What aspects of formulation impact spray characteristics of nasal sprays?

Since nasal sprays are drug/device combination products, the effectiveness of the drug product itself is dependent also on the nasal spray delivery device. This requires special attention during formulation development in order to develop an effective product. During formulation, it is important to consider the following;

• Viscosity -As a formulation’s viscosity increases, the formulation becomes more difficult to atomize. This leads to larger droplets, a narrower spray plume, and smaller spray area. 
• Surface Tension – As the surface tension of a formulation decreases, the formulation becomes easier to atomize and the droplet size decreases. Smaller droplets are usually accompanied by a broader spray plume and a larger spray area.
• Density – Formulation density has a similar effect to viscosity and surface tension – as the density decreases, the formulation becomes easier to atomize and the droplet size decreases.
• Particles – The presence of small solid particles within a nasal spray suspension typically has little effect on the spray characteristics. As the solid particles get larger, however, the spray characteristics can be affected producing a bimodal distribution of droplets – one peak corresponding to the liquid droplets, the other corresponding to the solid particles.

With over 20 years of experience in nasal spray formulation, Renaissance’s dedicated research and development team can support a wide range of formulation development and optimization or device selection activities. Contact us to learn more about our nasal spray formulation and development capabilities.