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*Pharm > Agonists and Antagonists > Flashcards

Agonists and Antagonists Flashcards

1
Q

What is the purpose of a selective beta 2 agonist?

A
  • bronchodilation and uterine relaxation

- trx asthma, COPD, premature labor

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2
Q

What is the s/e of a selective beta 2 agonist?

A
  • tremors from b2 (skeletal muscle action)
  • tachycardia (reflex from vasodilation)
  • hypokalemia (K+ uptake)
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3
Q

What is the prototype for beta 2 agonist?
What does it treat, what is the dosing?
S/E? What about lifethreatening dose?

A
  • albuterol for asthmatic bronchospasm
  • MDI 100 mcg per puff
  • 2 puffs Q6H, max of 20 puffs
  • life-threatening asthma = 15 mg/hr x 2hrs
  • s/e: tremors, hypokalemia w/ large doses
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4
Q

What type of drug is terbutaline? What is it used for? Describe dosing.

A

b2 agonist
for asthma/pre labor
PO, SQ (0.25 mg), puffs

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5
Q

What type of drug is salmeterol? What is it used for? How is it dispensed? ANd what is it’s DOA?

A

b2 agonist
asthmatic bronchospasm
MDI
DOA = >12hrs

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6
Q

What type of drug is ritordine? What is it used for? S/E?

A

beta 2 agonist
for premature labor
has some beta 1 activity = inc HR/CO
can cause pulm edema d/t dec Na, K, H2O excretion

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7
Q

What is midodrine (pramantine)? Trx?

A
  • direct acting non catecholamine
  • alpha 1 agonist
  • trx postural hypotension
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8
Q

What is oxymetaZOLINE tetrahydroZOLINE and xylometaZOLINE? Trx?

A
  • direct actiong non catecholamine
  • alpha 1 agonist
  • treats nasal/ocular decongestion
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9
Q

Name 3 direct acting non catecholamine alpha 2 agonists and their actions.
(Drugs your pt may be taking)

A
  1. clonidine (partial agonist) (BP)
  2. dexmedetomidine (full agonist)
  3. methyldopa (BP)
    - dec SNS outflow from CNS = dec BP, sedation, analgesia
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10
Q

Is amphetamine direct or indirect? What is its MOA?

A
  • indirect sympathomimetic
  • inc release of NE, 5HT (seretonin), DOPA
  • and blocks their reuptake, transport, and inhibits MAO
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11
Q

Name other drugs similar to amphetamine.

A
  • methamphetamine - similar to amph but inc CNS effects

- methylphenidate (Ritaline), pemoline (Cylert) - ADHD

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12
Q

What is the MOA of reserpine?

A
  • catecholamine inhibitor to trx htn
  • vesicles lose ability to store NE, 5HT, DOPA
  • MAO breaks down excess except in high doses causing hypotension and psych depression
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13
Q

What is the MOA of cocaine?

A
  • catecholamine inhibitor
  • prevents reuptake of catecholamines (NE, DOPA, 5HT)
  • interferes w/ catecholamine transport
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14
Q

What is miosis vs mydriasis?

A 
miosis = contraction/constriction of pupils
mydriasis = dilation of pupils
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15
Q

What happens w/ a non-selective alpha antagonist?

A

block alpha 1 = vasodilation > dec BP, baroreceptor activated = tachycardia

block alpha 2 = block presynaptic negative feedback (dec NTs) = inc NE release

since alpha 1 and 2 are blocked, only beta 1 will respond to NE = inc HR/CO = rebound/worse tachycardia

SUMMARY: If you give a non selective alpha blocker, you will get tachy from baroreceptors of alpha 1 block and tachy from beta 1 + NE

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16
Q

Name alpha 1 antagonists.

Which are competitive?

A

prazosin (competitive)
terazosin
doxazosin

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17
Q

Name a non selective alpha antagonist. Is it competitive or non?

A

phentolamine (competitive)

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18
Q

Name an alpha 2 antagonist (with some alpha 1 block)

A

yohimibine

tolazoline

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19
Q

Name mixed alpha/beta antagonists.

A

labetolol
carvedilol
B1=B2>=alpha1>alpha2

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20
Q

Name the beta 1 antagonists

A 
metoprolol
esmolol
atenolol
acebutolol
betazolol
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21
Q

Name non selective beta antagonist

A

propranolol
nadolol
timolol
pindolol

22
Q

Name beta 2 antagonist

A

butoxamine

23
Q

What are the CV effects of alpha 1 antagonist?

A
  • dec PVR, dec BP

- postural hypotension

24
Q

What are the CV effects of alpha 2 antagonist?

A
  • dec NT/inhibited negative feedback

- inc release NE

25
Q

What are other non-CV effects of alpha antagonists?

A
  • prostate/bladder relaxation (easier voiding)
  • miosis
  • inc nasal congestion
26
Q

Which alpha agonists is covalently bonded so it is tough to outcompete?

A
  • phenoxybenzamine

- can only leave by metabolism

27
Q

What is phentolamine? Trx?

A
  • non selective alpha antagonist
  • vasodilation, dec BP, inc HR/CO
  • used for HTN emergencies usually pheocromocytoma or autnomic dysreflexia
28
Q

What are the doses for phentolamine? onset/DOA?

A
  • HTN emergency - 30-70 mcg/kg IV
  • onset = 2min
  • DOA = 10-15 min
  • local infiltration of sympathomimetics - 2.5-5 mg in 10 ml
29
Q

What class is prazosin? Trx?

