ribavirin

Action and Spectrum

Actions and Spectrum:

ribavirin is an antiviral medication that exhibits a broad-spectrum activity against a variety of RNA and DNA viruses, including respiratory syncytial virus (RSV), hepatitis C virus (HCV), Lassa fever virus, and some influenza viruses.

The mechanism of action of ribavirin is not entirely understood, but it is thought to interfere with viral replication by inhibiting the synthesis of viral nucleic acids, among other mechanisms. Ribavirin has also been shown to modulate the host immune response, which may contribute to its antiviral effects.

ribavirin is available in various formulations, including oral capsules, oral solution, and inhalation solution. Its clinical use varies depending on the viral infection being treated and the patient population, and it is often used in combination with other antiviral drugs.

Drug Interaction

Adverse Reaction

Adverse drug reactions:   

Frequency Defined  

>10%  

Cough  

1-10%  

Nausea  

Vomiting  

Angina pectoris  

Dizziness   

Diarrhea   

Syncope  

Headache  

Vertigo  

<1%  

Angioedema   

Black Box Warning

Black Box Warning:

The black box warning for ribavirin states that the drug can cause serious, even fatal, side effects.

Contraindication / Caution

Contraindication / Caution:

Contraindications:

• Hypersensitivity to ribavirin or any of its components
• Pregnancy, as ribavirin is known to cause fetal harm and is contraindicated in pregnant women and their male sexual partners

Precautions/cautions:

• Patients with a history of significant or unstable cardiac disease or with pre-existing cardiac abnormalities should be closely monitored during ribavirin therapy, as ribavirin can cause cardiotoxicity.
• Patients with a history of significant or unstable pulmonary disease or with pre-existing pulmonary abnormalities should be closely monitored during ribavirin therapy, as ribavirin can cause pulmonary toxicity.

Pregnancy / Lactation

Pregnancy warnings:     

AU TGA pregnancy category: N/A 

US FDA pregnancy category: N/A 

Lactation: 

Excreted into human milk is unknown 

Pregnancy Categories:       

Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester.       

Category B: No evidence shown of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women       

Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a result in humans must take care of potential risks in pregnant women       

Category D: adequate data available 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:

ribavirin is a synthetic nucleoside analogue that resembles the purine nucleotides. It has a broad-spectrum activity against DNA and RNA viruses. Ribavirin inhibits the replication of viruses by disrupting the synthesis of viral RNA and DNA. It also has an immunomodulatory effect, which helps to enhance the antiviral activity of the drug.

Pharmacodynamics:

ribavirin’s precise mechanism of action is not fully understood. However, it is believed to work by inhibiting the synthesis of viral nucleic acids, disrupting viral replication, and inhibiting viral protein synthesis. Ribavirin may also enhance the host’s immune response to the virus, contributing to its antiviral activity.

Pharmacokinetics:

Absorption

ribavirin is rapidly absorbed following oral administration, with peak plasma concentrations occurring within 1-2 hours. Food may delay its absorption but does not significantly affect its overall bioavailability.

Distribution

ribavirin is distributed widely throughout the body, with a volume of distribution of approximately 1.2 L/kg. It crosses the placenta and is distributed into breast milk. It also penetrates into the cerebrospinal fluid, where its concentration is approximately 20% of that in plasma.

Metabolism

ribavirin is metabolized in the liver to several metabolites, including ribavirin mono-, di-, and triphosphate.

Adminstartion

Administration:

ribavirin is available in several different formulations, including oral capsules, oral solution, and inhalation solution. The specific administration method and dosing regimen for ribavirin will depend on the condition being treated and the patient population.

For example, in the treatment of hepatitis C virus (HCV), ribavirin is typically administered orally, usually in combination with other antiviral drugs. The recommended dose and duration of treatment will depend on various factors, such as the genotype of the virus, the patient’s medical history, and the severity of liver disease.

In the treatment of respiratory syncytial virus (RSV), ribavirin may be administered via inhalation, usually using a nebulizer. This method of administration allows the drug to be delivered directly to the respiratory tract, where the virus is causing the infection. The recommended dose and duration of treatment will depend on various factors, such as the age of the patient, the severity of illness, and the presence of underlying medical conditions.

Patient Information Leaflet

Patient Information Leaflet    

Generic Name: ribavirin 

Why do we use ribavirin? 

The use of ribavirin for the treatment of Human Metapneumovirus (HMPV) is controversial, and its efficacy in treating HMPV infection has not been clearly established.

However, ribavirin is sometimes used for the treatment of severe or complicated HMPV infections, particularly in immunocompromised patients or those with underlying respiratory conditions. This is because ribavirin has broad-spectrum antiviral activity, and some studies have suggested that it may have in vitro activity against HMPV.

In addition to its antiviral properties, ribavirin has also been shown to have immunomodulatory effects, which may be beneficial in the treatment of certain viral infections. For example, ribavirin has been shown to increase the production of interferon, which is a key component of the host immune response to viral infection.