Ribavirin monitoring in chronic hepatitis C therapy: anaemia versus efficacy

Nanomedicine for the Treatment of Viral Diseases: Smaller Solution to Bigger Problems

The continuous evolution of new viruses poses a danger to world health. Rampant outbreaks may advance to pandemic level, often straining financial and medical resources to breaking point. While vaccination remains the gold standard to prevent viral illnesses, these are mostly prophylactic and offer minimal assistance to those who have already developed viral illnesses. Moreover, the timeline to vaccine development and testing can be extensive, leading to a lapse in controlling the spread of viral infection during pandemics. Antiviral therapeutics can provide a temporary fix to tide over the time lag when vaccines are not available during the commencement of a disease outburst. At times, these medications can have negative side effects that outweigh the benefits, and they are not always effective against newly emerging virus strains. Several limitations with conventional antiviral therapies may be addressed by nanotechnology. By using nano delivery vehicles, for instance, the pharmacokinetic profile of antiviral medications can be significantly improved while decreasing systemic toxicity. The virucidal or virus-neutralizing qualities of other special nanomaterials can be exploited. This review focuses on the recent advancements in nanomedicine against RNA viruses, including nano-vaccines and nano-herbal therapeutics.

Potential RNA-dependent RNA polymerase (RdRp) inhibitors as prospective drug candidates for SARS-CoV-2

The SARS-CoV-2 pandemic is considered as one of the most disastrous pandemics for human health and the world economy. RNA-dependent RNA polymerase (RdRp) is one of the key enzymes that control viral replication. RdRp is an attractive and promising therapeutic target for the treatment of SARS-CoV-2 disease. It has attracted much interest of medicinal chemists, especially after the approval of Remdesivir. This study highlights the most promising SARS-CoV-2 RdRp repurposed drugs in addition to natural and synthetic agents. Although many in silico predicted agents have been developed, the lack of in vitro and in vivo experimental data has hindered their application in drug discovery programs.

An update on inhibitors targeting RNA-dependent RNA polymerase for COVID-19 treatment: Promises and challenges

The highly transmissible variants of SARS-CoV-2, the causative pathogen of the COVID-19 pandemic, bring new waves of infection worldwide. Identification of effective therapeutic drugs to combat the COVID-19 pandemic is an urgent global need. RNA-dependent RNA polymerase (RdRp), an essential enzyme for viral RNA replication, is the most promising target for antiviral drug research since it has no counterpart in human cells and shows the highest conservation across coronaviruses. This review summarizes recent progress in studies of RdRp inhibitors, focusing on interactions between these inhibitors and the enzyme complex, based on structural analysis, and their effectiveness. In addition, we propose new possible strategies to address the shortcomings of current inhibitors, which may guide the development of novel efficient inhibitors to combat COVID-19.

SARS-CoV-2 RNA-dependent RNA polymerase as a therapeutic target for COVID-19

Introduction: The current SARS-CoV-2 pandemic urgently demands for both prevention and treatment strategies. RNA-dependent RNA-polymerase (RdRp), which has no counterpart in human cells, is an excellent target for drug development. Given the time-consuming process of drug development, repurposing drugs approved for other indications or at least successfully tested in terms of safety and tolerability, is an attractive strategy to rapidly provide an effective medication for severe COVID-19 cases.Areas covered: The currently available data and upcominSg studies on RdRp which can be repurposed to halt SARS-CoV-2 replication, are reviewed.Expert opinion: Drug repurposing and design of novel compounds are proceeding in parallel to provide a quick response and new specific drugs, respectively. Notably, the proofreading SARS-CoV-2 exonuclease activity could limit the potential for drugs designed as immediate chain terminators and favor the development of compounds acting through delayed termination. While vaccination is awaited to curb the SARS-CoV-2 epidemic, even partially effective drugs from repurposing strategies can be of help to treat severe cases of disease. Considering the high conservation of RdRp among coronaviruses, an improved knowledge of its activity in vitro can provide useful information for drug development or drug repurposing to combat SARS-CoV-2 as well as future pandemics.

Population pharmacokinetics of ribavirin in lung transplant recipients and examination of current and alternative dosing regimens

BACKGROUND

Ribavirin is used in the treatment of respiratory paramyxovirus infection in lung transplant recipients; however, its pharmacokinetic profile in the transplant population is unknown despite the potential for alterations due to underlying pathology. Furthermore, the ability of current regimens to meet exposure targets has not been established.

OBJECTIVES

This study examined the pharmacokinetics of ribavirin in a lung transplant population for which current and alternative dosing regimens were assessed.

METHODS

Population pharmacokinetic modelling was conducted in NONMEM using concentration-time data from 24 lung transplant recipients and 6 healthy volunteers. Monte Carlo simulation was used to assess the ability of dosing regimens to achieve pre-specified target concentrations.

RESULTS AND CONCLUSIONS

A three-compartment model with first-order elimination most adequately described ribavirin concentration-time data, with CLCR and patient type (i.e. lung transplant) identified as significant covariates in the model. Simulations indicate that current regimens achieve efficacious concentrations within 24 h of treatment initiation that increase to supra-therapeutic levels over the treatment period. A regimen of 8 mg/kg q6h orally for 48 h followed by 8 mg/kg q24h orally for the remainder of the treatment period was predicted to result in >90% of patients exhibiting concentrations within the defined target range throughout the entire treatment course. Additional work to formally establish target therapeutic concentrations is required; however, this study provides a valuable first step in determining optimal ribavirin treatment regimens for paramyxovirus infections in the lung transplant population.

High rate of acute kidney injury in patients with chronic kidney disease and hepatitis C virus genotype 4 treated with direct-acting antiviral agents

BACKGROUND

Direct-acting antivirals (DAAs) have significantly improved the efficacy and safety of treating chronic hepatitis C (CHC), but their effectiveness and safety among patients with chronic kidney disease (CKD) remains poorly understood. Sofosbuvir/daclatasvir regimen is supposed to be used for patients with creatinine clearance more than 30 mL/min, while ombitasvir/paritaprevir/ritonavir regimen is used for patients with creatinine clearance less than 30 mL/min.

AIM

The aim of the study was to assess the safety and efficacy of DAAs among patients with CKD.

METHODS

Eighteen CKD stage 2-3b patients received sofosbuvir for 3 months. In addition, 42 CKD stage-4 patients received ritonavir-boosted paritaprevir plus ombitasvir for 3 months. Finally, ribavirin was added for 30 of them.

