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Boards Pathology > General Pharmacology > Flashcards

General Pharmacology Flashcards

1
Q

Michaelis-menten kinetics:

Km is ____ related to the affinity of the enzyme for its substrate

Vmax is _____ proportional to the enzyme concentration

Most enzymatic reactions follow a hyperbolic curve (i.e., Michaelis menten kinetics); however, enzymatic reactions that exhibit a ______ curve usually indicate cooperative kinetics (e.g., Hgb)

A

Inversely

Directly

Sigmoid

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2
Q

On a lineweaver-burk plot, the further to the right the x-intercept (i.e., the closer to zero), the _____ the Km and the _____ the affinity

A

Greater; lower

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3
Q

Reversible competitive inhibitors effects on Vmax and Km

A

Vmax unchanged

Km increased

[decrease the potency of the substrate, but can be overcome by increase substrate concentration]

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4
Q

Irreversible competitive inhibitors effects on Vmax and Km

A

Vmax decreased

Km unchanged

[decrease the efficacy of the substrate]

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5
Q

Noncompetitive inhibitors effects on Vmax and Km

A

Vmax decreased

Km unchanged

[decrease the efficacy of the substrate]

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6
Q

Fraction of administered drug reaching systemic circulation unchanged; equal to 100% for an IV dose

A

Bioavailability

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7
Q

Theoretical volume occupied by a total amount of the drug in the body relative to its plasma concentration

A

Volume of distribution (Vd)

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8
Q

Apparent Vd of plasma protein-bound drugs can be altered by liver and kidney disease (decreased protein binding, increased Vd); drugs may distribute in more than one compartment.

How is Vd calculated?

A

Vd = amount of drug in the body/plasma drug concentration

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9
Q

Large/charged molecules and plasma-protein bound drugs in the intravascular compartment are associated with a ______ Vd

A

Low

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10
Q

Small lipophilic molecules, especially if bound to tissue protein, found in all tissues including fat are associated with a _____ Vd

A

High

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11
Q

Small hydrophilic drugs found in the ECF are associated with a ____ Vd

A

Medium

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12
Q

Volume of plasma cleared of drug per unit time; may be imapired with defects in cardiac, hepatic, or renal function

A

Clearance (CL)

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13
Q

Clearance (CL) calculation (2 equations)

A

CL = Rate of elimination of drug/plasma drug concentration

[or]

CL =Vd x Ke (elimination constant)

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14
Q

1/2 life is the amount of time required to change the amount of drug in the body by 1/2 during elimination

in first order kinetics, a drug infused at a constant rate takes _____ half-lives to reach a steady state. It takes 3.3 half lives to reach ____ of the steady-state level

A

4-5; 90%

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15
Q

Calculation for half life in first order elimination

A

t(1/2) = [0.7 x Vd]/CL

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16
Q

Percent of drug remaining after 1, 2, 3, and 4 half lives in first order kinetics

A

50% remaining after 1 half life

25% remaining after 2 half lives

  1. 5% remaining after 3 half lives
  2. 25% remaining after 4 half lives
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17
Q

Calculation for loading dose

A

Loading dose = [Cp x Vd]/F

Cp = target plasma concentration at steady state

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18
Q

Calculation for maintenance dose

A

Maintenance dose = [Cp x CL x tau]/F

Cp = target plasma concentration at steady state

Tau = dosage interval (time between doses) if not administered continuously

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19
Q

In renal or liver disease, the maintenance dose typically ______ and the loading dose is ______

Time to steady state depends primarily on _______ and is independent of dose and dosing frequency

A

Decreases; unchanged

t(1/2)

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20
Q

Aspirin and acetaminophen are an example of a _______ drug interaction in which the effect of substance A and B together is equal to the sum of their individual parts

A

Additive

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21
Q

The effect of cortisol on catecholamine responsiveness is an example of a _______ drug interaction in which presence of substance A is required for the full effects of substance B

A

Permissive

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22
Q

Clopidogrel with aspirin is an example of a _______ drug interaction in which effect of substance A and B together is greater than the sum of their individual effects

A

Synergistic

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23
Q

Nitrates, niacin, phenylephrine, LSD, and MDMA are an example of a _______ drug interaction in which there is an acute decrease in response to a drug after initial/repeated adminstration

A

Tachyphylactic (aka tolerance)

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24
Q

What is zero-order elimination?

