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1-Chemistry Exam 4 > Pharmacology Review > Flashcards

Pharmacology Review Flashcards

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1
Q

Basic pharmacokinetic principles: A drug must be absorbed, then distributed to ______ before being metabolized and excreted

A

A drug must be absorbed, then distributed to its target before being metabolized and excreted

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2
Q

Basic pharmacokinetic principles: At all times, what is happening to a free drug in circulation?

A

At all times: a free drug in circulation is in equilibrium with tissues reservoirs, plasma proteins, target site (receptors)

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3
Q

Basic pharmacokinetic principles: What part of the drug will have a pharmacological effect?

A

Only the fraction of drug that binds to its specific receptor will have a pharmacologic effect

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4
Q

Basic pharmacokinetic principles: What can metabolism yeild?

A

active and inactive metabolites

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5
Q

What is pharmacokinetics?

A

What the body does to the drug

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6
Q

What is pharmacodynamics?

A

What the drug does to the body

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7
Q

What are the components of pharmacokinetics?

A

Absorption, distribution, metabolism/biotransformation, elimination

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8
Q

Plasma concentration & bound/unbound proteins are what type of pharmacological concepts (2)?

A

pharmacokinetics

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9
Q

What are some examples of pharmacokinetic components?

A

Molecular weight, protein binding and bioavailability

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10
Q

The ______ the molecular size of an agent, the better it crosses the lipid barriers and membranes of tissues.

A

smaller

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11
Q

What happens to the permeability of substances as the molecular weight approaches 100-200?

A

Generally, molecules with molecular weights greater than 100 to 200 do not cross the cell membranes. Transport across the membranes can occur passively or actively.

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12
Q

What is an example of an object that needs assistance getting through a membrane?

A

Example: Glucose

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13
Q

What is active transport?

A

mechanisms are generally faster and require energy (ATP). Primary versus secondary (co-transport)- Difference?

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14
Q

What is passive transport?

A

does not require energy and involves transfer of a drug from an area of high concentration to an area of lower concentration: facilitated versus simple diffusion. Difference?

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15
Q

What are most drugs?

A

salts of either weak acids or weak bases. When introduced into the body, they behave as a chemical in solution.

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16
Q

The don’t dissociate equally between unionized/ionized forms as altered by _______.

A

blood pH

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17
Q

What is the ionized form?

A

The charged (ionized) form is water soluble,

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18
Q

What is the nonionized form?

A

the uncharged (nonionized) form is lipophilic.,

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19
Q

What is important to know about the nonionized forms of molecules?

A

Because the nonionized molecules are lipid soluble, they can diffuse across cell membranes such as the blood-brain, gastric, and placental barriers to reach the effect site.

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20
Q

What happens to ionized molecules?

A

the ionized molecules are usually unable to penetrate lipid cell membranes easily because of their low lipid solubility.

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21
Q

Some drugs are bound extensively to proteins in the plasma because ______________

A

of their innate affinity for circulating and tissue proteins.

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22
Q

How are protein bound drugs trap?

A

The drug-protein molecule is too large to diffuse through blood vessel membranes and is therefore trapped within the circulatory system.

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23
Q

What happens to heavily protein bound drugs?

A

Drugs that heavily protein-bound can compete for binding sites (displace and lead to increase in free-fraction of displaced drug)
(Finite number of binding sites, weak attraction)

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24
Q

What is albumin?

A

(most abundant)- favors acidic compounds

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25
Q

What is a1 glycoprotein?

A

(AAG)- favors basic compounds

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26
Q

Does a protein bound drug interact with the receptor?

A

A protein-bound drug is not free to interact with a receptor, results in higher plasma concentration levels

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27
Q

What effect does protein binding have on drugs?

A

Protein-binding slows metabolism/elimination (important for some hormones)
Protein-binding proportional to lipid solubility

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28
Q

How are protein binding expressed?

A

Expressed in percentages (drug X is % protein-bound)

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29
Q

What does it mean to have a >90% protein bound drug?

A

If highly protein bound >90% which means majority not pharmacologically active so displacement can have big consequences (theoretically)

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30
Q

What can protein binding serve as? What does it create?

A

Protein-binding can serve as a reservoir from some drugs- diffusion gradient to unload as free form is metabolized/excreted. Creates stable distribution for some drugs/hormones

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31
Q

What is bioavailability?

A

Bioavailability is the extent to which a drug reaches its effect site after its introduction into the body.

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32
Q

What does the rate at which systemic absorption occur establish?

A

a drug’s duration of action and intensity.

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33
Q

What impacts bioavailability?

