Cardiac glycoside
Cardiac glycosides are the most effective drugs for treatment of C.H.F.
Digitoxins are plant alkaloids.
They increase myocardial contractions, which will increase blood supply to all
organs including the kidneys therefore causing diuresis, which will decrease
the edema.
They are used to treat cardiac arrhythmia because they decrease heart rate.
Action:
They increase the force of myocardial contractions (positive inotropic).
It increases the contractility of the heart muscle by minimizing the movement
of Na+ and K+ ions and increasing the release of Ca++ ions in the myocardial
cells.
It decreases the heart rate due to increase in parasympathetic nervous system
and decrease in the sympathetic tone.
They are primarily excreted through the kidneys.
The initial dose is the larger dose (the loading or digitalizing dose), the
subsequent doses are referred to as (Maintenance doses).
Results:
Decrease in venous pressure.
Coronary dilatation.
Reduce heart size.
Marked diuresis and decreasing edema.
Indications:
1. Congestive heart failure (C.H.F).
2. Cardiac arrhythmia (atrial fibrillation, atrial flutter and sinus tachycardia).
Contraindication:
1. Hypersensitivity.
2. Angina pectoris in absence of CHF.
3. Given with caution for elderly and people who have kidney failure.
Side effects:
1. They are extremely toxic and may cause death.
, 2. There is a narrow margin of safety between the therapeutic dose and the
toxic dose.
3. Could cause overdose by cumulative effects of the drug, so frequent
assessment of the serum level is essential.
4. May cause cardiac arrhythmia such as bradycardia (below than 60 beat/
minute), ventricular fibrillation (which may lead to cardiac arrest and
death), and Bigeminal rhythm.
5. Nausea, vomiting, and diarrhea.
6. Headache, malaise and muscle weakness.
7. Skin rashes, blurring of vision, diplopia and white halos.
Note:
Patients suffering from digitalis intoxication should be admitted to the
ICU for continuous monitoring of ECG. Administration of digitalis
should be halted.
If serum potassium is below normal, administer K+ salts and give
antiarrhythmic drugs as Lidocain as ordered by Dr.
Drug interactions:
1. Antacid (they decrease the effect of digitalis).
2. Fursemide (Lasix): it increase K+ loss and increase the chance for
digitalis toxicity.
Predisposing factors for digitalis toxicity:
1. K+ loss (hypokalemia) which results from: diuretics, NPO, gastric suction,
and poor K+ intake.
2. Pathological conditions;
a. Liver disease: they decrease metabolism and therefore increase digitalis
level.
b. Kidney disease: they decrease the excretion of drug and therefore increase
digitalis levels.
Nursing considerations:
Check doctor’s order, medication record and bottle label accurately.
Observe & monitor for evidence of bradycardia or arrhythmia.
Measure intake and output accurately.
Weigh the patient in daily basis.
Pulse should be checked by 2 nurses.
, Provide the client with food high in potassium as banana, orange.
Monitor serum digoxin level.
Elderly people should be assessed for early signs of toxicity.
Teach patients that bradyacadia, nausea, vomiting, diarrhea, appetite loss, and
visual disturbances could be early signs of toxicity.
Teach client if heart rate is less than 60/minute to hold the medication and see
the doctor.
Have digoxin antidote available (digoxin immune FAB).
Drugs:
1. Digitoxin: crystodigin
Class: cardiac glycoside
Uses: drug of choice for maintenance in CHF.
Dose: Digitalizing dose is 0.6 mg in 4-6 hours.
Maintenance: 0.05 – 0.3 mg/day.
2. Digoxin: Lanoxin
Class: cardiac glycoside.
It is the drug of choice for CHF because of:
1. It has rapid onset.
2. It has short duration.
3. It can be administered P.O. or IV.
Dose: digitalization dose = 0.4 – 0.6 mg followed by 0.05 – 0.35 mg once or
twice daily.
3. Digoxin Immune FAB: (Ovine)
Class: digoxin antidote.
Action: antibodies bind to digoxin and excreted through the kidneys.
Uses: life threatening digitalis toxicity or overdose.
Note: cardiac arrest can be expected if an adult ingests 10 mg
or if a child ingests 4 mg.
Coronary vasodilators
Antianginal drugs
Angina pectoris: is a clinical syndrome characterized by paroxysm of
pain in the anterior chest caused by insufficient coronary blood flow and/or
inadequate oxygen supply to the myocardial muscle.
, Causes: (1) Atherosclerosis. (2) Vasospasim.
There are three groups of drugs used for treatment of angina:
1. Nitrates/nitrites.
2. Beta-adrenergic blocking agents.
3. Calcium channel blocking agents.
Nitrates/nitrites:
- Nitrates/nitrites - Action: direct relaxation of blood vessels and smooth muscles
vasodilatation O2 requirements.
- Relaxation of smooth muscles of coronary arteries coronary
vasodilatation blood supply to the myocardium.
- Relaxation of arteries and veins BP workload in the
heart.
Objectives of treatment:
1. Treatment of anginal attack and thus relief pain.
2. Prophylactic treatment to prevent or delay the occurrence of MI.
3. Prolongs intervals between attacks.
Indications:
1. Prophylaxis and treatment of acute angina pectoris.
2. Treatment of chronic angina pectoris.
3. Treatment of hypertension associated with MI or CHF.
4. Nitroglycerin ointment for treatment of Raynaud’s disease.
Contraindications:
1. Sensitivity to nitrates Hypotension.
2. Severe anemia.
2. Hypotension.
3. Head trauma.
4. Cerebral hemorrhage.
Side effects:
1. Headache, syncope, dizziness.
2. Postural hypotension, transient flushing, and palpitation.
3. Topical application may lead to dermatitis.
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