Vasodilator Drugs- Melissa (3)* Flashcards
What is the overall mechanism of vasodilators?
BP= TPR x CO
- Aterial dilation–> LOWER TPR
- Venous Dilation–> LOWER Venous Return
- -> LOWER CO
Amlodipine:
Drug class?
Ca++ Channel blocker: Dihydropyridines*
Verapamil, Diltiazem:
Drug Class?
Ca++ Channel blocker: Non-dihydropyridines
Describe the direct effects (MOA) of Ca++ Inhibitors on vasculature (1) and the heart (3):
Vasculature:
1. INHIB L-Type Ca++ Channels–> vasodilation (more arteries)–> LOWER TPR (DHPs > non-DHPs)
Heart:
- INHIB L-Type Ca++ Channels (Verapamil>Diltiazem»>DHPs)
- INHIB Phase 2 (plateau) of AP in atrial/vent muscle (slow cntrxn)
- INHIB Phase 0 Depolarization (slow HR/AV block)
3 therapeutic uses for ca++ channel blockers:
- Angina
(coronary dilation, vasodilation–> ^O2 supply + lower O2 demand) - Supraventricular tachy (A-fib, PSVT)–>Verapamil
- HTN
- 2 contraindications for all ca++ channel blockers:
- 3 Contraindications for Verapamil/Diltiazem:
ALL:
- Hypotension
- Severe Hepatic Disease
Verapamil / Diltiazem:
- CHF
- AV block/ LV dysfunction
- Sick Sinus Syndrome
Verapamil Cardio Effects:
- vasodilation
- HR
- Cardiac contractility
- AV nodal conduction
\+ = Increase - = DECREASE 0 = NONE
- ++
- -
- -
- –
Diltiazem Cardio Effects:
- vasodilation
- HR
- Cardiac contractility
- AV nodal conduction
- ++
- 0/ -
- 0/ -
- -
Amlodipine (DHPs) Cardio Effects:
- vasodilation
- HR
- Cardiac contractility
- AV nodal conduction
- +++
- 0/ +
- 0/ +
- 0
Rank severity of HypoTN caused by ca++ blockers:
Verapamil/ Diltiazam/ Amlodipine
Verapamil: ++
Diltiazam: +
Amlodipine (DHPs): +++ (responsible for decreasing TPR!)
Rank severity of CHF caused by ca++ blockers:
Verapamil/ Diltiazam/ Amlodipine
Verapamil: ++
Diltiazam: +
Amlodipine (DHPs): 0/+
Rank severity of AV block caused by ca++ blockers:
Verapamil/ Diltiazam/ Amlodipine
Verapamil: ++
Diltiazam: +
Amlodipine (DHPs): 0
Why do DHPs have more balanced vascular and cardiac effects?
Trigger baroreceptor reflex
Meaning—-increased HR/ fluid retention (edema possible)
Which two ca++ channel blockers DECREASE HR/ contractility / O2 demand?
Verapamil + Diltiazem
4 drug-drug interactions with ca++ channel blockers:
- CYP3A4 inhibitors/ inducers
- B blockers (V, D)
- Digoxin (V) -Antiarrythmics
Minoxidil:
Drug class
Effects (2)
K+ Channel ACTIVATOR–> hyperpolarization of vascular SM
- Potent arterial dilator–> LOWER TRP
- ^ compensatory: HR, CO, fluid retention
Minoxidil: 3 clinical applications
- Refractory HTN (combo tx)
- Malignant HTN
- ROGAINE for baldness!
(probably causes too much fluid retention to use for acute CHF)
4 ADRs of Minoxidil + drugs to coadmin in order to avoid them:
- ^ Fluid Retention (COADMIN diuretic)
- Tachy*** (COADMIN B-blocker)
- Cardiac tamponade (due to fluid retention)
- Hypertrichosis (bad unless you’re bald)