Ingredient-Specific Particle Sizing of Aerosolized Nasal Spray Using Wide-Field Raman Chemical Imaging

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Intranasal drug delivery is an attractive delivery method for a broad range of pharmaceuticals that treat a variety of diseases. This patient-friendly delivery method can provide multiple benefits like the reduction in potential side effects and increased compliance of the drug treatment.

Creating the correct nasal formulation is challenging, yet critical. Nasal sprays formulated as suspensions typically contain micronized active pharmaceutical ingredient (API) in the presence of multiple excipient materials.

Drug particle size directly correlates to bioavailability and drug effectiveness, and is a key measurement in evaluating bioequivalence of generic nasal spray suspensions. Although particle size distribution (PSD) of the drug substance can be easily determined prior to the formulation, it has been a challenge to determine drug PSD in the formulation.

Particle sizing techniques based on laser scattering, cascade impaction or optical image analysis cannot discriminate between particles of API and those of an excipient or a surfactant. Optical microscopy is the current recommended method for particle sizing, but the selection of particles is manual and relies on human subjectivity. In vitro testing methods are frequently preferred over in vivo methods, which are often costly, time consuming and inconclusive. Consequently, the development of an efficient ingredient-specific particle sizing approach is essential for ensuring that all ingredients fall into the proper size range, particularly during the early stage of product development.


David Exline has more than 20 years of experience in managing and administering analytical laboratory and consulting services. As President of Gateway Analytical, he oversees the company’s day-to-day operations, business growth and service areas.