My eye was recently drawn to an interesting piece of research from Melbourn Scientific, in the first instance, I have to admit, because it was adorned with a beautiful shot of our Spraytec laser diffraction analyzer!
The article is about the attractions and challenges of formulating thixotropic nasal sprays but more generally it provides some useful information about the analytical techniques that can help to accelerate nasal spray development.
The benefits of thixotropy
Thixotropic substances are gel-like when stationary but have very low viscosity when subject to shear. Its easy to appreciate that such materials make ideal nasal spray formulations. Stable suspensions in the bottle they are rapidly converted with a quick shake into an easily delivered liquid that becomes gel-like once more when safely deposited in the nose.
As the article points out though, formulating such products can be quite demanding, one complication being that the additives needed to impart thixotropy can make it difficult to identify and size the active ingredient within the formulation.
The Melbourn Scientific team discusses two techniques that they use to rapidly acquire data for nasal spray development. One is laser diffraction which provides information about dispersed droplet size and the concentration of the delivered plume. The other is automated imaging, a faster more statistical alternative to microscopy for detailed of study of the particles in a formulation.
Both techniques are rapid, complementing more traditional inhaled product characterization methods that can be relatively time-consuming.
A good read
I’d recommend the article to those of you interested in nasal spray technology especially if you’re struggling to understand how a formulation is behaving. Alternatively contact us via the blog or any of our other channels and we’ll see if we can help.