Ribavirin

Limits on what this shows

• Null findings: No cohort compared didanosine with and without ribavirin in the abstracts read, and one review stated that adding ribavirin does not appear to raise the NRTI mitochondrial risk (not based on a ribavirin-alone comparison). Lactic acidosis is a clinical outcome, not a nutrient (Hard Rule 2).

Regulatory status

Label [1][2]: coadministration with didanosine is contraindicated because didanosine exposure increases; fatal hepatic failure, peripheral neuropathy, pancreatitis and symptomatic hyperlactatemia or lactic acidosis have been reported. Hepatic decompensation was seen in 14 of 129 (11%) cirrhotic HIV/HCV patients on HAART with ribavirin, all on NRTIs, 6 deaths [1].

Population evidence

Antivir Ther 2004 [29]: of 89 HAART-treated HCV-coinfected patients, 35 (39%) received didanosine plus ribavirin; 20 (57%) had adverse events at a mean of 87 days (hyperamylasemia 51%, hyperlactatemia 23%, pancreatitis 28%), 2 died (6%); interferon not named. Antivir Ther 2005 [31]: 113 patients on interferon-alpha plus ribavirin, 12% mitochondrial-toxicity events, didanosine the only independent risk factor; ribavirin effect not separable. Case report [30]: fatal lactic acidosis and pancreatitis on ribavirin, peginterferon alfa-2b and didanosine. FAERS review [32] reported a raised risk of these events with ribavirin plus didanosine (counts not given). All four read as PubMed listing summaries, not full texts.

Mechanism

For the interaction, raised didanosine exposure [1]. For ribavirin alone: IMPDH inhibition depletes intracellular GTP in cell culture [33], but a search for ribavirin effects on respiration or mitochondrial membrane potential returned no ribavirin-specific mitochondrial measurement (the one record returned tested nanogel carriers and AZT triphosphate, not ribavirin). The mechanism of ribavirin alone is therefore absent from the sources opened.

Counter-evidence held on record

Counter-evidence The signal is dominated by didanosine, which is itself a mitochondrial toxin; didanosine is rarely used now. No dossier reader should infer a ribavirin-alone mitochondrial effect. Framing caution A drug-drug interaction outcome, not a mitochondrial nutrient deficiency; no nutrient (including carnitine or CoQ10) is recommended.

Limits on what this shows

• Null findings: G6PD deficiency did not predict hemolysis [9], so the injury is not simply the classical G6PD oxidant pathway. No serum or tissue-level antioxidant capacity (vitamin C, E, whole-blood glutathione) was found measured in ribavirin-treated patients in the records opened.
• At-risk subgroups: Low pretreatment red-cell membrane thiols [9]; higher red-cell ribavirin exposure [12].

Regulatory status

The label does not describe oxidative mechanisms; it describes hemolytic anemia [1].

Population evidence

De Franceschi 2000 [8], Hepatology: in vitro, ribavirin lowered red-cell ATP and raised hexose monophosphate shunt activity; in vivo, 11 patients with chronic hepatitis C, 6 on ribavirin alone (1000 to 1200 mg/day) and 5 on ribavirin plus standard interferon (5 MU three times weekly, not peginterferon), sampled every two weeks to day 60: hemoglobin fell and reticulocytes rose in both groups, Na-K pump activity fell, K-Cl cotransport, malondialdehyde and methemoglobin rose and band 3 aggregation with bound IgG and C3 fragments increased. Numeric values and confidence intervals were not retrieved (OpenAlex reconstruction and summarizing fetch of the PubMed record). Hepatology 2004 [9]: 34 patients (4 G6PD-deficient) on ribavirin plus interferon-alpha (type unspecified); pretreatment membrane protein sulfhydryls were lower in the 5 with major hemolysis (median 28.4 vs 36.7 nmol/mg, P below.001); in vitro, ribavirin lowered red-cell glutathione and sulfhydryls and increased osmotic fragility, and glutathione ester or dipyridamole prevented the losses along with ATP, 2,3-DPG and TBARS changes. Brochot 2012 [10]: pretreatment in vitro hemolysis correlated with the in vivo hemoglobin fall in 24 patients on peginterferon plus ribavirin (P below 0.001); glutathione protected in vitro.

Mechanism

Present and named: ATP depletion with increased oxidant susceptibility, glutathione and membrane thiol loss, lipid peroxidation and methemoglobin formation [8][9][10].

Counter-evidence held on record

Counter-evidence The strongest human evidence is one 11-patient cohort whose abstract carries no effect sizes in the form retrieved, and a second cohort [9] that measured the redox markers mainly as a predictor and in vitro. The in vivo findings share their source with the Oxygen delivery entry (Overlap map). Orange rather than red for those reasons. Framing caution Red-cell oxidant injury caused by the drug, not a deficiency of vitamin C, E or glutathione precursors. No antioxidant supplement is recommended; supplement choices belong to the prescriber.

