Dry powder inhaler

A Dry Powder Inhaler (DPI) is a medical device designed to deliver therapeutic agents to the lungs in the form of a fine dry powder. DPIs play a pivotal role in the treatment of respiratory diseases and have even found applications in managing other conditions like diabetes mellitus.

Overview

Unlike the traditional aerosol-based inhalers known as metered-dose inhalers (MDIs), DPIs deliver the medication in a dry powder form. The fundamental advantage of DPIs lies in their propellant-free nature and the potential for improved drug deposition in the lungs.

Mechanism of Action

The medication in DPIs is typically encapsulated either in a capsule, which is manually loaded, or in a proprietary form integrated within the inhaler. Upon activation, the user places the inhaler's mouthpiece into their mouth and inhales deeply, holding the breath for a duration of 5-10 seconds. This process ensures the optimal delivery of the medication to the respiratory tract.

A crucial aspect of the DPI's functionality is the force of patient inhalation. It is this force that entrains the powder from the device, breaking it into minuscule particles, optimized for pulmonary delivery.

Dosage and Limitations

Given the nature of DPIs, the deliverable dose is often less than a few tens of milligrams per inhalation. Exceeding this can result in coughing, making it counterproductive. Furthermore, due to the inhalation force required, DPIs are typically recommended for older children and adults.

Lactose in DPIs

Some DPI formulations incorporate lactose as a bulking agent, aiding in the powder's uptake during inhalation. While concerns have been raised about its effects on lactose intolerant individuals, the minute quantities used in DPIs (typically a few milligrams) do not result in clinically significant adverse reactions in such patients.

Storage Recommendations

It's vital to store DPI medications in dry conditions, ideally at temperatures below 25°C, with a humidity level between 40-50%. Such storage conditions prevent the degradation of the powder's dispersal properties. The medication should also be kept in sealed packaging to maintain its efficacy. Some DPI medications might require protection from light to prevent degradation.

Advantages and Disadvantages

DPIs have garnered popularity owing to certain advantages over traditional inhalers:

• No Propellants: Unlike MDIs, DPIs do not utilize harmful propellants.
• Improved Lung Deposition: Optimal particle size ensures better drug deposition in the lungs.

However, DPIs also come with certain limitations:

• Inhalation Technique: Proper inhalation technique is pivotal for effective drug delivery.
• Humidity Sensitivity: DPIs are sensitive to moisture, which can compromise the drug's dispersion capability.

See Also

• Inhaler
• Metered-dose Inhaler
• Nebulizer
• Respiratory therapy

Dry powder inhaler Resources
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