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Pharmacokinetics

april yao 10 questions Updated 8 Oct 2016

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Questions in this quiz (10)

  1. 1To achieve its effect a drug must first be presented in a suitable formulation at an appropriate site of [blank_start]ADMINISTRATION[blank_end] and then (usually) [blank_start]ABSORBED[blank_end] and [blank_start]DISTRIBUTED[blank_end] through the body to its site of action. For the effect to wear off the drug must almost always be [blank_start]METABOLISED[blank_end] and/or [blank_start]EXCRETED[blank_end] with these residues being [blank_start]VOIDED[blank_end] (REMOVED) from the body.
    1. AADMINISTRATION
    2. BABSORBED
    3. CDISTRIBUTED
    4. DMETABOLISED
    5. EEXCRETED
    6. FVOIDED
  2. 2Administration:
    [blank_start]SYSTEMIC[blank_end] - the entire organism
    [blank_start]LOCAL[blank_end] – restricted to one area of the organism

    [blank_start]ENTERAL[blank_end] - Gastro-intestinal admin + involvement
    [blank_start]PARENTERAL[blank_end] – Outside GI tract admin

    1. ASYSTEMIC
    2. BLOCAL
    3. CENTERAL
    4. DPARENTERAL
  3. 3Absorption:
    Drug molecules move around the body in two ways:
    [blank_start]Bulk flow[blank_end] transfer i.e. in the bloodstream
    [blank_start]Diffusional[blank_end] Transfer i.e. molecule by molecule over short distances
    Drugs have to traverse both aqueous and lipid environment
    [blank_start]Compartments[blank_end] = Aqueous e.g. Blood, lymph, extra-cellular fluid, intra-cellular fluid
    [blank_start]Barriers[blank_end] = Lipid i.e. cell membranes (epithelium/endothelium)
    1. ABulk flow
    2. BDiffusional
    3. CCompartments
    4. DBarriers
  4. 4How do drugs cross barriers?
    1) Diffusing through [blank_start]lipid[blank_end]
    2) Diffusing through [blank_start]aqueous pores[blank_end] in the [blank_start]lipid[blank_end]
    3) [blank_start]Carrier[blank_end] molecules
    4) [blank_start]Pinocytosis[blank_end]

    1 and 3 being main mechanisms
    1. Alipid
    2. Baqueous pores
    3. Clipid
    4. DCarrier
    5. EPinocytosis
  5. 5Non-polar substances can freely dissolve in non-polar solvents i.e. can penetrate lipid membranes freely.
    Passive diffusion - the [blank_start]pH partition[blank_end] hypothesis
    Also gives rise to the mechanism of [blank_start]ion trapping[blank_end]

    Very Important:
    Most drugs are either [blank_start]weak[blank_end] acids or [blank_start]weak[blank_end] bases.

    Therefore drugs exist in ionised (polar) and non-ionised (non-polar) forms – the ratio depends on the [blank_start]pH[blank_end]
    1. ApH partition
    2. Bion trapping
    3. Cweak
    4. Dweak
    5. EpH
  6. 6Factors influencing drug distribution…

    [blank_start]Regional blood flow[blank_end] – rate of tissue perfusion
    [blank_start]Extracellular binding[blank_end] (Plasma-protein binding means only a certain amount is active to be absorbed)
    [blank_start]Capillary permeability[blank_end] (tissue alterations – renal, hepatic, brain/CNS, placental)
    [blank_start]Localisation[blank_end] in tissues, usually [blank_start]fatty[blank_end] tissues allow drugs to persist for a long time
    1. ARegional blood flow
    2. BExtracellular binding
    3. CCapillary permeability
    4. DLocalisation
    5. Efatty
  7. 7Distribution:
    If a drug is distributed through the bloodstream to tissues, the effect under strenuous exercise will be quite different
    If body is stressed, blood flow changes

    Localisation: Fat is [blank_start]15%[blank_end] body weight but [blank_start]2%[blank_end] blood supply
    Very fat soluble drugs – [blank_start]75%[blank_end] partitioned in fat at
    [blank_start]equilibrium[blank_end]
    1. A15%
    2. B2%
    3. C75%
    4. Dequilibrium
  8. 8The two major routes of drug excretion:
    Liver: Some drugs are concentrated in the [blank_start]bile[blank_end] (usually [blank_start]large[blank_end] molecular weight conjugates)
    [blank_start]Biliary[blank_end] excretion (effective for [blank_start]large[blank_end] molecular weight molecules, as they can [blank_start]concentrate[blank_end])
    Active transport systems – into [blank_start]bile[blank_end] (bile acids and glucuronides)

    [blank_start]Kidney[blank_end]:ultimately responsible for the elimination of most drugs
    1. [blank_start]Glomerulus[blank_end] – drug-protein complexes not filtered
    2. Proximal tubule – active secretion of [blank_start]acids and bases[blank_end]
    3. Proximal and distal tubules – lipid soluble drugs [blank_start]reabsorbed[blank_end]

    1. Abile
    2. Blarge
    3. CBiliary
    4. Dlarge
    5. Econcentrate
    6. Fbile
    7. GKidney
    8. HGlomerulus
    9. Iacids and bases
    10. Jreabsorbed
  9. 9First-order kinetics describes the rate of elimination of a drug where the amount of a drug decreases at a rate that is [blank_start]proportional[blank_end] to the concentration of the drug remaining in the body.
    [blank_start]First[blank_end]-order kinetics is dependent on the concentration of drug at any given time and applies to most drugs in clinical use.

    Co: is concentration at time zero – cannot be measured since instantaneously [blank_start]clearance[blank_end] begins, therefore [blank_start]extrapolated[blank_end]
    Vd: Volume of distribution
    Cl: clearance

    clearance is proportional to drug concentration in plasma/serum
    1. Aproportional
    2. BFirst
    3. Cclearance
    4. Dextrapolated
  10. 10Zero-order kinetics
    [blank_start]Half life[blank_end] doesn't apply.
    Note: drug-concentration axis is [blank_start]linear[blank_end]
    If it were on a log scale the first-order plot would be [blank_start]straight[blank_end] and the zero- order plot would be [blank_start]curved[blank_end]

    Implies a [blank_start]saturable[blank_end] (usually enzymic) metabolic process
    (applies to very few drugs) since drug is always metabolised at same ([blank_start]maximal[blank_end]) rate
    1. AHalf life
    2. Blinear
    3. Cstraight
    4. Dcurved
    5. Esaturable
    6. Fmaximal

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Description
Medicine (Pharmacology) Quiz on Pharmacokinetics, created by april yao on 07/10/2016.
Author
april yao
Language
English
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1
History
Created on 7 Oct 2016 · updated on 8 Oct 2016
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