Flashcards in Pharmacology basics Deck (59)
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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
