KINE 2475 Lecture Notes - Lecture 19: Nephron, Weak Base, Reabsorption
13 Jan 2020
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Document Summary
As free drug concentration in plasma increases, gfr for drug increases proportionately, increase clearance: active tubular secretion is carrier mediated that requires energy to transport against concentration gradient. For drugs partially reabsorbed without being secreted, clearance is less than. Reabsorption: reabsorption significantly reduce amount drug excreted , depending on ph of urinary fluid & pka of drug, urinary ph can vary from 4. 5-8. Undissociated are lipid soluble & has greater membrane permeability. Undissociated drug is readily absorbed from renal tubule back to body: amphetamine, a weak base will be reabsorbed if urine ph is made alkaline & more lipid soluble nonionized species formed. Acidification of urine will cause amphetamine to become more ionized. Salt it more water soluble & less likely to be reabsorbed & thus more excreted. Secretion is influenced by transported which are saturable. Reabsorption is influenced by urine ph, pka of drug, increase in blood flow to kidney.
