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PHRM 844 Exam 5 LOs > CCB > Flashcards

CCB Flashcards

1
Q

what are ion channels?

A
  1. proteins that form pores in the plasma membrane
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2
Q

what is a passive ion channel?

A

allow ions to flow down electrochemical gradient

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3
Q

what are the two gradients and what is the difference?

A
  1. concentration –> flow down
  2. electrical –> can go against gradient
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4
Q

what is the membrane potential for K+, Na+, and Ca2+?

A

K+ –> high inside and low outside
Na+ –> low inside and high outside
Free Ca2+ –> very low inside and high outside (15,000 fold differ)

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5
Q

What is the type of voltage-gated family that CCBs are a part of and what is the type and location?

A
  1. L type
    - Cav1.2
    - cardiac, smooth muscle/Ca2+ entry triggers contraction
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6
Q

what does a block of channels in the vascular smooth muscle do and cause?

A
  1. vasodilation
    – dec. BP
    – relief of angina pectoris
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7
Q

what does a block of channels in cardiac muscle & SA/AV node cause?

A

antiarrhthmic

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8
Q

what happens to trigger a vascular smooth muscle contraction?

A
  1. Ca2+ induced Ca2+ release (CICR)
  2. Ca2+ influx via Cav1.2 releases Ca2+ via RYR2 in the SR
  3. extracellular Ca2+ required for contraction (vascular and cardiac smooth muscle_
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9
Q

what causes the contraction in vascular smooth muscle?

A

the phosphorylation of myosin LC to myosin LC-PO4 and actin

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10
Q

what causes a smooth muscle contraction?

A
  1. Ca2+ released from SR binds to troponin C
  2. binding to troponin C displaces tropomyosin
  3. when tropomyosin displaced allows myosin to bind to actin making a contraction
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11
Q

what about skeletal muscle? how do we have a contraction? What is it coupled to?

A
  1. coupled to Cav1.1 & RYR1
  2. calcium is not required
    –> CCBs do not interfere with Ca2+
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12
Q

what are the 3 classes of CCBs?

A
  1. DHPs
  2. phenylalkylamines
  3. benzothiazepines
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13
Q

what are the clinical applications of CCBs?

A
  1. angina pectoris
  2. arrhythmia
  3. HTN
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14
Q

what do all DHPs have in common?

A

a dihydropyridine ring.
- 6 membered ring with an NH and H

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15
Q

what DHP is this?

A

amlodipine

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16
Q

what is interesting about clevidipine?

A
  1. it has 2 cleavage points (the second one is inactive)
  2. given IV to treat HTN, PO admin is not possible
17
Q

what is the blockade mechanism like for dihydropyridines?

A
  1. Clues from a pair of enantiomers
    • enantiomer blocks current and interferes with opening of gate
    • enantiomer potentiates current and interferes with closing of gates
18
Q

what is the tissue selectivity like for DHPs?

A

do not compromise cardiac function(NOT GOOD SELECTIVITY)

19
Q

vascular selectivity of DHPs are…..

A

observed in functional (cell intact) but not binding assays

20
Q

what type of block do DHPs have?

A

voltage dependence
- no frequency dependence

21
Q

what is DHP binding like?

A

allosteric; outside the pore
– bind to closed channels and prevent opening TONIC BLOCK

22
Q

what is the vascular selectivity like for DHPs?

A
  1. dilation of arterioles leading to decreased afterload
23
Q

what DHP exhibits greater selectivity for cerebral arteries (sub-arachnoid hemorrhage use) ?

A

nimodipine

24
Q

what is a clinical consideration for DHPs?

A

efficacy in angina due to the reduction of oxygen in the heart

25
Q

what are the PK factors of DHPs? Onset? Tachycardia?

A
  1. all DHPs are highly bound to proteins and have reflex tachycardia EXCEPT amlodipine due to slow onset and longer duration of actions (others are fast acting)
26
Q

what is important to know about nifedipine?

A
  1. prompt release of this formulation may increase heart attack due to tachycardia (rapid inc. in BP)
27
Q

what drug is a phenylalkylamine?

A

verapamil

28
Q

what are the clinical considerations for verapamil?

A
  1. it causes vasodilation = less potent than DHPs
  2. slows conduction through SA/AV nodes
    –> reduces heart rate and force of contraction
  3. blunted for reflex tachycardia
29
Q

what kind of block does verapamil have? How does it do it?

A

channel has to open for drug to enter into pore–>frequency-dependent block
–> very little tonic block

30
Q

what drug is a benzothiazepine?

A

diltiazem

31
Q

what does diltiazem do?

A

directly inhibits the heart less than verapamil but more than DHPs

32
Q

what type of block does diltiazem exhibit?

A
  1. frequency-dependent block of Ca2+ channels
33
Q

what is the characteristics of verapamil block on graph?

A
  • lonngg
  • marked frequency block
  • very little tonic block
34
Q

what does the graph for diltiazem look like?

A
  • some tonic block and some frequency dependence
35
Q

what drug is this?

A

verapamil

36
Q

what drug is this?

A

diltiazem

37
Q

what are the common side effects for Diltiazem? (want %s)

A
  1. ankle edema (5-10%)
38
Q

what are the common side effects for DHPs? (want %s)

A
  1. ankle edema (5-10%)
  2. facial flushing (10-20%)
  3. tachycardia (5-10%)
39
Q

what are the common side effects for Verapamil? (want %s)

A
  1. ankle edema (5-10%)
  2. constipation (>10%)

PHRM 844 Exam 5 LOs (7 decks)

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