Pharma
Pharma
Pharma
• also called Digitalis glycosides, naturally occurring cardiac glycosides found in number plants
(obtained from the purple and white foxglove plant, and it can be poisonous)
• one of the oldest drugs (used as early as CE 1200)
• Digitalis preparations have come to be known for their effectiveness in treating heart failure
(HF). (also known as cardiac failure (CF), and previously referred to as congestive heart failure
CHF)
• Heart failure is when the heart muscle (myocardium) weakens and enlarges (it loses its ability to
pump blood through the heart and into the systemic circulation)
• Digitalis Preparations has 3 effect:
Ø positive inotropic (action increases myocardial contraction stroke volume),
Ø negative chronotropic (action decreases heart rate)
Ø negative dromotropic (action decreases conduction of heart cells)
• The increase in myocardial contractility strengthens cardiac, peripheral, and kidney function
(enhancing cardiac output, decreasing preload, improving blood flow to the periphery and
kidneys, decreasing edema, and promoting fluid excretion) not sure pa!!
• The aim is to reduce the strain the heart is under because, over time, this can wear out the heart
muscle and lead to heart failure. DIGOXIN is
Indications:
Mechanism of Action:
- inhibiting the sodium and potassium pump, which results in an increase in intracellular sodium and an influx of
calcium into cardiac cells, causing the cardiac muscle fibers to contract more efficiently and increase cardiac output.
Digoxin has velocimetric effects on the AV node. By stimulating the parasympathetic nervous system, it
slows electrical conduction in the atrioventricular node, therefore, decreasing the heart rate.
- cardiac vagal tone modulation (represents the contribution of the parasympathetic nervous
system to cardiac regulation)
Pharmacokinetics
• Absorption rate:
- oral tablet form is 70% to 80%.
- Liquid form is 75% to 85% in liquid form.
- The protein-binding power for digoxin is 20% to 30%.
- The half-life is 30 to 40 hours
• Due to its long half-life, drug accumulation can occur (Side effects should be closely
monitored to detect digitalis toxicity.)
• Thirty percent of digoxin is metabolized by the liver, and 70% is excreted by the kidneys
mostly unchanged
• Thyroid dysfunction alters metabolism of cardiac glycosides
• Decreased dose for hypothyroidism; increased dose in hyperthyroidism
Adverse Effects:
• Digoxin toxicity
- Signs and symptoms:
include anorexia, diarrhea, nausea and vomiting, bradycardia (pulse rate below 60
beats/min), premature ventricular contractions, cardiac dysrhythmias, headaches,
malaise, blurred vision, visual illusions (white, green, or yellow halos around objects),
confusion, and delirium. (Older adults are more prone to toxicity.)
• Cardiotoxicity
- serious adverse reaction to digoxin, and ventricular dysrhythmias
- Three cardiac-altered functions can contribute to digoxin-induced ventricular
dysrhythmias:
1. suppression of AV conduction,
2. increased automaticity
3. a decreased refractory period in a decreased refractory period in ventricular
muscle
Ø Interactions with:
Nursing Responsibilities:
• Ascertain apical pulse rate before administering digoxin. Do not administer if pulse rate is
below 60 beats/min.
• Determine signs of peripheral and pulmonary edema, which indicate HF is present.
• Monitor serum digoxin level (normal therapeutic drug range is 0.8 to 2 ng/mL). A serum
digoxin level greater than 2 ng/mL is indicative of digitalis toxicity.
• Monitor serum potassium level (normal range is 3.5 to 5.0 mEq/L), and report if
hypokalemia (<3.5 mEq/L) is present.
- occurs when the muscles in your blood vessel walls relax or widens.
Type of Vasodilators:
- medications that lower your blood pressure. Direct vasodilators (directly affect the
muscle cells that line your blood vessel)
- such as benazepril (Lotensin®) or lisinopril (Prinivil®, Zestril®).
PHARMACOKINETICS
ADVERSE EFFECTS
• Dry cough. This is possible with all ACE inhibitors. For some people, it may go away. If it doesn’t,
you can ask your healthcare provider about ways to remedy it.
• Dizziness. This is common with all blood pressure medications. You shouldn’t stand up too
quickly after you start taking an ACE inhibitor. Standing up too quickly can make you feel dizzy or
pass out.
• Headache.
• Drowsiness.
• Feeling fatigued.
• Weakness
• Jaundice
• Allergic reactions
• ACE inhibitors should not be combined with ARBs because such combinations increase the risk
of hypotension, hyperkalemia, and renal impairment (ACE inhibitors and ARBs should not be
taken together. The combination may lead to dangerously low blood pressure, high blood
potassium levels, and kidney problems.)
- keep angiotensin from attaching to your blood vessel walls. Preventing this attachment
opens your blood vessels.
- Ex: losartan
- Works by blocking receptors that the hormone acts on, specifically AT1 receptors (which
are found in the heart, blood vessels and kidneys. Blocking the action of angiotensin II
helps to lower blood pressure and prevent damage to the heart and kidneys.)
- ARBs block the action of angiotensin II, allowing the blood vessels to widen, thus making
it easier for the heart to pump blood.
PHARMACOKINETICS
- relaxing smooth muscle, increasing salt and water excretion, reducing plasma volume,
and decreasing cellular hypertrophy.
Contraindications:
- may lead to hyperkalemia in patients with renal disease or patients taking agents likely
to cause hyperkalemia
- pregnant woman
ADVERSE EFFECTS
- headache.
- fainting.
- dizziness.
- fatigue.
- respiratory symptoms.
- vomiting and diarrhea.
- back pain.
- leg swelling.
Drug interactions
- prevent calcium from going into your artery walls (Your arteries use calcium for
constriction, so blocking calcium leads to artery opening. CCBs are systemic vasodilators,
not direct vasodilators)
Pharmacokinetics
Contraindications
Adverse effect
- Constipation.
- Dizziness.
- Fast heartbeat you can feel.
- Extreme tiredness.
- Flushing.
- Headache.
- Nausea.
- Swelling in the feet and lower legs.
Drug interaction
- Several calcium channel blockers [for example, diltiazem (Cardizem LA, Tiazac), felodipine
(Plendil)] increase the level of cyclosporine (Sandimmune, Neoral, Restasis) and similarly lead to
toxicity of cyclosporine.
References:
Digoxin (no date) Uses, Interactions, Mechanism of Action | DrugBank Online. Available at:
https://go.drugbank.com/drugs/
Digoxin (no date)- StatPearls - NCBI Bookshelf - National Center for ... Available at:
https://www.ncbi.nlm.nih.gov/books/NBK556025
professional, C.C. medical (no date) Vasodilators: Types and side effects, Cleveland Clinic.
Available at: https://my.clevelandclinic.org/health/drugs/23207-vasodilators
What to know about angiotensin 2 receptor blockers (2023) Mayo Clinic. Available at:
https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/angiotensin-
ii-receptor-blockers/art-20045009