How is the initial dose of warfarin sodium (warfarin) determined?
If the patient's CYP2C9 and VKORC1 genotypes are not known, the initial dose of Warfarin sodium is usually 2 to 5 mg once daily. Determine each patient's dosing needs by close monitoring of the INR response and consideration of the indication being treated. Typical maintenance doses are 2 to 10 mg once daily.
What is prothrombin time on warfarin sodium?
A client is at risk for pulmonary embolism and is on anticoagulant therapy with warfarin sodium (Coumadin). The nurse is told that the client's prothrombin time is 18 seconds with a control of 11 seconds. Which action should the nurse plan? Administer the next dose of warfarin sodium.
How long does the anticoagulant effect of warfarin sodium last?
The anticoagulant effect of Warfarin sodium persists beyond 24 hours. If a patient misses a dose of Warfarin sodium at the intended time of day, the patient should take the dose as soon as possible on the same day.
What medications are used in the treatment of pulmonary embolism (PE)?
A patient recovering from a pulmonary embolism after surgery is receiving low-molecular-weight heparin and warfarin. The patient's international normalized ratio (INR) is 2.4 today.
Which isozyme is involved in the metabolism of warfarin?
CYP450 isozymes involved in the metabolism of warfarin include CYP2C9, 2C19, 2C8, 2C18, 1A2, and 3A4. The more potent warfarin S -enantiomer is metabolized by CYP2C9 while the R -enantiomer is metabolized by CYP1A2 and 3A4.
How long does warfarin last?
For patients with an unprovoked DVT or PE, treatment with warfarin is recommended for at least 3 months. After 3 months of therapy, evaluate the risk-benefit ratio of long-term treatment for the individual patient. For patients with two episodes of unprovoked DVT or PE, long-term treatment with warfarin is recommended.
How long after heparin injection should INR be monitored?
As heparin may affect the INR, patients receiving both heparin and COUMADIN should have INR monitoring at least: 5 hours after the last intravenous bolus dose of heparin, or. 4 hours after cessation of a continuous intravenous infusion of heparin, or. 24 hours after the last subcutaneous heparin injection.
What is Coumadin used for?
Coumadin is prescription medicine used to treat blood clots and to lower the chance of blood clots forming in your body. Blood clots can cause a stroke, heart attack, or other serious conditions if they form in the legs or lungs.
Why does COUMADIN cause death?
This can happen soon after starting COUMADIN. It happens because blood clots form and block blood flow to an area of your body. Call your healthcare provider right away if you have pain, color, or temperature change to any area of your body.
When should anticoagulant therapy be continued?
Individualize the duration of therapy for each patient. In general, anticoagulant therapy should be continued until the danger of thrombosis and embolism has passed [see Recommended Target INR Ranges And Durations For Individual Indications ].
What happens if you take Coumadin?
You may need medical care right away to prevent death or loss ( amputation) of your affected body part. Kidney problems. Kidney injury may happen in people who take Coumadin.
What is the time for prothrombin in pulmonary embolism?
The nurse is told that the client's prothrombin time is 18 seconds with a control of 11 seconds. Which action should the nurse plan? Administer the next dose of warfarin sodium.
What medications are prescribed for heart failure?
The nurse has completed client teaching about heart failure and prescribed medications that include digoxin (Lanoxin) and furosemide (Lasix). The nurse documents that the teaching goals have been met if the client states knowing to report which symptom? Weight gain of 2 to 3 pounds in a few days.
What is the name of the medication that a child with a right to left cardiac shunt is receiving?
A child with a right-to-left cardiac shunt is receiving propranolol (Inderal-LA). The health care provider visits the child and writes prescriptions in the child's record. The licensed practical nurse (LPN) reviews the prescriptions and notes that the child is placed on a nothing-by-mouth (NPO) status.
What is a LPN in heparin?
A client is receiving heparin sodium by continuous intravenous (IV) infusion. The licensed practical nurse (LPN) is concerned that the client received a bolus of medication when the tubing was removed from the IV pump during a gown change.
What is the nurse administering?
The nurse is administering a dose of a prescribed diuretic to an assigned client. The nurse should plan to monitor the client for hypokalemia as a side effect of therapy if the client is receiving which medication? Bumetanide. A client is receiving heparin sodium by continuous intravenous (IV) infusion.
How long does it take for a patient to take prothrombin?
The nurse is told that the client's prothrombin time is 18 seconds with a control of 11 seconds.
