nirsevimab

Action and Spectrum

Actions and Spectrum: 

nirsevimab is a monoclonal antibody designed to provide passive immunization against respiratory syncytial virus (RSV) infection.  

Action:  

• nirsevimab works by binding to the RSV fusion (F) protein, an essential viral protein involved in the entry of RSV into host cells. By binding to the F protein, nirsevimab prevents the virus from penetrating and also infecting the cells, thereby reducing the severity of RSV infection. 

Spectrum:  

• nirsevimab is primarily being developed to prevent RSV infection in infants. Respiratory syncytial virus, which is a common respiratory virus that can cause severe respiratory illness, especially in young and older adults. It is a leading cause of hospitalizations due to respiratory infections in infants. nirsevimab is intended to provide passive immunity against RSV and protect infants from severe respiratory illness caused by the virus. 

Drug Interaction

Adverse Reaction

Frequency defined

1.2%
Mild to moderate in intensity

0.1% to 1%
Rash
Injection site reaction

Black Box Warning

Black Box Warning: 

Beyfortus carries cautions and warnings about potentially fatal hypersensitivity reactions, such as anaphylaxis, which have been linked to other human IgG1 monoclonal antibodies.

Infants and children with bleeding disorders that are clinically significant should not receive Beyfortus without caution.

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

For infants and children who have experienced severe allergic reactions (such as anaphylaxis) to nirsevimab or any of its constituents, nirsevimab should not be administered.

Caution 

• Hypersensitivity Reactions: Individuals with known hypersensitivity or a history of allergic reactions to nirsevimab or its components should not receive the medication. Allergic reactions, including severe ones, may require immediate medical attention. 
• Vaccination Schedule: nirsevimab should not replace routine immunizations, including the administration of the RSV vaccine, if available. It is essential to follow the recommended vaccination schedule for other infectious diseases as advised by healthcare professionals. 
• Immunosuppressed Patients: The safety and efficacy of nirsevimab in immunosuppressed individuals or those with compromised immune systems have not been well-established. Particular caution and consideration should be exercised when considering the use of nirsevimab in this population. 
• Monitoring and Reporting Adverse Reactions: Healthcare professionals should monitor patients for any adverse reactions or side effects following the administration of nirsevimab.

Pregnancy / Lactation

Pregnancy consideration:  

US FDA pregnancy category: Not assigned 

Lactation:   

Excreted into human milk: Not known. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

nirsevimab is a monoclonal antibody developed to prevent infant respiratory syncytial virus (RSV) infection. It targets the RSV fusion (F) protein, crucial for viral entry and replication. By binding to the F protein, nirsevimab inhibits the fusion of RSV with host cells, thereby preventing viral infection and subsequent disease development.

It has a long half-life, allowing for extended protection, and is administered via intramuscular injection. Clinical research studies have demonstrated its efficacy in reducing the incidence of severe RSV lower respiratory tract infection in high-risk infants. nirsevimab represents a promising pharmacological approach to preventing RSV infection and its associated complications in vulnerable populations. 

Pharmacodynamics: 

Mechanism of action: nirsevimab is a monoclonal antibody developed to prevent infant respiratory syncytial virus (RSV) infection. Its mechanism of action involves targeting the RSV fusion (F) protein, which plays a critical role in the viral entry process. 

Respiratory syncytial virus, which is a common respiratory virus that may cause severe illness, particularly in young children and infants. The RSV F protein is responsible for mediating the combination of the viral envelope with the host cell membrane, allowing the virus to penetrate and infect the host cells. 

nirsevimab binds explicitly to the RSV F protein, blocking its function and preventing the fusion of the virus with the host cell membrane. By inhibiting this crucial step in the viral life cycle, nirsevimab effectively neutralizes the virus and prevents its entry into the host cells. 

By providing passive immunity against RSV, nirsevimab helps protect infants at a high risk of severe RSV infection. It offers a targeted approach to reduce the incidence and severity of RSV-related respiratory illnesses in this vulnerable population. 

Pharmacokinetics: 

Absorption 

Monoclonal antibodies are usually administered via intravenous or subcutaneous injection, allowing direct delivery into the bloodstream. In the case of nirsevimab, it is administered via intramuscular injection, which allows for absorption into the bloodstream through the muscle tissue. 

Distribution 

Once in the bloodstream, monoclonal antibodies like nirsevimab can distribute throughout the body, reaching various tissues and organs. The distribution pattern can be influenced by factors such as the antibody’s size, affinity for target tissues, and the presence of specific transporters or receptors. 

Metabolism 

Monoclonal antibodies are primarily considered to undergo minimal metabolic processing. However, they can undergo some degree of catabolism or proteolytic degradation. Metabolism typically occurs through enzymatic processes in the liver or other tissues. 

Elimination and Excretion 

Monoclonal antibodies are primarily eliminated from the body via proteolysis and subsequent renal excretion. The intact antibodies or their breakdown products may be excreted in the urine. 

Adminstartion

Administration: 

Intramuscular administration 

nirsevimab is administered via intramuscular injection. It is typically given as a single dose every RSV season, which can vary depending on the geographic location. A healthcare professional should determine the exact dosage and timing of administration based on the individual’s age, weight, and specific risk factors for severe RSV infection. 

The injection is usually administered into the muscle, such as the thigh or the deltoid muscle of the upper arm. Proper injection techniques and aseptic practices should be followed to minimize the risk of infection or injury. It is essential to adhere to the recommended dosage and administration schedule to ensure optimal protection against RSV. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: nirsevimab-alip 

Why do we use nirsevimab-alip? 

nirsevimab primarily prevents respiratory syncytial virus (RSV) infection in infants. Respiratory syncytial virus, which is a common respiratory virus that may cause severe illness, particularly in young children and infants. Infants at a high risk of severe RSV infection include those born prematurely, those with certain underlying medical conditions, and those immunocompromised. 

nirsevimab helps provide passive immunity against RSV, reducing the incidence and severity of RSV-related respiratory illnesses in these vulnerable populations. By targeting the RSV fusion (F) protein, nirsevimab blocks the viral entry into host cells, effectively neutralizing the virus and preventing infection.