Evaluation of novel particles as an inhalation system for GLP-1

Engineering the right formulation for enhanced drug delivery

Dry powder inhalers (DPIs) can be used with a wide range of drugs such as small molecules and biologics and offer several advantages for inhaled therapy. Early DPI products were intended to treat asthma and lung chronic inflammatory disease by administering low-dose, high-potency drugs blended with lactose carrier particles. The use of lactose blends is still the most common approach to aid powder flowability and dose metering in DPI products. However, this conventional approach may not meet the high demand for formulation physical stability, aerosolisation performance, and bioavailability. To overcome these issues, innovative techniques coupled with modification of the traditional methods have been explored to engineer particles for enhanced drug delivery. Different particle engineering techniques have been utilised depending on the types of the active pharmaceutical ingredient (e.g., small molecules, peptides, proteins, cells) and the inhaled dose. This review discusses the challenges of formulating DPI formulations of low-dose and high-dose small molecule drugs, and biologics, followed by recent and emerging particle engineering strategies utilised in developing the right inhalable powder formulations for enhanced drug delivery.

Development of drug alone and carrier-based GLP-1 dry powder inhaler formulations

The study aimed to develop two types of dry powder inhaler (DPI) formulations containing glucagon-like peptide-1(7-36) amide (GLP-1): carrier-free (drug alone, no excipients) and carrier-based DPI formulations for pulmonary delivery of GLP-1. This is the first study focusing on the development of excipient free GLP-1 DPI formulations for inhaled therapy in Type 2 diabetes. The aerosolisation performance of both DPI formulations was studied using a next generation impactor and a DPI device (Handihaler®) at flow rate of 30 L min^-1. Carriers employed were either a 10% w/w glycine-mannitol prepared by spray freeze drying or commercial mannitol. Spray freeze dried (SFD) carrier was spherical and porous whereas commercial mannitol carrier exhibited elongated particles (non-porous). GLP-1 powder without excipients for inhalation was prepared using spray drying and characterised for morphology including size, thermal behaviour, and moisture content. Spray dried (SD) GLP-1 powders showed indented/dimpled particles in the particle size range of 1 to 5 µm (also mass median aerodynamic diameter, MMAD: <5 µm) suitable for pulmonary delivery. Across formulations investigated, carrier-free DPI formulation showed the highest fine particle fraction (FPF: 90.73% ± 1.76%, mean ± standard deviation) and the smallest MMAD (1.96 µm ± 0.07 µm), however, low GLP-1 delivered dose (32.88% ± 7.00%, total GLP-1 deposition on throat and all impactor stages). GLP-1 delivered dose was improved by the addition of SFD 10% glycine-mannitol carrier to the DPI formulation (32.88% ± 7.00% -> 45.92% ± 5.84%). The results suggest that engineered carrier-based DPI formulations could be a feasible approach to enhance the delivery efficiency of GLP-1. The feasibility of systemic pulmonary delivery of SD GLP-1 for Type 2 diabetes therapy can be further investigated in animal models.

Novel formulations and drug delivery systems to administer biological solids

Recent advances in formulation sciences have expanded the previously limited design space for biological modalities, including peptide, protein, and vaccine products. At the same time, the discovery and application of new modalities, such as cellular therapies and gene therapies, have presented formidable challenges to formulation scientists. We explore these challenges and highlight the opportunities to overcome them through the development of novel formulations and drug delivery systems as biological solids. We review the current progress in both industry and academic laboratories, and we provide expert perspectives in those settings. Formulation scientists have made a tremendous effort to accommodate the needs of these novel delivery routes. These include stability-preserving formulations and dehydration processes as well as dosing regimes and dosage forms that improve patient compliance.

Peptidyl and Non-Peptidyl Oral Glucagon-Like Peptide-1 Receptor Agonists

Glucagon-like peptide-1 (GLP-1) receptor agonists are efficacious glucose-lowering medications with salient benefits for body weight and cardiovascular events. This class of medications is now recommended as the top priority for patients with established cardiovascular disease or indicators of high risk. Until the advent of oral semaglutide, however, GLP-1 receptor agonists were available only in the form of subcutaneous injections. Aversion to needles, discomfort with self-injection, or skin problems at the injection site are commonly voiced problems in people with diabetes, and thus, attempts for non-invasive delivery strategies have continued. Herein, we review the evolution of GLP-1 therapy from its discovery and the development of currently approved drugs to the unprecedented endeavor to administer GLP-1 receptor agonists via the oral route. We focus on the pharmacokinetic and pharmacodynamic properties of the recently approved oral GLP-1 receptor agonist, oral semaglutide. Small molecule oral GLP-1 receptor agonists are currently in development, and we introduce how these chemicals have addressed the challenge posed by interactions with the large extracellular ligand binding domain of the GLP-1 receptor. We specifically discuss the structure and pharmacological properties of TT-OAD2, LY3502970, and PF-06882961, and envision an era where more patients could benefit from oral GLP-1 receptor agonist therapy.

Battle of GLP-1 delivery technologies

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) belong to an important therapeutic class for treatment of type 2 diabetes. Six GLP-1 RAs, each utilizing a unique drug delivery strategy, are now approved by the Food and Drug Administration (FDA) and additional, novel GLP-1 RAs are still under development, making for a crowded marketplace and fierce competition among the manufacturers of these products. As rapid elimination is a major challenge for clinical application of GLP-1 RAs, various half-life extension strategies have been successfully employed including sequential modification, attachment of fatty-acid to peptide, fusion with human serum albumin, fusion with the fragment crystallizable (Fc) region of a monoclonal antibody, sustained drug delivery systems, and PEGylation. In this review, we discuss the scientific rationale of the various half-life extension strategies used for GLP-1 RA development. By analyzing and comparing different approved GLP-1 RAs and those in development, we focus on assessing how half-life extending strategies impact the pharmacokinetics, pharmacodynamics, safety, patient usability and ultimately, the commercial success of GLP-1 RA products. We also anticipate future GLP-1 RA development trends. Since similar drug delivery strategies are also applied for developing other therapeutic peptides, we expect this case study of GLP-1 RAs will provide generalizable concepts for the rational design of therapeutic peptides products with extended duration of action.

