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Methods that study factors that influence absorption from GIT

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. Gamma scintigraphy

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Methods that study factors that influence absorption from GIT

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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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