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PHTH 561 > Lecture 1 - Part 2 > Flashcards

Lecture 1 - Part 2 Flashcards

1
Q

What is pharmacokinetics (PK)?

A
  • what the body does to the drug
  • absorption, digestion, metabolism, excretion (ADME)
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2
Q

What is pharmacodynamics (PD)?

A
  • what the drug does to the body
    • MOA (mechanism or action)
    • dose response (efficacy, potency, therapeutic index)
    • effects
    • side effects (SEs) aka Adverse Drug Reaction (ADRs)
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3
Q

What are the two ways drugs can be absorbed?

A

1) passive diffusion: water and water-soluble substances and small lipids move with a concentration gradient
2) active transport : minerals, some sugars, and most amino acids move against a concentration gradient with an input of energy

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4
Q

Define bioavailability

A
  • the extent to which the drug reaches the systemic circulation
  • the percentage of the drug administered that reaches the bloodstream
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5
Q

what does bioavailability depend on?

A

1) route of administration
2) drug’s ability to cross membrane barriers
- active, passive, facilitated, special processes

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6
Q

What does drug distribution mean?

A

after absorption, where the drug goes based on tissue permeability, blood flow, plasma proteins, and subcellular components

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7
Q

Where are drugs stored?

A

1) adipose
2) bone
3) muscle
4) organs

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8
Q

What is volume of distribution (Vd)

A

a ratio that expresses the amount of drug administered/concentration of drug in plasma

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9
Q

what factors affect distribution?

A

1) tissue permeability
2) blood flow
3) binding to plasma proteins
4)binding to subcellular components

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10
Q

What organ takes part in drug excretion?

A

kidneys (nephron)

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11
Q

Define clearance of drugs

A

the ability of all organs and tissues to eliminate the drug or the ability of a single organ or tissue to eliminate the drug

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12
Q

what is a drug’s half life?

A

amount of time required for 50% of the drug remaining in the body to be eliminated

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13
Q

What factors can cause variations in response to drugs?

A

1) genetics
2) disease (esp liver or kidneys)
3) age
4) diet
5) gender
6) drug interactions
7) environmental
8) cigarettes/alcohol
9) obseity
10) exercise
11) injuries

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14
Q

Drug absorption in infants

A
  • less acidic stomach –> increases bioavailability of acid labile drugs -PCN
  • delayed gastric emptying –> increases time to reach therapeutic concentrations
  • larger relative skin surface area –> increases cutaneous perfusion
  • thinner stratum corneum –> increases absorption (topicals)
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15
Q

Drug distribution in infants

A
  • body water
    • preterm: 85%; term: 75%; 5 months: 60% (adult level)
  • adipose tissue (baby fat 15%)
  • serum albumin binding decreased: ~90-92% (98% adult)
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16
Q

metabolism in infants

A
  • hepatic enzyme activity 50-70% of adult, but reach adult levels in 1st year
17
Q

excretion in infants

A
  • glomerular filtration and tubular secretion decreased
  • reach adult levels ~ 5-7 months (in first 7 months, need to worry about adverse reactions from drugs dependent upon the kidney for elimination
18
Q

absorption in the elderly

A
  • increased gastric pH vs adult (much more versus infant)
  • delayed gastric emptying (increases time to reach therapeutic concentrations)
19
Q

distribution in the elderly

A
  • body water: decreased TBW to 53% of adult
  • increased adipose tissue (more body fat)
  • decreased serum albumin binding: ~95% (98% in 40-50 year old adult)
20
Q

metabolism in the elderly

A

1) little change in liver function tests, however there is some decrease in hepatic biotransformation

21
Q

excretion in the elderly

A
  • decreased glomerular filtration and tubular secretion (this is the cause of most adverse drug reaction sin the elderly)
22
Q

what influences what the drug does to the body?

A
  • depends on the drug receptors and the ability of the drug to bind to those receptors
23
Q

What is a dose-response curve?

A
  • provides information about the dosage range over which the drug is effective
  • provides information about peak response
24
Q

What is E50

A
  • the median effective dose
  • dose at which 50% of the population responds to the drug in a specific manner
25
Q

What is T50

A
  • median toxic dose
  • dose at which 50% of the group exhibits the adverse reaction
  • in animal studies, the toxic effect studied is often the death of the animal
26
Q

What is L50

A
  • median lethal dose
  • dose that causes death in 50% of the group (animal studies)
  • not relevant term in clinical use of the D in humans
27
Q

therapeutic index (TI)

A
  • indicator of the drug’s safety
  • the greater the TI, the safe the drug is considered
  • a large TI indicates that it takes a much larger does to evoke a toxic response than it does to cause a beneficial response
  • TI = TD50/ED50
  • monitoring for low TI agents
    • not usually needed for high TI medications because there is a greater margin of error (blood levels can rise quite a lot above the therapeutic concentration before becoming dangerous)
28
Q

what are the 4 receptor types?

A

1) channel linked: open ion channel/membrane permeability
2) enzyme linked: activates enzyme within cell
3) G-protein coupled: linked to regulatory proteins controlled enzymatic processes within cell; primary, secondary messengers
4) intracellular: result in protein synthesis

29
Q

drug-receptor interactions

A

1) affinity: amount of attraction between drug and receptor
2) drug selectivity: a function of the ability of that drug to interact with specific receptors on the target tissue, and not with other receptors on the target tissue or receptors on other tissues

30
Q

agonist drugs

A
  • affinity and efficacy
  • partial agonist
    • do not evoke maximal response
    • does no fully activate receptor
  • mixed agonist-antagonist
    • simultaneously stimulate receptor subtype while blocking other receptor subtypes
31
Q

antagonist drugs

A
  • affinity only (however may have efficacy by inhibiting and inhibitory neuron, GABA to GABA
  • competitive antagonist
  • noncompetitive antagonist
32
Q

desensitization vs down regulation

A
  • desensitization: brief and transient decrease in responsiveness
  • down regulation: slower process in which the actual number of available receptors is diminished
33
Q

super sensitivity vs up regulation

A
  • super sensitivity: increase in sensitivity of existing receptors
  • increase in receptor number

PHTH 561 (2 decks)

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