The click and puff of inhalers is a universal signal for respiratory conditions. Inhalers quickly grew into preferred drug delivery systems for asthma and COPD. Dry inhaler powder formulation produces a more stable drug than liquid dosage forms. Moreover, inhaler ingredients are more resistant to bacterial growth.
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Mill inhaler powder materials to achieve good particle size distribution
The recommended particle diameters for optimal aerosols preparation range from 1 to 5 µm. Smaller particles clump together while larger diameters lose their cohesive properties.
Reduce the diameters of coarse particles before mixing the ingredients for dry inhaler powder formulation. Jet milling applies high-impact forces combined with compressed gas to produce micro sizes.
Engineered blends improve the processing of dry inhaler powder formulations
Add carrier particles to the API mix to improve the processing properties of bulk powders. However, the particles of drugs and carriers must be chemically compatible. Their reciprocal adhesive forces need to be powerful enough to hold the mixture together during filling and storage. At the same time, they need to be quickly detachable during aerosol administration.
Coarse lactose monohydrate improves powder flowability during manufacturing and provides good carrier-particle separation. Lactose blends are formulated with drug contents of 5% (w/w) or less.
HPMC capsules are more stable for mono-dose inhaler systems
Mono-dose inhalers deliver a single serving of powder formulation by loading a capsule into the device before each use. Depending on the system, the capsule is activated by sheer force opening, needle-piercing, or cutting the capsule. But moisture content is a critical consideration for each technique.
Very dry conditions apply pressure on traditional gelatin-based capsules, causing them to crack before use. Hypromellose capsules (HPMC), on the other hand, is less hygroscopic and behaves well in both wet and arid environments.