Drug Overview
Ribavirin is a broad-spectrum antiviral medication used in combination regimens. Marketed under the brand names Copegus, Rebetol, and Virazole, it is a synthetic nucleoside analog with activity against both RNA and DNA viruses.
It is approved for chronic hepatitis C virus (HCV) infection—typically in combination with peginterferon alpha or other direct-acting antivirals—as well as for severe respiratory syncytial virus (RSV) infections in infants. Ribavirin works by mimicking guanosine, inducing lethal mutagenesis in viral RNA and inhibiting viral RNA polymerase activity.
Relevant Genes and Their Roles
Response to ribavirin-based hepatitis C treatment is influenced by genetic variation in the IFNL3 gene (formerly known as IL28B). IFNL3 encodes interferon lambda-3, a cytokine that activates antiviral pathways and boosts the immune response against HCV.
Different IFNL3 genotypes affect how strongly a patient’s immune system responds to peginterferon alpha combined with ribavirin. Favorable genotypes lead to higher expression of interferon-stimulated genes and better viral clearance, while unfavorable genotypes result in a weaker response.
Impact of Genetics on Drug Response
Genetic variation in IFNL3 stratifies patients into groups with distinct probabilities of achieving a sustained virologic response. Those with favorable genotypes generally respond well to standard ribavirin regimens, whereas patients with unfavorable genotypes have lower response rates and may require alternative therapies or treatment durations.
Want to know what your genetics say about how you'll respond to Ribavirin?
A Gene2Rx report reads your own DNA to show how it may affect your response to Ribavirin and your other medications.
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Expected Clinical Effects of Genetic Variation
Favorable Response Genotype
- Effect: Standard ribavirin response with normal antiviral activity
- Clinical consequence: Higher likelihood of sustained virologic response (~70% after 48 weeks)
- Side effects: Typical ribavirin-related effects such as hemolytic anemia and fatigue; moderate severity and commonly observed
Unfavorable Response Genotype
- Effect: Reduced antiviral efficacy with standard regimens
- Clinical consequence: Lower chance of sustained virologic response (~30% after 48 weeks)
- Side effects: Similar safety profile—anemia, headache, nausea; moderate severity
Indeterminate/Not Available
- Effect: Unknown
- Clinical consequence: No specific guidance; follow standard dosing with clinical monitoring
Dosing Guidelines
The following dosing guidelines are based on the available guidelines for IFNL3 genotypes from CPIC.
IFNL3 Genotype-Based Dosing
| Phenotype |
Clinical Consequence |
Guideline Recommendation |
| Favorable response genotype |
High probability of sustained virologic response (~70% after 48 weeks) |
Consider standard ribavirin dosing and shortened treatment duration (24–28 weeks); strong recommendation for peginterferon alpha plus ribavirin regimens (90% SVR) |
| Unfavorable response genotype |
Lower probability of sustained virologic response (~30% after 48 weeks) |
Standard dosing may be less effective; consider alternative therapies or full-length treatment (48 weeks) based on clinical factors |
| Indeterminate / Not available |
Unknown impact |
Initiate standard starting dose and duration; monitor virologic response |
Alternative Treatment Options
Examples of alternative treatments include interferon-free, direct-acting antiviral regimens such as sofosbuvir/ledipasvir or sofosbuvir/velpatasvir. These therapies have demonstrated high cure rates and may be preferred for patients with unfavorable IFNL3 genotypes.
Genes that affect Ribavirin
See the full list of drugs affected by each gene:
Brand names containing Ribavirin
See how your genetics affect each product Ribavirin shows up in:
Disclaimer: This document is for informational purposes only and is not a substitute for medical advice. Clinical decisions should be made by a qualified healthcare professional.
Interested in learning more about how your genetics may affect your response to medication? Get started with Gene2Rx today.
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