Page 200 - Pharmaceutics IV (02-06-01305)

Peptides are naturally occurring or synthetic compounds that
contain one or more amino acid sequences or groups
,Radiolabeled peptides are new class of radiotracers that target a
cell or tissue & deliver a diagnostic agent or therapeutic agent to
the site of the disease. It has the advantage over MABs of being
more rapidly cleared from the body ,with lower level of toxicity,,
they provide physiological evidence of the nature of the disease
processor progress of treatment .The first peptide analogs is
somatostatin analogs to treat tumors ,brain tumor types
,pancreatic islet tumors.

Selection of radioisotopes as radiotherapy

It depends on:

1-The type &energy of radiation emitted by the isotope.

2-Its depth to tissue penetration .

Chemical identity & reactivity are of relatively less importance for

Radiotherapy applications.

Optimally , therapeutic radiopharmaceuticals are designed for site
specificity & based solely upon physiological function of the target
organ even if the actual location of the cancerous tumor is
unknown.

The mechanism of localization of the radiopharmaceutical in a
particular target organ depends upon processes as varied as
antigen-

antibody reactions ,physical trapping of particles ,receptor site
binding ,and transport of chemical species across a cell membrane
,among others .Ideally ,the radiopharmaceutical will cause minimal

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