A

Rate of elimination is constant regardless of amount of drug eliminated per unit time

Cp decreases linearly with time

Examples include Phenytoin, Ethanol, and ASA (at high or toxic concentrations)

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25
Q

The rate of first-order elimination is directly proportional to _____

A

The drug concentration

[constant fraction of drug eliminated per unit time; Cp decreases exponentially with time — applies to most drugs]

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26
Q

Phenobarbital, methotrexate, and aspirin (salicylates) are examples of _____ ____ in which overdoses can be treated with sodium bicarbonate to _______ urine

A

Weak acids; alkalinize

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27
Q

TCAs and amphetamines are examples of ____ ____ in which overdoses can be treated with ___ ____ to acidify urine

A

Weak bases; ammonium chloride

[note that TCA toxicity is generally treated with sodium bicarbonate to overcome the sodium channel-blocking activity of TCAs, but not for accelerating drug elimination]

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28
Q

Phase I drug metabolism

A

Reduction, oxidation, hydrolysis with cytochrome P450 usually yield slightly polar, water-soluble metabolites (often still active)

[geriatric pts lose phase I first R-OH]

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29
Q

Phase II drug metabolism

A

Conjugation (methylation, glucuronidation, acetylation, sulfation) usually yields very polar, inactive metabolites (renally excreted)

[geriatric pts retain phase II, pts who are slow acetylators have increased side effects from certain drugs because of low rate of metabolism (e.g. INH)]

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30
Q

Therapeutic index (TD50/ED50) is a measure of drug safety; safer drugs have _____ TI values

A

Higher

[TD = median toxic dose, ED50 = median effective dose]

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31
Q

G-protein class and major functions α-1 sympathetic receptors

A

Gq

Increase vascular smooth muscle contraction

Increase pupillary dilator muscle contraction (mydriasis)

Increased intestinal and bladder sphincter muscle contraction

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32
Q

G-protein class and major functions α-2 sympathetic receptors

A

Gi

Decreased sympathetic (adrenergic) outflow

Decreased insulin release

Decreased lipolysis

Increased platelet agg

Decreased aqueous humor production

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33
Q

G-protein class and major functions β1 sympathetic receptors

A

Gs

Increased heart rate, contractility, renin release, and lipolysis

34
Q

G-protein class and major functions β2 sympathetic receptors

A

Gs

Vasodilation, bronchodilation

Increased lipolysis, increased insulin release, increased glycogenolysis, decreased uterine tone (tocolysis), increased aqueous humor production, increased cellular K+ uptake

35
Q

G-protein class and major functions β3 sympathetic receptors

A

Gs

Increased lipolysis, thermogenesis in skeletal muscle, and bladder relaxation

36
Q

G-protein class and major functions M1 parasympathetic receptors

A

Gq

Mediates higher cognitive functions, stimulates enteric nervous system

37
Q

G-protein class and major functions M2 parasympathetic receptors

A

Gi

Decreased heart rate and contractility of atria

38
Q

G-protein class and major functions M3 parasympathetic receptors

A

Gq

Increased exocrine gland secretions (e.g., lacrimal, sweat, salivary, gastric acid), increased gut peristalsis, increased bladder contraction, bronchoconstriction, increased pupillary sphincter muscle contraction (miosis), ciliary muscle contraction (accomodation), increased insulin release, endothelium-mediated vasodilation

39
Q

G-protein class and major functions D1 receptors

A

Gs

Relaxes renal vascular smooth muscle

Activates direct pathway of striatum

40
Q

G-protein class and major functions D2 receptors

A

Gi

Modulates transmitter release, esp in the brain, inhibits direct pathway of striatum

41
Q

G-protein class and major functions H1 receptors

A

Gq

Increased nasal and bronchial mucous production

Increased vascular permeability

Bronchoconstriction, pruritis, pain

42
Q

G-protein class and major functions H2 receptors

A

Gs

Increased gastric acid secretion

43
Q

G-protein class and major functions V1 receptors

A

Gq

Increased vascular smooth muscle contraction

44
Q

G-protein class and major functions V2 receptors

A

Gs

Increased H2O permeability and reabsorption via upregulating aquaporin-2 in collecting tubules of kidney; increased release of vWF

45
Q

Cholinomimetic direct acting agonist that activates bladder smooth muscle; resistant to AChE. No nicotinic activity.