RESULTS

The patients'age was 49.2 ± 12 years. Baseline serum creatinine was 3.76 ± 1.67 mg/dL. Fifty patients were HCV genotype 4. A 3-month sustained viral response was achieved in 56 patients and 49 patients achieved a 6-month viral response. There were 11 relapsers. Acute kidney injury (AKI) upon CKD (AKI/CKD) occurred in 28 patients, of which 20 needed hemodialysis. Fifteen/28 recovered from AKI, whereas 13 were maintained on hemodialysis. In multivariate analysis, there were only two independent risk factors for developing AKI/CKD, i.e., being cirrhotic as defined by baseline abdominal ultrasound findings [odds ratio 4.15 (1.33-12.97); p = 0.013] and having had as DAA therapy OMV/PTV/RTV [odds ratio 7.35 (1.84-29.35); p = 0.001].

CONCLUSION

Treatment of HCV among stage 2, 3a, and 3b patients was achieved safely with a sofosbuvir-based regimen. We recommend that stage-4 patients wait until starting hemodialysis or transplantation.

Nanomedicine as a future therapeutic approach for Hepatitis C virus

Hepatitis C virus (HCV) is not easily cleared from the human body and in most cases turned into chronic infection. This chronicity is a major cause of liver damage, cirrhosis and hepatocellular carcinoma. Therefore, immediate detection and treatment of HCV guarantees eradication of the virus and prevention of chronicity complications. Since discovery of HCV in 1989, several emerging treatments were developed such as polyethylene glycol(PEG)-ylated interferon/ribavirin, direct acting antivirals and host targeting antivirals. Despite the progress in anti-HCV therapy, there is still a pressing need of new approaches for affordable and effective drug delivery systems using nanomedicine. In this review, the contribution of nanoparticles as a promising delivery system for HCV immunizing, diagnostic and therapeutic agents are discussed.

Ribavirin: pharmacology, multiple modes of action and possible future perspectives

Ribavirin is a unique guanosine analog with broad-spectrum activity against many RNA and DNA viruses. In addition to its mutational properties, ribavirin exerts extensive perturbation of cellular and viral gene expression. Furthermore, recent advances indicate that the impact of ribavirin on divergent cellular and viral pathways may be concentration dependent. This review aims at providing an overview of the pharmacology and multiple modes of action of ribavirin as well as pointing to possible novel future uses.

Inosine Triphosphate Pyrophosphatase Dephosphorylates Ribavirin Triphosphate and Reduced Enzymatic Activity Potentiates Mutagenesis in Hepatitis C Virus

A third of humans carry genetic variants of the ITP pyrophosphatase (ITPase) gene (ITPA) that lead to reduced enzyme activity. Reduced ITPase activity was earlier reported to protect against ribavirin-induced hemolytic anemia and to diminish relapse following ribavirin and interferon therapy for hepatitis C virus (HCV) genotype 2 or 3 infections. While several hypotheses have been put forward to explain the antiviral actions of ribavirin, details regarding the mechanisms of interaction between reduced ITPase activity and ribavirin remain unclear. The in vitro effect of reduced ITPase activity was assessed by means of transfection of hepatocytes (Huh7.5 cells) with a small interfering RNA (siRNA) directed against ITPA or a negative-control siRNA in the presence or absence of ribavirin in an HCV culture system. Low ribavirin concentrations strikingly depleted intracellular GTP levels in HCV-infected hepatocytes whereas higher ribavirin concentrations induced G-to-A and C-to-U single nucleotide substitutions in the HCV genome, with an ensuing reduction of HCV RNA expression and HCV core antigen production. Ribavirin triphosphate (RTP) was dephosphorylated in vitro by recombinant ITPase to a similar extent as ITP, a naturally occurring substrate of ITPase, and reducing ITPA expression in Huh 7.5 cells by siRNA increased intracellular levels of RTP in addition to increasing HCV mutagenesis and reducing progeny virus production. Our results extend the understanding of the biological impact of reduced ITPase activity, demonstrate that RTP is a substrate of ITPase, and may point to personalized ribavirin dosage according to ITPA genotype in addition to novel antiviral strategies.IMPORTANCE This study highlights the multiple modes of action of ribavirin, including depletion of intracellular GTP and increased hepatitis C virus mutagenesis. In cell culture, reduced ITP pyrophosphatase (ITPase) enzyme activity affected the intracellular concentrations of ribavirin triphosphate (RTP) and augmented the impact of ribavirin on the mutation rate and virus production. Additionally, our results imply that RTP, similar to ITP, a naturally occurring substrate of ITPase, is dephosphorylated in vitro by ITPase.

Liver decompensation predicts ribavirin overexposure in hepatitis C virus patients treated with direct-acting antivirals

AIM

To determine whether ribavirin (RBV) concentrations differ according to cirrhosis stage among cirrhotic patients treated with interferon-free regimens.

METHODS

We included patients with hepatitis C virus and cirrhosis [Child-Pugh (CP) A or B], Glomerular Filtration Rate ≥ 60 mL/min, who started therapy with DAAs and weight-based RBV between October 2014 and February 2016. RBV plasma levels were assessed during the treatment. We focused our analysis on the first 8 wk of therapy.

RESULTS

We studied 68 patients: 54 with compensated (CP-B) and 14 with decompensated (CP-A) cirrhosis. Patients with decompensated cirrhosis displayed significantly higher RBV concentrations than those with compensated cirrhosis at week 1, 2, 4 and 8 (P < 0.035). RBV levels were positively correlated with Hb loss over the treatment (P < 0.04). Majority (71%) of CP-B patients required a RBV dosage reduction during the treatment. After adjustment for confounders, Child-Pugh class remained significantly associated (95%CI: 35, 348, P = 0.017) to RBV levels, independently from baseline per-Kg RBV dosage.

CONCLUSION

Liver decompensation might affect RBV clearance leading to an overexposure and increased related toxicities in decompensated cirrhosis. Our findings underscore the importance of an early ribavirin therapeutic drug monitoring and suggest that an initial lower RBV dose, rather than weight-based, might be considered in those with advanced liver disease (CP-B) treated with direct-acting antivirals.

