Arikstra

"Arixtra" (fondaparinux sodium) is a drug belonging to the class of anticoagulants, specifically low molecular weight heparins. It is used for the prevention and treatment of thromboembolic complications in patients with various diseases, such as deep vein thrombosis, pulmonary embolism, myocardial infarction and other conditions associated with thrombosis and thromboembolism.

Fondaparinux sodium works by preventing the formation of thrombi (blood clots) by inhibiting the activity of factor Xa, which is a key enzyme in the blood clotting process. This reduces the tendency of the blood to form clots and helps prevent thrombosis and its complications.

The drug is usually given by subcutaneous injection and is available in different dosages to suit individual patient needs. It is usually used in hospitals or under the supervision of a physician in an outpatient setting.

Indications Arikstras

• Prevention and treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients at high risk of developing thromboembolic complications. This may include patients with acute myocardial infarction, patients following pelvic surgery or traumatic injury, and patients with an acute medical condition who are limited in mobility.
• Prevention and treatment of thrombosis during pregnancy and the postpartum period in women with a high risk of thromboembolic complications or a history of previous thrombosis.
• Prevention of thrombosis in patients with atrial fibrillation and other arrhythmias who are at high risk of thromboembolic complications and require anticoagulant therapy.
• Treatment and prevention of thrombosis in patients with arterial or venous catheters.

Release form

Injection solution: The drug is supplied in glass ampoules or syringe pens for subcutaneous administration. This is the most common way of using Arixtra, as it ensures rapid and reliable administration of the drug.

Pharmacodynamics

Its pharmacodynamics is based on its ability to inhibit the activity of factor Xa, which is a key enzyme in the blood clotting process.

The drug binds to antithrombin III, increasing its activity, which leads to increased inhibition of factor Xa. This in turn reduces the conversion of prothrombin to thrombin, which reduces the formation of blood clots and prevents further development of thromboembolic complications.

Thus, "Arixtra" exhibits antithrombotic action, reducing the tendency of blood to form blood clots and preventing their development in various vascular systems. This makes it an effective means for the prevention and treatment of thromboembolic complications in patients with various diseases.

Pharmacokinetics

• Absorption: Since Arixtra is usually administered intramuscularly or subcutaneously, it is absorbed fairly quickly. Peak plasma concentrations are usually reached within a few hours after administration.
• Distribution: The drug has a high volume of distribution, meaning that it is rapidly distributed throughout the body after absorption. Fondaparinux sodium is somewhat less bound to plasma proteins.
• Metabolism: Fondaparinux sodium is not metabolised in the liver, therefore there is no need for routine monitoring of liver function in patients.
• Excretion: The drug is excreted mainly unchanged by the kidneys. Its half-life in the body is about 4-6 hours.

Dosing and administration

• Prevention of thrombosis in surgical patients: The usual recommended dose is 2.5 mg of Arixtra once daily.
• Prevention of thrombosis in patients at high risk of thromboembolic complications: The dosage may be increased to 5 mg once daily, depending on the clinical situation.
• Treatment of thrombosis and embolism: It is usually recommended to start with 5 mg of Arixtra subcutaneously twice daily. For patients weighing more than 90 kg, an increase in the dose may be recommended.
• Prevention of thrombosis in pregnancy: The dosage may vary depending on the individual characteristics and clinical situation and should be determined by the physician.

Use Arikstras during pregnancy

• Use in case of hypersensitivity to heparin:

  • Fondaparinux is used as a safe alternative to heparin in hypersensitivity or heparin-induced thrombocytopenia in pregnant women. In one case, fondaparinux was successfully used to treat a pregnant woman with protein S deficiency and prior deep vein thrombosis who developed hypersensitivity to heparin (Mazzolai et al., 2006).

• Literature review:

  • A literature review of fondaparinux use in pregnant women included 65 cases. The drug was well tolerated and the incidence of pregnancy complications was similar to that observed in the general population. However, further studies are needed to assess the safety of the drug with regard to congenital malformations (De Carolis et al., 2015).

• Use in heparin-induced thrombocytopenia (HIT):

  • In one case, fondaparinux was successfully used to treat a pregnant woman with acute pulmonary thromboembolism and HIT in late pregnancy. The drug showed good results without complications for the mother and fetus (Ciurzyński et al., 2011).

