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1

Volume of distribution

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

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

2

Half-life of drug

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)

3

Clearance (CL)

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

4

Zero order elmination

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

Ex: Phenytoin, Ethanol, Aspirin

5

Urine pH/Drug elimination

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

Weak base (amphetamines): eliminate with ammonium chloride

6

Nicotinic receptors

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

Nn= autonomic ganglia
+ Adrenal medulla
Nm= Neuromuscular junction

7

Muscarinic receptors

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

8

Gq receptor types

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

9

Gs receptor types

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)

10

Gi receptor types

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

11

Vesamicol

Blocks VAchT (packaging of Ach in presynaptic terminals)

12

Hemicholinium

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

13

Metyrosine

Blocks tyrosine hydroxylase
- Can't convert Tyrosine to DOPA

14

Reserpine

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

15

Guanethidine, bretylium

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

16

Bethanchol

Direct cholinomimetic agonist
- Activates bowel, bladder smooth muscle
- Resistant to AchE

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

17

Carbachol

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

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

18

Pilocarpine

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"

19

Neostigmine

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)

20

Pyridostigmine

Indirect cholinomimetic (anti-AchE)
- no CNS penetration

Use:
- MG (long-acting)

21

Edrophonium

Indirect cholinomimetic (anti-AchE)

Use:
- MG (short-acting)- test

22

Physostigmine

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

Use:
- Atropine/anticholinergic overdose

23

Donepexil

Indirect cholinomimetic (anti-AchE)
- Increases Ach

Use:
- Alzheimer's disease

24

Cholinesterase inhibitor poisoning (organophosphate poisoning)

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

Atropine, homatropine, tropicamide

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

Benztropine

Muscarinic antagonist (M1)

CNS depression

Use:
- Parkinson's disease dystonia, tremor

27

Scopolamine

Muscarinic antagonist (M1)

Use: motion sickness (prevents vestibular transmission)

28

Ipratropium, Tiotropium

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

Use: COPD, asthma
- Blocks respiratory secretions

29

Oxybutynin

Muscarinic antagonist (M3)

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

30

Glycopyrrolate

Muscarinic antagonist (M3)

Use:
- Parenteral: pre-op to reduce airway secretions
- Oral: stop drooling, peptic ulcer

31

Terbutaline, Ritodrine

Beta agonists

Use: prevent premature contractions (tocolytics)

32

Clonidine, alpha-methyldopa

Centrally acting alpha-2 agonist
- Decreases sympathetic outflow

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

33

Phenoxybenzamine

Nonselective irreversible alpha blocker

Use:
- Pre-op pheochromocytoma excision

Tox: orthostatic hypotension, reflex tacchycardia

34

Phentolamine

Nonselective reversible alpha blocker

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

35

-zosins

Alpha-1 blockers

Use:
- HTN
- BPH--> urinary retention

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

36

Mirtazapine

Alpha-2 blocker

Use: depression

Tox: sedation, increased serum cholesterol, increased appetite

37

Beta-1-selective antagonists

Acebutolol (partial)
Betaxolol
Esmolol
Atenoolol
Metoprolol

38

Nonselective antagonists

Propanolol
Timolol
Nadolol
Pindolol (partial)

39

Nonselective alpha and beta antagonists

Carvedilol
Labetolol

40

Antidote for beta-blocker

Glucagon

41

Antidote for digitalis

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

42

Iron antidote

Deferoxamine, Deferasirox

43

Lead antidote

CaEDTA, dimercaprol, succimer, pencillamine

44

Mercury, arsenic, Gold antidote

Dimercaprol (BAL), succimer

45

Copper, arsenic, Gold antidote

pencillamine

46

Overdoses to treat with NaHCO3 (alkalinize urine):

Salicylates
TCAs
Barbituates

47

Benzo overdose tx

Flumazenil

48

tPA, streptokinase, urokinase overdose tx

Aminocaproic acid

49

Epinephrine

Stimulates: all sympathetics

Use: anaphylaxis, glaucoma, asthma, hypotension

50

Norepinephrine

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

Use: Hypotension (but decreases renal perfusion)

51

Isoproterenol

Beta-1 and beta-2 stimulation

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

52

Dopamine

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

Dobutamine

beta1 stimulation

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

54

Phenylephrine

Alpha1, alpha2 stimulation

Use: hypotension (vasoconstrictor) while allowing compensatory decrease in HR (vagal stimulation)
- Ocular procedures (mydriasis)
- Rhinitis (decongestant)

55

Albuterol, Salmeterol, terbutaline

B1, B2 stimulation

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

56

Ritodrine

B2

Use: reduces premature uterine contractions

57

Amphetamine

Indirect general agonist
- Releases stored catecholamines

58

Ephedrine

indirect general agonist
- Releases stored catecholamines

59

Cocaine

Inirect general agonist
- Reuptake inhibitor