Ribavirin steady-state plasma level is a predictor of sustained virological response in hepatitis C-infected patients treated with direct-acting antivirals

BACKGROUND

In the era of highly effective direct-acting antivirals (DAAs) for treatment of patients with chronic hepatitis C virus (HCV) infection, ribavirin (RBV) is still considered beneficial in certain patients.

AIM

To assess the association between RBV steady-state plasma levels and sustained virological response (SVR).

METHODS

Consecutive HCV-infected patients treated with DAAs plus RBV from four Dutch academic medical centres were enrolled. RBV steady-state plasma levels were prospectively measured at treatment week 8 using validated assays. Logistic regression analyses were performed to assess the influence of RBV steady-state plasma level on SVR, and RBV therapeutic range was explored using area under the ROC curve analyses.

RESULTS

A total of 183 patients were included, of whom 85% had one or more difficult-to-cure characteristics (ie treatment experienced, HCV genotype 3, cirrhosis). The majority was treated with a sofosbuvir-based regimen and 163 (89%) patients achieved SVR. Median RBV dose was 12.9 (interquartile range 11.2-14.7) mg/kg/d, and median RBV steady-state plasma level was 2.66 (1.95-3.60) mg/L. In multivariable analyses, higher RBV steady-state plasma level (adjusted odds ratio 1.79 [95% CI 1.09-2.93]) was an independent predictor of SVR. With regard to the optimal RBV therapeutic range, 2.28 mg/L was the optimal lower cut-off for achieving SVR and 3.61 mg/L was the upper cut-off for preventing significant anaemia (Haemoglobin < 10 g/dL).

CONCLUSION

In this cohort of mainly difficult-to-cure patients treated with DAAs plus RBV, higher RBV steady-state plasma level was an independent predictor of SVR.

DHEA prevents ribavirin-induced anemia via inhibition of glucose-6-phosphate dehydrogenase

Ribavirin has been widely used for antiviral therapy. Unfortunately, ribavirin-induced anemia is often a cause of limiting or interrupting treatment. Our team has observed that dehydroepiandrosterone (DHEA) has a protective effect against in vitro and in vivo ribavirin-induced hemolysis. The aim of this study was to better understand this effect as well as the underlying mechanism(s). DHEA was able to reduce in vitro intraerythrocytic ATP depletion induced by ribavirin. Only 1% of ATP remained after incubation with ribavirin (2 mM) at 37 °C for 24 h vs. 37% if DHEA (200 μM) was added (p < 0.01). DHEA also helped erythrocytes conserve their size, with a shrinkage of only 10% vs 40% at 24 h with ribavirin alone (p < 0.01), and reduced phosphatidylserine exposure at the outer membrane, i.e. 27% vs 40% at 48 h, (p < 0.05). DHEA also inhibits ribavirin-induced hemolysis, i.e. 34% vs 46.5% at 72 h (p < 0.01). DHEA is an inhibitor of glucose-6-phosphate dehydrogenase (G6PD), a key enzyme in the hexose monophosphate shunt connected to the glycolytic pathway which is the only energy supplier of the red blood cell in the form of ATP. We have confirmed this inhibitory effect in the presence of ribavirin. All these observations suggest that ribavirin-induced hemolysis was initiated by ATP depletion, and that the inhibitory effect of DHEA on G6PD was able to rescue enough ATP to limit this hemolysis. This mechanism could be important for improving the therapeutic management of patients treated with ribavirin.

The role of ITPA and ribavirin transporter genes polymorphisms in prediction of ribavirin-induced anaemia in chronic hepatitis C Egyptian patients

Few data are available concerning the roles of polymorphisms of inosine triphosphatase (ITPA) gene and ribavirin (RBV) transporter genes in the prediction of RBV-induced anaemia among Egyptians with chronic hepatitis C (CHC). Genotyping of three ITPA gene variants and two variants of RBV transporter genes has been performed in 123 patients under pegylated interferon-α/ribavirin treatment. The baseline haemoglobin and ITPA rs1127354 CA/AA have been found as predictors of anaemia at 4, 8 and 12 weeks of RBV therapy. In addition, ITPA rs7270101 AC/CC and age predicted anaemia after 12 weeks of therapy. In conclusion, the ITPA variant rs1127354C>A significantly predict RBV-induced anaemia during the first 3 months of treatment and it is recommended to be assessed before RBV administration.

Ribavirin inhibits Zika virus (ZIKV) replication in vitro and suppresses viremia in ZIKV-infected STAT1-deficient mice

Zika fever, a mosquito-borne infectious disease caused by Zika virus (ZIKV), is an epidemic disease for which no effective therapy has been established. The recent outbreaks of ZIKV in Brazil and French Polynesia have been linked to a considerable increase in the incidence of fetal microcephaly and other diseases such as Guillain-Barre syndrome. Because there is currently no specific therapy or vaccine, the early exploitation of a method to prevent expansion of ZIKV is a high priority. To validate commonly used antiviral drugs, we evaluated the effect of ribavirin, a drug used to treat hepatitis C with interferon-β (IFN-β), on ZIKV replication. In mammalian cells, we observed an inhibitory effect of ribavirin on ZIKV replication and ZIKV-induced cell death without cytotoxic effect. Furthermore, we found that STAT1-deficient mice, which lack type I IFN signaling, were highly sensitive to ZIKV infection and exhibited lethal outcome. Ribavirin abrogated viremia in ZIKV-infected STAT-1-deficient mice. These data suggest that the inhibition of viral RNA-dependent RNA polymerases may be effective for treatment of ZIKV infection. Our data provide a new insight into the mechanisms for inhibition of ZIKV replication and prevention of Zika fever.

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Ribavirin inhibits ZIKV replication in mammalian cells.

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Ribavirin prevents ZIKV-induced apoptosis and cell death.

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Ribavirin administration abrogates viremia in ZIKV-infected STAT1-deficient mice.

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Leading to a prolonged survival.

