How does warfarin interact with phenytoin?

Phenytoin may decrease or increase the anticoagulant effect of warfarin. A decrease has been attributed to hepatic enzyme induction,’ and an increase to displace- ment of warfarin from protein binding sites. 2’3 Also, phenytoin itself may prolong the prothrombin time.

Does warfarin affect phenytoin?

Using warfarin together with phenytoin may cause you to bleed more easily. It may also increase phenytoin levels. Phenytoin levels and prothrombin time or International Normalized Ratio (INR) should be monitored whenever the dosage is changed or discontinued.

What does phenytoin do to INR?

[15] Phenytoin can lead to increases or decreases in the INR. Upon initiation of phenytoin, the INR may increase due to the displacement of warfarin from protein binding sites. Long-term phenytoin use with warfarin can decrease the INR since it is a CYP inducer.

What interferes with phenytoin?

Drugs that may decrease phenytoin levels and reduce effectiveness include carbamazepine, chronic alcohol abuse, reserpine, and sucralfate (Carafate).

What anticoagulant can be taken with phenytoin?

In patients taking phenytoin who require an anticoagulant, only warfarin should be prescribed to minimize the risk of stroke.

What is the interaction of phenobarbitone and warfarin?

PHENobarbital can reduce the blood levels of warfarin, which may make the medication less effective in preventing blood clots.

How does warfarin affect coagulation cascade?

Warfarin blocks one of the enzymes that uses vitamin K to make some of the clotting factors, and in turn reduces their ability to work correctly in the blood. As a result, the clotting mechanism is disrupted and it takes longer for the blood to clot.

Why does bactrim interact with warfarin?

Bactrim inhibits CYP 2C9, which you remember is responsible for breaking down the more potent S-isomer of warfarin. Bactrim also inhibits CYP 3A4, which you remember is responsible for breaking down the less potent R-isomer of warfarin.

How do I remember the drug interactions with warfarin?

Interaction Mnemonics

  1. O-DEVICES – is a mnemonic you can use to remember drugs that inhibit the cytocrhome p450 enzyme system and thus increase the effects of warfarin:
  2. O – Omperazole.
  3. D – Disulfiram.
  4. E – Erythromycin.
  5. V – Valproate.
  6. I – Isoniazid.
  7. C – Cimetidine + Ciprofloxacin.
  8. E – Ethanol (Acutely)

How does vitamin K affect warfarin?

To ensure that warfarin is effectively thinning your blood, it’s important to eat about the same amount of vitamin K every day. Vitamin K normally helps your blood clot so wounds don’t bleed too much. Warfarin works against vitamin K, making your blood clot more slowly.

What should you avoid when taking phenytoin?

What should I avoid while taking phenytoin? Avoid drinking alcohol while you are taking phenytoin. Alcohol use can increase your blood levels of phenytoin and may increase side effects. Daily alcohol use can decrease your blood levels of phenytoin, which can increase your risk of seizures.

What medications should not be taken with phenytoin?

Other medications can affect the removal of phenytoin from your body, which may affect how phenytoin works. Examples include amiodarone, azole antifungals (such as itraconazole), macrolide antibiotics (such as erythromycin), estrogens, isoniazid, rifamycins (such as rifabutin), St.

Which one of the following seizure categories is not effectively managed by phenytoin?

Phenytoin is best used for partial-onset seizures. It generally is not effective against generalized-onset absence seizures or infantile spasms. It has limited value in clonic, myoclonic, and atonic seizures and in the Lennox-Gastaut syndrome.

What drugs interact with anticoagulants?

There are many medicines that can interact with anticoagulants.

Other medications that increase the effect of anticoagulants, thus increasing the chance of bleeding:

  • Allopurinol.
  • Anabolic steroids.
  • Aspirin.
  • Amiodarone.
  • Capecitabine.
  • Cephalosporins.
  • Cimetidine.

Is phenytoin an anticoagulant?

