Ch 12: Anti-Anginals Flashcards
Anti-Anginals
a drug that’s used to treat Angina Pectoris (severe pain & constriction in chest region)
** which is usually associated w/ MI
- Imbalance b/w oxygen requirements of heart and oxygen supply via coronary vessels
(what actually causes the pain is unknown, and there could be many causes; ie: lactic acid)
Types of Angina
A. Effort-induced/classic (cor. occlusion)
- squeezing or behind sternum pressure
- occurs upon exertion; goes away @ rest
B. Unstable (rapid coronary tone, blockage, etc)
- potential MI
C. Silent
- “Silent” ischemia w/out symptoms
- possibly diagnostic (ST depression)
D. Prinzetmal: “variant” .. transient spasm
Therapy Goals
- dilate coronary vasculature
- decrease myocardial oxygen demand
- reverse an attack/ episode
- prevent an attack/ episode
Medications
- Nitrates & nitrites
- structure
- Mechanism of action
- donate NO
- NO activates guanylate cyclase
- cGMP levels in vasculature smooth muscle rise
- vasculature is dilated (coronary & periphery)
NO mechanisms
Coronary vasodilation*
- Increases myocardial O2 supply
Peripheral venous dilation*
- Reduced venous return/ reduced pre-load
- Law of Laplace (reduced heart size causes more efficient pumping)
- Lower O2 demand
Peripheral arteriolar dilation*
- Reduced after-load (reduced O2 demand)
Specific Nitrates/ Nitrites
Sublingual Nitroglycerin Buccal Nitroglycerin Topical Nitroglycerin Isosorbide Dinitrate/ Mononitrate Erythrityl/ Pentaerytrityl Tetranitrate Amyl nitrite
Nitroglycerin
- sublingual most often used for acute angina attacks (30 second onset)
- evaporated (bottle good for 2 weeks)
- Buccal will give constant rate over 3-6 hrs
- Patch also gives longer term release
SIDE EFFECTS:
headache, dizziness, postural hypotension, tolerance, dependence
Isosorbide’s
- Long lasting effect (hours)
- for acute attacks & onset prevention
- REVERSE acute attacks (using sublingual administration)
- for PREVENTION (prophylactic use) use oral tablets
Tetra-nitrates
- used for prevention (prophylactic use) of attacks
- long lasting, but somewhat slow onset
- usually orally, sublingual, etc
Amyl Nitrite
- VERY efficacious
- low usage
- stored in a glass ampule
- ampule broken and the drug inhaled
- very QUICK onset (under 30 sec)
Beta Blockers
- Use both B1 selective (atenolol, metoprolol) and B1/B2 (watch for bronchoconstriction)
- decrease CO, HR, BP (thus REDUCE O2 DEMAND)
- increase exercise tolerance, reduce incidence, and severity of acute attacks
Calcium Channel Blockers
- decrease contractility
- decrease arteriolar resistance
- REDUCE O2 DEMAND
- certain ones are also coronary dilators (verapamil, diltiazem)
Specific Calcium Blockers
- Dihydropyridines (nifedipine, nicardipine, felodipine)
- mostly affect smooth muscle (not myocardial)
- won’t reduce cardiac excitability/ contractility
- cause reflex tachycardia
- REDUCE O2 DEMAND BY REDUCING AFTER-LOAD
More Cardio Selective Agents
Verapamil, Diltiazem, Bepridil
- Also reduce electrical conductivity
- thus, H.R. (may be beneficial in some)
- don’t get reflex tachycardia
Mibefradil (new)
- specifically block T-type channels (others block L)
- no decrease in myocardial contractile force
- no reflex Tachycardia
Angina Pectoris: Agents of Choice
Acute attacks: sublingual Nitroglycerin
Stable angina: beta blockers
Variant angina (due to focal vasospasm in coronary): calcium channel blockers
Unstable angina: beta blockers (w or w/out calcium blockers)