Hemoglobin during ribavirin-based HCV therapy is closely related to circulating levels of DHEA

Ribavirin-induced anemia is the major side effect observed during HCV therapy. In an in vitro study, we recently discovered that DHEA can strongly inhibit this adverse event. We also evaluated a possible link between pre-treatment serum DHEA and hemoglobin during HCV therapy. Among the 108 patients of our cohort serum baseline DHEA levels were associated with hemoglobin levels at week 12 of treatment (r = 0.35; P = 0.0021). Patients with low baseline serum DHEA developed severe anemia. A serum level of DHEA less than 1,500 ng/ml had a sensitivity of 94.3% and a positive predictive value of 93.1% for the detection of hemoglobin less than 11 g/dl during the first 12 week of treatment. With pre-treatment DHEA levels below the cutoff, anemia was observed in 24.4% and 60.5% of patients treated with dual therapy and triple therapy, respectively, versus 0% and 15% of patients with higher DHEA levels. At week 12, the mean difference between patients with serum DHEA below and above the cutoff, in terms of absolute hemoglobin for dual and triple therapy groups were 1.2 and 1.7 g/dl, respectively (P = 0.005 and <0.001). Pretreatment DHEA levels are associated with hemoglobin levels during treatment. Based on these data, pretreatment assay of DHEA could be considered systematically in order to propose DHEA supplementation to potentiate the efficacy of the current and future use of ribavirin for HCV and HEV therapy. J. Med. Virol. 89:1033-1039, 2017. © 2016 Wiley Periodicals, Inc.

Randomized Trial Evaluating the Impact of Ribavirin Mono-Therapy and Double Dosing on Viral Kinetics, Ribavirin Pharmacokinetics and Anemia in Hepatitis C Virus Genotype 1 Infection

In this pilot study (RibaC), 58 hepatitis C virus (HCV) genotype 1 infected treatment-naïve patients were randomized to (i) 2 weeks ribavirin double dosing concomitant with pegylated interferon-α (pegIFN-α), (ii) 4 weeks ribavirin mono-therapy prior to adding pegIFN-α, or (iii) standard-of-care (SOC) ribavirin dosing concurrent with pegIFN-α. Four weeks of ribavirin mono-therapy resulted in a mean 0.46 log₁₀ IU/mL HCV RNA reduction differentially regulated across IL28B genotypes (0.89 vs. 0.21 log₁₀ IU/mL for CC and CT/TT respectively; P = 0.006), increased likelihood of undetectable HCV RNA week 4 after initiating pegIFN-α and thus shortened treatment duration (P<0.05), and decreased median IP-10 concentration from 550 to 345 pg/mL (P<0.001). Both experimental strategies impacted on ribavirin concentrations, and high levels were achieved after one week of double dosing. However, by day 14, double dosing entailed a greater hemoglobin decline as compared to SOC (2.2 vs. 1.4 g/dL; P = 0.03). Conclusion: Ribavirin down-regulates IP-10, and may have an anti-viral effect differently regulated across IL28B genotypes.

Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Ribavirin

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release solid oral dosage forms containing ribavirin are reviewed. Ribavirin is highly soluble, but its permeability characteristics are not well defined. Therefore according to the Biopharmaceutical Classification System, and taking a "worst case" approach, ribavirin should be assigned to class III. As ribavirin is transported across the brush border membrane of the human jejunum by hCNT2, it shows saturable uptake in the intestine. However, no common excipients have been shown to compete for ribavirin absorption, nor have problems with BE of immediate release ribavirin formulations containing different excipients and produced by different manufacturing methods been reported in the open literature. So the risk of bioinequivalence caused by these factors appears to be low. Ribavirin is considered a narrow therapeutic index drug, as judged by comparing the minimum effective concentration and minimum toxic concentrations in blood. Although ribavirin would not be eligible for approval via a Biopharmaceutical Classification System-based biowaiver procedure according to today's guidances due to its narrow therapeutic index, the risks of biowaiving should be weighed against the considerable risks associated with studying BE of ribavirin products in healthy subjects.

Ribavirin concentration determines treatment success of first-generation DAA-based chronic HCV therapy

BACKGROUND

Monitoring ribavirin concentrations during hepatitis C treatment with dual therapy can help optimize treatment response and minimize anaemia. A defined therapeutic range for ribavirin during direct-acting antiviral-based therapies is lacking. This analysis explores whether a therapeutic range for ribavirin concentrations can be defined in patients treated with boceprevir- or telaprevir-based triple therapies.

METHODS

Treatment-naive patients from ADVANCE, ILLUMINATE, OPTIMIZE and SPRINT-2, and treatment-experienced patients from RESPOND-2 were included. Multivariable logistic regression analyses were performed to evaluate whether ribavirin concentrations were an independent predictor of sustained virological response or anaemia. Optimal cutoff values and the percentage of patients within the proposed therapeutic range were determined, along with the associated chance of response.

RESULTS

Overall, 1,502 patients were included. In both regimens, ribavirin concentrations were significantly associated with anaemia (haemoglobin level <10 g/dl) at all time points (1.75 < odds ratio [OR] <2.45) and sustained virological response was associated with ribavirin concentrations at week 8 (OR=1.43 for telaprevir and 1.78 for boceprevir). A therapeutic range for ribavirin at week 8 of 2.2-3.5 mg/l was defined for telaprevir treatment. Of the 48% of patients with a concentration within this range, 81% achieved sustained virological response and only 5.1% reported anaemia. For boceprevir treatment, the week 8 optimal range was defined as 2.2-3.6 mg/l and 50% of patients had a concentration within this range, of whom 69% achieved sustained virological response and 46% developed anaemia.

CONCLUSIONS

We established the therapeutic range for ribavirin in boceprevir- and telaprevir-based therapy that balances safety and efficacy.

Roles of ITPA and IL28B genotypes in chronic Hepatitis C patients treated with peginterferon plus ribavirin in Tunisian population

BACKGROUND

Despite considerable progress in the treatment of chronic hepatitis C, many countries do not have access to these new treatments.

OBJECTIVES

Predictive markers of response to treatment are therefore necessary before initiating with historical combination therapy (PEG-IFN+ribavirin) for these populations.

STUDY DESIGN

We therefore evaluated the influence of IL28B polymorphisms on treatment response and Inosine Triphosphate (ITPA) polymorphisms on the incidence of anaemia in a population of 120 Tunisian patients infected with HCV genotype 1b and treated.

RESULTS

The frequencies of favourable IL28B genotypes were 47% (CC for rs12979860) and 63% (TT for rs8099117). Patients in whom favourable IL28B alleles were identified had a higher chance of successful therapy: 82% for CC (rs12979860) and 75% for TT (rs8099117). Viral load decline during the first twelve weeks of treatment was more pronounced in patients with a favourable genotype (p<0.0001). For patients with an unfavourable genotype, the second phase of viral decline was more pronounced in patients with SVR. A viral load decline cut-off of 2.68logIU/mL at week 12 was best suited to discriminate responders from non-responders with an odds ratio of 40 (95% CI:11.53-170.3). Analysis of ITPA polymorphisms revealed that 16% of Tunisian patients presented ITPase deficiency. None of these patients experienced a decline of ribavirin doses during treatment versus 67% for patients without ITPase deficiency (p<0.001).

