Basic Requirements on Dry Powder Inhalation Excipients

Introduction
Dry powder inhalation excipients are ingredients used in the formulation of dry powder formulations for inhalation delivery. These excipients provide essential functionalities to enhance the dispersion, flowability, stability, and drug delivery performance of the dry powder formulations. They play a crucial role in achieving optimal drug deposition in the lungs for effective respiratory therapy.

Subtypes of Dry Powder Inhalation Excipients
Carriers
Dry powder inhalation carriers are excipients that provide bulk to the formulation and aid in the dispersion and delivery of the active pharmaceutical ingredient (API) to the lungs. They improve the flow properties of the powder, ensure uniform mixing with the API, and enhance powder dispersion during inhalation. Common carrier excipients include lactose, mannitol, and trehalose.

Dispersants
Dry powder inhalation dispersants are excipients that promote the breakup of agglomerates and improve the dispersibility of the powder upon inhalation. They enhance the fine particle fraction and ensure consistent drug delivery to the lungs. Dispersants help overcome the cohesive forces between particles, improving the aerosolization and deposition of the drug in the respiratory tract.

Surface Modifiers
Dry powder inhalation surface modifiers are excipients used to modify the surface properties of the powder particles, enhancing their dispersibility and reducing particle interactions. They can improve the flowability, reduce aggregation, and enhance the aerosol performance of the dry powder formulation. Surface modifiers include surfactants, anti-static agents, and surface-active materials.

Co-solvents
Dry powder inhalation co-solvents are excipients used to enhance the solubility and dissolution rate of poorly soluble drugs in the respiratory tract. They improve drug absorption and bioavailability by increasing drug solubility in the lung fluid. Co-solvents can enhance drug delivery to the target site and improve therapeutic outcomes.

Basic Requirements on Dry Powder Inhalation Excipients
1. No odor, easily absorbed by respiratory mucosa, and no irritation to respiratory mucosa or cilia.

2. Should be physiologically acceptable substances

3. The surface roughness is suitable, while maintaining appropriate adhesion with the drug micropowder

4. Suitable size, so as not to produce a large mechanical resistance. The type of carrier, particle size determines the amount of drug micropowder settled in various parts of the respiratory tract.

5. Have appropriate cohesion and good fluidity

Conclusion
The percentage of the carrier used to prepare the aerosol is greater than the percentage of the APIs, therefore, the quality and efficacy of the drug can be guaranteed by choosing the appropriate excipients.