Particle size is an important characteristic for many dosage forms. Stability, flowability, dissolution rate, and bioavailabilty are among the parameters affected by the size distribution of particles. Cirrus Pharmaceuticals, Inc. provides a wide range of services to meet our clients' particle sizing needs, from formulation development to in-line process monitoring to quality control and release of finished product. Our highly trained scientists carry out particle sizing method development, validation, and routine analysis under cGMP guidelines to address the complexities of technical and regulatory challenges.

Particle size reduction is often used to:

Cirrus has the staff and equipment to reduce compound particle size using a variety of milling machinery. Milling process development can be conducted and scaled-up at Cirrus, then transferred to a manufacturing facility as needed.

Laser diffraction is a rapid and highly reproducible means of determining the particle size distribution of powders, emulsions, suspensions, and sprays over a range of 0.1 µm to 1000 µm. A wide range of accessories and lenses allow us to sensitively measure particle and droplet size distributions of bulk powders and particulate products as well as emitted doses from devices such as metered dose inhalers, nasal sprays, and nebulizers. With dry dispersion and aqueous/non-aqueous wet dispersion capabilities, we have a wide range of options in optimizing a method for drug product or in-process samples. We have also perfected techniques for reducing sample size to the low milligram range for precious materials. With correctly optimized sample dispersion, method precision is typically in the 1% range. A Malvern Zetasizer is used for nanparticle (submicron) measurements.

Inertial impaction methods are widely used to determine the aerodynamic particle size distribution of aerosols. Aerosol particles with sufficient inertia impact upon the collection stage while smaller particles follow the airflow out of the impaction region. Since each stage represents a discrete particle size range, a size distribution can be determined by assaying the drug particles collected on each stage.

Microscopy can be used as a stand-alone particle sizing method or as a complement to other methods. As an absolute method, it can be used to verify results from other methods; to differentiate between primary particles and aggregates; and to provide information on particle shape and morphology.