antianginal drugs Flashcards
what is angina
chest pain
- supply of nutrients and oxygen in the blood is insufficient to meet the demands of the heart
- reduction in blood flow to the heart
types of angina
1) stable angina
2) unstable angina
3) variant angina
4) microvascular angina
stable angina
- predictable and comes with exercise/excitement
- blood flow sufficient to meet heart metabolic demands at rest
- atherosclerosis narrows vessels
unstable angina
- occurs without activity
- atherosclerosis
- platelets adhere to plaque and add to blockage (potential complete blockage)
variant angina
- coronary artery vasospasm
- vasoconstriction, reduction in blood flow
microvascular angina
- spasms in smallest coronary arteries
- pain is longer lasting (<10 to 30 min)
- more common in women
therapeutic goals of antianginal drugs
- relieve pain of a current attack
- prevent angina (limit number of attacks, used prophylactically in someone with CAD)
what do antianginal drugs do
1) improve blood flow in coronary circulation
2) reduce heart muscle metabolic demands (stops the heart from working so hard so oxygen demands are lower)
firstline antianginal drugs
- organic nitrates
- beta blockers
- calcium channel blockers (CCB)
also used in combination
other anti anginal drug
ranolazine
organic nitrates mechanism of action
- organic nitrates metabolize in cell and act as nitric oxide
- nitric oxide causes vessels to dilates (2nd messenger-cGMP pathway)
what do organic nitrates do
cause vasodilation (relaxation of vascular smooth muscles)
1) dilate coronary arteries
- increased coronary blood flow
- useful in variant angina
2) reduce cardiac preload (relax veins, decrease SV and CO and BP which decreases cardiac work) and afterload (relax systemic arteries and decrease TPR and decrease BP which less cardiac work)
preload
- stress on ventricular wall before systole
- volume of blood in ventricles at the end of diastole (frank-starling law)
afterload
resistance heart has to pump against
- determined by arteriolar pressure
organic nitrate examples
nitroglycerin
- large first pass effect
- SL for symptomatic treatment (acute rescue)
- patch/po for prevention
isosorbide mononitrate
- prolonged action for prophylaxis
- high bioavailability
organic nitrates acute, prophylaxis, long-term
acute: SL tablet or spray for relief of angina, starts in a few minutes, lasts 1 hr
prophylaxis in situations that may provoke angina (exercise): SL, oral
long-term prophylaxis: transdermal patches, oral
organic nitrates adverse effects
headache
- most patients (vessel dilation in head)
- diminish in frequency/intensity with continued use
postural hypotension
- peripheral edema due to pooling of blood in venous system
reflex tachycardia
- partially offsets beneficial effects (baroreceptor compensation)
- may combine with b blocker
beta blocker examples
b adrenoceptor antagonists
- atenolol
- metoprolol
- propranolol
organic nitrate tolerance
- over 1 day
- take patch off at night so body can rest before putting it on again in the morning
- site rotation
b blocker mechanism of action
decrease HR and decrease myocardial contractility
- decrease cardiac work
- decrease myocardial oxygen demand
(long term prevention)
b blocker indications
- angina
- anti hypertension
- cardioprotective effects (like after MI)
- migraines
b blocker adverse effects
cardiovascular: bradycardia, hypotension, heart failure
metabolic: altered glucose and lipid metabolism
CNS: dizziness, fatigue, mental depression, lethargy, drowsiness, unusual dreams
other: impotence, wheezing, dyspnea
b blockers client implications
monitor pulse and report for <60bpm
never abruptly stop meds (rebound hypertensive crisis, physical dependence)
only for longterm prevention
calcium channel blockers
- diltiazem
- verapamil
- nifedipine (DHP)
CCB mechanism of action
- reduce myocardial contractility (negative inotropic action): verapamil and diltiazem
- cause peripheral arterial vasodilation: all CCBs
- decrease myocardial oxygen demand
CCB indications
first-line treatment for
- angina
- hypertension
- supraventricular tachycardia
CCB client implications
constipation is common
- high fibre diet, adequate fluids