Wk4 Absorption And Distribution Of Drugs

Question 1

What does the ability of drugs to diffuse through membrane depend on?

Answer 1

lipid solubility and a good indication of lipid solubility is the solubility of the drug in a non-polar solvent such as octanol

Question 2

Reversed-phase TLC

Answer 2

TLC plates, which consist of a thin layer of methylcellulose on a glass or plastic backing sheet, are precoated with octanol to provide an organic stationary phase.
Drugs are then “spotted” carefully onto the plate along a line 1cm from the bottom (the origin). The plate is placed in a glass tank containing an aqueous buffer as the mobile phase and this aqueous buffer is allowed to run up the plate by capilliary action. When the solvent front has travelled a suitable distance up the plate, the plate is removed from the tank, the position of the solvent front is marked and the plate is dried. The plate is viewed under a UV lamp to visualize the spots of drug, which can been seen as either fluorescent spots or dark “shadows” against the slightly fluorescent background of the plate.

Question 3

RF value

Answer 3

Distance of drug from origin/distance of solvent front from origin