Qfitlia (fitusiran sodium)

Measure AT activity using an FDA-cleared test at weeks 4, 12, 20, and 24 following the initial dose and after any dosage modification; adjust the dose and/or dosing interval of fitusiran accordingly to maintain AT activity between 15-35% (see Table 1).

If AT activity <15%, reduce the dosage starting 3 months after the prior dosage.

If AT activity >35% after 6 months or if the patient has not achieved adequate bleed control, consider dosage increase.

The recommended AT monitoring schedule should be restarted after dosage reduction or escalation.

Once target dosage identified based on AT activity 15-35%, measure AT activity annually and when clinically indicated.

When therapy is discontinued, there is no need to continuing monitoring AT levels unless the patient is bleeding and treatment with clotting factor concentrates or bypassing agents is needed.

Table 1. Dosage Modification Based on AT Activity Level

Last Dosage Administered Antithrombin Activity Dosage Modification Level 50 mg every 2 months <15% 20 mg every 2 months 50 mg every 2 months 15-35% Continue current dosage 50 mg every 2 months >35% after 6 months 50 mg every month 20 mg every 2 months <15% 10 mg every 2 months 20 mg every 2 months 15-35% Continue current dosage 20 mg every 2 months >35% after 6 months 20 mg every month 10 mg every 2 months <15% Discontinue 10 mg every 2 months 15-35% Continue current dosage 10 mg every 2 months >35% after 6 months 10 mg every month

Administer fitusiran by subcutaneous injection only. Fitusiran is available as a 50 mg/0.5 mL (100 mg/mL) single-dose prefilled pen and a 20 mg/0.2 mL (100 mg/mL) single-dose vial.

No dosing information is available for this tab.

No formal drug interaction studies have been conducted.

In vitro studies show that fitusiran is unlikely to cause or be affected by cytochrome P-450 or transporter-mediated drug interactions at clinically relevant concentrations.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

*None

There are no contraindication contraindications for this drug.

• Child-pugh class A hepatic impairment
• Child-pugh class B hepatic impairment
• Child-pugh class C hepatic impairment
• Disease of liver
• Gallbladder disease
• Thromboembolic disorder
• Thrombotic disorder

There are no moderate contraindications for this drug.

The most common adverse reactions, occurring in >=10% of patients treated with fitusiran at the recommended AT-based dosage regimen, were viral infection, nasopharyngitis, and bacterial infection.

Less Frequent

• Drug-induced hepatitis

More Frequent

• Bacterial infection
• Pharyngitis
• Viral infection

Less Frequent

• Arthralgia
• Cough
• Headache disorder
• Injection site sequelae
• Thrombotic disorder

Rare or Very Rare

• Acute abdominal pain
• Biliary calculus
• Cholecystitis
• Dyspepsia
• Pruritus of skin

No enhanced messaging available.

Safety and effectiveness of fitusiran for the treatment of hemophilia A or B, with or without factor VIII or IX inhibitors, in pediatric patients >=12 years of age have been established. Use in this pediatric population is supported by evidence from adequate and well-controlled studies in adult and pediatric patients. Clinical studies included 60 pediatric patients 12-17 years of age treated with fitusiran. Safety and effectiveness have not been established in pediatric patients <12 years of age.

There are no data in pregnant women to assess the risk of birth defects, miscarriage, or other adverse maternal or fetal outcomes with fitusiran. Animal reproduction studies have not been conducted. It is unknown whether fitusiran causes fetal harm or affects reproductive capacity. Use fitusiran during pregnancy only when the potential benefits outweigh the risks to the fetus.

It is not known whether fitusiran or its metabolites are distributed into human milk or if the drug has any effects on the breastfed infant or on milk production. The safety of fitusiran during breastfeeding is unknown. The benefits of breastfeeding should be weighed against the clinical need for fitusiran and the potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition.

The manufacturer makes no specific dosage recommendations for geriatric patients.

Clinical studies of fitusiran included 3 patients with hemophilia >=65 years of age. The number of patients >=65 years of age was insufficient to determine whether response to fitusiran differs from that of younger patients.