EP-4740940-A1 - POLLEN PARTICLES AS CARRIERS FOR PULMONARY DELIVERY

EP4740940A1EP 4740940 A1EP4740940 A1EP 4740940A1EP-4740940-A1

Abstract

The present invention relates to microparticles for pulmonary release that comprise a purified pollen capsule, which comprises an intine layer and an exine layer, and at least one nanosystem encapsulated in said capsule. Said nanosystem comprises a pharmaceutically active compound, wherein the exine layer is coated with a pharmaceutically acceptable excipient. The present invention further relates to a method of obtaining said microparticles and medical uses thereof, in particular for the treatment of tuberculosis.

Inventors

CSABA, NOEMI
ROBLA ÁLVAREZ, Sandra
VALVERDE FRAGA, Lorena
SANCHEZ POZA, Sandra
AMBRUS, Rita
CSÓKA, Ildikó

Assignees

Universidade de Santiago de Compostela
University of Szeged

Dates

Publication Date: 20260513
Application Date: 20240711

Claims (20)

A microparticle for pulmonary release comprising: - a purified pollen capsule, which comprises an intine layer and an exine layer; and - at least one nanosystem encapsulated in said capsule, wherein the nanosystem comprises a pharmaceutically active compound; wherein the exine layer is coated with a pharmaceutically acceptable excipient.
The microparticle according to claim 1, characterized in that the pharmaceutically acceptable excipient constitutes the outermost layer of the microparticle.
The microparticle according to any of claims 1 or 2, characterized in that the pharmaceutically acceptable excipient reduces the mass median aerodynamic diameter of the microparticle by at least 10%, when compared to an identical microparticle but without a pharmaceutically acceptable excipient, using an Andersen Cascade Impactor.
The microparticle according to any of claims 1 to 3, characterized in that the pharmaceutically acceptable excipient is selected from the group consisting of amino acids, peptides, proteins, polymers polyols, carbohydrates, fatty acids, fatty acid salts, phospholipids, and combinations thereof.
The microparticle according to any of claims 1 to 4, characterized in that the pharmaceutically acceptable excipient is selected from the group consisting of mannitol, leucine, trehalose, lactose, albumin, dipalmitoylphosphatidylcholine, magnesium stearate, and combinations thereof.
The microparticle according to any of claims 1 to 5, characterized in that the pharmaceutically acceptable excipient is selected from the group consisting of mannitol, leucine, and combinations thereof.
The microparticle according to any of claims 1 to 6, characterized in that the pharmaceutically acceptable excipient is in an amount comprised between 10% and 95% by weight, with respect to the weight of the microparticle of the invention without the coating.
The microparticle according to any of claims 1 to 7, characterized in that the nanosystem comprises polypeptides, polysaccharides, and/or polyamino acids.
The microparticle according to any of claims 1 to 8, characterized in that the nanosystem comprises chitosan or protamine.
The microparticle according to any of claims 1 to 9, characterized in that the nanosystem comprises a protamine layer encapsulating the pharmaceutically active compound.
The microparticle according to any of claims 1 to 10, characterized in that the nanosystem presents a hydrodynamic diameter comprised between 100 and 500 nm, measured by means of dynamic light scattering.
The microparticle according to any of claims 1 to 11, characterized in that the nanosystem comprises an oily component.
The microparticle according to any of claims 1 to 12, characterized in that the pharmaceutically active compound is an antibiotic.
The microparticle according to any of claims 1 to 13, characterized in that the pharmaceutically active compound is an antibiotic for treating tuberculosis.
The microparticle according to any of claims 1 to 14, characterized in that the pharmaceutically active compound is in a concentration comprised between 0.5% and 20% by weight, with respect to the weight of the nanosystem.
The microparticle according to any of claims 1 to 15, characterized in that the pharmaceutically active compound is selected from the group consisting of insulin and rifabutin.
The microparticle according to any of claims 1 to 16, characterized in that the purified pollen capsule is devoid of its lipid layer.
The microparticle according to any of claims 1 to 17, characterized by a mass median aerodynamic diameter of 1 to 10 µm.
A method for the preparation of a microparticle as defined in any of the preceding claims, characterized in that it comprises: (a) a washing stage which comprises washing a pollen particle; (b) a stage which comprises treating the pollen particle obtained in the preceding stage with an acidic medium to obtain hollow purified pollen capsules; (c) a stage which comprises incubating the hollow capsules obtained in the preceding stage with a nanosystem comprising a pharmaceutically active compound; and (d) a stage which comprises coating the resulting capsules with a pharmaceutically acceptable excipient.
A microparticle for pulmonary release, characterized in that it is obtained according to the method of claim 19.

