Warfarex, tablets 3 mg 100 pcs

Pharmacodynamics

Warfarex belongs to the group of anticoagulants – drugs that prevent blood clotting and is intended for long-term use. It has an indirect anticoagulant effect, inhibiting the liver synthesis of several factors involved in the regulation of blood clotting. Warfarex prevents formation of new clots and prevents increase in the already formed ones.

Pharmacokinetics

The drug is a racemic mixture of the stereoisomers R and S. The stereoisomer S is 2-5 times more active than the stereoisomer R, but its action is less prolonged. Warfarex (warfarin) is completely absorbed from the gastrointestinal tract. C_max in blood is reached 4 hours after oral administration. Plasma concentration is 1-5 µg/ml (0.003-0.015 mmol/L).

Bound to blood proteins by 97-99%. Warfarex (warfarin) undergoes chemical transformations in the liver with the participation of microsomal enzyme system containing cytochrome P450, with formation of inactive and inactive metabolites. It is eliminated mainly in the urine (92% – as metabolites, a minimal part – unchanged) and in small amounts – in the bile. T_1/2 after a single oral administration is 20-60 (on average 40) hours.

There are no significant changes in the pharmacokinetics of Warfarex (warfarin) in elderly patients. It has been found that patients in this group are more sensitive to anticoagulants, but the nature of this phenomenon has not been clarified. In liver dysfunction synthesis of clotting factors is decreased and metabolism of Varfarex (warfarin) slows down, which leads to increase of its inhibitory effect on blood clotting.

Indications

Prevention and treatment of diseases caused by the formation of blood clots in the blood vessels:

Active ingredient

Composition

1 tablet contains:

the active ingredient:

sodium warfarin (in the form of clathrate) 3 mg,

excipients:

lactose;

MCC;

crospovidone;

Magnesium stearate;

dye – indigo carmine.

How to take, the dosage

Ingestion, once a day, preferably at the same time of day. The dose, regimen and duration of use of Warfarex are determined for each patient individually, guided by the severity of the disease and the results of blood clotting control (INR). It is not allowed to change the dose or stop treatment with Varfarex without physician’s permission.

The initial dose is 2.5-5 mg per day for the first 2 days, then it is gradually adjusted according to the patient’s individual clotting response (INR). After reaching the desired INR level (2.0-3.0, and in some cases 3.0-4.5) a maintenance dose is prescribed.

Elderly, frail, or at-risk patients are prescribed lower starting doses and are cautious about increasing them. Warfarex is not routinely prescribed in children.

In the beginning of treatment, laboratory control of INR is performed every day, during the next 3-4 weeks the control is performed 1-2 times a week, later – every 1-4 weeks. More frequent additional control is necessary when the patient’s health condition changes, before a planned operation or other procedure, or when any other medication is prescribed or cancelled.

Interaction

High levels of vitamin K in foods (spinach, broccoli, lettuce, and other leafy vegetables) may reduce the effects of Warfarex. However, you should not change your diet too drastically or use vitamins or supplements without consulting your doctor.

Smoking may decrease the anticoagulation effects of the drug.

The effect of Warfarex may be altered by a variety of medications.

NSAIDs, dipyridamole, valproic acid, cytochrome P450 inhibitors, cimetidine, chloramphenicol, laxatives increase the risk of bleeding. Combined use of these drugs and Warfarex should be avoided (cimetidine can be replaced by ranitidine or famotidine). If treatment with chloramphenicol is necessary, anticoagulant therapy may be temporarily discontinued. Diuretics may reduce the effect of anticoagulants (in case of marked hypovolemic effect, which may lead to increased concentration of clotting factors). Weaken the effect of: barbiturates, vitamin K, glutethimide, griseofulvin, dicloxacillin, carbamazepine, mianserine, paracetamol, retinoids, rifampicin, sucralfate, phenazone, cholestyramine.

The effects are enhanced by: Allopurinol, amiodarone, anabolic steroids (alkylated at position C-17), acetylsalicylic acid and other NSAIDs, heparin, glibenclamide, glucagon, danazol, diazoxide, disopyramide, disulfiram, isoniazid, ketoconazole, clarithromycin, clofibrate, levamisole, metronidazole, miconazole, nalidixic acid nilutamide, omeprazole, paroxetine, proguanil, oral hypoglycemic agents – sulfonamide derivatives, sulfonamides, tamoxifen, thyroxine, quinine, quinidine, fluvoxamine, fluconazole, fluorouracil, quinolones, chloral hydrate, chloramphenicol, cephalosporins, cimetidine, erythromycin, etacrynic acid, ethanol.

When using Warfarex in combination with the above drugs it is necessary to monitor INR at the beginning and end of treatment and, if possible, 2-3 weeks from the beginning of therapy. When using drugs that may increase the risk of bleeding due to decreased normal coagulation (inhibition of clotting factors or liver enzymes), the strategy of anticoagulant therapy should be determined by the possibility of laboratory monitoring. If frequent laboratory monitoring is possible, the dose of Warfarex can be reduced by 5-10% if therapy with such agents is necessary. If laboratory monitoring is difficult, Warfarex treatment should be discontinued if indicated agents are necessary.

Special Instructions

The use of anticoagulants increases the risk of bleeding. To monitor the condition of the blood clotting system, you should visit your doctor regularly during treatment with Warfarex and have the prescribed tests done.

You should tell doctors, dentists, or pharmacists when you see them that you are taking Warfarex.

You should see a doctor if you have digestive problems accompanied by diarrhea (diarrhea), fever.

Pregnancy during treatment with Varfarex is highly undesirable, so effective methods should be used to prevent it.

We must be careful when handling sharp and traumatic objects, avoid activities involving the risk of injury and subsequent bleeding.

At the time of treatment, refrain from drinking ethanol (risk of hypoprothrombinemia).

The safety of the drug in children has not been adequately studied in clinical trials.

There are no data on adverse effects of Warfarex on the ability to drive vehicles and operate other mechanisms.

Patients with lactose intolerance should note that 1 tablet of Varfarex contains 106-112 mg of lactose.

Contraindications

Side effects

The most common side effects observed during treatment with anticoagulants are bleeding and hemorrhage in various organs and tissues. The possible risk of these side effects can be significantly reduced by strict adherence to the physician’s recommendations related to the administration of Warfarex.

In some cases, treatment with anticoagulants may cause circulatory disorders in extremities or internal organs. Circulatory disorders are most often indicated by pain and dark red skin color of the toes. You should see a doctor right away if you have these symptoms.

Other rare side effects include skin allergic reactions (itching, urticaria, dermatitis), nausea, vomiting, diarrhea, abdominal pain, liver disorders (increased liver enzymes in the blood, jaundice), fever, general weakness, changes in blood count, transient alopecia.

Overdose

Symptoms of chronic intoxication: bleeding from gums, nosebleeds, excessive menstrual bleeding, heavy or prolonged bleeding for minor superficial injuries, bleeding in the skin, presence of blood in urine and feces, etc.

Treatment: In case of minor bleeding, it is necessary to reduce the drug dose or stop treatment for a short time. If severe bleeding develops – transfusion of prothrombin complex factor concentrates, or fresh frozen plasma, or whole blood.

Pregnancy use

Warfarex should not be prescribed to pregnant women due to the identified teratogenic effect, development of bleeding in the fetus and its death.

The drug is excreted in the mother’s milk in small amounts and has almost no effect on the baby’s blood clotting, therefore the drug can be used during lactation, but it is recommended to refrain from breast-feeding in the first 3 days of warfarin therapy.

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