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Summary

Abstract

Introduction

Protocol

Representative Results

Discussion

Acknowledgements

Materials

References

Medicine

Disposable Dosators Intended for Dry Powder Delivery to Mice

Published: August 18th, 2023

DOI:

10.3791/65756

1Technology Advancement and Commercialization, RTI International, 2Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, 3Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center

Pharmaceutical dry powder development necessitates reliable in vivo testing, often using a murine model. Device technology for accurately and reproducibly delivering dry powder aerosols to mice is restricted. This study presents disposable dosators for pulmonary drug delivery at mouse-relevant doses, aiding initial proof-of-concept research.

Dry powder inhalers offer numerous advantages for delivering drugs to the lungs, including stable solid-state drug formulations, device portability, bolus metering and dosing, and a propellant-free dispersal mechanism. To develop pharmaceutical dry powder aerosol products, robust in vivo testing is essential. Typically, initial studies involve using a murine model for preliminary evaluation before conducting formal studies in larger animal species. However, a significant limitation in this approach is the lack of suitable device technology to accurately and reproducibly deliver dry powders to small animals, hindering such models' utility. To address these challenges, disposable syringe dosators were developed specifically for intrapulmonary delivery of dry powders in doses appropriate for mice. These dosators load and deliver a predetermined amount of powder obtained from a uniform bulk density powder bed. This discrete control is achieved by inserting a blunt needle to a fixed depth (tamping) into the powder bed, removing a fixed quantity each time. Notably, this dosing pattern has proven effective for a range of spray-dried powders. In experiments involving four different model spray-dried powders, the dosators demonstrated the ability to achieve doses within the range of 30 to 1100 µg. The achieved dose was influenced by factors such as the number of tamps, the size of the dosator needle, and the specific formulation used. One of the key benefits of these dosators is their ease of manufacturing, making them accessible and cost-effective for delivering dry powders to mice during initial proof-of-concept studies. The disposable nature of the dosators facilitates use in animal procedure rooms, where cleaning and refilling reusable systems and weighing materials is inconvenient. Thus, developing disposable syringe dosators has addressed a significant hurdle in murine dry powder delivery for proof-of-concept studies, enabling researchers to conduct more accurate and reproducible preliminary studies in small animal models for pulmonary drug delivery.

The use of dry powder inhalers (DPIs) for pulmonary drug delivery has garnered significant interest over the past three decades due to the global phase-out of chlorofluorocarbon propellants1,2. DPIs offer numerous benefits over other pulmonary delivery systems, such as metered dose inhalers and nebulizers, including formulation stability, portability, ease of use, and propellant-free dispersal mechanisms2. However, before moving DPI products toward clinical translation, several preclinical studies must be conducted, many of which are initially completed using a murine model. Nevertheles....

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All animal experiments were conducted in accordance with the Animal Welfare Act and the Public Health Service Policy on Humane Care and Use of Laboratory Animals. The study protocol was approved by the Institutional Animal Care and Use Committee of the University of Tennessee Health Science Center. Healthy female BALB/c mice, ~6-8 weeks old, were administered the dry powder content of one dosator by intrapulmonary aerosol delivery for a pharmacokinetic study using spectinamide 1599 dry powders9. T.......

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The aerosol performance of various spray-dried powders was established prior to use in this study. The aerodynamic particle size distribution (APSD) was described by the mass median aerodynamic diameter (MMAD), representing the size that divides the distribution in two at the 50th percentile (d50), and the geometric standard deviation (GSD), reflecting the breadth of the distribution. The GSD is defined by the square root of the aerodynamic diameter at the 80th percentile divided by .......

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As mice are obligate nose breathers, delivery via passive inhalation for initial proof-of-concept studies makes efficiency and dose estimation challenging as the powder must pass the nose and throat in a manner dependent on particle properties and powder dispersion efficiency7,8,14. The use of the dosators developed herein bypasses the nose and throat, with the dosator inserted to the first bronchial bifurcation

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The authors wish to acknowledge funding from the National Institutes of Health (R01AI155922). Microscopy was performed at the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), a member of the North Carolina Research Triangle Nanotechnology Network, RTNN, which is supported by the National Science Foundation, Grant ECCS-1542015, as part of the National Nanotechnology Coordinated Infrastructure, NNCI.

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Name Company Catalog Number Comments
0.6 mL microcentrifuge tubes Fisher Scientific 05-408-120
Analytical balance Mettler Toledo AR1140 Any analytical balance with sufficient range can be used
Blunt stainless-steel needle, 1 inch, 21 G McMaster-Carr 75165A681
Blunt stainless-steel needle, 1 inch, 22 G McMaster-Carr 75165A683
Blunt stainless-steel needle, 1 inch, 25 G McMaster-Carr 75165A687
Disposable syringe with luer lock (1 mL) Fisher Scientific 14-823-30 3-mL syringes can also be used
Female BALB/c mice  Charles River, Wilmington, MA, USA
High-performance cascade impactor  Next Generation Impactor Apparatus 5
Lab film (e.g., Parafilm) Fisher Scientific S37440
Low-lint wiper (e.g., Kimwipes) Kimberly-Clark Professional 34133
Low-resistance dry powder inhaler  RS01 mod 7
Polypropylene needle, 1.5 inch, 16 G McMaster-Carr 6934A111
Polypropylene needle, 1.5 inch, 18 G McMaster-Carr 6934A53
Polypropylene needle, 1.5 inch, 20 G McMaster-Carr 6934A55
Precision sectioning saw TedPella 812-300 Belt sander can be used as an alternative
PTFE needle, 2 inch, 20 G McMaster-Carr 75175A694
USP General Chapter <601>  http://www.uspbpep.com/usp31/v31261/usp31nf26s1_c601.asp

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