CONCLUSION

These data obtained in a Tunisian population should optimize before and during treatment the chances of success for treatments currently available in Tunisia for chronic HCV infection.

An index to predict ribavirin-induced anemia in asian patients with chronic genotype 1 hepatitis C

BACKGROUND

Single-nucleotide polymorphisms (SNP) in the inosine triphosphate pyrophosphatase (ITPA) gene correlate with ribavirin (RBV)-induced anemia in patients with chronic hepatitis C (CHC) receiving combination therapy. Managing anemia is an early priority in the treatment process.

OBJECTIVES

The aim was to develop a predictive index based on ITPA SNP status to identify CHC patients at risk of anemia.

PATIENTS AND METHODS

A total of 418 eligible East Asian patients diagnosed with CHC genotype 1 (G1) received combination therapy in this study. Participant DNA was genotyped for a functional ITPA SNP (C/C, A/A or C/A) on chromosome 20 at rs1127354. A predictive index was constructed by incorporating independent factors identified for severe anemia events (hemoglobin < 10 g/dL). Areas under the receiver-operating characteristic curves (AUCs) represented the diagnostic accuracies of the predictive index in randomly assigned development and validation cohorts.

RESULTS

Multiple logistic regressions identified age (≥ 50 y: OR = 9.7, 95% CI = 5.0 - 18.6), ITPA rs1127354 (C/C: OR = 3.3, 95% CI = 1.8 - 5.8) and baseline hemoglobin (< 14.0 g/dL: OR 6.4, 95% CI = 3.3 - 12.1; 14.0 - 14.9: OR = 2.4, 95% CI = 1.2 - 4.6) as predictors of severe anemia throughout the treatment. For severe anemia, the predictive index incorporating age, ITPA SNP status and baseline hemoglobin yielded diagnostic accuracies (AUCs) of 0.830 (95% CI = 0.783 - 0.871) in the development (n = 324) and 0.902 (0.826 - 0.925) in the validation (n = 81) cohorts.

CONCLUSIONS

In patients with CHC G1 and receiving combination therapy, ITPA SNP-based index was an accurate and practical solution for prediction of severe anemia.

Patients treated with first-generation HCV protease inhibitors exhibit high ribavirin concentrations

Anemia is a well-known RBV-related event in HCV therapy which is exacerbated by the addition of telaprevir and boceprevir. This retrospective study evaluated and compared ribavirin exposure and parameters able to influence hemoglobin decrease in a large population of patients treated with dual or triple therapy. Patients on triple therapy had higher ribavirin concentrations at week 12 of treatment (3460 ng/mL vs. 1843 ng/mL; P < .0001). An association was also observed between week 12 eGFR and ribavirin concentration only for patients on triple therapy (P = .002). The proportion of patients with a  >20 mL/min/1.73 m(2) decrease in eGFR at week 12 was higher among patients on triple therapy: 32%, 14%, and 5% for boceprevir, telaprevir, and dual therapy, respectively (P = .025 and .026). No correlation was observed between boceprevir and telaprevir concentrations and hemoglobin or eGFR decrease. Exacerbation of anemia in patients on triple therapy is related to higher ribavirin concentrations. We provide an explanation for this increase in plasma RBV concentration. Triple therapy with PEG-IFN, RBV, and telaprevir or boceprevir will remain the only HCV treatment option for many patients. Our data show that the RBV dose can be decreased while maintaining adequate plasma concentrations and reducing anemia.

The ARRIBA concept: adequate resorption of ribavirin

BACKGROUND

Adequate ribavirin exposure is essential for optimal sustained virological response (SVR) rates in chronic HCV treatment. It has been proposed that the area under the concentration-time curve up to 4 h after intake of ribavirin (AUC0-4 h) of the first weight-based ribavirin dose should be ≥1.755 mg•h/l to guarantee the highest chance of SVR. Our ARRIBA concept comprises a test dose of ribavirin to select the optimal starting dose to achieve adequate exposure. This study aims to evaluate whether adequate exposure can be achieved after dose advice based on the AUC0-4 h of a single weight-based ribavirin test dose.

METHODS

(Formerly) HCV-infected subjects received a single weight-based ribavirin test dose (<75 kg: 400 mg; ≥75 kg: 600 mg) and the AUC0-4 h was calculated. If ribavirin AUC0-4 h was ≥1.755 mg•h/l, subjects received the same dose 4 weeks later; if the AUC0-4 h was <1.755 mg•h/l, an adjusted dose was administered. The ribavirin AUC0-4 h was recorded again. The primary outcome was the proportion of subjects with an AUC0-4 h ≥1.755 mg•h/l after the second dose.

RESULTS

A total of 26 subjects were included. The geometric mean (95% CI) ribavirin AUC0-4 h was 1.67 (1.44-1.92) mg•h/l with 9 subjects (35%) reaching the target AUC on day 1. Thus, on day 29, 17 subjects (65%) received an adjusted dose. The geometric mean (95% CI) AUC0-4 h increased to 1.90 (1.62-2.21) mg•h/l and then 16 subjects (62%) had an AUC0-4 h ≥1.755 mg•h/l, which is significantly higher than day 1 (P<0.05).

CONCLUSIONS

Our ARRIBA concept of a ribavirin test dose, with dose adjustment if necessary, leads to an increased proportion of patients with an AUC≥1.755 mg•h/l compared to traditional weight-based ribavirin dosing.

Telaprevir enhances ribavirin-induced anaemia through renal function impairment

BACKGROUND

Alterations in renal function have been described with telaprevir (TVR). We examined the relationship between ribavirin (RBV) trough concentration (C), estimated glomerular filtration rate (eGFR) and severe anaemia, before and after TVR introduction in HIV-HCV-coinfected patients included in ANRS HC26 TelapreVIH study.

