Controlled release implies that the activity of a
substance is controlled.
Controlled, or sustained, release from a formulation
is achieved e.g. by use of polymers or structured
systems like liquid crystals and lipid crystals.

During oral delivery, release properties are commonly
adjustable by changes in pH of the gastric tract or
by enzymatic activity.

An example of a product, where both drug targeting
and drug release are used, is described at the
website of Microbionical.

      Drug targeting    
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