Microparticles are spherical particles between 0.1μm and 100μm in diameter. They fall into two broad groups. Microspheres are homogenous mixtures of polymers and active ingredients, and microcapsules have a core of one substance surrounded by a shell of a different material.
Microparticles are suitable for a broad range of drug delivery applications, and they offer many advantages.
- Their small particle size offers improved reproducibility in the drug release mechanism.
They offer improved control over the release rate of the drug.
- They present a range of options for immediate, modified, delayed, pulsed, sustained and extended release.
- They allow the preparation of dosage forms for targeted delivery through the use of coatings designed, for example, for enteric protection or colonic delivery.
- They can be easily filled into capsules.
- They can be used to manufacture high-dose suspensions suitable for preclinical toxicology programmes.
- They do not require expensive processing equipment, and so allow quick, cost effective development studies to be carried out.
- Their reduced particle size gives them the potential to improve solubility and bioavailability.