ASUNRA TABLETS

Indications

• Chronic iron overload due to repeated blood transfusions
• Beta-thalassemia major
• Sideroblastic anemia
• Other conditions leading to secondary hemochromatosis

Dosage

Children: Refer to pediatric dosing guidelines in the BNF for Children, as doses vary based on age, weight, and clinical condition.

Adults: Refer to specific guidelines for dosing recommendations based on the severity of iron overload, typically started at an initial dose and adjusted based on serum ferritin levels and clinical response.

Mechanism of action

Defarasirox chelates free iron in the bloodstream, forming stable complexes that are excreted mainly via the feces. This process reduces the iron burden in the body, which is crucial in conditions of iron overload where excess iron can lead to toxicity and damage to organs such as the heart and liver.

Pharmacodynamics

Defarasirox exhibits a dose-dependent response in reducing serum ferritin levels, which is a marker of total body iron stores. Its effectiveness in lowering iron levels is measured by its ability to improve laboratory parameters and decrease the risk of complications associated with iron overload.

Pharmacokinetics

Defarasirox is rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1 to 4 hours. It has a bioavailability of approximately 70%. The drug is extensively metabolized in the liver, primarily by glucuronidation, and the metabolites are excreted mainly in the feces. The half-life of defarasirox is around 8 to 16 hours, allowing for once-daily dosing.

Contra-indications

• Hypersensitivity to defarasirox or any of its components
• Severe renal impairment
• Active hepatic disease

Adverse effects

• Gastrointestinal disturbances such as diarrhea, nausea, and vomiting
• Hepatotoxicity, including elevated liver enzymes and liver failure
• Renal impairment, including acute kidney injury
• Hypersensitivity reactions, including rash and anaphylaxis
• Ocular toxicity, including retinal pigmentary changes

Interactions

• Antacids may decrease the absorption of defarasirox
• Caution with other drugs that are nephrotoxic or hepatotoxic
• May interact with drugs that affect renal function or are highly protein-bound

Precautions

• Monitor liver and renal function regularly during treatment
• Caution in patients with a history of gastrointestinal disease
• Assess for signs of hypersensitivity reactions
• Use with caution in elderly patients or those with comorbid conditions

Pregnancy

Defarasirox is classified as category D. It should only be used in pregnancy if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known if defarasirox is excreted in human milk. Caution is advised when administered to a nursing mother.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Oral tablet
• Oral suspension