A

The environment into which the drug is introduced also has an impact on its bioavailability. The patient’s age, sex, pathology, pH, blood flow, and temperature are all factors to consider.

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34
Q

What is pulmonary first pass uptake?

A

the loss of some drugs after a single passage through the lung (think IV). Net result of uptake of X into lung tissue or binding to lung vasculature/tissue and back diffusion of the drug from lung tissue or vasculature into the blood

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35
Q

What is first pass hepatic effect?

A

The reduced bioavailability of some drugs due to immediate extraction & metabolism via the liver as drug enters portal system before reaching systemic circulation

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36
Q

What is most effected by first pass hepatic effect?

A

Oral

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37
Q

The rectal route bypasses the hepatic first pass ______-________%.

A

50-75%.

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38
Q

What are compartmental models?

A

Used to quantitatively describe the pharmacokinetics of a drug and predict drug concentrations in the blood and tissues with little physiologic detail

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39
Q

What is an example of a one compartment model? What does it describe?

A

Linear pharmacokinetics; bolus pharmacokinetics

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40
Q

What is clearance?

A

= fluid circulating though a clearance organ at a constant rate (k)

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41
Q

What is the equation for clearance?

A

Clearance=k * Vd

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42
Q

What is half-life?

A

directly proportional to Vd and inversely to clearance

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43
Q

What is the 2-compartment model?

A

the central compartment is the first to receive the drug and represent intravascular fluid and highly perfused tissue

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44
Q

What is the multicompartment model?

A

Expands the 1 compartmental model to explain anesthetic drugs to account for distribution to site of action

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45
Q

What is the phases of the 3 model follows?

A

the phases of anesthetic drugs: Rapid distribution phase Slower distribution phase, Terminal elimination phase

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46
Q

What is hysteresis?

A

time delay between measured concentration and effect

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47
Q

What is volume of distribution?

A

Vd= Dose/[Drug]plasma
Pharmacokinetic parameter describing a drug’s propensity to either remain in the plasma (central) or redistribute to other tissues

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48
Q

What is dilution/apparent volume?

A

The ratio of the dose present in the body and its plasma concentrationwhen the distribution of the drug between the tissues and the plasma is at equilibrium.

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49
Q

What are many anesthetics?

A

highly fat soluble (lipophilic), poorly soluble in H2O- have ⬆️ Vd (ex. prop)

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50
Q

What effects volume of distribution?

A

Affected by molecular size, lipid solubility and plasma protein binding (also, disease state & fluid shifts (pregnancy)

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51
Q

A drug that is free, unbound to plasma proteins and lipid soluble tend to cross cell membranes more freely, thus ______ Vd with _____ plasma [ ] after injectio

A

large; low

52
Q

What is zero order kinetics?

A

Zero order kinetics (saturation): Elimination rate is independent of concentration (can quickly become toxic)

53
Q

Saturating the amount of drug does _________ elimination

A

does not speed up elimination

54
Q

What are some examples of zero order kinetics (5)?

A

Coumadin, heparin, ethanol, salicylates, phenytoin, theophylline

55
Q

What can happen quickly at therapeutic levels?

A

May start off at first-order at low concentrations (saturate quickly at therapeutic levels)

56
Q

What is first order kinetics?

A

Concentration dependent process (most drugs): rate proportional to amount

57
Q

What is elminiation half life?

A

The amount of time over which the drug concentration in the plasma decreases to 50% of its original value

58
Q

What factors effect the elimination half life?

A

Kinetics= Clearance & Volume of distribution

59
Q

What is a negligible therapeutic effect?

A

In general, the effect of a drug is considered to have a negligible therapeutic effect after 4-5 half-lives, or when only ~6.25% of the original dose remains in the body

60
Q

What is steady state?

A

When the overall intake of a drug is at equilibrium with the elimination

61
Q

When is steady state accomplished?

A 
Accomplished at 4-5 half-lives
Steady state (infusion)=input/clearance
62
Q

What is context sensitive half life?

A

Time required for plasma concentration to ⬇️ 50% after D/C drug iv infusion

63
Q

What is important about context sensitive half life?

A

Often cannot be predicted by elimination ½ life (metabolism & elimination)

64
Q

What determines context sensitive half life?

A

Volume of central compartment; rate of systemic clearance

65
Q

What is context sensitive half life most common in?

A

Useful concept with infusions (accumulation)

“Context;” duration of infusion

66
Q

What are some examples of drugs that under go context sensitive half life?

A
  • remifentanil (stable, short context sensitive half-time) 3 min after 3 hr infusion
  • Fentanyl, dexmedetomidine, midazolam, ketamine, remifentanil, propofol
67
Q

What is biotrnasformation?

