Pharmacology basics Flashcards

1
Q

Volume of distribution

A

Vd= (amount of drug in body)/(plasma drug concentration)

  • Vd high when drug goes everywhere OR if plasma proteins low (cirrhosis, kidney disease)
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2
Q

Half-life of drug

A

First-order elimination (rate of elimination proportional to drug concentration in blood= constant fraction eliminated per unit time)
- Exponential elimination

Takes 4-5 half-lives to reach steady state with a drug infused at steady rate
- 97% of a drug is excreted in 4x t1/2

    • To calculate clearance of drug, need to know t1/2= (0.7 x Vd)/CL or
      (0. 7 xVd) / (rate of elimination of drug/plasma drug concentration)
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3
Q

Clearance (CL)

A

CL= rate of elimination of drug/plasma drug concentration= Vd x elimination constant (Ke)

Loading dose= Cp x Vd/F
- Cp= target plasma concentration

Maintenance dose= Cp x CL/F
- F= bioavailability

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4
Q

Zero order elmination

A

Drug elimination constant
- Cp decreases linearly (vs first-order exponential)

Ex: Phenytoin, Ethanol, Aspirin

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5
Q

Urine pH/Drug elimination

A

Weak acid (phenobarbital, methotrexate, aspirin): eliminate with bicarb

Weak base (amphetamines): eliminate with ammonium chloride

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6
Q

Nicotinic receptors

A

Stimulated by Ach
- Ligand-gated Na+/K+ channels

Nn= autonomic ganglia
+ Adrenal medulla
Nm= Neuromuscular junction

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7
Q

Muscarinic receptors

A

Stimulated by Ach
- G-protein coupled receptors of parasympathetic system
+ Sympathetic sweat glands

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8
Q

Gq receptor types

A

H1, alpha-1, V1, M1, M3
- HAVe 1 M&M

Activate Phospholipase C–> cleave PIP2 (lipid-derived)–>

  1. DAG==> PKC
  2. IP3–> Ca+2 increase in cell–> smooth muscle contraction
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9
Q

Gs receptor types

A

Beta1, Beta2, D1, H2, V2

Activates adenylyl cyclase

  • -> cAMP–> PKA–>
    1. increase Ca+2 concentration in heart muscle–> contractility
    2. block myosin light chain kinase (prevent smooth muscle contraction)
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10
Q

Gi receptor types

A

M2, alpha-2, D2
- MAD 2s

Blocks adenylyl cyclase

  1. Decreased Ca+2 in heart (decreased contractility)= M2
  2. Increases myosin light chain kinase activity (MLCK)–> smooth muscle contraction= alpha-2
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11
Q

Vesamicol

A

Blocks VAchT (packaging of Ach in presynaptic terminals)

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12
Q

Hemicholinium

A

Blocks ChT (influx of choline)–> can’t use with choline acetyl transferase to make Ach

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13
Q

Metyrosine

A

Blocks tyrosine hydroxylase

- Can’t convert Tyrosine to DOPA

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14
Q

Reserpine

A

Blocks VMAT: can’t packages DA, NE, epi

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15
Q

Guanethidine, bretylium

A

Blocks release of Noradrenergic vesicles from presynaptic terminal (NE, DA, Epi can’t get out)

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16
Q

Bethanchol

A

Direct cholinomimetic agonist

  • Activates bowel, bladder smooth muscle
  • Resistant to AchE

Use:
- Post-operative ileus, neurogenic ileus, urinary retention (nonobstructive)

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17
Q

Carbachol

A

Direct cholinomimetic agonist (Ach)
- Identical to Ach (not AchE resistant)

Use:
- Glaucoma, pupillary contraction, relief of IOP
“Carbon copy of Ach”

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18
Q

Pilocarpine

A

Direct Cholinomimetic agonist

  • Contracts ciliary muscle of eye
  • Pupillary sphincter contraction
  • Resistant to AchE

Use:

  • Stimulates sweat, tears, saliva
  • Open/closed angle glaucoma

“Cry onto your pillow”

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19
Q

Neostigmine

A
Indirect cholinomimetic (anti-AchE)
- No CNS penetration (Neo= No-CNS penetration)

Use:

  • Post-op ileus
  • Neurogenic ileus, urinary retention
  • MG
  • Reverse NM junction blockade (post-op)
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20
Q

Pyridostigmine

A
Indirect cholinomimetic (anti-AchE)
- no CNS penetration

Use:
- MG (long-acting)

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21
Q

Edrophonium

A

Indirect cholinomimetic (anti-AchE)

Use:
- MG (short-acting)- test

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22
Q

Physostigmine

A
Indirect cholinomimetic (anti-AchE)
- Crosses BBB (thus can reverse CNS effects of anticholinergic toxicity)

Use:
- Atropine/anticholinergic overdose

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23
Q

Donepexil

A
Indirect cholinomimetic (anti-AchE)
- Increases Ach

Use:
- Alzheimer’s disease

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24
Q

Cholinesterase inhibitor poisoning (organophosphate poisoning)

A

Organophosphates (parathion) inhibit AchE
- Pupils small, decreased breathing/HR
- Lots of fluid excretion
- Muscle twitching
(Diarrhea, diaphoresis, urination, miosis, bronchospasm, bradycardia, emesis, lacrimation, salivation)

