Disposable Dosators Intended for Dry Powder Delivery to Mice

Summary

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.

Abstract

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.

Introduction

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 propellants^1,2. 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....

Protocol

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.......

Discussion

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 efficiency^7,8,14. The use of the dosators developed herein bypasses the nose and throat, with the dosator inserted to the first bronchial bifurcation

Materials

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