pathological conditions on the mucociliary clearance mechanism and the possible effect of such disease states on nasal drug transport are also discussed. Strategies for the exploitation of bioadhesive drug delivery systems and especially nasal absorption enhancers for the improvement of nasal drug delivery are evaluated to include considerations of the mechanism of action and correlation between the degree of bioadhesion and absorption enhancement and transport of drugs across the nasal membrane. A range of studies involving bioadhesive/absorption enhancer systems are detailed. A selected bioadhesive material, chitosan, which has been shown to have excellent absorption enhancer properties for a variety of drugs is discussed in some detail.

Absorption enhancers for nasal drug delivery

This paper describes the basic concepts for the transmucosal delivery of drugs, and in particular the use of the nasal route for delivery of challenging drugs such as polar low-molecular-weight drugs and peptides and proteins. Strategies for the exploitation of absorption enhancers for the improvement of nasal delivery are discussed, including consideration of mechanisms of action and the correlation between toxic effect and absorption enhancement. Selected enhancer systems, such as cyclodextrins, phospholipids, bioadhesive powder systems and chitosan, are discussed in detail. Examples of the use of these enhancers in preclinical and clinical studies are given. Methods for assessing irritancy and damage to the nasal membrane from the use of absorption enhancers are also described. Finally, the mucosal use of absorption enhancers (chitosan) for the improved nasal delivery of vaccines is reported with reference to recent phase I/II clinical studies.

Nasal glucagon delivery using microcrystalline cellulose in healthy volunteers

We developed an intranasal powder form of glucagon to improve metabolic status and fatty liver in patients with pancreatectomy. Microcrystalline cellulose, which is commonly used in commercial preparations for allergic rhinitis was used as an absorption enhancer. We compared the intranasal powder form with some spray solutions of glucagon with regard to glucagon absorption, concentration of blood glucose, stability and nasal irritation. The absorption of glucagon from the spray solution including 1.5% sodium glycocholate or 1% sodium caprate was 1.3- and 2.6-fold higher than that from the powder form mixed with microcrystalline cellulose at a ratio of 1:69, respectively. The C(max) values of plasma glucose were 2.18, 3.39 and 1.56 mmol l(-1) in the spray solutions including sodium glycocholate and sodium caprate and in the powder form, respectively. However, glucagon in spray solutions was unstable, but that in the powder form was stable at 5 and 25 degrees C for at least 84 days. The spray solution caused strong irritation, but the powder form did not. These results suggested usefulness of the powder form of glucagon for treatment of pancreatectomized patients.

Efficacy, safety and mechanism of cyclodextrins as absorption enhancers in nasal delivery of peptide and protein drugs

Cyclodextrins are used in nasal drug delivery as absorption enhancing compounds to increase the intranasal bioavailability of peptide and protein drugs. The most effective cyclodextrins in animal experiments are the methylated derivatives, dimethyl-beta-cyclodextrin and randomly methylated beta-cyclodextrin, which are active at low concentrations ranging between 2% and 5%. However, large species differences between rats, rabbits and humans exist for the nasal absorption enhancement by cyclodextrins. Based on toxicological studies of the local effects of cyclodextrins on the nasal mucosa dimethyl-beta-cyclodextrin and randomly methylated beta-cyclodextrin are considered safe nasal absorption enhancers. Their effects were quite similar to controls (physiological saline), but smaller than those of the preservative benzalkonium chloride in histological and ciliary beat frequency studies. In these studies, and in a study of the release of marker compounds after nasal administration, methylated beta-cyclodextrins were less toxic than sodium glycocholate, sodium taurodihydrofusidate, laureth-9 and L-alpha-phosphatidylcholine. Systemic toxicity after nasal cyclodextrin administration is not expected, because very low doses of cyclodextrins are administered and only very small amounts are absorbed. The mechanism of action of cyclodextrins may be explained by their interaction with the nasal epithelial membranes and their ability to transiently open tight junctions.