A
  • alpha 1 antagonist
  • controls BP in pheochromocytoma
  • *LESS reflexive tachy d/t min alpha 2 effects
30
Q

What class is yohimibine? What is its MOA? Trx?

A
  • alpha 2 antagonist
  • inc release of NE at post-synaptic neuron
  • trx orthostatic hypotension, impotence
31
Q

What are the effects of beta antagonists?

A
  • compete w/ sympathomimetics from provoking a beta response on
    1. heart (improve O2 supply/demand)
    2. a/w (bronchospasm)
    3. blood vessels (vasoconstriction sk muscle; inc PVD symptoms i.e. cramping)
    5. juxtoglomerular cells (dec renin, indirect dec BP)
    6. pancreas (dec insuline release by epi/NE at B2 and masked hypoglycemia at b1?)
32
Q

What is the MOA of beta antagonists?

A
  • selective binding to beta receptors (inotropy/chronotropy) to inhibit endogenous agents
  • competitive and reversible inhibition; large dose agonists will overcome antagonism
  • non selective = no sympathomimetic activity
33
Q

What are the concerns with chronic use of beta antagonists?

A

upregulated receptors which becomes problem if pts stops antagonist abruptly > will have massive reaction to agonist binding perioperatively which can be dangerous

34
Q

What is unique about beta antagonist structure?

A

-derivative of isoproteronol (non selective beta agonist) so they will ahve some sympathomimetic effects

35
Q

What is the betablocker prototype?

A

Propranolol

36
Q

How do you administer propranolol?

A

stepwise manner; titrate to HR goal of 55-60

37
Q

What are the CV effects of propranolol (prototype)

A
  • dec HR/CO/contractility (B1)
  • inc PVR, coronary vascular resistance (B2)
  • Na+ retention d/t response in dec CO (blocked renin so kidneys retain Na+)
38
Q

Propranolol Dose?

A
  • high first-pass effect (95%)
  • 0.05 mg/kg IV or 1-10 mg
  • GIVE SLOW - 1MG Q5min
39
Q

Propranolol pharmacokinetics?

A
  • 95% protein bound
  • metabolized in liver
  • e 1/2t = 2-3 hrs (longer in low hepatic flow)
40
Q

What effect does propranolol have on fentanyl or amid LAs?

A
  • dec pulmonary first pass effect of fentanyl

- dec amide LA clearance d/t drop in hepatic flow

41
Q

What class is timolol? Trx? S/E?

A
  • non selective beta blocker
  • trx glaucoma, dec IOP by dec aqueous humor
  • eye gtts can cause dec BP/HR and inc a/w resistance
42
Q

What class is nadolol? e1/2t?

A
  • non selective beta blocker
  • e1/2t = 20-40 hrs
  • once daily
43
Q

What class is metoprolol? Dose? e1/2t?

A
  • beta 1 blocker
  • prevents inotropy and chronotropy
  • 60% via first pass effect; e1/2t = 4 hrs
  • PO = 50-400 mg
  • IV = 1-15 mg
44
Q

What class is atenolol? e1/2t? What patients is it useful for?

A
  • beta 1 blocker (least CNS effects)
  • e1/2t = 7 hrs
  • eliminated via kidneys unchanged - inc 1/2t w/ renal dz
  • useful for CAD cardiac pts
45
Q

What class is betaxolol? e1/2t? trx? How else is it used?

A
  • beta 1 blocker
  • e1/2t = 11-22 hrs
  • trx HTN
  • topical for glaucoma; good alternative for ASTHMATICS w/ glaucoma (dec risk of spasm)
46
Q

What class is esmolol? dose? Effects?

A
  • beta 1 blocker
  • 0.5 mg/kg IV (10-180mg IV)
  • infusion 50-300 mcg/kg/min
  • effects HR w/o big dec BP in small doses
47
Q

What is esmolol’s DOA? e 1/2t? How is it metabolized?

A
  • < 15 min
  • 9 min
  • PLASMA ESTERASE (does not affect sux, diff esterase)
  • fast on/fast off*
48
Q

What are s/e of beta blockers?

A
  • *may dec BP w/ inhaled anesthetics**
  • dec HR, contractility, BP
  • exacerbates PVD (d/t b2 block-vasodilation)
  • bronchospasm, a/w resistance
  • alter carb/fat metabolism, masks hyoglycemic inc HR
  • inc EC K+ (inhibited uptake of sk muscle)
  • CNS - fatigue, lethargy, N/V
49
Q

What are relative contraindications of beta blockers?

A
  • AV heart block
  • cardiac failure
  • asthmatics
  • DM w/o BG monitoring
  • hypovolemia
50
Q

What are clinical uses of beta blockers?

A
  • trx HTN, manage angina
  • used preop and periop for pts at risk for MI
  • suppress tachyarrhthmias
  • prevent excess SNS activity
51
Q

What class is labetolol? Effects?

A
  • beta&raquo_space; alpha 1 antagonist (7:1 via IV)
  • dec BP, SVR, HR (afterload)
  • CO unaffected
  • **Max drop in BP = 5-10 min after admin IV
52
Q

What is dose for labetolol? S/E?

A
  1. 1 mg - 0.5 mg/kg
    - 5 mg at a time for mild HTN in OR
    - ortho hypotension, bronchospasm, heart block, CHF, bradycardia

*Pharm (6 decks)

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