Stability and efficacy of synthetic cationic antimicrobial peptides nebulized using high frequency acoustic waves

Surface acoustic wave (SAW), a nanometer amplitude electroelastic wave generated and propagated on low-loss piezoelectric substrates (such as LiNbO3), is an extremely efficient solid-fluid energy transfer mechanism. The present study explores the use of SAW nebulization as a solution for effective pulmonary peptide delivery. In vitro deposition characteristics of the nebulized peptides were determined using a Next Generation Cascade Impactor. 70% of the peptide-laden aerosols generated were within a size distribution favorable for deep lung distribution. The integrity of the nebulized peptides was found to be retained, as shown via mass spectrometry. The anti-mycobacterial activity of the nebulized peptides was found to be uncompromised compared with their non-nebulized counterparts, as demonstrated by the minimum inhibition concentration and the colony forming inhibition activity. The peptide concentration and volume recoveries for the SAW nebulizer were significantly higher than 90% and found to be insensitive to variation in the peptide sequences. These results demonstrate the potential of the SAW nebulization platform as an effective delivery system of therapeutic peptides through the respiratory tract to the deep lung.

Aerosolized GLP-1 for treatment of diabetes mellitus and irritable bowel syndrome

Diabetes is a global burden and the prevalence of the disease, in particular diabetes mellitus type 2 is rapidly increasing worldwide. After introduction of insulin into clinical therapy about 90 years ago a major number of pharmaceuticals has been developed for treatment of diabetes mellitus type 2. One of these, the incretin glucagon-like peptide 1 (GLP-1), like insulin, needs subcutaneous administration causing inconvenience to patients. However, administration of GLP-1 plays also a role for treatment of irritable bowel syndrome (IBS). To improve patient convenience inhaled insulin (Exubera(®)) was developed and approved but failed market acceptance some years ago. Recently, another inhalative insulin (Afrezza(®)) received market approval and GLP-1 may serve as another candidate drug for inhalative administration. This review analyzes the current literature investigating alternative administration of GLP-1 and GLP-1 analogs focusing on inhalation. Several formulations for inhalative administration of GLP-1 and analogs were investigated in animal studies, whereas there are only few clinical data. However, feasibility of GLP-1 inhalation has been shown and should be further investigated as such type of drug administration may serve for improvement of therapy in patients with diabetes mellitus or irritable bowel syndrome.

Peptide therapeutics: it's all in the delivery

Recent work has demonstrated that the route of administration affects the pharmacokinetics and biological activity of peptides. For example, the physiological profile of insulin consists of basal and prandial components with a small-scale oscillatory element. Insulin is used more efficiently when the pharmacokinetic profile mimics features of physiological release. Noninvasive administration of insulin by oral, transdermal, nasal and pulmonary routes resembles the relatively sharp peak and short duration of exposure of prandial release. The route of administration per se, can affect the response by avoiding first-pass metabolism or perhaps altering the timing in which the peptide reaches different sets of receptors. GLP-I delivered by injection and inhalation produces different side effect profiles. Nonclinical studies on two potential treatments for obesity, oxyntomodulin and PYY 3-36, are also presented to illustrate the relationship between exposure and effect as functions of route of administration.

Receptor-mediated inhibition of small bowel migrating complex by GLP-1 analog ROSE-010 delivered via pulmonary and systemic routes in the conscious rat

BACKGROUND

ROSE-010, a Glucagon-Like Peptide-1 (GLP-1) analog, reduces gastrointestinal motility and relieves acute pain in patients with irritable bowel syndrome (IBS). The rat small bowel migrating myoelectric complex (MMC) is a reliable model of pharmacological effects on gastrointestinal motility. Accordingly, we investigated whether ROSE-010 works through GLP-1 receptors in gut musculature and its effectiveness when administered by pulmonary inhalation.

MATERIALS AND METHODS

Rats were implanted with bipolar electrodes at 5, 15 and 25 cm distal to pylorus and myoelectric activity was recorded. First, intravenous or subcutaneous injections of ROSE-010 or GLP-1 (1, 10, 100 μg/kg) with or without the GLP-1 receptor blocker exendin(9-39)amide (300 μg/kg·h), were studied. Second, ROSE-010 (100, 200 μg/kg) Technosphere® powder was studied by inhalation.

RESULTS

The baseline MMC cycle length was 17.5±0.8 min. GLP-1 and ROSE-010, administered intravenously or subcutaneously, significantly inhibited myoelectric activity and prolonged MMC cycling; 100 μg/kg completely inhibited spiking activity for 49.1±4.2 and 73.3±7.7 min, while the MMC cycle length increased to 131.1±11.4 and 149.3±15.5 min, respectively. Effects of both drugs were inhibited by exendin(9-39)amide. Insufflation of ROSE-010 (100, 200 μg/kg) powder formulation totally inhibited myoelectric spiking for 52.6±5.8 and 70.1±5.4 min, and increased MMC cycle length to 102.6±18.3 and 105.9±9.5 min, respectively.

CONCLUSIONS

Pulmonary delivery of ROSE-010 inhibits gut motility through the GLP-1R similar to natural GLP-1. ROSE-010 causes receptor-mediated inhibition of MMC comparable to that of intravenous or subcutaneous administration. This suggests that ROSE-010 administered as a Technosphere® inhalation powder has potential in IBS pain management and treatment.