Limits on what this shows

• Null findings: In [13] serum iron and ferritin were unchanged despite the biopsy rise, so circulating markers did not track hepatic iron there. In interferon plus ribavirin therapy for thalassaemia (11 patients, interferon-alpha 2b 3 MU three times weekly plus ribavirin 1 g/day, no peginterferon), transfusion needs rose, attributed to ribavirin hemolysis, but serum ferritin fell significantly in responders [15] (chelation was strengthened per the abstract; interferon-confounded). In 206 patients on peginterferon alfa-2a or interferon alfa-2 plus ribavirin, serum iron, transferrin saturation and ferritin rose markedly by week 1 and the authors stated the ferritin rise was largely independent of hemolysis [16], so on-treatment ferritin in combination therapy is confounded by interferon and inflammation and is not used as evidence here.
• At-risk subgroups: Prolonged ribavirin exposure, repeated transfusion (thalassaemia, transplant), pre-existing hepatic fibrosis or hemochromatosis-range iron (inference from the mechanism, not studied).

Regulatory status

The label does not mention iron, ferritin or iron overload [1][2]. The label documents the hemolysis that is the proposed source of the iron.

Population evidence

(a) Di Bisceglie 1994 [13], J Hepatol: 15 patients treated 6 to 12 months with ribavirin (no interferon indicated); serum iron and ferritin did not change significantly; hepatic iron staining rose in nearly all patients (mean rank 3.9 to 8.5, p below 0.01); in six with tissue quantification hepatic iron rose from 826 to 1857 micrograms/g dry weight, about 1500 micrograms/g per year. The OpenAlex record has no abstract, so these figures come from a PubMed listing read through a summarizing fetch tool, not the paper. (b) J Med Virol 2005 [14]: 11 renal transplant patients on ribavirin monotherapy for 1 year (no interferon); serum ferritin rose (P=0.02), intrahepatic iron deposition rose (P=0.04), transferrin and total iron-binding capacity fell (P=0.004) and fibrosis scores rose; ribavirin dose and transfusion or erythropoietin use were not stated in the abstract reconstruction. Confidence intervals were not available for either study.

Mechanism

Named and plausible: hemolysis-driven release of heme iron into reticuloendothelial and hepatic stores; the authors of [14] propose that severe chronic hemolysis causes iron overload and liver iron deposition that may accelerate fibrosis. This mechanism is shared with the Oxygen delivery entry.

Counter-evidence held on record

Counter-evidence Both cohorts are uncontrolled before-after series of 15 and 11 patients, serum ferritin was discordant between them, and there is no ribavirin-free comparator. Graded orange rather than red for those reasons; this is the entry most likely to rise with full texts (see Monitoring and the near-red note in the report). Framing caution Excess/retention risk. Supplemental iron is the hazard here, not the remedy; ribavirin anemia is hemolytic and iron stores can be rising. No iron dose is recommended and any iron decision belongs to the prescriber.

Limits on what this shows

• Null findings: A zinc trial listed copper as measured but its abstract reports only zinc [20].

Regulatory status

The label does not mention copper [1][2].

Population evidence

J Inorg Biochem 2015 [35]: ribavirin coordinates Cu(II) through a triazole nitrogen from about pH 0.5 and forms a two-ligand complex above pH 6.0. The abstract could not be reconstructed (OpenAlex null); detail read through a PubMed listing summary. No patient or animal copper measurement was found in a PubMed search for "ribavirin copper" (13 results, none clinical).

Mechanism

Chelation by the triazole nitrogen in vitro; no in vivo absorption, plasma or excretion effect shown.

Counter-evidence held on record

Counter-evidence In vitro coordination chemistry does not establish an in vivo effect; ribavirin is systemically absorbed (64% bioavailability, Tier D) so luminal chelation is unlikely to dominate. Framing caution Theoretical only; no copper recommendation. Not a finding of copper depletion.

Limits on what this shows

• Why no grade: Dual condition met as far as tooling allowed: no Tier B or C source supporting even a yellow grade was found, and no circulating consumer claim was located to rebut. This is a disclosed gap, not a finding of safety. Mixed genuine gap and tooling-limited: PubMed listing access worked, but consumer search and several databases were unavailable. Re-check when search access returns.