METHODS

69 HIV-HCV genotype-1 coinfected patients received 4 weeks of pegylated interferon (PEG-IFN)-α2a/RBV, followed by 12 weeks of TVR/PEG-IFN/RBV, then 32 to 56 weeks of PEG-IFN/RBV. RBV C was determined at week (W)4, W8 and W20/24. eGFR was estimated by the Modification of the Diet in Renal Disease (MDRD) equation. Severe anaemia was defined as haemoglobin <70 g/l, RBV dose reduction, prescription of erythropoietin or blood transfusion.

RESULTS

67 patients were analysed. eGFR remained normal between baseline (97.9 ml/min) and W4 (103.4 ml/min), declined to 86.3 ml/min at W8 (P<0.0001), stabilized until W16 and increased back to baseline level at W20 (98.4 ml/min). RBV C increased from 1.88 mg/l at W4 to 2.88 mg/l at W8 (P<0.0001), then decreased to 2.73 mg/l at week 20/24 (P=0.015). An inverse correlation was observed between W8 eGFR and W8 RBV C (r2=0.429; P=0.0005). RBV C≥3 mg/l was observed in 12% of patients at W4, 45% at W8 (P<0.0001) and 38% at W20/24 (P=0.0005). Severe anaemia was observed in 23.9% of patients at W4 and 45.3% at W8. RBV C≥3 mg/l at W8 (OR 7.7 [95% CI 2.2, 27.4]) and baseline haemoglobin <150 g/l (OR 6.4 [1.7, 23.8]) were independently associated with W8 severe anaemia.

CONCLUSIONS

Association of TVR to PEG-IFN/RBV was associated with a decrease in eGFR and increase in RBV C, leading to severe anaemia in 45% of patients.

Viral hepatitis C therapy: pharmacokinetic and pharmacodynamic considerations

Chronic hepatitis C is a global health problem. To prevent or reduce complications, the hepatitis C virus (HCV) infection needs to be eradicated. There have been several developments in treating these patients since the discovery of the virus. As of 1 January 2014, the drugs that are approved for treatment of chronic HCV infection are peginterferon-α, ribavirin, boceprevir, telaprevir, simeprevir and sofosbuvir. In this review we provide an overview of the clinical pharmacokinetic characteristics of these agents by describing their absorption, distribution, metabolism and excretion. In the pharmacodynamic part we summarize what is known about the relationships between the pharmacokinetics of each drug and efficacy or toxicity. We briefly discuss the pharmacokinetics and pharmacodynamics of chronic hepatitis C treatment in special patient populations, such as patients with liver cirrhosis, renal insufficiency or HCV/HIV coinfection, and children. With this knowledge, physicians, pharmacists, nurse practitioners, etc. should be educated to safely and effectively treat HCV-infected patients.

Development of biodegradable nanoparticles for liver-specific ribavirin delivery

Ribavirin is an antiviral drug used for the treatment of chronic hepatitis C. However, ribavirin induces severe side effects such as hemolytic anemia. In this study, we prepared biodegradable nanoparticles as ribavirin carriers to modulate the pharmacokinetics of the drug. The nanoparticles encapsulating ribavirin monophosphate (RMP) were prepared from the blend of poly(d,l-lactic acid) homopolymer and arabinogalactan (AG)-poly(l-lysine) conjugate by using the solvent diffusion method in the presence of iron (III). RMP was efficiently and stably embedded in the nanoparticles and gradually released for 37 days in phosphate-buffered saline at 37°C. The coating of AG on the nanoparticles surfaces was verified by measuring the zeta potentials and performing an aggregation test of the nanoparticles using galactose-binding lectin. Moreover, the nanoparticles were efficiently internalized in cultured HepG2 cells. Ribavirin was drastically accumulated to the liver of mice after intravenous administration of the RMP-loaded nanoparticles, after which the ribavirin content gradually decreased for at least 7 days. Our results indicated successful development of nanoparticles with dual functions, targeting to the liver and sustained release of ribavirin, and suggested that the present strategy could help to advance the clinical application of ribavirin as a therapeutic agent for chronic hepatitis C.

ITPA genotype protects against anemia during peginterferon and ribavirin therapy but does not influence virological response

On-treatment anemia is associated with higher sustained virological response (SVR) rates during peginterferon plus ribavirin (RBV) therapy. Inosine triphosphatase (ITPA) variants causing ITPase deficiency have been shown to protect against RBV-induced anemia. However, ITPase activity has not been associated with SVR. To study this discrepancy, we examined the relationships between ITPase activity, on-treatment anemia, SVR, and RBV levels in hepatitis C virus genotype 1 (HCV-1) patients from the CHARIOT study. ITPA genotype (rs7270101, rs1127354) was used to define ITPase activity in 546 patients. Plasma RBV levels were measured using high-performance liquid chromatography (HPLC). Relationships between ITPase activity, on-treatment hemoglobin (Hb) levels, RBV levels, and SVR were tested using regression modeling, survival analysis, and locally weighted scatterplot smoothing (LOWESS) plot analysis. Hb decline was independently associated with SVR (P<0.0001). ITPase deficiency was present in 35%. ITPase deficiency strongly protected against Hb decline (P<0.0001), but was not associated with SVR (P=0.28). The probability of SVR increased with lower nadir Hb for both wild-type and deficient ITPase activity, but the association curve shifted to describe a parallel relationship at higher Hb levels in patients with ITPase deficiency. In a subset (n=203), we tested the hypothesis that the association between Hb decline and SVR reflected RBV levels rather than actual Hb level. RBV levels were associated with on-treatment Hb decline and SVR, but not ITPase activity. In regression models, adjustment for RBV levels attenuated the association between Hb decline and SVR.

CONCLUSION

ITPase deficiency protects against RBV-induced anemia, but is not associated with SVR. Our data suggest that the relationship between Hb decline and SVR is not mechanistic, but is linked to RBV levels.

Identification of naïve HVC-4 patients who may be treated with pegylated-interferon and ribavirin according to IL28B polymorphisms

BACKGROUND

The current treatment of HCV-4 patients is dual therapy with PEG-IFN and ribavirin; however, new drugs against this genotype will be available within few months. Despite the evidenced good virological response in IFN-free regimens, the high cost of these new therapies will require patient selection. In our paper we propose the use of both rs8099917 and rs12979860 IL28-B polymorphisms, in order to identify potentially categories of SVR, null-responder and relapse and consequently to choose the dual therapy or novel approach.

METHODS

One hundred and sixty-nine patients with chronic hepatitis C and genotype 4 treated with pegylated interferon and ribavirin for 48weeks were retrospectively studied. All patients were genotyped for rs8099917 and rs12979860 interleukin-28B polymorphisms.

