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Pharmacokinetics & Pharmacodynamics Flashcards

chapter 1-7 (79 cards)

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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

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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)

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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

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22
Q

CYP450 induction

A

Increase in enzyme concentration

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

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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)

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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

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25
Minimum effective concentration
Lowest plasma concentration of a drug that elicits a therapeutic response
26
Therapeutic range
The range of plasma drug concentrations between the minimum effective concentration and toxic concentration. I.e. the range we aim for with pharmacotherapy
27
Half life
Time required for the amount of drug in the body to be decreased by 50%
28
What number of half lives is required to reach drug plateau?
Approx 4
29
Zero order kinetics
The same amount of drug is metabolized per hour regardless of total drug concentration
30
First order kinetics
The same percentage of drug is metabolized per hour regardless of total drug concentration *most drugs
31
Pharmacodynamics
What the drug does to the body How the drug elicits it’s response
32
4 types of receptors
- cell membrane embedded enzymes - ligand gated ion channels - G protein coupled receptors (GPCRs) - transcription factors (in nucleus)
33
Potency
How much drug must be administered to elicit response Related to the affinity of the drug for its receptor
34
Efficacy
Intensity of the effect the drug produces The intrinsic activity of the drug
35
Agonist
Mimics the action of the endogenous ligand
36
Partial agonist
Mimics the action of the endogenous ligand, but to a lesser intensity The drug will have a lower maximal effect
37
Antagonist
Blocks the action of the endogenous ligand
38
Draw the dose response curve
https://www.merckmanuals.com/professional/clinical-pharmacology/pharmacodynamics/dose-response-relationships
39
Upregulation
Increase in number of receptors due to continuous antagonist usage
40
Downregulation
Decrease in number of receptors due to continuous agonist usage
41
Effective dose 50 (ED50)
The dose required to produce a therapeutic effect in 50% of the population
42
Lethal dose 50 (LD50)
The dose that would produce death in 50% of the population
43
Therapeutic index (TI)
The range between ED50 and LD50. Determination of the drug’s safety
44
Black boxed warning
FDA-implemented safety warning
45
Quaternary ammonium
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
P- glycoprotein
ATP-dependent pump that pumps substances OUT of cells
47
Protein Binding
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
48
Pharmacology
Defined as the properties & reactions of drugs especially with relation to their therapeutic value The dose makes the poison!
49
Ideal drug
Effective (efficacy), safe, selective (lack of off target effects) No drug is ideal - looking to develop best drug we can, mitigate drawbacks, and work with what we have
50
Clinical pharmacology
Study of medications in humans
51
Therapeutic objective
Provide maximum therapy with minimal harm
52
Pharmacology and the nursing process
Assessment - your knowledge & assessment of patient Analysis - is drug regimen appropriate? Risks? Concerns Planning - nursing interventions and PRN Implementation - 5 rights (pt, drug, dose, route, time) Evaluation - therapeutic, adverse, toxic effects
53
Drug nomenclature
Chemical name Generic name (drug class) Brand name
54
PK curve characteristics
T max - time it takes for drug to reach peak levels C max - max concentration of drug in the blood AUC - total amount of drug patient sees over course of dose, exposure
55
Formulations of oral / PO meds
Tablets, suspensions / liquids, enteric coated, sustained release
56
Parenteral / non-GI meds
IV - zero barriers to absorption IM - capillary wall (insignificant) only barrier to absorption
57
Other med routes
Transdermal, subcutaneous, topical (ears, eyes, nose, mouth, vagina, anus), local injections, inhalations
58
Consequences of drug metabolism
Accelerated renal excretion Drug inactivation = inactive metabolites Increased therapeutic action = metabolite more effect Activation of prodrugs Increased toxicity Decreased toxicity
59
Factors that modify renal excretion
pH dependent ionization, competition for active tubular transport, age (old = low GFR)
60
Steady state
If drug is given at every 1/2 life, it takes 4-5 times to reach steady state Loading dose - helps achieve steady state faster
61
Orthosteric binding site
The main binding site of a receptor that induces a physiological response
62
Allosteric binding site
A secondary site that modifies the physiological response
63
Positive allosteric modifiers / negative allosteric modifiers
Drugs that bind to the allosteric site but increase/decrease the strength of the normal physiologic response
64
Factors that impact drug action
Age, comorbidities, up/down regulation of receptors, polypharmacy (PK or PD interactions), nutritional status, genetics
65
Types of drug interactions
Drug-drug, drug-food, drug-supplement
66
Direct drug interactions
Chemical or physical interactions, usually IV (1 drug pushes other out of solution)
67
Drug interactions - PK
Altered absorption - antacids, laxatives, vomiting inducers, food intake Altered distribution- protein binding competition, pH alteration Altered metabolism - CYP450 induction/inhibition (grapefruit juice = CYP3A4 inhibitor) Altered excretion - alteration of any of the 3 steps in renal excretion Drug
68
Drug interactions - PD
Can be potentiative or inhibitory Combined toxicity
69
Adverse drug effects
Any noxious, unintended & undesired effect that occurs at normal drug doses, can be annoying and life threatening
70
Side effect
Nearly unavoidable effect that occurs at therapeutic doses Classical antihistamines = excessive drowsiness
71
Toxicity
Negative effects due to excessive drug doses Opioid overdose = fatal outcomes
72
Allergic reaction
Immune response, rash to anaphylaxis
73
Idiosyncratic
Not related to the pharmacological effects of the drug
74
Iatrogenic
Adverse effect caused by medical intervention
75
Paradoxical
Adverse effect that counteracts therapeutic effects of drug
76
Physical dependence
A drug that causes a physical addiction
77
Carcinogenic
Side effects leading to cancerous cells
78
Teratogenic
Leading to malformation of embryo
79
Highest fatal potential medication error
Giving overdose of med Giving wrong drug Using wrong route

Pharm (27 decks)

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