Medications for respiratory syncytial virus (RSV): Nursing pharmacology

Respiratory syncytial virus, or RSV for short, is an enveloped RNA virus that causes the cells lining the respiratory tract to merge, forming a large multinucleated cell called syncytia. RSV commonly affects the lower respiratory tract of young children, causing bronchiolitis.

Initially, bronchiolitis often resembles the common cold, but in some cases, it can also progress to atelectasis, or airway collapse, which causes severe symptoms such as wheezing, dyspnea, and even apnea in young infants.

There are two main classes of medication used in the treatment of RSV infection; these include monoclonal antibodies like palivizumab, and antiviral medications like ribavirin.

Starting with palivizumab, this medication is administered via intramuscular injection and is given for prevention, during the winter months, to infants at high risk for RSV, including prematurely-born infants, and to those with chronic lung disease or congenital heart disease.

Now, palivizumab is a monoclonal antibody that targets the fusion protein on the surface of RSV. The fusion protein helps the virus fuse to the host cell membrane and enter it, also facilitates the fusion between infected cell membranes, resulting in syncytium formation.

So by neutralizing the fusion protein, palivizumab prevents RSV from infecting the host cells and forming syncytia.

Common side effects of palivizumab include injection site reactions like pain, redness, and swelling. Some clients may also present with fever, chills, and myalgia.

Other side effects include nausea, vomiting, dyspnea, and hypersensitivity reactions like skin rashes, pruritus, angioedema, and even anaphylaxis.

Additionally, palivizumab can also cause thrombocytopenia, which can result in easy bruising or bleeding.

Now, palivizumab should be used with caution in children with thrombocytopenia and other bleeding disorders due to increased risk of bleeding.

Additionally, palivizumab should be used with caution when combined with thrombolytic, antiplatelet, and anticoagulant medications, as it can increase the risk of bleeding.

Now let’s switch gears and look at ribavirin, which is usually given orally or through inhalation to reduce the viral load in severe cases of bronchiolitis and to children who are immunocompromised and have an RSV infection.

In addition, ribavirin can be used to treat clients with chronic hepatitis C or E infection. Ribavirin is a purine nucleoside analog, which once administered, goes inside the infected cells, and gets picked up by the viral RNA-dependent RNA polymerase when trying to synthesize new nucleic acid.

As a result, these fake nucleotides are incorporated into the growing RNA, so no additional nucleotides can be added. Ultimately, this brings viral replication to a halt.

Additionally, ribavirin also inhibits the enzyme inosine-5′-phosphate dehydrogenase, which is essential to synthesize guanine nucleotides. As a result, the lack of guanine nucleotides further impairs viral replication.

Now, the most common side effects of ribavirin include headache, fatigue, abdominal pain, and nausea.

Some clients may also experience insomnia, depression, or develop a skin rash, pruritus, and cough.

In addition, ribavirin can cause hyperuricemia, or increased uric acid levels, since it's not metabolized by cells that lack a nucleus like the red blood cells and accumulates within them. Finally, ribavirin has boxed warnings for causing hemolytic anemia and teratogenic effects.

Ribavirin is contraindicated during pregnancy, in males whose female partners are pregnant, as well as in clients with hemoglobinopathies like thalassemia and sickle-cell anemia.

Ribavirin should be used with caution in clients with autoimmune hepatitis and severe renal disease.