L30- Antianginal Drugs Flashcards
describe the classification scale for angina
Class - Description:
0- asymptomatic
1- angina with strenous exercise
2- angina with moderate exertion
3- angina with mild exertion (1 flight of stairs, walking 1-2 blocks)
4- angina at any level of physical exertion
list the types of Angina and a brief pathophysiological explanation
Stable/Typical: fixed plaque / stenosis
Unstable/Crescendo: disrupted plaque with superimposed thrombus (like a MI)
Variant/Prinzmetal: intense vasospasm
briefly describe the pathogenensis of pain seen in angina
1a) inc HR, contractility, afterload, preload –> inc O2 consumption by the heart
1a) vasospasm, fixed stenosis, thrombus –> dec coronary blood flow
1a/1b –> hypoxic myocardium –> activates pain receptors in heart –> chest pain / Angina
describe the treatment approach(es) to angina
1) Inc O2 delivery:
- vasodilators
- anti-thrombic drugs
2) Dec O2 demand:
- vasodilators (reduce preload, afterload)
- cardiac depressants (β-blocker, reduce HR and contractility)
list each type of Angina and name the required type of therapy
Stable/Typical: (fixed stenosis) demand ischemia — dec O2 demand
Unstable/Crescendo: (thrombus) supply ischemia — inc O2 delivery
Prinzmetal/Variant: (vasospasm) — inc O2 delivery
list the drug groups used to treat Angina
Nitrates: isosorbide dinitrate, isosorbide mononitrate, nitroglycerin, sodium nitroprusside
β-blockers: atenolol, metoprolol, propanolol
Ca channel blockers (all): dihydropyridines (amlodipine, nifidipine), non-dihydropyridines (verapamil, diltiazem)
Na+ channel blocker: ranolazine
list the nitrates used in Angina
isosorbide dinitrate
isosorbide mononitrate
nitroglycerin
sodium nitroprusside
______ is the Na channel blocker used to treat Angina
ranolazine
Nitrates work by mimicing the functions of (1), with the goal being (2). The main functions of nitrates is (3), with (4) and (5) as secondary function. This is all due to the change in (6) intracellularly.
1- nitric oxide
2- rapid reduction in myocardial O2 demand and relief of Sxs
3- systemic vasodilation
4- anti-thrombic
5- anti-inflammatory
6- inc cGMP formation
list the effects of Nitrates on systemic vasculature and cardiac function
Systemic vasculature:
- vasodilation, veins > arteries
- dec venous pressure
- slight dec in arterial pressure (slightly dec MAP does not lead to reflex tachycardia)
Cardiac:
- reduction in preload, slight afterload reduction
- dec myocardium O2 demand
what are the effect of nitrates on the coronary arteries
- prevents/reverses vasospasm
- vasodilation
- improves subendocardial perfusion
- inc O2 delivery
Clinical Applications of Nitrates:
(1) is used for unstable/crescendo angina and acute HF
(2) is first-line therapy for acute anginal symptoms
(3) is used for prophylaxis of angina symptoms
1- IV nitroglycerin
2- SL or spray nitroglycerin (high bioavailability/F)
3- isosorbide mononitrate (high F)
describe pharmacokinetics of Nitroglycerin
- significant 1st pass effect, therefore given SL, IV, transdermally, buccal
- fast acting: 2-5 min onset, lasts for ~30min
- long-preparations available via transdermal patches
describe the pharmacokinetics of Isosorbide Mononitrate
-long onset, but long duration of action in comparison to nitroglycerin –> long-term and prophylaxis use
- > 1hr onset
- ~100% bioavailability
Note: metabolites have longer half-lives and significant activity
explain the role of tolerance in terms of using Nitrates
-rapid tolerance to nitrates due to vessel desensitization to vasodilation
- over come by nitrate-free intervals of 10-12 hrs
e. g. patches on for 12hrs, off for 12hrs