COPEGUS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COPEGUS (COPEGUS).
Ribavirin is a nucleoside analogue that inhibits viral RNA synthesis by interfering with RNA capping and polymerase activity, and may also modulate immune responses.
| Metabolism | Metabolized via reversible phosphorylation and deribosylation; approximately 40% of an oral dose is excreted unchanged in feces. Phosphorylated forms accumulate in erythrocytes. |
| Excretion | Ribavirin is primarily eliminated renally as unchanged drug (61%) and metabolites (30%); biliary/fecal excretion accounts for ~9%. |
| Half-life | Terminal elimination half-life is approximately 120-170 hours following multiple doses, supporting once-daily dosing with prolonged viral suppression. |
| Protein binding | Ribavirin is approximately 0% bound to plasma proteins. |
| Volume of Distribution | Volume of distribution is approximately 200-300 L (2.9-4.3 L/kg), indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability averages 64% (range 36-76%) due to first-pass metabolism, with food increasing absorption. |
| Onset of Action | Oral administration: declines in serum HCV RNA detectable within 2-4 weeks of initiating combination therapy with interferon alfa-2a. |
| Duration of Action | Clinical effect duration aligns with treatment course (24-48 weeks via pharmacokinetic-pharmacodynamic modeling); steady-state achieved in ~4 weeks, and viral suppression persists through dosing interval. |
| Molecular Weight | 244.21 |
800 mg orally twice daily to 1200 mg orally twice daily based on body weight (≤75 kg: 800 mg; >75 kg: 1200 mg), in combination with ribavirin, for 24 to 48 weeks depending on genotype.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if CrCl < 50 mL/min. For CrCl 30-50 mL/min: reduce to 400 mg orally twice daily; not recommended if CrCl < 30 mL/min. |
| Liver impairment | Contraindicated in decompensated cirrhosis (Child-Pugh class B or C). No specific dose adjustment for Child-Pugh class A; use with caution and monitor. |
| Pediatric use | Weight-based: <47 kg: 45 mg/kg/day (max 2400 mg) in two divided doses; ≥47 kg: 1200 mg orally twice daily. Duration determined by genotype and response. |
| Geriatric use | No specific dose adjustment based on age alone; monitor renal function and reduce dose if CrCl < 50 mL/min; use with caution due to increased risk of anemia and other adverse effects. |
| 1st trimester | COPEGUS (ribavirin) is contraindicated in the first trimester due to significant teratogenic effects observed in animal studies; use is not recommended unless potential benefit outweighs risk in life-threatening conditions. |
| 2nd trimester | Ribavirin is contraindicated throughout pregnancy due to embryocidal and teratogenic effects; indicated for use in females and males only if effective contraception is used during treatment and for 6 months post-therapy. |
| 3rd trimester | Same as t2: contraindicated; risk of fetal harm outweighs any potential benefit. |
Clinical note
Comprehensive clinical and safety monograph for COPEGUS (COPEGUS).
| Placental transfer | Ribavirin readily crosses the placenta in animal models; although human data are limited, the drug is lipophilic and has a low molecular weight, suggesting significant placental transfer in humans. |
| Breastfeeding | Ribavirin is excreted into human milk; due to potential for serious adverse reactions in nursing infants, including hemolytic anemia and carcinogenicity, breastfeeding is not recommended during treatment and for at least 6 months after the last dose. |
■ FDA Black Box Warning
Ribavirin monotherapy is not effective for chronic HCV infection. Hemolytic anemia (worsening of cardiac disease). Teratogenicity and embryolethality.
| Serious Effects |
PregnancyFemale partners of male patients who are pregnantHemoglobinopathies (e.g., thalassemia major, sickle cell anemia)Severe pre-existing cardiac disease (e.g., unstable or uncontrolled cardiovascular disease)Autoimmune hepatitisHypersensitivity to ribavirin or any component of the formulationConcomitant use with didanosine
| Precautions | Hemolytic anemia (monitor hemoglobin), cardiac disease exacerbation, pulmonary insufficiency, pancreatitis, hepatic decompensation, myelosuppression, fetal harm. |
| Food/Dietary | Take with food to reduce gastrointestinal irritation. Avoid grapefruit products as they may affect drug metabolism. No specific dietary restrictions beyond a balanced diet. |
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| Lactation Rating | L5 - Contraindicated |
| Teratogenic Risk | FDA Pregnancy Category X. Ribavirin, the active component, is contraindicated in pregnant women and partners of male patients due to demonstrated teratogenicity and embryolethality in all animal species tested. Risk of fetal harm (including CNS, skeletal, and eye malformations) if exposure occurs during first trimester. Use during second or third trimester also carries risk; pregnancy must be excluded before initiation and avoided during treatment and for 6 months after completion in both female patients and female partners of male patients. |
| Fetal Monitoring | Monthly pregnancy testing during treatment and for 6 months after discontinuation in all women of childbearing potential. In male patients, monitor partner's pregnancy status. Fetal ultrasound if unintended pregnancy occurs. Monitor maternal CBC, LFTs, and thyroid function monthly due to combination therapy with interferon alfa. |
| Fertility Effects | Reversible oligospermia and reduced sperm motility reported in male patients receiving ribavirin-containing regimens. Women may experience temporary menstrual irregularities. No permanent effect on fertility documented; contraception required during and for 6 months post-treatment for both sexes. |
| Clinical Pearls | Ribavirin (COPEGUS) is used in combination with peginterferon alfa or direct-acting antivirals for hepatitis C; it is teratogenic and requires two forms of contraception in both male and female patients during and for 6 months after therapy. Monitor hemoglobin closely as hemolytic anemia is dose-limiting; dose reduction is recommended if hemoglobin drops below 10 g/dL. Avoid in patients with hemoglobinopathies. Pancreatitis and pulmonary infiltrates have been reported. Use with caution in renal impairment (CrCl <50 mL/min contraindicated). |
| Patient Advice | Take COPEGUS with food to reduce nausea and enhance absorption. · You must use two forms of effective contraception during treatment and for 6 months after stopping, as this drug can cause birth defects. · COPEGUS can cause severe anemia; report symptoms such as fatigue, shortness of breath, or pale skin to your doctor immediately. · Do not breastfeed while taking this medication. · Avoid alcohol during treatment as it may worsen liver damage. · Drink plenty of fluids unless advised otherwise by your doctor. · Do not stop taking COPEGUS without consulting your healthcare provider, even if you feel better. |