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GT BSN/CNL PHARM > Pharmacokinetics & Pharmacodynamics > Flashcards

Pharmacokinetics & Pharmacodynamics Flashcards

chapter 1-7

1
Q

Pharmacokinetics

A

What the body does to the drug; what happens to the drug as it moves through the body

(ADME: absorption, distribution, metabolism, excretion)

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2
Q

Absorption

A

Movement of a drug from the site of administration to the blood

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3
Q

Distribution

A

Movement of the drug from the blood to the interstitial spaces and cells

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4
Q

Metabolism

A

Biochemical reactions that alter the drug (usually inactivates but NOT always)

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5
Q

Excretion

A

Exit of the drug from the body

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6
Q

Acid

A

H+ (proton) donor

  • in neutral or basic environments, the substance ionizes
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7
Q

Base

A

H+ (proton) acceptor

  • in neutral or acidic environment, the substance ionizes
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8
Q

Ion Trapping

A

Accumulation of drug on one side of a membrane due to ionization

(Drug diffuses along concentration gradient, and then ionizes and cannot get back across. Further drug then diffuses, ionizes.)

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9
Q

pKa

A

The pH at which a drug is 50% ionized and 50% unionized

(lower pKa = stronger acid)

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10
Q

approx pH of:
- plasma
- stomach
- placenta
- urine

Why does this matter?

A
  • plasma = 7.4
  • stomach = 1-3
  • fetus = 7.3
  • urine = 6.0

Ionized drug can accumulate on one side of a membrane. (Fetal overdose, increased urinary excretion, decreased absorption from GI tract)

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11
Q

Factors that affects drugs’ absorption

A
  • rate of dissociation
  • surface area for absorption
  • blood flow (including cardiac output)
  • lipid solubility
  • administration route
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12
Q

First pass effect

A

Metabolism by the liver prior to entering the systemic circulation

(PO drugs since they are absorbed to the portal vein which goes straight to liver)

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13
Q

Enterohepatic cycling

A

Drug passage from GI tract to portal vein to liver, which excretes drug or metabolites into bile.

The drug is then retaken up into the portal vein and the cycle continues

(Only some drugs)

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14
Q

Volume of distribution (Vd)

A

How widespread the drug distributes throughout the body
(Small Vd- drug is mostly in the vasculature
Large Vd- drug is in various body compartments, interstitial spaces, and cells)

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15
Q

Where is the drug if it has a small Vd?

A

Vasculature

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16
Q

What affects Vd?

A
  • blood flow (including cardiac output)
  • tissue perfusion
  • type of capillary system (especially BBB)
  • drug polarity
  • protein binding
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17
Q

Blood brain barrier

A

Specialized capillaries surrounding the CNS
- tight junctions
- p-glycoprotein (PGP)

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18
Q

What is the main site of metabolism?
List a couple other sites as well.

A

Liver

Others:
- kidneys
- GI tract
- lungs
- skin
- plasma
- placenta

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19
Q

Phase I metabolism

A

Oxidation/reduction/hydrolysis
(CYP450 reactions are phase I)

Prepares drug for phase II reactions or direct renal elimination

20
Q

Phase II metabolism

A

Conjugation reactions
May (or may not) be preceded by phase I reactions.

Prepares drug for excretion (usually kidneys or bile)

21
Q

Cytochrome P450 Enzyme system

A

12 enzyme families
- CYP1-3 metabolize drugs
- CYP4-12 metabolize endogenous substances

Designed to biochemically convert substances into polar molecules

22
Q

CYP450 induction

A

Increase in enzyme concentration

Leads to faster metabolism of drugs that are metabolized through that pathway (inadequate drug levels)

23
Q

CYP450 Inhibition

A

Decrease in enzyme concentration

Leads to a decrease in metabolism of drugs that are metabolized through that pathway (drug accumulation)

24
Q

What is the main site of drug excretion?
List a couple other sites of drug excretion.

A

Urine

Others:
- feces
- sweat
- saliva
- breast milk
- expired air

25
Q

Minimum effective concentration

A

Lowest plasma concentration of a drug that elicits a therapeutic response

26
Q

Therapeutic range

A

The range of plasma drug concentrations between the minimum effective concentration and toxic concentration.

I.e. the range we aim for with pharmacotherapy

27
Q

Half life

A

Time required for the amount of drug in the body to be decreased by 50%

28
Q

What number of half lives is required to reach drug plateau?

A

Approx 4

29
Q

Zero order kinetics

A

The same amount of drug is metabolized per hour regardless of total drug concentration

30
Q

First order kinetics

A

The same percentage of drug is metabolized per hour regardless of total drug concentration

*most drugs

31
Q

Pharmacodynamics

A

What the drug does to the body

How the drug elicits it’s response

32
Q

4 types of receptors

A
  • cell membrane embedded enzymes
  • ligand gated ion channels
  • G protein coupled receptors (GPCRs)
  • transcription factors (in nucleus)
33
Q

Potency

A

How much drug must be administered to elicit response

Related to the affinity of the drug for its receptor

34
Q

Efficacy

A

Intensity of the effect the drug produces

The intrinsic activity of the drug

35
Q

Agonist

A

Mimics the action of the endogenous ligand

36
Q

Partial agonist

A

Mimics the action of the endogenous ligand, but to a lesser intensity

The drug will have a lower maximal effect

37
Q

Antagonist

A

Blocks the action of the endogenous ligand

38
Q

Draw the dose response curve

A

https://www.merckmanuals.com/professional/clinical-pharmacology/pharmacodynamics/dose-response-relationships

39
Q

Upregulation

A

Increase in number of receptors due to continuous antagonist usage

40
Q

Downregulation

A

Decrease in number of receptors due to continuous agonist usage

41
Q

Effective dose 50 (ED50)

A

The dose required to produce a therapeutic effect in 50% of the population

42
Q

Lethal dose 50 (LD50)

A

The dose that would produce death in 50% of the population

43
Q

Therapeutic index (TI)

A

The range between ED50 and LD50.
Determination of the drug’s safety

44
Q

Black boxed warning

A

FDA-implemented safety warning

45
Q

Quaternary ammonium

A

Drug that contains a Nitrogen with four Hydrogens - makes it a positively charged drug

Thus, the drug cannot cross membranes freely. Cannot be absorbed through GI tract and or respiratory membranes

46
Q

P- glycoprotein

A

ATP-dependent pump that pumps substances OUT of cells

47
Q

Protein Binding

A

Binding of drugs to proteins in the plasma and tissues

Usually, only UNBOUND drug is pharmacologically active, so high protein binding % results in lower drug activity

GT BSN/CNL PHARM (26 decks)

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