Warfarin: Difference between revisions
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== | ==General== | ||
* | *Type: | ||
* | *Dosage Forms: | ||
* | *Common Trade Names: | ||
==Dosing== | ==Adult Dosing== | ||
*Day 1: 5 - 7.5 mg oral at bedtime (to ensure absorption on empty stomach) | *Day 1: 5 - 7.5 mg oral at bedtime (to ensure absorption on empty stomach) | ||
*Day 2 and beyond: 2.5 - 7.5 mg daily (usually 5 mg) | *Day 2 and beyond: 2.5 - 7.5 mg daily (usually 5 mg) | ||
| Line 14: | Line 10: | ||
*Response also influenced by congestive heart failure, liver disease, Vitamin K deficiency, many drugs | *Response also influenced by congestive heart failure, liver disease, Vitamin K deficiency, many drugs | ||
==Target Range of INR== | ===Target Range of INR=== | ||
*2.5 - 3.5: Mechanical prosthetic valves or recurrent thromboembolism | *2.5 - 3.5: Mechanical prosthetic valves or recurrent thromboembolism | ||
*2.0 - 3.0: All other indications | *2.0 - 3.0: All other indications | ||
== | ==Pediatric Dosing== | ||
==Special Populations== | |||
*[[Drug Ratings in Pregnancy|Pregnancy Rating]]: Contraindicated | |||
*[[Lactation risk categories|Lactation risk]]: | |||
*Renal Dosing | |||
**Adult | |||
**Pediatric | |||
*Hepatic Dosing | |||
**Adult | |||
**Pediatric | |||
==Contraindications== | |||
*Allergy to class/drug | |||
==Adverse Reactions== | |||
*Bleeding | *Bleeding | ||
**Risk increased when INR >3 | **Risk increased when INR >3 | ||
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**Usually in patient with protein C deficiency | **Usually in patient with protein C deficiency | ||
**Occurs 3 - 8 days after starting treatment | **Occurs 3 - 8 days after starting treatment | ||
*Treatment: see [[Warfarin (Coumadin) Reversal]] | |||
== | ==Pharmacology== | ||
* | *Half-life: | ||
*Metabolism: Liver | |||
*Excretion: | |||
*Mechanism of Action: | |||
**Blocks activation of vitamin K dependent prothrombotic factors II, VII, IX, X | |||
**Blocks synthesis of vitamin K dependent antithrombotic proteins C and S | |||
*Albumin bound | |||
==Comments== | |||
*Because of differing factor half-lives, can cause transient (24-36 hour) prothrombosis at start of therapy | |||
**Bridge with heparin for 1-2 days until INR is in desired range | |||
==See Also== | ==See Also== | ||
*[[Warfarin (Coumadin) Reversal]] | |||
*[[Coagulopathy (Main)]] | *[[Coagulopathy (Main)]] | ||
== | ==References== | ||
<references/> | |||
[[Category:Drugs]] | [[Category:Drugs]] | ||
[[Category:Heme/Onc]] | [[Category:Heme/Onc]] | ||
Revision as of 13:08, 10 June 2015
General
- Type:
- Dosage Forms:
- Common Trade Names:
Adult Dosing
- Day 1: 5 - 7.5 mg oral at bedtime (to ensure absorption on empty stomach)
- Day 2 and beyond: 2.5 - 7.5 mg daily (usually 5 mg)
- INR increase of >0.3 - 0.4 per day requires dose reduction
- Response also influenced by congestive heart failure, liver disease, Vitamin K deficiency, many drugs
Target Range of INR
- 2.5 - 3.5: Mechanical prosthetic valves or recurrent thromboembolism
- 2.0 - 3.0: All other indications
Pediatric Dosing
Special Populations
- Pregnancy Rating: Contraindicated
- Lactation risk:
- Renal Dosing
- Adult
- Pediatric
- Hepatic Dosing
- Adult
- Pediatric
Contraindications
- Allergy to class/drug
Adverse Reactions
- Bleeding
- Risk increased when INR >3
- Exponential increase when INR >5
- Avoid giving NSAIDs, sulfas, macrolidies (azithromycin ok), fluoroquinolones
- Skin necrosis
- Usually in patient with protein C deficiency
- Occurs 3 - 8 days after starting treatment
- Treatment: see Warfarin (Coumadin) Reversal
Pharmacology
- Half-life:
- Metabolism: Liver
- Excretion:
- Mechanism of Action:
- Blocks activation of vitamin K dependent prothrombotic factors II, VII, IX, X
- Blocks synthesis of vitamin K dependent antithrombotic proteins C and S
- Albumin bound
Comments
- Because of differing factor half-lives, can cause transient (24-36 hour) prothrombosis at start of therapy
- Bridge with heparin for 1-2 days until INR is in desired range