INR Above or Below the Therapeutic Range
Increased INR, Coumadin over-dosage; low INR, inadequate Coumadin dosage
Clinical conditions that increase Coumadin effect and elevate INR include:
Low vitamin K intake
Poor nutritional state
Congestive heart failure
Connective tissue diseases
Conditions known to decrease Coumadin effect and decrease INR include:
High vitamin K intake
Many drugs are known to increase warfarin effect and elevate INR:
Effects may be dose-dependent & may not occur in all pts receiving Coumadin & the drug mentioned.
Drugs in this category include carbenicillin, allopurinol, erythromycin, indomethacin, ibuprofen, fluconazole, fenoprofen, isoniazid, ketoconazole, naproxen, metronidazole, phenylbutazone, moxalactam, cephalosporins, trimethoprim-sulfa (Bactrim), amiodarone, quinidine, cimetidine, clofibrate, lovastatin, omeprazole, phenytoin, tamoxifen, thyroxine, quinolones, rofecoxib, celecoxib.Drugs that can decrease warfarin effect & lower INR in some pts include antacids, antihistamines, barbiturates, rifampin, sucralfate, trazodone, carbamazepine, cholestyramine, griseofulvin, haloperidol, oral contraceptives, penicillin, dicloxacillin, and nafcillin.
Suggested Additional Lab Testing
Most important: INR value on a daily basis until patient shows a consistent value within therapeutic range at least 2 or 3 times.
Monitoring is then less frequent but at least 1 times per month.
Lab tests may be helpful in uncovering other conditions, such as liver disease, which lowers the level of coagulation factors and makes therapeutic anticoagulation difficult. Pharmacogenomics testing is a consideration, either before initiation of warfarin, shortly after initiation, or for patients with apparent hypersensitivity to warfarin.
Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved.
No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. The Licensed Content is the property of and copyrighted by DSM.
Psychiatry Advisor Articles
- ADHD, Comorbid Bipolar Disorder Share Similar Neurocognitive Profiles
- Anxiety Prevention Interventions: How Effective Are They?
- ACOG Update: Marijuana Use Discouraged During Pregnancy, Breastfeeding
- Depression Profiles in Patients With Type 1 Diabetes vs Type 2 Diabetes
- No Evidence of Personality Changes Prior to Developing Cognitive Impairment, Dementia
- Suicidal Behavior, Thoughts Associated With Perfectionist Tendencies
- Physicians Spend Nearly 6 Hours on EHR Tasks Per Day
- CBT, Acceptance Commitment Therapy Helpful for Those With Chronic Pain
- Depression Reduced by Social Belonging, Feelings of Inclusion
- Sleep Disturbance May Be Causal Factor in Psychotic Experiences
- Is Hypertension Linked to an Increased Risk of Dementia?
- Continuing Research, Emerging Treatments Hold Promise for Treating Anorexia Nervosa
- Maternal Glucocorticoid Exposure Not Associated With ADHD in Offspring
- Ketamine Not Associated With PTSD Development in Military Trauma Setting
- Content, Quality Issues for Both Paper-Based and Electronic Health Records