A novel gas phase method for the combined synthesis and coating of pharmaceutical particles

Purpose

A novel aerosol flow reactor method for the combined gas phase synthesis and coating of particles for drug delivery has been developed.

Materials and Methods

As an example, micron-sized salbutamol sulfate particles were produced via droplet-to-particle conversion and in-situ coated by the physical vapor deposition (PVD) of l-leucine vapor.

Results

During the deposition, l-leucine vapor crystallized on the surfaces of amorphous salbutamol particles. The size of l-leucine crystallites increased with increasing vapor concentration of l-leucine. The salbutamol particles with rough l-leucine surfaces exhibited good flowability enabling to them to be dispersed into air flow without the delivery aid of coarse lactose carriers.

Conclusions

The fraction of particles smaller than 5 micrometers varied between 0.35 and 0.48 when dispersed into 60 l/min air flow having a jet Reynolds number of 30700. When the coated fine particles were blended with lactose carriers, the fine particle fraction was as high as 90%. The l-leucine coating also improved the stability of salbutamol particles when stored at 45% relative humidity atmosphere.