Designing carriers for inhalation drug delivery

10 Nov 2016. Pharmaceutical scientists from NUS have developed tchniques to modify lactose carrier particles in dry powder inhalers for efficient drug delivery to the lungs.

A team headed by Prof Paul W S HENG and Prof CHAN Lai Wah from the GEA-NUS Pharmaceutical Processing Research Laboratory in the Department of Pharmacy, NUS has successfully developed techniques for producing carrier particles which improve drug delivery through inhalation to the lungs. The reported findings are from the research work conducted by the Ph.D. student, Ms Bernice TAN Mei Jin. To achieve maximum deposition in the lungs, drug particles must be easily detached from their carrier particles in the airstream when the patient forcefully inhales the medication. The team found that the efficiency of drug delivery is controlled by the amount of carrier surface roughness. Rough granular carrier particles, produced by roller compaction, doubled the amount of drug that can be delivered into the lungs, compared to unprocessed lactose particles. These newly developed “rough” carrier particles also performed significantly better than inhalable grades of lactose particles which are available commercially.

Administration of medications through the inhalation route, like the oral route, is a non-invasive and convenient method for most patients. However, inhalable drug products have to be designed effectively to overcome the natural barriers created by the respiratory tract which potentially block inhaled drug particles. For many dry powder inhalers used clinically, only about 10 – 30 % of each dose of drug can be successfully delivered to the lungs. The remaining drug particles may either remain trapped in the inhaler or are deposited in other regions of the respiratory tract, where they do not exert any therapeutic effect. Therefore, formulation scientists are actively seeking ways to improve either the drug formulation or the design of inhalers.

The team’s strategies, which only result in the physical (and not chemical) modification of lactose carriers, are likely to be well-received by the pharmaceutical industry. This is because a very limited number of pharmaceutical excipients (substance formulated alongside the active ingredient of a medication) are available for use in inhalable drug products. In addition, the techniques for surface roughness modification can be adopted rapidly on an industrial scale as they use pharmaceutical manufacturing equipment common to the industry.

Moving forward, the applicability of the team’s findings will be tested in formulations containing different inhalable drug compounds. The concept of using rough lactose particles as carriers for fine drug particles may also be explored in other areas of solid dosage form processing, such as in blending and tableting operations.

Figure with scanning electron microscope images showing surface morphologies of smooth (left) and rough (right) carrier particles. Surface roughness can be quantified by profiling the surface topographies of carrier particles using an optical profiler. [Image credit: Tan BMJ]

Reference

Tan BMJ; Chan LW; Heng PWS*, “Improving Dry Powder Inhaler Performance by Surface Roughening of Lactose Carrier Particles” PHARMACEUTICAL RESEARCH Volume: 33 Issue: 8 Pages: 1923-1935 DOI: 10.1007/s11095-016-1928-y Published: 2016