A

Covert pharmacological active drugs to inactive state for elimination (lipophilic drugs to hydrophilic)
However, some have active metabolites

68
Q

What is an example of a drug that produces an active metabolite?

A

morphine to morphine-6-glucuronide

69
Q

What is a prodrug? What is an example of this

A

Convert a “pro-drug” into an active state (ex: codeine to morphine)
W

70
Q

Where does biotransformation occur?

A

Hepatocytes are primary site (⬆️ concentration of enzymes, especially CYP 450)
Mitochondria/**ER
Others: kidneys, GI tract, lungs, plasma, placenta, skin

71
Q

What is a phase I reaction?

A

include oxidation, reduction, and hydrolysis, increasing the drug’s polarity and preparing it for Phase II reactions- occurs mainly in the endoplasmic reticulum

72
Q

What is a phase II reaction?

A

are conjugation reactions that covalently link the drug metabolite with a highly polar molecule, rendering it more even water soluble for excretion bile, feces, urine- occurs mainly in the cytoplasm

73
Q

What are some enzymes involved in phase 1 reactions?

A

Cytochrome P450 (CYP) enzymes, Non-cytochrome P450 enzymes, Flavin-containing monooxygenase enzymes,

74
Q

What is cytyochrome P450 enzymes?

A

Subclassifications to genotype and individual enzymes

Involve both oxidative and reduction steps

75
Q

What CYP450 metabolizes most anesthetic drugs?

A

CYP 3A4 (P450 3A4):

76
Q

What is non cytochrome P450?

A

(Ex: monoamine oxidase, important in the metabolism of catecholamines as dopamine/NE- target for psychiatric drugs)

77
Q

What can alter biotransformation?

A

by enzyme induction or inhibition

78
Q

What is an example of induction?

A

phenobarbital, rifampin, phenytoin, prednisone

79
Q

What is an example of inhibition?

A

grapefruit, simvastatin

80
Q

What are enzymes of phase 2?

A
  • Glucuronosyltransferases
  • Glutathione-S-transferases (GST)- protects against oxidative stress
  • N-acetyl-transferases (NAT)
  • Sulfotransferases
81
Q

What is the primary metabolic pathway of phase two?

A

Glucuronidation

82
Q

What three drugs are metabolized by glucuronidation?

A

Propofol, Morphine and Midazolam

83
Q

What is the active metabolity of midazolam?

A

active metabolite: 1-hyrdroxymidazolam

84
Q

What is hepatic clearance?

A

A concept that characterizes drug elimination based on both blood flow and intrinsic clearance

85
Q

What is the relationship of metabolism and drug concentration?

A

Metabolism increases proportionally with concentration as long metabolic rate <1/3 of max metabolic capacity (liver has limits- saturation)

86
Q

What effects hepatic clearance?

A

Affected by liver disease, enzyme induction, flow

87
Q

What are higher extraction ratios? What is an example of this phenomenon?

A

Some drugs have higher extraction ratios than others (example: propofol vs alfentanil)
What does this mean?
Drugs with higher extraction ratios (nearly 1)- flow to liver can reduce clearance; whereas flow has little influence on drugs with low extraction ratios. Anesthesia reduces blood flow to the liver thus can affect

88
Q

What renal clearance?

A

Renal flood flow, glomerular filtration rate, and protein-binding affect amount of drug that enters the glomerulus for excretion.

89
Q

What is factors of renal clearance?

A

Glomerular filtration
Active tubular secretion
Passive tubular reabsorption

90
Q

What is potency?

A

Effective Concentration (EC50) is the dose required for an individual to experience 50% of the maximum effect.

91
Q

What is efficacy?

A

the max effect that can be expected from a drug

92
Q

What is effective dose?

A

Effective dose (ED50): dose of a drug required to produce a therapeutic effect in 50% of individuals

93
Q

What is lethal dose?

A

LD50): dose of a drug required to produce death in 50% of patients receiving the drug

94
Q

What is therapeutic index?

A

ratio between the LD50 and the ED50

95
Q

What is LD50/ED50?

A

The larger the therapeutic index of a drug, the safer the drug is considered

96
Q

What is therapeutic window?

A

Range of doses that produces a therapeutic response without causing any significant adverse effects in patients (toxicity)

97
Q

What is therapeutic index?

A

The therapeutic window can be quantified by the Therapeutic Index
TD50
TI = ——-
ED50

98
Q

What is the TD50?

A

is the dose that causes a toxic response in 50% of the population

99
Q

What is ED50?

