Main Requirements for a Pharmaceutical Suspension

The main criteria for pharmaceutical suspensions are [35-37] Colloid and physical stability, with acceptable shelf-life under storage conditions colloid stability indicates the lack of any strong irreversible flocculation. On application, any aggregates should be broken down to single particles (weak flocks are broken under shear). 

One of the main requirements of pharmaceutical suspension is the lack of Ost-wald ripening (crystal growth), i.e. the growth of particles on storage that results in shift of particle size distribution to larger values. This may affect bioavailability and results in physical instability. 

Physical stability implies uniformity of the suspension whereby the particles are equally distributed across the whole vehicle. Uniformity of the suspension on application is vital. This means that the viscosity of the suspension should be low enough to ensure uniformity. 

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