VOXAPARIN 60

Indications

• Prevention of deep vein thrombosis (DVT) in surgical patients

Mechanism of action

Enoxaparin exerts its anticoagulant effect primarily by binding to antithrombin III, which enhances its activity. This binding inhibits factor Xa and, to a lesser extent, thrombin (factor IIa). The inhibition of factor Xa prevents the conversion of prothrombin to thrombin, thereby reducing the formation of fibrin clots. The preferential inhibition of factor Xa over thrombin is characteristic of low molecular weight heparins, resulting in a more predictable anticoagulant response and a lower risk of bleeding compared to unfractionated heparin.

Pharmacodynamics

The pharmacodynamics of enoxaparin involve dose-dependent anticoagulation, which is monitored through anti-factor Xa levels in patients at high risk for thromboembolic events. The onset of action is rapid following subcutaneous administration, with peak anticoagulant activity typically occurring 3 to 5 hours post-injection. The therapeutic window is broader compared to unfractionated heparin, allowing for fixed dosing regimens in many clinical scenarios.

Pharmacokinetics

Enoxaparin has a bioavailability of approximately 90% when administered subcutaneously. It has a volume of distribution of about 4 L/kg and is primarily eliminated by the kidneys, with a half-life of approximately 4.5 hours in healthy individuals. The pharmacokinetics can be affected in patients with renal impairment, necessitating dose adjustments. Enoxaparin does not cross the placenta and is considered safe for use during pregnancy. It is also excreted in breast milk, but the concentrations are low and considered negligible.

Contra-indications

• Hypersensitivity to unfractionated or low molecular weight heparin
• Mechanical prosthetic heart valve patients
• Active bleeding
• Severe thrombocytopenia
• Recent intracranial hemorrhage

Adverse effects

• Hemorrhagic anemia
• Headache
• Hypersensitivity reactions
• Thrombocytopenia
• Injection site necrosis
• Acute generalized exanthematous pustulosis (AGEP)
• Hyperkalemia
• Eosinophilia

Interactions

• Increased risk of bleeding with NSAIDs, antiplatelet agents, and other anticoagulants
• Caution with drugs affecting hemostasis
• Avoid concurrent use with thrombolytics

Precautions

• Use with caution in patients with low body weight or obesity
• Monitor renal function and platelet counts
• Assess risk of bleeding in patients with hepatic impairment or existing coagulopathy
• Consider monitoring plasma-potassium levels in at-risk patients

Pregnancy

Not known to be harmful, low molecular weight heparins do not cross the placenta.

Breast-feeding

Manufacturer advises suitable for use during breastfeeding; passage into breast milk is negligible.

Storage

Store in a refrigerator (2-8°C). Do not freeze. Protect from light.

Formulations

• Enoxaparin sodium 150 mg/1 ml solution for injection pre-filled syringe
• Enoxaparin sodium 100 mg/0.4 ml solution for injection pre-filled syringe
• Enoxaparin sodium 40 mg/0.4 ml solution for injection pre-filled syringe

Indications

• Prevention of venous thromboembolism (VTE)
• Treatment of deep vein thrombosis (DVT)
• Treatment of pulmonary embolism (PE)
• Prevention of thrombus formation in patients undergoing surgery
• Management of unstable angina and non-ST elevation myocardial infarction (NSTEMI)

Dosage

Adults: Refer to the BNF for specific dosing recommendations based on the indication and patient characteristics, such as renal function.

Mechanism of action

Enoxaparin enhances the activity of antithrombin III, leading to the inhibition of factor Xa and, to a lesser extent, thrombin. By binding to antithrombin III, enoxaparin induces a conformational change, allowing antithrombin to inactivate these coagulation factors more effectively. This results in decreased thrombin generation and fibrin formation, thus reducing clot formation.

Pharmacodynamics

Enoxaparin exhibits dose-dependent anticoagulant effects. Its primary pharmacodynamic action is the inhibition of factor Xa, which plays a crucial role in the coagulation cascade. This leads to a reduction in the ability of the blood to clot, which is beneficial in conditions where thrombus formation is a risk. The anticoagulant effect can be monitored using anti-Xa assay, although routine monitoring is not typically required in most clinical settings.

Pharmacokinetics

Enoxaparin is well absorbed after subcutaneous administration, with a bioavailability of approximately 90%. Peak plasma concentrations occur about 3 to 5 hours after injection. It has a half-life of approximately 4 to 5 hours in healthy individuals, but this can be prolonged in patients with renal impairment. Enoxaparin is primarily eliminated by the kidneys, and its clearance is reduced in patients with renal dysfunction.

Adverse effects

• Bleeding complications
• Thrombocytopenia
• Hematoma at the injection site
• Injection site reactions
• Anemia
• Elevated liver enzymes
• Osteoporosis with long-term use

Interactions

• Increased risk of bleeding with other anticoagulants or antiplatelet agents
• NSAIDs may increase bleeding risk
• Certain antibiotics may affect coagulation
• Thrombolytic agents may potentiate bleeding risk

Precautions

• Use with caution in patients with renal impairment
• Monitor platelet counts regularly
• Caution in patients with a history of gastrointestinal bleeding
• May need to adjust dose in elderly patients or those with unstable health conditions

Pregnancy

Enoxaparin is generally preferred over warfarin in pregnancy due to a better safety profile, but its use should be carefully considered and monitored.

Breast-feeding

Enoxaparin is considered compatible with breastfeeding, but caution is advised and monitoring is recommended.

Storage

Store at room temperature, away from moisture and heat. Do not freeze. Dispose of properly after use.

Formulations

• Pre-filled syringes for subcutaneous injection
• Vials for intravenous or subcutaneous administration

Indications

• Pain management
• Vaccination
• Antibiotic therapy
• Hormonal therapies
• Anesthesia
• Nutritional support
• Chemotherapy

Dosage

Children: Refer to specific drug guidelines for paediatric dosing, as it requires careful consideration of weight and age.

Adults: Refer to specific drug guidelines for adult dosing, as it varies widely depending on the medication and clinical condition.

Mechanism of action

The mechanism of action of injected drugs varies widely based on the specific medication being administered. Generally, injected drugs enter the bloodstream directly, allowing them to circulate rapidly throughout the body. For instance, antibiotics may work by inhibiting bacterial cell wall synthesis, while analgesics may modulate pain pathways in the central nervous system. Each drug has unique pathways through which it achieves its therapeutic effects.

Pharmacodynamics

Pharmacodynamics refers to the effects of drugs on the body and their mechanisms of action. For injectable medications, effects can be immediate or delayed, depending on the drug's formulation and route of administration. Factors influencing pharmacodynamics include receptor affinity, drug concentration, and the presence of other substances that may enhance or inhibit the drug's effects. For example, some injectable drugs may require specific receptors to exert their effects, while others may have a broader range of action.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of injected drugs. After administration, drugs are rapidly absorbed into the bloodstream, leading to quick therapeutic effects. The distribution depends on factors such as blood flow, tissue permeability, and protein binding. Drugs are metabolized primarily in the liver and excreted through the kidneys or bile. The pharmacokinetic profile can vary widely based on the drug's chemical nature, dosage, and individual patient factors.

Pregnancy

Safety during pregnancy depends on the specific injection and its active ingredients. It is essential to consult a healthcare professional for guidance.

Breast-feeding

The safety of injections during breastfeeding varies by the specific medication. It is recommended to seek advice from a healthcare provider.

Storage

Store injections as per manufacturer's guidelines, usually in a cool, dry place away from direct sunlight. Some may require refrigeration.