Dry Powder Inhalers (DPI) are used to deliver a controlled dose of active pharmaceutical ingredient (API) to the deep lung. Lactose is a commonly used as an excipient in this process, carrying the fine particles of the API from the capsule before being carried away as the API continues to the lungs. The coarser lactose is usually trapped in the throat and subsequently swallowed. The properties of the lactose will influence performance of the DPI, including during processes such as filling, dosing and drug release.
Identifying the properties of a powder or blend which enable the production of capsules of uniform mass allows new formulations to be optimised, without the significant financial and time implications associated with running samples through the process, and helps reduce the occurrence of poor dosage uniformity and high weight variation.
Obtaining Process Performance
Five lactose powders, with varying particle size distributions, were run through a dosator (Lab Dosator, 3P Innovation, Warwick, UK) using four different size outlets, (decreasing from Dosator 1 to Dosator 4). A dosed mass of 50mg with RSD<2% was targeted. RSD values for each lactose-dosator combination are shown in Table 1.
| D50 Particle Size Range, µm | Dosator 1 | Dosator 2 | Dosator 3 | Dosator 4 |
Lactose 1 | 180-250 | 2.27 | 2.4 | 2.06 | 0.89 |
Lactose 2 | 110-155 | 3.77 | 1.54 | 1 | 1.08 |
Lactose 3 | 70-110 | 1.84 | 0.85 | 0.79 | 0.56 |
Lactose 4 | 40-70 | 1.34 | 2.02 | 2.13 | 4.41 |
Lactose 5 | 4-11 | 3.76 | 7.05 | 7.59 | 8.32 |
The FT4 Powder Rheometer® is a universal powder tester that provides automated, reliable and comprehensive measurement of bulk material characteristics. This information can be correlated with process experience to improve processing efficiency and aid quality control. Specialising in the measurement of dynamic flow properties, the FT4 also incorporates a Shear Cell, and the ability to measure bulk properties such as density, compressibility and permeability, enabling a comprehensive characterisation of the powder in a process relevant context.
Dynamic testing employs a patented measurement technique to determine a powder’s resistance to flow. A specially shaped blade traverses along a prescribed path through a...
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