Treatment for urinary retention

A

Bethanechol

46
Q

Cholinomimetic direct acting agonist that works like ACh but is resistant to AChE; constricts pupils and relieves intraocular pressure in open-angle glaucoma

A

Carbachol

47
Q

Cholinomimetic direct acting agonist that stimulates muscarinic receptors in airway when inhaled; used in challenge test for dx of asthma

A

Methacholine

48
Q

Cholinomimetic direct acting agonist that contracts ciliary muscle of eye (open-angle glaucoma), pupillary sphincter (closed-angle glaucoma); resistant to AChE, can cross BBB (tertiary amine)

Potent stimulator of sweat, tears, and saliva; treats open and close-angle glaucoma as well as xerostomia found in Sjogren syndrome

A

Pilocarpine

49
Q

Cholinomimetic indirect acting agonist (AChE’s) that are first-line for Alzheimer disease

A

Donepezil
Rivastigmine
Galantamine

50
Q

Cholinomimetic indirect acting agonist (AChE’s) historically used to diagnose to dx myasthenia gravis; replaced by Anti-AChR Ab test

A

Edrophonium

51
Q

Cholinomimetic indirect acting agonist (AChE’s) that does not penetrate the CNS; used to tx postop and neurogenic ileus and urinary retention, myasthenia gravis, reversal of neuromuscular blockade (postop)

A

Neostigmine

52
Q

Cholinomimetic indirect acting agonist (AChE’s) that freely crosses the BBB —> CNS (tertiary amine); antidote for anticholinergic toxicity (e.g., atropine overdose)

A

Physostigmine

53
Q

Cholinomimetic indirect acting agonist (AChE’s) that increases muscle strength; often used with glycopyrrolate, hyoscyamine, or propantheline to control its side effects; used to tx Myasthenia gravis (long acting); does not penetrate CNS (quaternary amine)

A

Pyridostigmine

54
Q

Use of cholinomimetic agents should prompt you to watch for exacerbation of what 3 conditions in susceptible patients?

A

COPD
Asthma
Peptic ulcers

55
Q

Muscarinic effects of anticholinesterase poisoning

A

DUMBBELSS:

Diarrhea
Urination
Miosis
Bronchospasm
Bradycardia
Emesis
Lacrimation
Sweating
Salivation
56
Q

Nicotinic and CNS effects of anticholinesterase poisoning

A

Nicotinic: neuromuscular blockade (mechanism similar to succinylcholine)

CNS: respiratory depression, lethargy, seizures, coma

57
Q

Methods for reversal of muscarinic and nicotinic effects of anticholinesterase poisoning

A

Muscarinic effects reversed by atropine, a competitive inhibitor (can cross BBB to relieve CNS symptoms as well)

Nicotinic effect reversed by pralidoxime, regenerates AChE if given early; pralidoxime does not readily cross BBB

58
Q

3 muscarinic antagonists that produce mydriasis and cycloplegia

A

Atropine
Homatropine
Tropicamide

59
Q

2 muscarinic antagonists that treat Parkinson disease and acute dystonia

A

Benztropine

Trihexyphenidyl

60
Q

Muscarinic antagonist that can be used parenterally in pre-op to reduce airway secretions, or orally to treat drooling and peptic ulcer

A

Glycopyrrolate

61
Q

2 muscarinic antagonists used as antispasmotics for IBS

A

Hyoscyamine

Dicyclomine

62
Q

2 muscarinic antagonists used to treat COPD and asthma

A

Ipratropium

Tiotropium

63
Q

3 muscarinic antagonists used to reduce bladder spasms and urge urinary incontinence (overactive bladder)

A

Oxybutynin
Solifenacin
Tolterodine

64
Q

Muscarinic antagonist used to treat motion sickness

A

Scopolamine

65
Q

Effects of atropine (muscarinic antagonist) on eye, airway, stomach, gut, and bladder