Description

Field of the Invention The present invention is comprised within the field of purified pollen particles as carriers for pulmonary release. Background of the Invention Standard treatment for tuberculosis (TB) caused by Mycobacterium tuberculosis includes therapy with oral antibiotics. The low solubility and high metabolism of drugs in the oral treatment of tuberculosis leads to the use of prolonged therapies that favor the appearance of resistances, hindering patient adherence. Furthermore, the appearance of mycobacterial strains which are resistant to medicinal products requires more medicinal products and longer treatments. Alternatively, pulmonary drug delivery offers direct access to lung epithelium and alveolar macrophages, preventing side effects associated with oral delivery. However, several factors, such as physical barriers, pulmonary defense mechanisms such as macrophages, alveolar enzymes, and mucociliary clearance, constitute an obstacle in pulmonary drug release, so there are currently no inhalable antitubercular formulations available for clinical use. Rifabutin, a class II drug according to the Biopharmaceutical Classification System (BCS), exhibits poor dissolution and limited absorption. This compound shares structural and activity similarities with rifampicin, but has greater antimycobacterial activity and extensive tissue distribution. However, its large volume of distribution and low oral bioavailability (less than 20% reaches systemic circulation) result in low plasma concentrations. Encapsulation of such drugs within nanoparticles could be an effective solution, as nanoparticles with sizes of about 200 nm are considered suitable for pulmonary delivery. However, nanoparticles exhibit low inertia and are exhaled before reaching the airways. This challenge could be overcome by incorporating nanoparticles into micrometer-sized particles, serving as a delivery system to make it easier for them to reach alveolar macrophages. Strategies using microparticle delivery in the form of dry powder inhalers (DPIs) have shown to be effective in the generation of inhalable particles for the treatment of TB [Mehta, P.; Bothiraja, C.; Kadam, S.; Pawar, A. Potential of Dry Powder Inhalers for Tuberculosis Therapy: Facts, Fidelity and Future. Artif. Cells, Nanomedicine, Biotechnol. 2018, 46, S791-S806, doi:10.1080/21691401.2018.1513938]. The publication by Robla, S., et al. ("A ready-to-use dry powder formulation based on protamine nanocarriers for pulmonary drug release", European Journal of Pharmaceutical Sciences, 2023, 185, 106442) describes rifabutin-loaded protamine nanocapsules for pulmonary release. The nanocapsules are incorporated into microparticles by lyophilization with mannitol, obtaining an inhalational dry powder formulation for the treatment of tuberculosis. These approaches use particle engineering techniques such as spray drying and lyophilization to produce suitable inhalable particles. In this context, pollen grains have emerged in recent years as viable candidates for drug encapsulation and delivery due to their micrometer-sized structure. Pollen grains exhibit a uniform size and essentially comprise genetic material contained in a cytoplasm (sporoplasm), which is coated by a first inner layer called intine and a second layer called exine. The exine of pollen particles has on its surface an additional lipid layer, a complex mixture of proteins, lipids, and other molecules (known as "pollenkitt"). The intine generally consists of cellulose, while the exine is composed of a proteinaceous material called sporopollenin the exact composition of which is not known. The exine is an extremely strong layer that is stable in acidic and basic conditions and has high porosity. Given these properties, various technologies that allow isolating exine, i.e., hollowing out the interior of exine, removing its intine and genetic material, as well as cleaning the outer surface of the lipid layer or pollenkitt, have been tested. These natural structures can be easily processed to create a low-density platform with a large inner cavity, suitable for drug delivery by means of encapsulation of both polar and non-polar drugs, providing them with protection. Furthermore, it has been shown that the use of sporopollenin improves drug adhesion capacity and increases contact surface between drug and mucosa [Diego-Taboada, A.; Beckett, S.T.; Atkin, S.L.; Mackenzie, G. Hollow Pollen Shells to Enhance Drug Release. Pharmaceutics 2014, 6, 80-96, doi:10.3390/pharmaceutics6010080]. To date, the potential use of pollen particles for pulmonary drug delivery remains unexplored. While pollen is deposited primarily in the oropharynx, prolonged exposure, particularly to specific proteins, can cause sensitization and the development of allergies and asthma, both in the lower respiratory tract and following ingestion in the form of food allergies. Allergens can be removed by means of chemical treatment methods, resulting in pur