What was searched

PubMed listings: "ribavirin gut microbiota" (7 records: mouse models using ribavirin only as a positive control, a one-patient sofosbuvir plus ribavirin subgroup within a 12-patient DAA study, and an in vitro glycosidase screen with no ribavirin-specific result), "ribavirin dysbiosis" (2 records) and a blocked "peginterferon ribavirin fecal microbiome dysbiosis" attempt (client error). OpenAlex, Crossref and Europe PMC search endpoints were not available.

Channel outcomes

Closest human data: Aliment Pharmacol Ther 2016 [36], 105 HCV cirrhotics; the 21 with SVR after peginterferon plus ribavirin (median 15 months earlier) did not differ in microbiota composition from non-SVR cirrhotics (UniFrac P=0.3), and both were dysbiotic vs 45 healthy controls. This is counter-evidence for lasting change, interferon-confounded and not a ribavirin-specific measurement. New Microbiol 2023 [37]: 12 DAA-treated patients, one on sofosbuvir plus ribavirin; not separable. WebSearch (consumer claims) failed because its shared budget was exhausted. The consumer-claim audit therefore could not confirm that no circulating claim exists.

Limits on what this shows

• Null findings: G6PD deficiency did not predict ribavirin hemolysis in the 34-patient cohort [9]. Folic acid 1 mg daily did not alter hemoglobin decline in 43 patients on interferon plus ribavirin [19]. L-carnitine reduced the hemoglobin fall in two small studies [17][18] (nutrient-to-drug direction; see the carnitine entry). The label comparison arms always contain ribavirin, so the label gives no ribavirin-free hemoglobin comparison.
• At-risk subgroups: Pre-existing cardiac disease (boxed warning) [1]; weight-based and higher dosing [2]; moderate to severe renal impairment (clearance about 30% of normal) [1]; decompensated cirrhosis or post-transplant [4]; low pretreatment red-cell membrane protein sulfhydryls (28.4 vs 36.7 nmol/mg in those with major hemolysis, P below.001) [9]; zidovudine co-therapy [1]; azathioprine co-therapy (pancytopenia) [1].

Regulatory status

Boxed warning [1]: the primary toxicity is hemolytic anemia, which may worsen cardiac disease and cause fatal or nonfatal myocardial infarction. Section 5.2: anemia in about 13% of ribavirin/PEGASYS-treated subjects; onset within 1 to 2 weeks; check hemoglobin or hematocrit pretreatment and at weeks 2 and 4. Section 6.1: hemoglobin below 10 g/dL in 13% (8.5 to 9.9 g/dL in 11%; below 8.5 g/dL in 2% with PEGASYS plus ribavirin vs below 1% with interferon alfa-2b plus ribavirin); ribavirin dose reduced for anemia in 22% of CHC and 16% of CHC/HIV patients. Dose rules: reduce to 600 mg/day at hemoglobin below 10 g/dL (no cardiac disease) or a fall of 2 g/dL or more in 4 weeks (stable cardiac disease); stop below 8.5 g/dL. Capsule label [2]: hemoglobin below 11 g/dL in about 30% (Study 2); 47% with weight-based vs 33% with flat-dose ribavirin (Study 3), and below 9 g/dL in 4% vs 2%. All label figures are from peginterferon or interferon plus ribavirin arms, so interferon marrow suppression contributes to the combination figures.

Population evidence

(a) Interferon-free, placebo-controlled: sofosbuvir label pooled phase 3 data [3] (weight-based ribavirin 1000 or 1200 mg/day): placebo 12 weeks (N=71) anemia 0%, hemoglobin below 10 g/dL 0%, below 8.5 g/dL 0%; sofosbuvir plus ribavirin 12 weeks (N=650 and 647) anemia 10%, below 10 g/dL 8%, below 8.5 g/dL 1%; 24 weeks (N=250) 6%, 6%, below 1%. The same table shows peginterferon plus ribavirin 24 weeks (N=243) 12%, 14%, 2%, and sofosbuvir plus peginterferon plus ribavirin 12 weeks (N=327) 21%, 23%, 2%, so peginterferon adds to the fall. Sofosbuvir alone was not an arm, so attribution to ribavirin rather than sofosbuvir is inferred from the ribavirin toxicity profile on the label, not from an isolating arm (a limit). (b) Harvoni label [4], interferon-free: 336 subjects with decompensated cirrhosis or post-transplant given ledipasvir/sofosbuvir plus ribavirin 12 weeks had hemoglobin below 10 g/dL in 38% and below 8.5 g/dL in 13%; ribavirin permanently stopped in 11%; no ribavirin-free comparator in that statement, and baseline anemia in decompensated cirrhosis and transplant is a likely contributor (inference). (c) De Franceschi 2000 [8]: 11 patients, 6 on ribavirin alone (1000 to 1200 mg/day) and 5 with standard interferon (5 MU three times weekly, not peginterferon); both groups showed a hemoglobin fall to steady state by day 45 and marked reticulocytosis. Numeric hemoglobin values were not retrieved. (d) Muller 2007 [11], retrospective cohort of 306 Toronto SARS patients (183 ribavirin, 123 not; 155 very high dose): progressive anemia OR 3.0 (99% CI 1.5 to 6.1), attributable risk 27%; interferon not reported. (e) Exposure-response, interferon-free [12]: in sofosbuvir plus ribavirin patients (NIAID SPARE trial), day-14 red-cell ribavirin monophosphate was 6.54 vs 4.48 pmol/10^6 cells in those with a hemoglobin nadir below 10 vs 10 g/dL or more (P=0.02). (f) Hepatology 2004 [9]: 34 patients on ribavirin plus interferon-alpha (type not specified): of 30 without G6PD deficiency, 5 had major hemolysis (hemoglobin fall above 6 g/dL) and 25 minor (below 2.5 g/dL). Sources (a), (b), (d) and (f) read as label text through a summarizing fetch tool or as abstracts (OpenAlex reconstructions and PubMed listing summaries); no full texts opened.

