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Methods Studying Factors Influencing Absorption and GI Transit of Sophisticated Dosage Forms

Explore innovative methods like pharmacoscintigraphy and in vitro permeability studies to track drug absorption and transit in the gastrointestinal tract. Radiolabeling and cell line techniques offer insights into dosage form integrity and transport mechanisms. Learn how to conduct these studies step-by-step for effective drug development.

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Methods Studying Factors Influencing Absorption and GI Transit of Sophisticated Dosage Forms

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  1. Methods that study factors that influence absorption from GIT Study GI transit of dosage forms • Newer sophisticated dosage forms • Performance: in vitro, in vivo • Plasma concentration time profiles

  2. Gamma scintigraphy A very popular, non-invasive technique for monitoring gastric transit under physiological conditions In these studies we follow • the distribution of the dosage form within the body • the integrity of the dosage form (dispersion of a controlled release pellet system within the stomach)

  3. Radiolabelling • Direct incorporation of a radiolabelled compound into the preparation • Neutron activation of a dosage form that contains a non radioactive tracer. • Technetium-99m (99mTc) or indium 111(In111) in the formulation. • Isotopes selected are those that are safe, short half-life, not absorbed.

  4. How is the procedure done? • Preparation of the dosage form • Selection of volunteers and administration of the dosage form: Healthy, non-smokers, certain age group, and we administer the labeled dosage form • Imaging • What we need is an anatomical marker and a gamma camera • Expression of the results Pharmacoscintigraphy

  5. Caco2 cells for in vitro permeability studies • For in vitro permeability specific requirements are to be met • A cell line that represent the intestinal epithelium • Polarized cell line • Tight junctions • Presence of transporters and carrier mechanisms

  6. For a transport experiment • Grow cells in transwell (compartments that have apical and basolateral compartments) • Give cells time to differentiate; develop apical and basolateral sides • Test the cells for integrity: epithelial voltometer, test the transport of a substance that is only transported paracellulary (Na fluoresein, mannitol) • Incubate the cells with buffer of interest for few minutes and let the cells equilibrate. • Add the substance to be transported at the apical side • Place in a shaker incubator • Take samples • Analyze samples • Plot the cumulative amount in the receptor vs time • Check the integrity of your cells at the end of the experiment

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