Phenytoin dimin- ishes the anticoagulant effect of dicumarol and may pro- duce a clinically significant increase in the anticoagulant action of warfarin.

Does amiodarone affect INR?

The combination of amiodarone and warfarin potentiates the effect of warfarin and prolongs the International Normalized Ratio (INR), increasing the risk of bleeding.

Should aspirin and warfarin be taken together?

In conclusion, the combination of warfarin plus aspirin should not be used, with the exception of patients with mechanical heart valves at high stroke risk.

What does warfarin interact with?

Common drugs that can interact with warfarin include: Aspirin or aspirin-containing products. Acetaminophen (Tylenol, others) or acetaminophen-containing products. Antacids or laxatives.

What affects warfarin absorption?

In addition to genetic factors, diet, drugs, and various disease states influence the anticoagulant effect of warfarin. Fluctuations in dietary vitamin K intake affect the activity of warfarin. A wide variety of drugs can alter absorption, clearance, or metabolism of warfarin.

Why does warfarin affect the extrinsic pathway?

Warfarin is taken per-oral and it affects the extrinsic pathway first since factor VII has the shortest half life and it’s the first coagulation factor to run out. Next, levels of factor II, IX, and X also drop, causing inhibition of the intrinsic and common pathways.

Does warfarin affect PT or PTT?

PT: prothrombin time, aPTT: activated partial thromboplastin time, LMW heparin: low molecular weight heparin. * Warfarin has a weak effect on most aPTT reagents. However, warfarin use will increase the sensitivity of the aPTT to heparin effect.

Drug class Heparins
Drug Unfractionated heparin
PT – ¶

How does warfarin increase INR?

A nice “rule of thumb” for dose adjustments near the target range (generally works for INRs from the high 1s to low 4s): If you want to change the INR by 0.5-1 unit, increase or decrease the weekly dose by a daily dose. Example: Your patient has been taking warfarin 5mg daily for more than 2 weeks and INR is 1.8.

Does Bactrim affect INR?

Yes. In fact, the adjusted relative risk (RR) for over anticoagulation (i.e., INR &gt, 6) when starting TMP/SMX (Bactrim) in a patient on stable doses of warfarin has been reported to be 20.1 (95% CI, 10.7 to 37.9).

Which antibiotics do not affect warfarin?

Cephalexin and clindamycin, which have minimal interactions with warfarin, are considered low-risk antibiotics, said the researchers.

Does digoxin interact with warfarin?

No interactions were found between digoxin and warfarin. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

How many interactions does warfarin have?

A total of 604 drugs are known to interact with warfarin, categorized as 136 major, 397 moderate, and 71 minor interactions.

Which of the following drugs should generally be avoided in geriatric patients?

Here are seven common types of anticholinergic medication that older adults should avoid, or use with caution:

  • Sedating antihistamines. …
  • PM versions of over-the-counter (OTC) painkillers. …
  • Medications for overactive bladder. …
  • Medications for vertigo or motion sickness. …
  • Medications for itching. …
  • Medications for nerve pain.

Does amiodarone inhibit warfarin?

Abstract: Amiodarone inhibits warfarin metabolism and is associated with major bleeding during warfarin therapy. Managing this drug‐drug interaction (DDI) is challenging because of substantial interpatient variability in DDI magnitude.

Can you eat eggs while on warfarin?

Keep in mind, you may have other dietary restrictions based on your individual medical conditions. Foods you can eat on a warfarin diet: Meat, fish, eggs. Milk, cheese, yogurt.

Do nuts affect warfarin?

Similarly, most fruits are not important sources of vitamin K, with the exception of some berries, green fruits, and prunes. Menu planning for patients on warfarin can include a healthy diet including fruits and nuts without compromising the stability of their oral anticoagulation therapy.

Why do you take warfarin at 6pm?

It’s usual to take warfarin in the evening. This is so that if you need to change the dose after a routine blood test, you can do this the same day rather than waiting until the following morning. Warfarin does not usually upset your stomach, so you can take it whether you have eaten recently or not.