• Pharmacokinetics and absence of placental transfer:

  • In vitro studies have shown no placental transfer of fondaparinux, reducing the risk of exposure to the fetus (Lagrange et al., 2002).

• General experience of use:

  • A retrospective study of 120 pregnant women receiving fondaparinux for VTE prophylaxis found the drug to be well tolerated and effective. Complications included bleeding (5 cases), miscarriage (2 cases), and preterm birth (2 cases) (Dempfle et al., 2021).

Contraindications

• Hypersensitivity: Arixtra is contraindicated in patients with known hypersensitivity to fondaparin, sodium, other low molecular weight heparins or any other component of Arixtra.
• Severe bleeding: The drug should be used with caution in patients with active bleeding or an increased risk of its development. In the presence of severe bleeding, the use of "Arixtra" is contraindicated.
• Thrombocytopenia: In patients with thrombocytopenia (decreased number of platelets in the blood) or other bleeding disorders, the drug should be used with caution.
• Unstable patient condition: The drug should be used with caution in patients with unstable conditions that may lead to severe bleeding or other serious complications.
• Active gastric and intestinal ulcers: The use of Arixtra may increase the risk of bleeding in patients with active gastrointestinal ulcers.
• Epidural or spinal anesthesia: The drug should be used with caution in patients who are planning or currently undergoing epidural or spinal anesthesia, as it may increase the risk of developing spinal or epidural hematoma and subsequent spinal cord compression injury.

Side effects Arikstras

• Bleeding: This is the most serious side effect of anticoagulants, including low-molecular-weight heparins. Bleeding of various localizations may occur: internal (for example, intestinal or hemorrhagic stroke), intracranial, from the nose, hematomas on the skin, etc.
• Thrombocytopenia: Some patients may develop thrombocytopenia (a decrease in the number of platelets in the blood), which may lead to an increased risk of thrombosis.
• Heparin-induced thrombocytopenia (HIT): This is a serious complication that can lead to thrombosis and thromboembolic complications.
• Allergic reactions: Include allergic skin rashes, itching, hives and in rare cases anaphylaxis.
• Focal bleeding and hematoma: Hematoma or bleeding may develop at injection sites.
• Increased liver enzymes: Some patients may experience temporary increases in aminotransferases and other liver enzymes.
• Alopecia: In rare cases, temporary hair loss may occur.
• Increased potassium in the blood: Some patients may experience hyperkalemia.

Overdose

Overdose of Arixtra may lead to an increased risk of bleeding. If overdose or bleeding is suspected, seek immediate medical attention.

Treatment for overdose may include the following measures:

1. Discontinuation of drug administration.
2. Symptomatic treatment aimed at controlling bleeding.
3. Conducting transfusion of fresh frozen plasma or other blood substitutes to restore circulating blood volume and coagulation.

Interactions with other drugs

• Drugs that enhance the anticoagulant effect: The combination of Arixtra with other anticoagulants such as warfarin, acenocoumarol, dabigatran, rivaroxaban and apixaban may increase the risk of bleeding. These combinations require careful medical supervision and possible dosage adjustments.
• Medicines that increase the risk of bleeding: Certain medicines, such as nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, ticagrelor, clofibrate, and others, may increase the risk of bleeding when taken with Arixtra.
• Drugs that reduce the anticoagulant effect: Some drugs, such as antiepileptic drugs (eg, carbamazepine, phenytoin), rifampicin and other inducers of liver microsomal enzymes, may reduce the effectiveness of Arixtra.
• Medicines that increase the risk of hyperkalemia: Certain medicines, such as potassium-sparing diuretics, angiotensin-converting enzyme inhibitors (ACE inhibitors), certain nonsteroidal anti-inflammatory drugs (NSAIDs), and others, may increase the risk of hyperkalemia when used concomitantly with Arixtra.
• Medicines that increase the risk of thrombosis: Using Arixtra with certain medicines, such as estrogens and hormonal drugs, may increase the risk of thrombosis.

Storage conditions

• Store the medicine in the original packaging or in a dark container, protected from light.
• Store "Arixtra" at a temperature of 15°C to 25°C.
• Avoid freezing the drug.
• Keep the medicine out of reach of children.
• Follow manufacturer's instructions for expiration dates after opening (if applicable).
• If the product is stored in a refrigerator, avoid direct contact with a freezer or other location where significant temperature changes may occur.