Table 1.

Exponent n of the power law and drug release mechanism from polymeric controlled delivery systems of different geometries.

Exponent, n			Drug release mechanism
Thin film	Cylinder	Sphere
0.5	0.45	0.43	Fickian diffusion
0.5 < n< 1.0	0.45 < n< 0.89	0.43 < n< 0.85	Anomalous transport
1.0	0.89	0.85	Case II transport