Indications and Usage For Warfarin
Warfarin Dosage and Administration
- Individualized Dosing
The dosage and administration of Warfarin sodium must be individualized for each patient according to the patient's International Normalized Ratio (INR) response to the drug. Adjust the dose based on the patient's INR and the condition being treated. Consult the latest evidence-bas… - Recommended Target INR Ranges and Durations for Individual Indications
An INR of greater than 4.0 appears to provide no additional therapeutic benefit in most patients and is associated with a higher risk of bleeding. Venous Thromboembolism (including deep venous thrombosis [DVT] and PE) Adjust the Warfarin dose to maintain a target INR of 2.5 (INR r…
Contraindications
- Warfarin sodium tablets, USP are contraindicated in: • 1. Pregnancy Warfarin sodium tablets, USP are contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism [see Warnings and Precautions (5.7) and Use in Specific Populations (8.1)]. Warfarin sodium can cause fetal harm when administered to a pregn…
Warnings and Precautions
- Hemorrhage
Warfarin sodium can cause major or fatal bleeding. Bleeding is more likely to occur within the first month. Risk factors for bleeding include high intensity of anticoagulation (INR >4.0), age greater than or equal to 65, history of highly variable INRs, history of gastrointestinal bleeding, hypertens… - Tissue Necrosis
Warfarin sodium can cause necrosis and/or gangrene of skin and other tissues, which is an uncommon but serious risk (<0.1%). Necrosis may be associated with local thrombosis and usually appears within a few days of the start of Warfarin sodium therapy. In severe cases of ne…
Adverse Reactions
- The following serious adverse reactions to Warfarin sodium are discussed in greater detail in other sections of the labeling: • 1. Hemorrhage [see Boxed Warning, Warnings and Precautions (5.1), and Overdosage (10)] • 1. Tissue Necrosis [see Warnings and Precautions (5.2)] • 1. Calciphylaxis [see Warnings and Precautions (5.3)] • 1. Acute Kidney Injury [see Warnings and Pr…
Drug Interactions
- General Information
Drugs may interact with Warfarin sodium through pharmacodynamic or pharmacokinetic mechanisms. Pharmacodynamic mechanisms for drug interactions with Warfarin sodium are synergism (impaired hemostasis, reduced clotting factor synthesis), competitive antagonism (vi… - CYP450 Interactions
CYP450 isozymes involved in the metabolism of Warfarin include CYP2C9, 2C19, 2C8, 2C18, 1A2, and 3A4. The more potent Warfarin S-enantiomer is metabolized by CYP2C9 while the R-enantiomer is metabolized by CYP1A2 and 3A4. • 1. Inhibitors of CYP2C9, 1A2, and/or 3A4 have …
Use in Specific Populations
- Pregnancy
Risk Summary Warfarin sodium tablets, USP are contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism, and for whom the benefits of Warfarin sodium may outweigh the risks [see … - Lactation
Risk Summary Warfarin was not present in human milk from mothers treated with Warfarin from a limited published study. Because of the potential for serious adverse reactions, including bleeding in a breastfed infant, consider the developmental and health benefits of breastfeeding along wit…
Overdosage
- Signs and Symptoms
Bleeding (e.g., appearance of blood in stools or urine, hematuria, excessive menstrual bleeding, melena, petechiae, excessive bruising or persistent oozing from superficial injuries, unexplained fall in hemoglobin) is a manifestation of excessive anticoagulation. - Treatment
The treatment of excessive anticoagulation is based on the level of the INR, the presence or absence of bleeding, and clinical circumstances. Reversal of Warfarin sodium anticoagulation may be obtained by discontinuing Warfarin sodium therapy and, if necessary, by administration …
Warfarin Description
- Warfarin sodium tablets contain Warfarin sodium, an anticoagulant that acts by inhibiting vitamin K-dependent coagulation factors. The chemical name of Warfarin sodium is 3-(α-acetonylbenzyl)-4-hydroxycoumarin sodium salt, which is a racemic mixture of the R- and S-enantiomers. Crystalline Warfarin sodium is an isopropanol clathrate. Its empirical formula is C 19H 15NaO 4, …
Warfarin - Clinical Pharmacology
- Mechanism of Action
Warfarin acts by inhibiting the synthesis of vitamin K-dependent clotting factors, which include Factors II, VII, IX, and X, and the anticoagulant proteins C and S. Vitamin K is an essential cofactor for the post ribosomal synthesis of the vitamin K-dependent clotting factors. Vitamin K promote… - Pharmacodynamics
An anticoagulation effect generally occurs within 24 hours after Warfarin administration. However, peak anticoagulant effect may be delayed 72 to 96 hours. The duration of action of a single dose of racemic Warfarin is 2 to 5 days. The effects of Warfarin sodium may become mor…