RESULTS

80 patients with SVR (88.8%) had the TT/CC or TT/TC (rs8099917/rs12979860) (p<0.001) genotypes; the null-responders (n=13), 9 (69.2%) showed the GG/TT allelic distribution (p<0.001); relapsers showed a prevalent distribution of the TG/TC genotype (83.3%) (p<0.001). The 6 (100%) breakthrough patients showed TT/TC genotype, while the partial responders patients did not show any particular IL-28B genetic profile. Genetic profiles different from TT/CC showed 94.9% negative predictive value for SVR, with 92.6% of sensitivity and 65.2% of specificity. Insulin-resistance, diabetes and liver fibrosis were not relevant in our multivariate analysis.

CONCLUSIONS

The combination of both rs8099917/rs12979860 polymorphisms is useful for early identification of SVR, null-responders and relapsers. This could be used to chose between standard dual therapy or novel approach with IFN-free regimens.

Kinetics of relapse after pegylated interferon and ribavirin therapy for chronic hepatitis C

To optimize standard treatment of chronic hepatitis C in responder patients who have achieved undetectable viral load, a prospective study was conducted to determine the factors and kinetics of virologic relapse. Responder patients were monitored 2, 4, 8, 12, 16, and 24 weeks after the end of treatment with pegylated interferon and ribavirin. Forty-seven of the 154 patients (30.5%) relapsed. Relapse was significantly associated with absence of rapid virologic response (RVR), retreatment, higher baseline viral load, older age, and lower weight-based dose of pegylated interferon. Relapse was more frequent in patients failing to achieve a RVR after receiving pegylated interferon alpha 2a < 2.5 µg/week or alpha 2b < 1.5 µg/week (P = 0.002). Among patients infected with hepatitis C virus (HCV) genotype 1 with non-CC IL-28B polymorphism (rs12979860), viral decay during treatment was lower in relapsers (P = 0.003 at week 4). Relapse was detected at weeks 2, 4, 8, and 12 after the end of treatment for 5, 8, 10, and 6 patients infected with HCV genotype 1, respectively. Positive predictive values for sustained virologic response were 70.9%, 80.2%, 91.9%, and 98.8% at weeks 2, 4, 8, and 12, respectively. Only one patient relapsed beyond 24 weeks. Closer follow-up and treatment adaptation in patients failing to achieve RVR may decrease the relapse rate in slower responders and heavier patients. Monitoring viral load as early as 1 month after the end of treatment could be useful to assess virologic response.

Impact of ribavirin priming on viral kinetics and treatment response in chronic hepatitis C genotype 1 infection

Ribavirin amplifies the interferon-alpha (IFN) signalling cascade. As ribavirin needs 4 weeks to reach steady state, ribavirin priming may optimize hepatic IFN sensitivity before starting a pegylated (PEG)-IFN/ribavirin combination therapy. This study investigated potential benefits of ribavirin priming prior to PEG-IFN2a/ribavirin combination therapy on viral kinetics, on-treatment and sustained virological response (SVR) in chronic hepatitis C virus (HCV) genotype 1 infection. Sixty-eight treatment naive patients were randomized 2:2:1 to ribavirin (ribavirin arm) or placebo (placebo arm) or PEG-IFN2a (PEG-IFN2a arm) for 6 weeks prior to 12 weeks of PEG-IFN2a/ribavirin combination therapy within a double-blind, placebo-controlled trial. Then, standard PEG-IFN2a/ribavirin combination therapy according to the German guidelines was continued under the responsibility of the investigators. Ribavirin was given according to body weight and PEG-IFN2a at a dose of 180 μg subcutaneously once/week. During ribavirin priming, HCV RNA showed a decline of -0.58 log10  IU/mL (P < 0.001) that was unrelated to the IL28B rs12979860 genotype (CC vs CT/TT, P = 0.244). Ribavirin priming did neither increase the PEG-IFN2a-induced first- or second-phase viral decline (P values >0.100) nor on-treatment response or SVR (HCV RNA undetectable at week 12 of combination therapy: ribavirin arm 56%, placebo arm 38%, PEG-IFN2a arm 50%; SVR: ribavirin arm 41%, placebo arm 54%, PEG-IFN2a arm 50%; P values >0.300). In conclusion, ribavirin monotherapy showed a significant antiviral activity that was not influenced by the IL28B genotype. Ribavirin priming prior to PEG-IFN2a/ribavirin combination therapy did neither increase the first- or second-phase viral decline nor on-treatment response or SVR.

Broad-spectrum antivirals for the emerging Middle East respiratory syndrome coronavirus

OBJECTIVES

Middle East respiratory syndrome coronavirus (MERS-CoV) has emerged to cause fatal infections in patients in the Middle East and traveler-associated secondary cases in Europe and Africa. Person-to-person transmission is evident in outbreaks involving household and hospital contacts. Effective antivirals are urgently needed.

METHODS

We used small compound-based forward chemical genetics to screen a chemical library of 1280 known drugs against influenza A virus in Biosafety Level-2 laboratory. We then assessed the anti-MERS-CoV activities of the identified compounds and of interferons, nelfinavir, and lopinavir because of their reported anti-coronavirus activities in terms of cytopathic effect inhibition, viral yield reduction, and plaque reduction assays in Biosafety Level-3 laboratory.

RESULTS

Ten compounds were identified as primary hits in high-throughput screening. Only mycophenolic acid exhibited low EC50 and high selectivity index. Additionally, ribavirin and interferons also exhibited in-vitro anti-MERS-CoV activity. The serum concentrations achievable at therapeutic doses of mycophenolic acid and interferon-β1b were 60-300 and 3-4 times higher than the concentrations at which in-vitro anti-MERS-CoV activities were demonstrated, whereas that of ribavirin was ∼2 times lower. Combination of mycophenolic acid and interferon-β1b lowered the EC50 of each drug by 1-3 times.

CONCLUSIONS

Interferon-β1b with mycophenolic acid should be considered in treatment trials of MERS.

