BIOL 3327 Lecture Notes - Lecture 28: Acid Dissociation Constant, Tight Junction, Lipid Bilayer
15 Jul 2020
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Dose of drug administered drug concentration in systemic circulation. Transfer of drug from site of administration to systemic circulation. A weak acid, for example, is in equilibrium with the ionized and the unionized form. Physicochemical drug properties (i. e. lipid solubility, ionized state, molecular weight) Oral medications get into the acidic stomach. If the ph is lower than the pka, the drug predominantly exists in the non-ionized form. The state of ionization of the drug is dependent on the pka of the. The non-ionized state is what crosses the membrane; the ionized state can"t permeate. If the ph < pka of a weak acid, it is in the non-ionized form. Drugs are absorbed through the epithelium of the gi tract by passive diffusion and carrier-mediated transport. Drugs get into the cell via epithelial barriers. Passive diffusion: because of the concentration gradient, something that is very lipophilic can pass through (because of the lipid bilayer)
