1 / 24

Margaret Jin, BScPHM, PharmD, CGP November 2007

Margaret Jin, BScPHM, PharmD, CGP November 2007. Learning Objectives. To review the mechanism of action, indications, contraindications, adverse reactions, & common drug interactions of warfarin To provide effective patient education To understand general concepts in warfarin dosing

haley
Télécharger la présentation

Margaret Jin, BScPHM, PharmD, CGP November 2007

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Margaret Jin, BScPHM, PharmD, CGP November 2007

  2. Learning Objectives • To review the mechanism of action, indications, contraindications, adverse reactions, & common drug interactions of warfarin • To provide effective patient education • To understand general concepts in warfarin dosing • To be able to use vitamin K1 appropriately

  3. Mechanism of Action Vitamin K Antagonism of Vitamin K VII Synthesis of Non Functional Coagulation Factors IX X II Warfarin

  4. Mechanism of ActionClotting Cascade

  5. Indications & Recommended Therapeutic Range Chest 2004;126(3 Suppl):204S-233S

  6. Contraindications • Pregnancy • Risk of hemorrhage > clinical benefits • Active hemorrhage (e.g., GI bleed) • Uncontrolled alcohol/drug abuse • Unsupervised dementia/psychosis • Unable to monitor INR

  7. A/E to report to MD: Blood in stools or urine Excessive menstrual bleeding Bruising Excessive nose bleeds/bleeding gums Persistent oozing from superficial injuries Intracranial Hemorrhage Factors that may influence bleeding risk: Intensity of anticoagulation Concomitant clinical disorders Hx of bleeding Hx of stroke Renal/Liver insufficiency Anemia Hypertension Concomitant use of other medications Adverse Effects Chest 2004;126(3):204S-233S

  8. Skin necrosis – 0.01-0.1% Day 3 – 8 Painful skin lesions Purple toe syndrome Week 3 – 8 Blue/purple toes/fingers Allergic Dermatitis Skin rash, hives, itching Vasculitis Fever, itching, skin sores or blisters Adverse Effects

  9. Absorption Rapid absorption Food does not affect absorption Distribution 99% protein bound Metabolism Liver Cytochrome P450 2C9 Pharmacokinetics

  10. Increase Warfarin Response NSAIDS, ASA Acetaminophen > 2g/d Amiodarone Quinolones (e.g., Cipro), sulfonamides, metronidazole Fibrates Ginkgo, Garlic, Ginseng Grapefruit Decrease Warfarin Response Phenobarbital Carbamazepine Phenytoin Vitamin K rich foods Green leafy vegetables Drug Interactions

  11. Effective Patient Education • Teach basic concepts of safe, effective anticoagulation • Discuss importance of regular INR monitoring • Counsel on use of other medications, alcohol • Develop creative strategies for improving compliance • Evening, same time • Dosettes, blisterpacks

  12. 1mg – pink 2mg – lavendar 2.5mg – green 3mg – tan 4mg – blue 5mg – peach 6mg – teal 7.5mg – yellow 10mg - white Warfarin Tablets

  13. Warfarin MaintenanceTarget INR 2.0 - 3.0 ^If INR is 1.8 to 1.9, consider no change with repeat INR in 7 to 14 days *If INR is 3.1 to 3.2, consider no change with repeat INR in 7 to 14 days

  14. Warfarin MaintenanceTarget INR 2.5 - 3.5 ^If INR is 2.3 to 2.4, consider no change with repeat INR in 7 to 14 days *If INR is 3.6 to 3.7, consider no change with repeat INR in 7 to 14 days

  15. 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Warfarin Dosing Schedule Total Weekly Dose Mon Tue Wed Thu Fri Sat Sun 21 mg 19 mg 2 2  10%  15% 18 mg 2 2 2

  16. 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Warfarin Dosing Schedule Total Weekly Dose Mon Tue Wed Thu Fri Sat Sun 21 mg 23 mg 4 4  10%  15% 24 mg 4 4 4

  17. Types of Bleeds • No significant bleeding = Minor bleeding • Bruises • Reported, but does not require additional testing, referrals or visits • Serious bleeding = Major bleeding • Black tarry stools, blood in urine, hematoma • Requiring treatment, medical evaluation or at least 2 units of blood • Life-threatening bleeding • Intracranial hemorrhage, retroperitoneal bleed, leading to cardiac arrest, surgical/angiographic intervention, or irreversible sequelae

  18. Warfarin Management *High risk = factors that may influence bleeding risk - Hx of bleeding, stroke, renal & liver insufficiency, anemia, hypertension, other medications

  19. Warfarin Management

  20. Warfarin Management • Serious bleeding, any INR • Hold Warfarin • Give Vitamin K1 10mg slow IV plus fresh plasma or prothrombin complex concentrate, depending on urgency • Repeat Vitamin K1 every 12 hours as needed • Life-threatening bleeding, any INR • Hold warfarin • Give prothrombin complex concentrate (or recombinant factor VIIa as an alternative) supplemented with vitamin K1 10mg slow IV; repeat as needed

  21. Vitamin K1, Phytonadione • Injection Formulation • 10mg/mL – 1mL vial • 2mg/mL – 1mL vial • Tablets are not available in Canada • Administer PO or IV • Do not administer SC • Elimination Half-life = 26-193 hours

  22. Summary • Use clinical judgment • Educate patient • Adjusting warfarin dose is better than adjusting patient’s quality of life • Monitor INR appropriately • Refer to Thrombosis Clinic if necessary

  23. References • The Thrombosis Interest Group of Canada (www.tigc.org) • Vitamin K diet • www.gicare.com/pated/edtot39.htm • http://www.drgourmet.com/warfarin/vitaminkcontent.pdf • Ansell J, et al. The pharmacology and management of the vitamin K antagonists. Chest 2004;126:204S-233S • Singer DE, et al. Antithrombotic therapy in atrial fibrillation. Chest 2004;126:429S-456S • http://www.ccs.ca/download/consensus_conference/consensus_conference_archives/2004_Atrial_Fib_full.pdf

  24. Questions

More Related