Investigation into the impact of fines on electrical charging of lactose in dry powder inhalers

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Summary

Lactose powder blends have been prepared by blending in a high shear mixer, followed by filling into gelatin and HPMC capsules. The lactose blends consisted of a coarse grade of lactose, mixed with one of two types of fine grades of lactose, in order to engineer the particle size distribution. The electrical charging properties were characterized using the BOLAR, Dekati, Finland, by actuation from two different devices: The CDM-haler and the Cyclohaler.  The electrical charging data was analysed in order to understand which factors were governing the charging behaviour of the described placebo powders.  It was found that positive and negative charge levels were primarily governed by the amount of lactose fines and by the material of the capsule. In contrast to this, the net charging of the placebo lactose was governed by the inhalation device used. It is suggested that the way the capsules are punctured has an impact on this outcome, although more research is required to fully understand these effects.

Key Message

Electrical charging of lactose is largely determined by the particle size of lactose, however net charge is mainly determined by type of inhaler.  A deeper understanding factors that influence lactose electrical charging in dry powder inhalers may improve drug product performance.