Physicochemical Properties
Solubility:
Drugs should have moderate solubility to ensure consistent release.
Extremely soluble drugs may release too quickly; poorly soluble drugs may not release adequately.
Partition Coefficient:
Affects drug permeability across biological membranes.
Optimal balance between lipophilicity and hydrophilicity is crucial.
Molecular Weight and Size:
Smaller molecules diffuse more readily through polymers and membranes.
Larger molecules may require specialized systems like nanoparticles.
Stability:
Chemical and physical stability in the formulation and biological environment.
Sensitivity to pH, enzymes, or other degradation pathways must be considered.
Biological Properties
Absorption:
Consistent and predictable absorption profiles are necessary.
Drugs absorbed throughout the GI tract are ideal.
Metabolism:
Drugs extensively metabolized in the first pass may not benefit from oral CDDS.
Alternative routes or targeted delivery may be required.
Half-life:
Drugs with short half-lives are good candidates as CDDS can prolong their action.
Extremely long half-life drugs may not need controlled release.
Therapeutic Index:
Drugs with a narrow therapeutic window require precise control over release rates.
Safety margins must be maintained to prevent toxicity.