A

is the dose of a drug that is therapeutically effective in 50% of the population

100
Q

What can effect pharmacokinetics?

A

Bioavailability, renal/hepatic function, cardiac function, patient age

101
Q

What is pharmacodynamics?

A

Enzyme activity, genetic differences and drug interactions

102
Q

What are pharmacokinetic drug interactions?

A

Coadministered drugs affecting absorption, distribution, elimination of other

103
Q

What are pharmacodynamic interactions?

A

Drug on drug interactions leading to synergism or antagonism of other

104
Q

Describe the bonds of receptors from weakest to strongest.

A

van der Waals, hydrogen, ionic and covalent (rare)

105
Q

What is G protein-couple receptors?

A

binds to extracellular substance and results in conformation change of the receptor (switch)

106
Q

What is the process of G protein couple receptor transmission?

A

Signal to an intracellular molecule called a G protein comprised of a and BY subunits

  • alpha dissociation from trimeric as bound GDP is exchanged for GTP
  • subunits are active when bound to GTP, once GTP hydrolyzed back to GDP becomes inactive
107
Q

What is the moa of G protein couple receptors?

A

To mediate intracellular effects as enzyme cascades or ion channels activation (Depending on the ligand)

108
Q

What is an example of g protein couple receptors? What effect can opioids have on this?

A

Ga stimulates release of adenylate cyclase which converts ATP to 2nd messenger cAMP causing further enzymatic activities as protein kinase A> phosphorylation of glycogen to glucose (specific to epinephrine)

Opioids: decrease release of adenylate cyclase by the a subunit (decrease cAMP) and hyperpolaize a cell via ion channels through the By subunits (opioid u receptors are G protein

109
Q

What is tolerance?

A

Requirement of higher doses to elicit a given response (occurs over time)

110
Q

What effects tolerance?

A

increase clearance (enzyme induction),
drug receptor changes (ex. downregulation from persistent exposure (vs. sensitivity )
physical ADAPTATION
behavior tolerance

111
Q

What is an example of a medication that promotes tolerance?

A

Opioids

112
Q

What is sensitivity

A

where lower requirement needed (Up regulation of receptors after chronic blockade)

113
Q

What is tachyphylaxis?

A

A rapid decrease in response to repeated doses (Same dose) over a short period

114
Q

What are examples of drugs produce tachyphylaxis?

A

Ephedrine, local anesthetics

115
Q

What are reasons that tachyphylaxis occurs?

A

Increased destruction of agonist, exhaustion of a transmitter, changes in binding (increase) of agonist to its receptors or receptor saturation

116
Q

What does knowing about hysteresis allow us to do (3)?

A

Knowing about hysteresis allows us to optimize the dose, frequency and duration of exposure

117
Q

What is classified as steady state or the goal of the third compartment model?

A

Basically 3 Volumes of distributions with varying clearance constants and varying rates of distribution (concentration gradients) that are occurring simultaneously until drug is removed from system. Maintaining equilibrium among the subcompartments is achieving a steady state after a bolus (goal for infusions).

118
Q

What is the relationship between zero order kinetics and elimination half life?

A

the elimination half life is dependent on the initial drug concentration and rate constant

119
Q

What is the relationship between first order kinetics and elimination half life?

A

half life is not dependent on concentration: constant rate (length of half life will be constant)

120
Q

What is an example of a drug that is effected by pulmonary uptake?

A

Fentanyl is an example of a drug influenced by pulmonary uptake (microvascular endothelial cells), especially at lower doses (pulmonary site saturable at higher, repeated doses for fentanyl with less extraction).

121
Q

What must steady state account for?

A

The steady state for oral drugs and other routes must account for fraction of bioavailability due to first pass hepatic effect (especially oral),

122
Q

What is the rate of elimination for drugs with small central compartments and rapid clearance?

A

Drugs with small central compartment and rapid clearances are cleared rapidly regardless size of peripheral compartment or how long the infusion (remifentanil; propofol).

123
Q

What is the rate of elimination for drugs with large central compartments and slow clearance?

A

eliminated much slower.

124
Q

What happens to weak acids in an alkaline environment?

A

Weak acids excreted more rapidly in alkaline urine (alkalization created more ionized form of the drug and can’t be reabsorbed- Trapped. (example: NaBicarb given for aspirin toxicity)

125
Q

Age ______ correlated to renal blood flow and creatine clearance

A

Age inversely correlated to renal blood flow and creatine clearance

126
Q

Two drugs can have the same C50 but different ______

A

EFFICACY

1-Chemistry Exam 4 (8 decks)

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