What is the pharmacodynamics of warfarin?

What is the pharmacodynamics of warfarin?

Warfarin is essentially completely absorbed, reaching a maximum plasma concentration between 2 and 6 hours. It distributes into a small volume of distribution (10 L/70kg) and is eliminated by hepatic metabolism with a very small clearance (0.2 L/h/70kg). The elimination half-life is about 35 hours.

What is the mode of action of warfarin?

Warfarin decreases blood clotting by blocking an enzyme called vitamin K epoxide reductase that reactivates vitamin K1. Without sufficient active vitamin K1, clotting factors II, VII, IX, and X have decreased clotting ability. The anticlotting protein C and protein S are also inhibited, but to a lesser degree.

Is warfarin an acid or base?

Warfarin is used in the UK as the sodium salt, which strongly suggests that the drug is acidic, although the presence of the acidic hydrogen may not be immediately apparent.

Why is warfarin given orally?

Warfarin comes only as a tablet you take by mouth. Warfarin is used to treat and prevent blood clots that might result in heart attack, stroke, or death. It’s also used for blood clots in atrial fibrillation, heart valve replacement, venous thrombosis, and pulmonary embolism.

Where is warfarin metabolized?

Warfarin accumulates in the liver, where the two isomers are metabolized via distinct pathways. Oxidative metabolism of the more active S isomer is effected by CYP2C9.

Where in the GI tract is warfarin absorbed?

Oral warfarin appears to be well absorbed after removal of the majority of the jejunum and ileum. This may indicate a proximal site of warfarin absorption.

Where is warfarin absorbed in the body?

If similar differences in the absorption of the isomers would be demonstrated, it could account for an apparent lack of response in some patients. Generally, warfarin is rapidly and completely absorbed from the gastrointestinal tract after oral administration.

Where does warfarin work in the clotting cascade?

Anticoagulants are divided into 4 different groups depending on which part of the clotting cascade they effect. Warfarin (trade name: Coumadin) is the main drug listed in this category. It works by inhibiting Vitamin K expoxide reluctase, an enzyme that recycles oxidized vitamin K.

Where does warfarin come from?

Warfarin is derived from coumarin, a sweet-smelling anticoagulant (blood-clotting) chemical found naturally in sweet clover and many other plants. In 1954, warfarin was approved for clinical use and has remained a popular anticoagulant ever since.

Is warfarin metabolized?

The anticoagulant drug warfarin occurs as a pair of enantiomers that are differentially metabolized by human cytochromes P450 (CYP). R-warfarin is metabolized primarily by CYP1A2 to 6- and 8-hydroxywarfarin, by CYP3A4 to 10-hydroxywarfarin, and by carbonyl reductases to diastereoisomeric alcohols.

Is warfarin metabolised in the liver?

(Warfarin is metabolized in the liver. CYP1A1, CYP1A2, and CYP3A4 metabolize the (R)-enantiomer and CYP2C9 metabolizes the more potent (S)-enantiomer.

Where is Coumadin metabolized?

The elimination of warfarin is almost entirely by metabolism. COUMADIN is stereoselectively metabolized by hepatic microsomal enzymes (cytochrome P-450) to inactive hydroxylated metabolites (predominant route) and by reductases to reduced metabolites (warfarin alcohols).

What kind of medication is warfarin used for?

Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner).

How does warfarin work to decrease blood clotting?

Warfarin decreases blood clotting by blocking an enzyme called vitamin K epoxide reductase that reactivates vitamin K1. Without sufficient active vitamin K1, clotting factors II, VII, IX, and X have decreased clotting ability.

Are there any side effects to taking warfarin?

Warfarin can make you bleed more easily, especially if you have ever had: high blood pressure or serious heart disease; kidney disease; cancer or low blood cell counts; an accident or surgery; bleeding in your stomach or intestines; a stroke; or. if you are 65 or older.

Are there any over the counter drugs for warfarin?

herbal (botanical) products – coenzyme Q10, cranberry, echinacea, garlic, ginkgo biloba, ginseng, goldenseal, or St. John’s wort. This list is not complete and many other drugs can interact with warfarin. This includes prescription and over-the-counter medicines, vitamins, and herbal products.