Download to read offline
![Drug Interaction
Drug X → Warfarin
Other Antidepressants Drugs Fluvoxamine, Fluoxetine
Antidepressants Drugs Paroxetine
Biopharmaceutics
Warfarin
CYP2C9
inhibition
Paroxetine
−
↑ INR
mild ↑ bleeding
risk, but no
change in PT
Effects
“an increased bleeding tendency
[may occur with] the
coadministration of paroxetine and
warfarin.”
Warfarin
CYP1A2,
CYP2C9,
CYP2C19,
CYP3A4
inhibition
−
Fluvoxamin
e
↑ INR
CYP2C9,
CYP2C19,
and
CYP3A4
inhibition
Fluoxetine
−
↑ INR
Effects
Interactions between fluoxetine and
warfarin may occur, leading to
increased therapeutic response and
toxicity.
Fluvoxamine exhibits the highest
potential for the inhibition of
warfarin through the 2C9 isoenzyme.
fluvoxamine and fluoxetine appear
to harbor the highest potential risk
for inhibiting warfarin metabolism.](https://image.slidesharecdn.com/newmicrosoftworddocument-210524085858/85/Warfarin-Drug-drug-interactions-1-320.jpg)
![Drug Interaction
Drug X → Warfarin
Other Antidepressants Drugs Fluvoxamine, Fluoxetine
Antidepressants Drugs Paroxetine
Biopharmaceutics
Warfarin
CYP2C9
inhibition
Paroxetine
−
↑ INR
mild ↑ bleeding
risk, but no
change in PT
Effects
“an increased bleeding tendency
[may occur with] the
coadministration of paroxetine and
warfarin.”
Warfarin
CYP1A2,
CYP2C9,
CYP2C19,
CYP3A4
inhibition
−
Fluvoxamin
e
↑ INR
CYP2C9,
CYP2C19,
and
CYP3A4
inhibition
Fluoxetine
−
↑ INR
Effects
Interactions between fluoxetine and
warfarin may occur, leading to
increased therapeutic response and
toxicity.
Fluvoxamine exhibits the highest
potential for the inhibition of
warfarin through the 2C9 isoenzyme.
fluvoxamine and fluoxetine appear
to harbor the highest potential risk
for inhibiting warfarin metabolism.](https://image.slidesharecdn.com/newmicrosoftworddocument-210524085858/75/Warfarin-Drug-drug-interactions-1-2048.jpg)
More Related Content
Similar to Warfarin Drug drug interactions
Warfarin Drug drug interactions
- 1. Drug Interaction Drug X→ Warfarin Other Antidepressants Drugs Fluvoxamine, Fluoxetine Antidepressants Drugs Paroxetine Biopharmaceutics Warfarin CYP2C9 inhibition Paroxetine − ↑ INR mild ↑ bleeding risk, but no change in PT Effects “an increased bleeding tendency [may occur with] the coadministration of paroxetine and warfarin.” Warfarin CYP1A2, CYP2C9, CYP2C19, CYP3A4 inhibition − Fluvoxamin e ↑ INR CYP2C9, CYP2C19, and CYP3A4 inhibition Fluoxetine − ↑ INR Effects Interactions between fluoxetine and warfarin may occur, leading to increased therapeutic response and toxicity. Fluvoxamine exhibits the highest potential for the inhibition of warfarin through the 2C9 isoenzyme. fluvoxamine and fluoxetine appear to harbor the highest potential risk for inhibiting warfarin metabolism.
- 2. Warfarin & Tamoxifen Warfarin& Simvastatin Warfarin inhibit CYP2C9- mediated warfarin metabolism Elevated risk of bleeding Tamoxifen − Warfarin and tamoxifen are known to interact with each other with a resultant increase in the bleeding tendency. Consider using lower warfarin doses and closely monitor the INR (International Normalized Ratio) when Tamoxifen and Warfarin use is necessary. Effect Warfarin Inhibit CYP3A4 mediated metabolism Simvastatin Increased risk of Bleeding and Rhabdomyolysis Effects − Simvastatin and/or its active acid form may inhibit CYP2C9 or CYP3A4-dependent warfarin metabolism. Concurrent use of Warfarin and Simvastatin warrants the monitoring of Prothrombin time ratio or International normalized ratio (INR). Monitor the patients also for signs and symptoms of myopathy or rhabdomyolysis (muscle pain, tenderness, or weakness). ↑ INR
- 3. Warfarin & Penicillin’s Warfarin& Cephalosporins Warfarin Amoxicillin, Cloxacillin, Ticarcillin, Methicillin, penicillin alter the intestinal flora that synthesize vitamin K Elevated risk of bleeding Vitamin K epoxide Reductase Vitamin K1 dihyroquinone Vitamin K1 epoxide Acting Clotting Factors II, VII, IX, X / Active Proteins C + S Inactive Clotting Factors / Active Proteins Warfarin Effect − − − Substitute penicillin with an antibiotic with a low-risk profile for bleeding. Vitamin K can change how warfarin works, which changes your INR. Vitamin K lowers your INR values. The lower your INR, the less time it takes for your blood to clot. Warfarin Cefixime, Cefepime, Ceftazidime Cephalosporins alter the intestinal flora that synthesize vitamin K Elevated risk of bleeding Vitamin K epoxide Reductase Vitamin K1 dihyroquinone Vitamin K1 epoxide Acting Clotting Factors II, VII, IX, X / Active Proteins C + S Inactive Clotting Factors / Active Proteins Warfarin Effect − − − Substitute Cephalosporins with an antibiotic with a low-risk profile for bleeding. Vitamin K can change how warfarin works, which changes your INR. Vitamin K lowers your INR values. The lower your INR, the less time it takes for your blood to clot.
