Dry-powder inhaler

Dry Powder Inhaler

Various types of dry powder inhalers

A dry powder inhaler (DPI) is a device that delivers medication to the lungs in the form of a dry powder. It is commonly used for the treatment of asthma, chronic obstructive pulmonary disease (COPD), and other respiratory diseases. Unlike metered-dose inhalers, which use a propellant to deliver medication, DPIs rely on the patient's own inhalation effort to disperse the powder into the lungs.

Mechanism of Action

Dry powder inhalers work by using the patient's inspiratory flow to aerosolize the medication. When the patient inhales through the device, the air flow carries the powder into the lungs. The effectiveness of a DPI depends on the patient's ability to generate sufficient inspiratory flow to disperse the powder.

Types of Dry Powder Inhalers

There are several types of dry powder inhalers, each with unique mechanisms for delivering medication:

• Single-dose inhalers: These devices require the patient to load a single dose of medication before each use. An example is the HandiHaler.

• Multi-dose inhalers: These devices contain multiple doses of medication, which are preloaded by the manufacturer. Examples include the Diskus and Turbuhaler.

• Reservoir inhalers: These devices have a reservoir of medication that can be used for multiple doses. The Twisthaler is an example of a reservoir inhaler.

Advantages and Disadvantages

Advantages

• No propellant required: DPIs do not use propellants, making them environmentally friendly compared to some metered-dose inhalers.
• Ease of use: Many patients find DPIs easier to use because they do not require coordination between actuation and inhalation.
• Portable and convenient: DPIs are typically small and easy to carry, making them convenient for patients to use on the go.

Disadvantages

• Dependence on inspiratory flow: Patients with low inspiratory flow, such as young children or those with severe respiratory impairment, may have difficulty using DPIs effectively.
• Humidity sensitivity: DPIs can be sensitive to humidity, which may affect the stability and delivery of the medication.

Usage and Technique

Proper technique is crucial for the effective use of dry powder inhalers. Patients should be instructed to:

1. Prepare the inhaler: Depending on the type of DPI, this may involve loading a dose or twisting the device to prime it. 2. Exhale fully: Before inhaling, the patient should exhale fully away from the inhaler to avoid moisture entering the device. 3. Inhale forcefully and deeply: The patient should place the mouthpiece in their mouth and inhale forcefully and deeply to ensure the medication reaches the lungs. 4. Hold breath: After inhaling, the patient should hold their breath for about 10 seconds to allow the medication to settle in the lungs.

Related Pages

• Asthma
• Chronic obstructive pulmonary disease
• Metered-dose inhaler
• Inhaler