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pharmacology > chapter 2 basic principles > Flashcards

chapter 2 basic principles Flashcards

1
Q

agonist-cell receptor relationship

A

-fits like lock and key to produce pharmacological response

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2
Q

antagonist-receptor relationship (blockers)

A
  • interferes with naturally occurring agonists or drugs

- incapable of producing biological effect

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3
Q

down-regulation/desensitization

A
  • responsiveness decreases
  • occurs when continually stimulated receptors
  • due to decreased number of available receptors or change in existing receptors
  • can ultimately result in lack of response to drug
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4
Q

up-regulation/hypersensitization

A
  • receptor’s activity chronically reduced from antagonists

- if antagonists rapidly stopped receptors will exaggerate natural agonists response

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5
Q

therapeutic index

A
  • relationship btwn therapeutic effects and adverse effects
  • ratio of doses required to produce death/serious toxicity in 50% of pts versus doses required to produce effective treatment for 50% of pts.
  • index is “wide”-drug safe and no need for close monitoring
  • index is “narrow”-close monitoring needed
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6
Q

drug effect

A
  • result of interaction between target cell/receptor to produce therapeutic effect
  • usually temporary and reversible
  • drug-receptor binding very specific (lock and key)
    • usually graded-larger the dose the greater the effect
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7
Q

onset of action

A
  • time needed for drug concentration to reach minimum level

- changes with manner of administration (i.e. IV, IM)

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8
Q

time to peak

A

-time required for maximum effect after administration

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9
Q

duration of action

A
  • blood levels are above minimum effective concentration

- not effected by route of administration

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10
Q

termination of action

A

-drug level drops below minimum effective concentration

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11
Q

drug efficacy

A

-measured by maximum effect that drug can achieve

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12
Q

drug potency

A
  • compares doses of two different drugs required to achieve same effect
  • influenced by absorption, distribution, metabolism, and excretion
    i. e 10mg rosuvarstatin = 20mg atorvaststin–rosuvarstatin is more potent
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13
Q

drug absorption

A
  • passive diffusion-no energy, usually in GI tract, only nonionized lipid soluble drugs work well
  • active transport-needs energy. usually opposite concentration gradient, uses absorption of electrolytes and pinocytosis (i.e. fat soluble drugs like vitamins)
  • IV-begins distribution immediately
  • IM/SQ-must undergo absorption from injection site; affected by blood flow@ site of injection
  • PO: empty v. Full stomach;
    - chelation-usually supplement that binds with drug and not free to be absorbed
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14
Q

first-pass metabolism

A

-ONLY FOR PO MEDS
-metabolism in liver of part of drug before it reaches systemic circulation
-IV and sublingual don’t use portal circulation
-PO-absorbed in stomach and then move to liver via portal vein
-the > amount of drug absorbed via first-pass the > dose
-drugs the large first metabolism:
dopamine, lidocaine, propanolol, imipramine, morphine, reserpine, nitro, isoproterenol, warfarin

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15
Q

enterohepatic recycling

A
  • some drugs leave liver circulation and enter biliary tract to be excreted in bile eventually being available for reabsorption through intestinal wall
  • bile reabsorbs every 80 days and therefore drug could re-circulate for a long time
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16
Q

bioavailability

A
  • am’t of drug dose that reaches systemic circulation
  • doesn’t take into account rate of absorption–only extent of absorption
    • not usually important when taking meds chronically
  • IV drug=1
17
Q

drug distribution

A
  • initial phase: distributes drug to high-flow areas-heart, liver, kidney, brain
  • 2nd phase: areas of slower blood flow-fat, bone, skin
  • influenced by body composition, cardiac output, regional blood flow, protein binding, lipid solubility
18
Q

plasma protein binding

A
  • protein bound drugs cannot cross over membrane to leave vasculature–inactive and unavailable to bind with receptor sites–unable for therapeutic effect to occur
  • unbound drug–“free drug” able to pass membrane and bind with receptor sites
  • %of free drug constant for any particular drug but differs btwn drugs
19
Q

volume of distribution

A
  • mathematically determined measure of size of compartment that would be filled by amount of drug in same concentration in blood/plasma
  • larger volume of distribution indicates larger dose needed to achieve target concentration
  • drug dependent on: lipophilicity–very large volume distribution needed
    - protein binding: increased volume distribution with drug in circulation longer–only free drug is active form
    - pt with hypoalbuminemia (cachectic, liver dz, elderly) risk for toxicity
20
Q

drug metabolism

A
  • chemically changing drug into metabolite
  • increase of h2o solubility and decrease lipid solubility to be excreted in urine
  • some drugs are inactive until turned into metabolite before any effect can occur (i.e.ACE inhibitors)
  • drugs can undergo phase 1 or phase 2 or both reactions to be excreted into urine
  • kidneys and liver major site
  • other locations: skin, plasma, GI tract, lungs
21
Q

phase 1 reactions

A
  • oxidation-inserting oxygen atom into drug (i.e. CYP450)
  • reduction
  • hydrolysis
22
Q

phase 2 reactions

A
  • synthetic/conjugation reactions

- attachment of other chemical groups to become more water soluble and easily excreted

23
Q

enzyme induction

A
  • synthesize drug-metabolizing enzymes
    i. e. alcohol, cigarette smoke
  • if coadministered with CYP450 enzymes will affect therapeutic level
24
Q

enzyme inhibitors

A

-inhibit the metabolism of other drugs

25
Q

variation in drug metabolism

A
  • genetics
  • age
  • pregnancy
  • liver dz
  • time of day-station
  • environment
  • diet
  • alcohol and nicotine
  • drug interactions
26
Q

drug elimination

A
  • removal of drugs from tissues and circulation
  • usually excreted through kidneys
  • some through biliary
  • others through lungs, skin, breast milk, and sweat
27
Q

biological half-life

A
  • amount of time takes to eliminate 1/2 of drug from body
  • determines how often drug administered
  • not dose dependent
  • if pt has renal or hepatic disease could take longer
  • used for: estimating time needed to reach steady state; time required to eliminate all/portion of drug; plasma initiation therapy; plasma concentration;
28
Q

Pharmacokinetics

A 
-what your body does to drug
Absorption
Distribution
Metabolism
Elimination
29
Q

Drug concentration

A

Concentration (mg/dL) = amount (mg)/volume (V.D.) (dL)

-used for loading dose-to achieve target concentration right away
I.e. Phenytoin

30
Q

Renal dysfunction

A

-estimating renal function: 24 hour urine (gold standard), Cockcroft-Gault, GFR

31
Q

Steady-state

A
  • kinetic principle that basically states am’t lost equals am’t gained in body
  • when draw drug levels we will wait until steady-state achieved
  • knowing the half life helps predict when steady-state will be reached

pharmacology (37 decks)

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