- 4. Warfarin & MacrolideAntibiotics Warfarin & Sulfonamides Warfarin Azithromycin, Clarithromycin, Roxithromycin Macrolide antibiotics alter the intestinal flora that synthesize vitamin K Elevated risk of bleeding Vitamin K epoxide Reductase Vitamin K1 dihyroquinone Vitamin K1 epoxide Acting Clotting Factors II, VII, IX, X / Active Proteins C + S Inactive Clotting Factors / Active Proteins Warfarin Effect − − − Substitute Macrolide antibiotics with an antibiotic with a low-risk profile for bleeding. Vitamin K can change how warfarin works, which changes your INR. Vitamin K lowers your INR values. The lower your INR, the less time it takes for your blood to clot. Warfarin Amoxicillin, Cloxacillin, Ticarcillin, Methicillin, Sulfonamides alter the intestinal flora that synthesize vitamin K & Inhibit CYP2C9-mediated metabolism of warfarin Elevated risk of bleeding Vitamin K epoxide Reductase Vitamin K1 dihyroquinone Vitamin K1 epoxide Acting Clotting Factors II, VII, IX, X / Active Proteins C + S Inactive Clotting Factors / Active Proteins Warfarin Effect − − − When these two medicines are taken together, your body may not process your blood-thinner properly. You may experience an increased chance for bleeding including bleeding from your gums, nosebleeds, unusual bruising, or dark stools.
- 5. Warfarin & ChemotherapicAgents Warfarin & Amiodarone Warfarin Inhibit CYP450 System Cyclophosphamide Methotrexate, Doxorubicin Increased risk of Bleeding Effects − Most interactions between chemotherapy agents and warfarin appear to be caused by inhibition of the CYP450 system. Patients taking gemcitabine have an increased INR and, consequently, a reduced requirement for warfarin. This may be due either to decreased warfarin metabolism as a result of CYP450 inhibition or to decreased synthesis of clotting factors. ↑ INR Warfarin Inhibit CYP2C9 Amiodarone Serious Bleeding Effects − Coadministration of Warfarin and Amiodarone increases the prothrombin time by 100% after 3 to 4 days. The combination of amiodarone and warfarin potentiates the effect of warfarin and prolongs the International Normalized Ratio (INR), increasing the risk of bleeding. Decreased Metabolism
- 6. Warfarin & Enoxaparin Warfarin& Enoxaparin + Warfarin & Danaparoid Warfarin Additive anticoagulation Enoxaparin Increased risk of bleeding Effects − If coadministration of Warfarin and Enoxaparin is required, closely monitor the patient for signs and symptoms of bleeding, and neurological impairment in patients who are receiving neuraxial anesthesia or undergoing spinal puncture. ↑ INR Warfarin Additive anticoagulation Danaparoid Enoxaparin Increased risk of bleeding Effects − Both danaparoid and warfarin can increase the risk of bleeding. More frequent monitoring of Prothrombin time/INR is recommended, When concomitant use is required ↑ INR
- 7. Warfarin & Antiplanets Warfarin& Fish oil Warfarin Additive anticoagulation Aspirin Clopidogrel Increased risk of bleeding Effects − Warfarin Vitamin K (reduced) Vitamin K (oxidized) Reductase CO2 and O2 Descarboxyprothrombin Prothrombin Carboxylase Warfarin and antiplatelet drugs increase the risk of bleeding, their combination can put patients at risk of a major haemorrhage. Monitor patients closely for signs or symptoms of bleeding. Warfarin Eicosapentaenoic Acid (EPA) of fish oil decreases the availability of the Thromboxane precursor in the phospholipids of the cell membrane Fish oil (Omega 3 Fatty Acids) supplements Increased risk of bleeding Effects − omega-3 polyunsaturated fatty acid, consists of eicosapentaenoic acid & docosahexaenoic acid. This fatty acid may affect platelet aggregation and/or vitamin K—dependent coagulation factors. Omega-3 fatty acids may lower thromboxane A2 supplies within the platelet as well as decrease factor VII levels Decreased Thromboxane A2 levels Decreased platelet aggregation
- 8. Warfarin & NSAIDs Warfarin& Selective serotonin reuptake inhibitors (SSRIs) Warfarin NSAIDs possess antiplatelet effects Ibuprofen Diclofenac Naproxen Increased risk of bleeding Effects The clinical relevance of protein binding displacement in the interaction between warfarin and NSAIDs has been overstated, although a significant one may be more likely in the presence of high concentrations of NSAIDs in patients with slow elimination of warfarin (e.g., those with severe heart failure or impaired liver function). NSAIDs can induce gastrointestinal bleeding Warfarin SSRIs block the uptake of serotonin by platelets Sertraline, Nefazodone vilazodone Decreased function of platelets Effects Serotonin is essential in initiating the hemostatic response of platelets to vascular injury. Monitor patient for signs of increased bleeding When SSRIs and an anticoagulant are given concurrently Increased risk of bleeding
- 9. Warfarin & NSAIDs DrugInteraction Drug X → Cimetidine Effects