Release or Activation of D at the Target Site

The release or activation of a drug at non-target sites is the undesirable counterpart of release at the target site (see Section 13.3.1.3), determining the selectivity of the release or activation of the drug, and thus of the drug targeting. 

In principle, the release at non-target sites can be measured by the same methods as used for the target site (Section 13.3.1.3). In practice, however, measurement must be limited to one or more selected cell hues, which do not necessarily include all the non-target sites in which the drug may be released outside the intended target tissue. 

The distribution and elimination characteristics of the active drug have a profound influence on the efficiency of drug targeting. This topic is dealt with in Section 13.5. 

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