A

Eye — pupil dilation, cycloplegia

Airway — bronchodilation, decreased secretions

Stomach — decreased acid secretion

Gut — decreased motility

Bladder — decreased urgency in cystitis

66
Q

AEs of atropine

A 
Increased body temp
Increased HR
Dry mouth
Dry flushed sin
Cycloplegia
Constipation
Disorientation

Can cause acute angle-closure glaucoma in the elderly (due to mydriasis), urinary retention in men with BPH, and hyperthermia in infants

[Hot as a hare, Dry as a bone, Red as a beet, Blind as a bat, Mad as a hatter, Full as a flask]

67
Q

3 direct sympathomimetics that act at beta2>beta1:

_______ is used for acute asthma/COPD

_______ is used for long-term asthma/COPD

_______ is used for acute bronchospasm in asthma and tocolysis

A

Albuterol

Salmeterol

Terbutaline

68
Q

Direct sympathomimetic that acts on beta1>beta2, alpha; applications include heart failure, cardiogenic shock (inotropic>chronotropic), and cardiac stress testing

A

Dobutamine

69
Q

Direct sympathomimetic that acts on D1 = D2 > beta > alpha; applications include unstable bradycadia, HF, shock; inotropic and chronotropic effects at lower doses due to beta effects; vasoconstriction at high doses due to alpha effects

A

Dopamine

70
Q

Direct sympathomimetic that acts on beta > alpha receptors; applications include anaphylaxis, asthma, open-angle glaucoma; alpha effects predominate at high doses. significantly stronger effect at beta 2 receptors than NE

A

Epinephrine

71
Q

Direct sympathomimetic that acts on D1 receptors; treats postop HTN, hypertensive crisis. Acts as a vasodilatory (coronary, peripheral, renal, and splanchnic); promotes natriuresis. Can cause hypotension and tachycardia

A

Fenoldopam

72
Q

Direct sympathomimetic that acts on beta 1= beta 2 receptors; applications include electrophysiologic eval of tachyarrythmias. Can worsen ischemia; has negligible alpha effect

A

Isoproterenol

73
Q

Direct sympathomimetic that acts on alpha1 receptors; treats autonomic insufficiency and postural hypotension. May exacerbate supine HTN

A

Midodrine

74
Q

Direct sympathomimetic that acts on beta3 receptors; treats urinary urge incontinence or overactive bladder

A

Mirabegron

75
Q

Direct sympathomimetic that acts on alpha 1> alpha 2 > beta1 receptors; applications include hypotension, septic shock

A

NE

76
Q

Direct sympathomimetic that acts on alpha 1 > alpha 2 receptors; treats hypotension, used in ocular procedures (mydriatic), rhinitis (decongestant), and ischemic priapism

A

Phenylephrine

77
Q

Indirect sympathomimetic that acts as indirect general agonist, reuptake inhibitor, also releases stored catecholamines; treats narcolepsy, obesity, and ADHD

A

Amphetamine

78
Q

Indirect sympathomimetic that acts as an indirect general agonist and reuptake inhibitor; causes vasoconstriction and local anesthesia. Caution when giving beta blockers if intoxication is suspected — can lead to unopposed alpha1 activation —> extreme HTN and coronary vasospasm

A

Cocaine

79
Q

Indirect sympathomimetic that acts as indirect general agonist and releases stored catecholamines; applications include nasal decongestion, urinary incontinence, and hypotension

A

Ephedrine

80
Q

2 sympatholytics (alpha-2 agonists) that are used in hypertensive urgency (limited situations), ADHD, tourette syndrome, and symptom in opioid withdrawal; AEs include CNS depression, bradycardia, hypotension, respiratory depression, miosis, rebound HTN with abrupt cessation

A

Clonidine

Guanfacine

81
Q

Sympatholytic (alpha-2 agonists) that treats HTN in pregnancy; AEs include direct Coombs + hemolysis and drug-induced lupus

A

Alpha-methyldopa

82
Q

Sympatholytic (alpha-2 agonists) that is used for relief of spasticity; AEs include hypotension, weakness, xerostomia

A

Tizanidine

Boards Pathology (19 decks)

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