Antidote= Atropine (anticholinergic) + Pralidoxime (regenerates active AchE- otherwise muscle spasm–> paralysis)

25
Q

Atropine, homatropine, tropicamide

A

Muscarinic antagonists (M3)

Use: mydriasis, cycloplegia

“Belladonna/Nightshade”
- Atropine also decreases airway secretions, acid secretion, gut motility, bladder urgency

Toxicity of Atropine:

  • Hot as a hare, Dry as a bone, Red as a beet, Blind as a bat, Mad as a hatter
    • Jimson weed–> Gardner’s pupil (mydriasis d/t plant alkaloids)
26
Q

Benztropine

A

Muscarinic antagonist (M1)

CNS depression

Use:
- Parkinson’s disease dystonia, tremor

27
Q

Scopolamine

A

Muscarinic antagonist (M1)

Use: motion sickness (prevents vestibular transmission)

28
Q

Ipratropium, Tiotropium

A

Muscarinic antagonist (M3) (parasympathetic control of asthma vs noradrengergic)

Use: COPD, asthma
- Blocks respiratory secretions

29
Q

Oxybutynin

A

Muscarinic antagonist (M3)

Use:
- Reduce urgency in mild cystitis, reduce bladder spasms

30
Q

Glycopyrrolate

A

Muscarinic antagonist (M3)

Use:

  • Parenteral: pre-op to reduce airway secretions
  • Oral: stop drooling, peptic ulcer
31
Q

Terbutaline, Ritodrine

A

Beta agonists

Use: prevent premature contractions (tocolytics)

32
Q

Clonidine, alpha-methyldopa

A

Centrally acting alpha-2 agonist
- Decreases sympathetic outflow

Use:
- Hypertension, esp. with renal disease (no decrease in blood flow to kidney)

33
Q

Phenoxybenzamine

A

Nonselective irreversible alpha blocker

Use:
- Pre-op pheochromocytoma excision

Tox: orthostatic hypotension, reflex tacchycardia

34
Q

Phentolamine

A

Nonselective reversible alpha blocker

Use:
- Give to patients who have eaten tyramine-containing food while on MAO-I

35
Q

-zosins

A

Alpha-1 blockers

Use:

  • HTN
  • BPH–> urinary retention

Tox: 1st dose orthostatic hypotension, dizziness, H/A

36
Q

Mirtazapine

A

Alpha-2 blocker

Use: depression

Tox: sedation, increased serum cholesterol, increased appetite

37
Q

Beta-1-selective antagonists

A
Acebutolol (partial)
Betaxolol
Esmolol
Atenoolol
Metoprolol
38
Q

Nonselective antagonists

A

Propanolol
Timolol
Nadolol
Pindolol (partial)

39
Q

Nonselective alpha and beta antagonists

A

Carvedilol

Labetolol

40
Q

Antidote for beta-blocker

A

Glucagon

41
Q

Antidote for digitalis

A

Normalize K+, Lidocaine, Anti-dig Fab fragments, Mg+2

42
Q

Iron antidote

A

Deferoxamine, Deferasirox

43
Q

Lead antidote

A

CaEDTA, dimercaprol, succimer, pencillamine

44
Q

Mercury, arsenic, Gold antidote

A

Dimercaprol (BAL), succimer

45
Q

Copper, arsenic, Gold antidote

A

pencillamine

46
Q

Overdoses to treat with NaHCO3 (alkalinize urine):

A

Salicylates
TCAs
Barbituates

47
Q

Benzo overdose tx

A

Flumazenil

48
Q

tPA, streptokinase, urokinase overdose tx

A

Aminocaproic acid

49
Q

Epinephrine

A

Stimulates: all sympathetics

Use: anaphylaxis, glaucoma, asthma, hypotension

50
Q

Norepinephrine

A

Alpha-1, Alpha-2, some Beta-1 stimulation

Use: Hypotension (but decreases renal perfusion)

51
Q

Isoproterenol

A

Beta-1 and beta-2 stimulation

Use: Torsades de Pointes (tachycardia decreases shortened QT interval)
- Bradyarrhythmias (can worsen ischemia)

52
Q

Dopamine

A

High dose: Alpha-1, 2 stimulation
Medium dose: beta-1, 2 stimulation
Low dose: D1 receptors

Use: shock (renal perfusion), heart failure, inotrope and chronotrope

53
Q

Dobutamine

A

beta1 stimulation

Use: heart failure, cardiac stress-test
- Inotrope, chronotrope

54
Q

Phenylephrine

A

Alpha1, alpha2 stimulation

Use: hypotension (vasoconstrictor) while allowing compensatory decrease in HR (vagal stimulation)

  • Ocular procedures (mydriasis)
  • Rhinitis (decongestant)
55
Q

Albuterol, Salmeterol, terbutaline

A

B1, B2 stimulation

Metaproterenol and albuterol for acute asthma
Salmeterol for long-term asthma or COPD control
Terbutaline to decrease premature contractions

56
Q

Ritodrine

A

B2

Use: reduces premature uterine contractions

57
Q

Amphetamine

A

Indirect general agonist

- Releases stored catecholamines

58
Q

Ephedrine

A

indirect general agonist

- Releases stored catecholamines

59
Q

Cocaine

A

Inirect general agonist

- Reuptake inhibitor