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15 Cards in this Set
- Front
- Back
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What form of a drug commonly crosses the cell membrane? What is ion trapping?
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Nonionized form because it is more lipid soluble. Ion trapping occurs when there is a pH gradient -- drug is trapped on side with higher ionized fraction.
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Which route has the least first-pass effect? What limits the use of this route?
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Sublingual -- limited by small surface area available.
Rectal also less first-pass but variable absorption |
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What is redistribution?
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Rapid entry and exit for lipophilic drugs from richly perfused organs (brain, heart)
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How will drugs distribute across the placenta?
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Simple distribution.
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What is a competitive antagonist and what is its significance in anesthesia?
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Compete with receptor agonists for receptor site. They are all reversible.
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What is drug clearance? Upon what is it dependent?
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Theoretic volume of blood from which drug is completely removed. Dependent on 3 factors:
1) Hepatic blood flow 2) Intrinsic ability of liver to eliminate drug 3) Degree of protein binding |
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What is first-order elimination?
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Constant fraction of drug eliminated per unit of time
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How do low extraction ratio and high extraction ratio affect drug clearance?
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Low extraction is intrinsic clearance -- more dependent on liver intrinsic avility, less on HBF. High extraction more dependent on HBF with extensive first pass metabolism.
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How does liever disease decrease drug clearance?
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Decreases drug clearance by:
1) Hepatic dysfunction 2) Altered hepatic blood flow 3) Both of the above |
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How do volatile anesthetic agents affect hepatic blood flow?
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All VA decrease it
Iso < Hal < Enflurane |
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What are the types of drugs that are filtered/reabsorped?
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Only unbound drug passes through the glomerular mem. to be filtered or reabsorped. Passive diffusion is reabsorption method
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What is the relationship between RBF, GFR and mean arterial pressure?
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RBF and GFR are autoregulated at MAP between 70 and 160 mmHg
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Name a few drugs commonly used in anesthesia with sig renal excretion
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Aminoglyocosides
Atenolol Cephalospoins Neostigimine Penicillin |
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What are the two main plasma proteins responsible for drug binding? What is the major difference between the two?
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Two main plasma proteins are:
1) Albumin 2) Alpha acid glycoprotein (AAG) Albumin bind acids and some bases; AAG basic only |
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What is volume of distribution? How does it affect dosing of medications in anesthesia? What is drug clearance?
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Volume of distribution is index of drug dist'n. If drug has larger VD -- it takes more drug to "fill up the box" Various path conditions alter it.
Drug clearance is ability of system to irreversibly eliminate a drug. It is portion of VD in a given interval. |