What should you do before administering phenytoin?

Before taking phenytoin,

  1. tell your doctor and pharmacist if you are allergic to phenytoin, other hydantoin medications such as ethotoin (Peganone) or fosphenytoin (Cerebyx), any other medications, or any of the ingredients in phenytoin. …
  2. tell your doctor if you are taking delavirdine (Rescriptor).

What is status epilepticus?

A seizure that lasts longer than 5 minutes, or having more than 1 seizure within a 5 minutes period, without returning to a normal level of consciousness between episodes is called status epilepticus. This is a medical emergency that may lead to permanent brain damage or death.

Can you take phenytoin with milk?

You may give phenytoin with food or milk, but be consistent. Always give phenytoin with food or milk or always give it on an empty stomach. If your child is taking chewable tablets, encourage your child not to swallow them whole.

What are the most common drug drug interactions with phenytoin?

Drugs Affected By Phenytoin

Interacting Agent Examples
Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D
Drugs whose level is decreased by phenytoin

Does phenytoin affect blood pressure?

In previous decades, several patients experienced adverse effects of intravenous phenytoin such as severe heart arrhythmias and decrease of blood pressure. These potential adverse effects caused a reluctance to use intravenous phenytoin which has also led to a search for safer antiepileptic drugs.

Does phenytoin affect blood sugar?

It is known that phenytoin interferes with carbohydrate metabolism. Indeed, it may inhibit the release of glucose stimulated insulin and induce a consequent hyperglycaemia.

What medications should epileptics avoid?

Medications that may cause seizures:

  • Diphenhydramine – the active ingredient in Benadryl and other medications that treat colds or allergies. …
  • Pseudoephedrine – a decongestant that shrinks blood vessels in the nasal passages.

How does phenytoin work in preventing seizures?

Phenytoin is an anti-epileptic drug, also called an anticonvulsant. Phenytoin works by slowing down impulses in the brain that cause seizures. Phenytoin is used to control seizures. It does not treat all types of seizures, and your doctor will determine if it is the right medicine for you.

What is the most common drug of choice prescribed for the treatment of seizure activity in adults?

Anticonvulsant agents, including lamotrigine, levetiracetam, oxcarbazepine, topiramate, and valproic acid, are commonly used for the treatment of seizures.

What medications should not be taken with warfarin?

What medicines should I avoid while taking warfarin?

  • aspirin.
  • acetaminophen (Tylenol)
  • ibuprofen (Advil, Motrin)
  • diclofenac (Cataflam, Voltaren)
  • indomethacin (Indocin)
  • naproxen (Aleve, Naprosyn)
  • piroxicam (Feldene)
  • celecoxib (Celebrex)

What is contraindicated with warfarin?

Contraindicated in:

Recent brain, eye, or spinal cord injury or surgery, Severe liver or kidney disease, Uncontrolled hypertension, OB: Pregnancy (may cause fetal harm).

What to avoid while on anticoagulants?

Crites recommends patients who take Coumadin or Warfarin avoid or limit the following:

  • Leafy greens. Leafy greens like kale, spinach, Brussels sprouts and lettuce contain high amounts of vitamin K. …
  • Green tea. …
  • Cranberry juice. …
  • Grapefruit. …
  • Alcohol.

What anticoagulant can be taken with phenytoin?

In patients taking phenytoin who require an anticoagulant, only warfarin should be prescribed to minimize the risk of stroke.

Do anticoagulants treat epilepsy?

Anticoagulation always carries risks, but the risks are greater for people with epilepsy. Regardless of the antiepileptic drugs (AEDs) taken, the risk of prescribing anticoagulants chronically to epilepsy patients is increased because of the danger of falling during a seizure.

What are examples of anticoagulants?

What are anticoagulants?

  • apixaban (Eliquis)
  • dabigatran (Pradaxa)
  • edoxaban (Lixiana)
  • rivaroxaban (Xarelto)
  • warfarin (Coumadin)