Mechanism

Present and named. Ribavirin is trapped in red cells as ribavirin triphosphate (about 81% of red-cell metabolites) because red cells lack phosphatase activity to clear it [5]; in vitro it lowered erythrocyte ATP and increased hexose monophosphate shunt activity [8]; in treated patients, red-cell malondialdehyde and methemoglobin rose, Na-K pump activity fell and band 3 aggregated with bound autologous IgG and complement C3 fragments, consistent with removal by the reticuloendothelial system [8]. In vitro hemolysis was concentration-dependent and was inhibited by ATP (IC50 about 1.63 mM), glutathione (IC50 about 767 micromolar) and dipyridamole [10].

Hard Rule 2 justification for orange

This entry is graded above yellow on purpose, by the category-endpoint convention used for the Oxygen delivery/utilization entries of dapsone and primaquine in this series. The category is defined by hemoglobin, hematocrit and red-cell mass, which were measured directly in [1][2][3][4][8][9][11]. The entry makes no iron, folate, B12 or carnitine deficiency claim and no supplementation claim; anemia here is explicitly not filed as iron deficiency (iron stores rise, see the iron entry) and it is not a nutrient deficiency. It stays orange and not red because it is a drug toxicity outcome and because exposure, dose, cardiac status and renal function bound it.

Counter-evidence held on record

Counter-evidence Peginterferon contributes marrow suppression and independently lowers hemoglobin, so combination-arm figures overstate ribavirin alone; the interferon-free arms [3][4][12] and the monotherapy subgroup [8] address this. Inhaled ribavirin for RSV (low systemic exposure) was not searched, so it is not used. Framing caution A hemolytic drug reaction, not a vitamin or mineral deficiency. Do not add iron, folic acid or any supplement on the assumption that this anemia is nutritional; any change is a prescriber decision (dose reduction is the label response).

Limits on what this shows

• Null findings: No human measurement of ATP in a ribavirin-treated tissue was found. The IMPDH hypothesis was contradicted for Lassa virus [34] and is flagged "failed verification" on the Wikipedia page that states it [6].

Regulatory status

The label says the mechanism is not fully understood, mentions IMPDH only in the azathioprine interaction, and does not mention ATP or GTP [1]. The capsule label mentions IMPDH inhibition by ribavirin as the azathioprine mechanism [2].

Population evidence

Tier B only: De Franceschi 2000 [8] reports lowered erythrocyte ATP in vitro (human cells). In Hepatology 2004 [9] and the Brochot assay [10] ATP (or 2,3-DPG) preserved or inhibited ribavirin-induced hemolysis in vitro (ATP IC50 about 1.63 mM); the patient data in those papers (peginterferon or interferon-alpha co-exposure) did not report patient red-cell ATP in the abstracts. IMPDH inhibition and GTP depletion is the predominant antiviral mechanism for flaviviruses and paramyxoviruses in Vero cells [33], while for Lassa virus GTP depletion was not the predominant mechanism (guanosine reversed mycophenolic acid but not ribavirin) [34]. Guanosine triphosphate is an intracellular nucleotide, not a dietary nutrient, so it is not filed as a nutrient entry.

Mechanism

Named: phosphorylation consumes ATP and ribavirin triphosphate accumulates in cells that cannot clear it [5]; IMPDH inhibition depletes guanine nucleotides in cell culture [33].

Counter-evidence held on record

Counter-evidence In vitro and cell-culture evidence only; red-cell ATP in patients and any systemic ATP effect remain unmeasured. Framing caution Mechanistic hypothesis, not a finding of low cellular energy in patients and not a basis for any supplement.