(T1230-09-48) Development of Dissolving Microneedles for Delivery of Semaglutide for Treatment of Type 2 Diabetes and Obesity

Purpose: Semaglutide (SMG), a glucagon-like peptide-1 (GLP-1) receptor agonist, has emerged as a promising therapeutic agent for both Type 2 Diabetes Mellitus (T2DM) and obesity. Obesity and T2DM are among the most prevalent chronic diseases globally, with a significant correlation between the two conditions. According to the Center for Disease Control and Prevention (CDC), approximately 38.4 million individuals in the United States, representing 11.6% of the population, are affected by diabetes. SMG is currently available as subcutaneous injection and Oral tablet with permeation enhancer. However, SC delivery is painful with poor patient compliance while oral product yield less than 1% bioavailability. Drug delivery of macromolecules is very challenging due to the issues associated with permeability and physicochemical stability. Therefore, considering the tremendous therapeutic potential of SMG in millions of patients worldwide, a novel drug delivery system with high patient compliance is the need of an hour. Transdermal route offers advantage but limited to small skin permeable molecules. Rapidly dissolving microneedles (MN) is an emerging field for efficient delivery of peptide molecules. The purpose of this study: 1) to explore novel polymeric matrix for the preparation of MN with high compatibility with peptide and high strength 2) to develop and characterize SMG-loaded dissolving microneedles containing dose equivalent to subcutaneous injection.

Methods: MNs were developed using solvent casting with custom-made molds (6x6 array, height 1000μm, base 250μm, pitch 1000μm, pyramidal shape) from Micropoint Technologies (Fig. 1). The polymer screening process explored biocompatible, water-soluble polymers, including Poly-vinyl Alcohol (PVA), Poly-vinyl pyrrolidone K17 (PVPK17), hyaluronic acid (HA), and poly(2-ethyl-2-oxazoline) (PeTOx). Alone and combination of polymers with small molecules were screened to achieve a MN with high reproducibility and strength. SMG stability and drug-excipient compatibility were evaluated at 25°C and 40°C, via High Performance Liquid Chromatography (HPLC). An isocratic system with acetonitrile:phosphate buffer pH 3.5 containing 0.1% trifluoroacetic acid (60:40 v/v) at 0.5 mL/min was employed, detecting SMG at 280 nm. Mechanical properties, including needle insertion and fracture force, were analyzed using a TA. XT plus Texture Analyzer. Stereomicroscopy revealed morphological changes, while a novel 3D-printed mold mimicking skin aided in optimizing drug release. SMG loading and release from dissolving MNs were quantified using reversed-phase HPLC (Agilent HC-C18 column, 150mm × 4.6mm, 5μm particle size). Ongoing studies include circular dichroism (CD) and Thioflavin T (ThT) analysis to assess effect of pH, excipient and processing parameters on fibril formation/in-vitro aggregation. In-vitro cytotoxicity tests of SMG-MNs in HEK001 cells and permeability studies using rat skin in Franz cells are also being conducted.

Results: Though HA is highly biocompatible, low molecular weight HA (10-15k) did not form needle with structural integrity. The combination of HA with PeTOx and arginine showed complete MN array formation, with adequate strength and additional biocompatibility and biodegradability. The differences in morphological trends in MNs due to changes in polymers for the dimensions of 1000μm microneedles was studied via stereomicroscope imaging shown in Fig. 2.1. There are several reports of possible aggregation patterns of GLP-1 agonist peptides. Incorporation of arginine provided ideal microenvironment the chemical stability of SMG. Drug-excipient compatibility studies showed the absence of any interactions between the excipients HA, PeTOx, Arginine, and SMG indicated in Fig.2.2. The accelerated stability study shows negligible gradation of the peptide SMG at 40⁰C over 24h (Drying time). As shown in Fig 3.1, it is evident that insertion of SMG loaded MNs is nearly 100% until 400 μm, and >25% until 600 μm. Addition of SMG maintains the MNs insertion depth showing better penetration ability. The base polymeric blend of HA 65%: PETOX 45% exhibited the highest fracture force at approximately 130 N. Interestingly, further addition of 2% SMG peptide restored the fracture force to nearly the original level, around 125 N shown in Fig. 3.2. These findings suggest that while ARG alone tends to decrease the microneedle strength, the combination of ARG and SMG peptide can maintain high mechanical strength comparable to the original HA-PETOX blend. The in vitro dissolution release of optimized SMG-loaded MNs showed sustained, erosion-based release of SMG for 12 hrs as shown in Fig 3.3. Considering the half life of semaglutide once weekly dosing of microneedle will be sufficient to achieve desired therapeutic outcomes.

Conclusion: A rapidly dissolving microneedles of SMG with >1 mg drug loading was prepared using combination of hyaluronic acid, arginine and poly 2-ethyl-2-oxazoline. It offers a minimally invasive, biocompatible and biodegradable microneedle patch for the delivery of SMG. Microneedle based delivery could be significantly valuable for oral and subcutaneous delivery of SMG in the management of T2DM and obesity.

Acknowledgements: We are thankful to Dr. Pulkit Khatri and Dr. Simrat Singh from Ambio, Inc. for generously providing high purity semaglutide and analytical guidance.

Figure 1. Overall schematic illustration of the preparation of dissolving microneedles of HA: PetOx-ARG loaded with semaglutide (SMG) peptide.

Figure 2.1. Microneedle morphological characterization studies 2.2. Semaglutide (SMG) drug excipient compatibility studies at 25°C and 40°C.

Figure 3. Microneedle (MN) Characterization studies 3.1. Mechanical properties characterization using ex vivo parafilm® M method indicates better microneedles insertion 3.2. Maximum Fracture force analysis 3.3. Microneedle in vitro dissolution assessment.