Microspheres, nano suspensions
Microspheres - sometimes referred to as microparticles - are small spherical particles with diameters in the micrometer range (typically 1 μm to 1000 μm). Poorly soluble drugs, depending on the dose and desired duration, are generally formulated as micro- or nanosuspensions to control drug release in vivo. Flow-through cell dissolution can serve as an in vitro testing method to monitor critical quality attributes of nanonized drug suspension parenteral long-acting formulations to drive formulation development and process optimization. For example, dissolution procedures for polymeric LAP formulations aim to address differences in the erosion and/or hydration of the polymer during drug release, while methods for suspension formulations primarily target the differences in API physico-chemical properties (i.e. particle sizes, morphology, intrinsic dissolution rate, etc.).