Dry-Powder Inhalers

Dry-Powder Inhalers

Ariel Berlinski, MD, FAAP

Introduction

•Dry-powder inhalers (DPIs) are devices than can deliver medications to the lungs without the need for a suspending medium.

•DPIs are mainly used in pediatric patients to treat asthma (bronchodilators, corticosteroids, and combination corticosteroid and long-acting bronchodilator) and cystic fibrosis (tobramycin).

•Currently, all devices available in the United States are passive and breath actuated.

•The inspiratory force (peak inspiratory flow) required of the patient to overcome the internal resistance of the device is responsible for the deagglomeration of the dry powder when it is released from the device.

—A minimum inspiratory flow threshold is needed (30–40 L/min for most devices).

—For most devices, the higher the inspiratory flow, the higher the intrapulmonary deposition of the drug.

•DPIs can deliver larger quantities of drugs than pressurized metered-dose inhalers.

•Many formulations use a carrier, such as lactose.

•The advantages and disadvantages of the use of DPIs are listed in Box 108-1.

Types of DPI Devices

•There are many configurations of DPI devices.

—Single-dose devices (Figure 108-1)

▪These devices require placement of a capsule in the device.

—Multidose devices (Figure 108-2)

▪Common reservoir

▪Individually packed blister strips or cartridge

▪Incorporated dose counters

Proper use of DPIs

Dose Preparation

•The dose to be inhaled has to be loaded in the device.

•For some devices, this step automatically occurs when the patient opens the device or removes the cap.

Box 108-1. Advantages and Disadvantages of the Use of Dry-Powder Inhalers

Advantages	Disadvantages
Compact, portable	Strong and consistent inspiratory effort is needed
Rapid delivery	High oropharyngeal deposition
Multidose with counters	Vulnerable to humidity
Breath actuated	Not suitable for younger children
No need for a valved holding chamber or spacer	Technique confusion is possible if used with other devices that require slow inhalation

Modified from Geller D, Berlinski A . Aerosol delivery of medication . In: Light MJ, Homnick DN, Schechter MS, Blaisdell CJ, Weinberger MM, eds . Pediatric Pulmonology. Elk Grove Village, IL: American Academy of Pediatrics; 2011:913–932 .

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