Solid State Properties

The surface area is an important parameter for solid material, which provides information on the available void spaces on the surfaces of individual particles or aggregates of particles. The surface area of a solid dosage drug plays a role in its dissolution profile. We carry out surface area determination by using BET method which is considered as the most widely used and reliable method.

Pharmaceutical particle and powder characterization plays a key role in pharmaceutical manufacturing processes. Particle size distribution will influence the flowability of a powder, thereby affecting processing, blending, tableting, dissolution, delivery and bioavailability. The appropriate particle size distribution is important for preventing aggregation or agglomeration of particles in suspensions and emulsions, which could impacts stability and distribution of materials in the drug product. We apply a variety of methods to determinate the particle size distribution of solid pharmaceutical. Normally, size distribution of particle in suspensions is analyzed using Dynamic Laser Light Scattering (Zetasizer Nano), and size distribution of powders is tested using the Laser Light Scattering.

A drug substance can exist in two or more crystalline phases which are chemically identical but physically distinct, the property is defined as polymorphism. The existence of drug polymorphism can impact formulation strategies and bioavailability. Characterization of relevant polymorphism properties provides the understanding needed for subsequent substance development, including crystallization process scale-up. Many techniques we use to confirm polymorphic form may involve optical microscopy, XRD, DSC, FTIR, near infrared (NIR), Raman spectroscopy, and solid-state NMR.

Stability of dosage forms is critical to proper drug release, which is defined as the capability of a particular formulation to retain its physical, chemical, therapeutic, microbiological & toxicological specification in a specific container/closure system. Solid state stability testing aims to identifying stable storage conditions for drug product, and compatible excipients for the formulation. Stability testing is performed at various stages of the product development to ensure the maintenance of product quality, safety and efficacy. Solid-State NMR can help us to shed light on pharmaceutical solid state stability.

How fast a compound is released from the crystal lattice into solution can be described by the parameter dissolution rate. The dissolution rate is one of the important parameters for solid pharmaceutical since it influences dissolution from dosage forms, and then has an impact on therapeutic effectiveness. The intrinsic dissolution rate (IDR) is the dissolution rate when extrinsic factors (such as temperature, pH, and surface area conditions) are held constant. There are two types of IDR test method listed in pharmacopeias: a fixed-disk system and a rotating-disk system (known as "Wood's apparatus"). Our analytical scientists obtain IDR through the rotating-disk system which is used most commonly.

Thermal analytical is important methods for characterizing the properties and structure of pharmaceutical product. Thermal analysis techniques are used in solid-state characterization, there are a range of applications: study of physicochemical properties of crystalline solids, identification of compound polymorphic forms, study of solid-state kinetics and analyzing the effects of lyophilization. The thermal analysis techniques we used commonly for the pharmaceutical materials include differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA).