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Therapeutics II > Vasodilators > Flashcards

Vasodilators Flashcards

1
Q

Vasodilator classes

A

-Cyclic GMP modulators
-K channel agonists
-endothelin receptor antagonists
-PGI2 analogs- IP receptor agonists

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2
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10
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11
Q

Why does inc K channel opening relax vasc smooth muscle?

A

-K flux set membrane potential
-the longer K channels are open, the closer the membrane potential is to the K equilibrium potential
-the closer the membrane potential is to the K equilibrium potential, the harder it is to depolarize membrane enough to open gated Ca channels

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12
Q

K channel agonists/openers

A

-minoxidil
-diazoxide
-adenosine?

-regulate membrane potential
-reduce Ca channel activity

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13
Q

Minoxidil

A

-activated in vivo by sulfotransferase 1A1
-K opener
-use w loop diurtics and beta blockers
-potent
-effective in severe, drug resistant HTN
-cAMP PDE inhibition may be efficacy
-give orally or topically for hair growth
-hypertrichosis

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14
Q

Diazoxide

A

-K-opener
-used IV to tx acute HTN
-very potent (resistnant HTN)
-inhibits release of insulin form pancreatic B cells
-used orally for hypoglycemia 2’ to hyperinsulinemia

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15
Q

Adenosine

A

-binds A1 (GPCR)
-inc conductance of a K channel (hyperpolarization and relaxation)
-give IV coronary stress test
-also for supraventricular arrhythmias

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16
Q

Hyperpolarization of vasc smooth muscle by adenosine

A

-A1 receptor
-G-protein activated inwardly rectifyin K channel
-Gby binds and activates GIRK-conducts K efflux and membrane hyperpolarization

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17
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18
Q

Drugs that stimulate nitric oxide production

A
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19
Q

Nitric Oxide Synthase

A

-NOS in vascular endothelium
-NO diffuses to vasc smooth muscle
-nNOS
-iNOS
-eNOS in vasc endothelium activated by Ca-CAM

-exogenous NO can relax smooth muscle

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20
Q

Nitric oxide-cyclic GMP pathway

A

-eNOS found in endothelial cells of vasculature
-NO referred to as EDRF
-guanylate cyclase found in vasc smooth muscle
-exogenously applies NO can directly relax smooth muscle

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21
Q

Acetylcholine relaxes smooth muscle via NO

A
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22
Q

Nitric oxide binds to

A

-heme in iron prosthetic group in guanylate cyclase
=stimulate production of cGMP and activating cGKI (protein kinase G)
-

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23
Q

how does protein kinase G relax smooth muscle?

A

-inhibition of L-type Ca channels (Cav1.2)
-stimulation of Ca activated K channels (BKca)
-dec MLC phosphorylation (myosin phosphatase 1)
-enhanced Ca uptake in to ER (phospholamban

24
Q

Organic nitrates

A

-non-selective vasodilators
-breakdown to nitric oxide (bioactivation)
-dont require functional endothelium
-acute or chronic admin

25
Organic nitrate drugs
-amylnitrite -glyceryl trinitrate (GTN) -pentaerythritol tetranitrate (PETN) -isosorbide dinitrate -isosorbide mononitrate -nitroprusside
26
PK of organic nitrates
-GTN 3min <1% bioavailability -ISDN 10 min 20% -5-ISMN 280 min 100% -give sublingually in tx of acute attacks of angina -tolerance occurs w continuous administration
27
Tolerance to glyceryl trinitrate
-munitions workers -monday headaches -slide 21 mech
28
genetics of glycerol trinitrate
-glu504 polymorphism -glu504 metabolize glycerol trinitrate -lack of efficacy in large % of Asian population -the lys 504 allele also accounts for alcohol intolerance as acetaldehyde metabolism also reduced
29
Differences in activation of GTN and ISMN/ISDN
30
mech of cell damage initiated by hyperglycemia
-AGE precursor methylglyoxal inhibits vasorelaxation stimulated by acetylcholine/nitric oxide
31
Sodium nitroprusside (SNP)
-give IV for acute managemnet of HTN crisis and severe heart failure -dilates veins and arterioles -metabolized in erythrocytes to NO, 4CN, and cyanmethemoglobin (limits duration) -CN can inhibit oxidative metabolism = lactic acid accumulation -CN converted to less toxic SCN- by rhodanase, excreted via kidney -may be used for detox
32
Hydrazaline
-nitrate -dilates arterioles preferentially -can induce lupus-like syndrome -give orally or IV -combined w B-blocker, diuretic
33
hydralazine combo w ISDN in BiDil
-antioxidant activity potentiates vasodilatory activity of ISDN -BiDil decreases mortality in black people w CHF
34
Human type B Natriuretic peptide (BNP)
-cleaved by Neprilysin -synthesized and secreted from heart muscle in response to inc blood volume -binds to and activates membrane-bound gunaylate cyclase in vasc smooth muscle and endothelial cells
35
BNP mech
36
Sacubritril
-combo w ARB valsartan (entresto) ARNI -oral BID -prodrug activated by esterases -prevents breakdown of BNP enhancing its action -NOT USED W ACEi -use to tx heart failure -inhibitor of neprilysin (protease)
37
Drugs that inhibit breakdown of cGMP/AMP: phosphodiesterase inhibitors
-amrinone (PDE3 cAMP) -milrinone (PDE3 cAMP) -dipyridamole (PDE5 cGMP) -sildenafil (PDE5 cGMP)
38
mech for controlling smooth muscle tone
-Ca channel pathway -GPCR pathway: -inc cAMP PDE3 makes cAMP to AMP
39
Amrinone and milrinone
-give IV -inotropic -vasodilatory effect on smooth muscle -used maily in CHF
40
sildenafil (PDE5 inhibitors)(viagra)
-inhibit cGMP -10 fold selectivity over PDE6 inhibition (retina) -bluish vision -lack of systemic vasodilation -corpus cavernosum
41
levitra (vardenafil)
-shorter time to onset than viagra -more selective for PDE5 than viagra
42
tadalafil (cialis)
-more selective than viagra -longer duration of action
43
PDE5 inhibitor contraindication
-DO NOT USE w organic nitrates -precipitous drop in blood pressure =both drugs inc cGMP accumulation -cGMP also inhibits PDE3 =inc cAMP levels -both stimulate vasodilation
44
Vasodilators used in Pulmonary arterial HTN (PAH)
-endothelin antagonists -PGI2 analogs -guanylyl cyclase activators -PDE5 inhibitors -activin neutralizers
45
endothelin signaling
-increased in PAH
46
vasoconstrictor (endothelin) ANTAgonists
-Bosentan (Tracleer) -Macitentan (Opsumit) Ambrisentan (Letairis)
47
Bosentan (traccleer) and Macitentan (opsumit)
-specific low MW -endothelin receptor antagonists -block both ETA (VSM and ETB (VSM + endothel receptor)
48
Ambrisentan (letairis)
-blocks only ETA receptors -approved for PAH
49
Vasoconstrictor ANTAgonist contraindications (-sentan)
-contraindicated in pregnancy -hepatotoxicity (bosentan) -only available to females thru special programs
50
Prostacyclin analogs
-PGI2 (epoprostenol; 3-5min t1/2) IV -Treprostinil (Remodulin 4h) PO or IV -Iloprost (Ventavis 30 min) inhalation -selexipag (uptravi 6-13h) PO or IV -tx PAH
51
Allosteric activator of sGC
-Riociguat (adempas) -for PAH -potentiates the effect of NO -stimulates sGC activity allosterically -inc cGMP concentration in VSM
52
Riociguat
-allosteric activator of sGC -not combo w nitrates of PDE5s -dont use if pregnant -risk of hemorrhage -substrate for P-gp, CYP1A1,3A -only available to females thru special programs
53
PDE5 inhibitors for PAH
-sildenafil and tadalafil are both indicated for PAH -both thought to enhance effect of NO
54
Sotatercept-CSRK (winrevair)
-activin type IIA-Fc -binds/neutralizes activin and other TGF ligands -for PAH -reduces proliferation of vas smooth muscle cells -reduces pulmonary vasc resistance -inj SQ q3weeks
55
Sotatercept-CSRK (winrevair) potential toxicities
-erythrocytosis -thrombocytopenia -bleeding -terrtogen -impaired fertility -HA, rash, nosebleed, telangiectasia
56
PAH

Therapeutics II (55 decks)

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