The synthesis, antiviral, cytostatic and cytotoxic evaluation of a new series of acyclonucleotide analogues with a 1,2,3-triazole linker

The efficient synthesis of a new series of acyclonucleotide analogues with a 1,2,3-triazole linker is described starting from diethyl azidomethyl-, 2-azidoethyl-, 3-azidopropyl-, 4-azidobutyl-, 2-azido-1-hydroxyethyl-, 3-azido-2-hydroxypropyl- and 3-azido-1-hydroxypropylphosphonates and selected alkynes under microwave irradiation. Several O,O-diethylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and cytostatic activity against murine leukaemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Acyclonucleotide 22e exhibited activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC₅₀ = 17 μM) and feline herpes virus (EC₅₀ = 24 μM) in CRFK cell cultures, while compounds 20k, 21k, 22k and 23k preferentially inhibited proliferation of human T-lymphocyte CEM cells at IC₅₀ in the 2.8–12 μM range.

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Nucleotide analogues with aliphatic linker between phosphorus and 1,2,3-triazole.

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Efficient synthesis of 1,2,3-triazole analogues of nucleotides.

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Antiviral activity and inhibitory effect on the proliferation of CEM cells.

Narrow therapeutic window of ribavirin as an inhibitor of nitric oxide synthesis is broadened by macromolecular prodrugs

Ribavirin (RBV), a broad-spectrum antiviral agent, is a standard medication against hepatitis C virus (HCV). However, despite the decades of clinical success, the mechanism of action of this drug against HCV remains a subject of debate. Furthermore, the appeal of this therapeutic agent is considerably lessened by unfavorable pharmacokinetics. This interdisciplinary study contributes to the understanding of intracellular effects exerted by RBV and presents a successful design of macromolecular prodrugs of RBV to achieve a safer treatment. Specifically, we demonstrate that RBV exhibits a pronounced anti-inflammatory activity in cultured macrophages as is evidenced by a 2-fold decrease in the levels of produced nitric oxide achieved using a clinically relevant concentration of this drug. However, this effect was characterized by a rather narrow therapeutic window with experimental values of EC50 and IC50 being 7 and 19 μM, respectively. Macromolecular prodrugs were obtained using an acrylate derivative of RBV, RAFT polymerization technique, and N-vinyl pyrrolidone as a partner monomer. The synthesized polymers were characterized with uniform molecular weights, relatively narrow polydispersities, and gradually increasing content of RBV. The resulting polymer therapeutics were effective in delivering their payload to the cultured macrophages and afforded a significantly wider therapeutic window, as much as >1000 μM (18-fold in relative values). Taken together, this work contributes significantly to the development of safer methods for delivery of RBV, as well as understanding the mechanism of action and origins of the side effects of this broad-spectrum antiviral agent.

Inhibition of novel β coronavirus replication by a combination of interferon-α2b and ribavirin

The identification of a novel β coronavirus, nCoV, as the causative agent of severe respiratory illness in humans originating in Saudi Arabia, Qatar and Jordan has raised concerns about the possibility of a coronavirus pandemic similar to that of SARS-CoV. As a definitive treatment regimen has never been thoroughly evaluated for coronavirus infections, there is an urgent need to rapidly identify potential therapeutics to address future cases of nCoV. To determine an intervention strategy, the effect of interferon-α2b and ribavirin on nCoV isolate hCoV-EMC/2012 replication in Vero and LLC-MK2 cells was evaluated. hCoV-EMC/2012 was sensitive to both interferon-α2b and ribavirin alone in Vero and LLC-MK2 cells, but only at relatively high concentrations; however, when combined, lower concentrations of interferon-α2b and ribavirin achieved comparable endpoints. Thus, a combination of interferon-α2b and ribavirin, which are already commonly used in the clinic, may be useful for patient management in the event of future nCoV infections.

Hepatitis C virus infection in nephrology patients

CONTEXT

Hepatitis C virus (HCV) infection leads to chronic liver disease, but also to extra-hepatic manifestations.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Herein, we provide an overview of renal diseases related to HCV and their therapies, as well as the treatment options available for HCV (+)/RNA (+) dialysis patients. We will not mention, however, HCV infection-related complications in the post-kidney transplantation setting.

CONCLUSIONS

Extra-hepatic manifestations of HCV infection include mixed cryoglobulinemia, lymphoproliferative disorders, and renal disease. HCV infection has been reported in association with distinct histological patterns of glomerulonephritis in native kidneys.

Negative predictive value of IL28B, SLC28A2, and CYP27B1 SNPs and low RBV plasma exposure for therapeutic response to PEG/IFN-RBV treatment

OBJECTIVES

The response rate to treatment of chronic hepatitis C virus-genotype 1 and 4 infections was recently found to be strongly influenced by many polymorphisms. The aim of our study was to carry out an integrated analysis of the effects of polymorphisms and ribavirin (RBV) plasma exposure on outcome.

METHODS

The retrospective analysis included 174 patients. IL28B, CYP27B1, SLC29A1, SLC28A3, and SLC28A2 polymorphisms were genotyped and tested for association with sustained virological response. The impact of RBV plasma exposure during the first 3 months of therapy on outcome was also investigated.

RESULTS

Considering patients infected by hepatitis C virus-1/4, 3 polymorphisms (IL28B rs8099917TT, CYP27B1 rs4646536TT, and CNT2 rs11854484TT) were associated with sustained virological response. The number of negative variant allele and low RBV exposure were correlated to percentage increasing to therapy failure, suggesting some degree of cumulative effect of the 4 factors. A cutoff of 2.5 μg/mL of RBV was found to be associated with outcome (area under ROC [AUROC] curve = 0.64, sensitivity = 55.0%, and specificity = 71.2%, P = 0.020). In multivariate logistic regression analyses, each variant allele and RBV plasma exposure cutoff were independently associated with outcome.

CONCLUSIONS

In this study, we found that additional polymorphisms and RBV plasma exposure are also able to influence the achievement of response. Regardless of the magnitude of RBV pharmacokinetic exposure, the negative predictive value of the polymorphisms here investigated is much stronger than the positive one.

Chronic hepatitis C in saudi arabia: three years local experience in a university hospital

BACKGROUND

Chronic hepatitis C (CHC) is a global infection. In Saudi Arabia, the prevalence of CHC is declining due to the implementation of a blood screening program. However, CHC still remains a leading cause of liver cirrhosis and hepatocellular carcinoma.

OBJECTIVES

This is a retrospective study of CHC patients at the King Abdul Aziz University Hospital, Jeddah, Saudi Arabia.

PATIENTS AND METHODS

Out of a total of 291 CHC patients from the hepatology clinic at King Abdul Aziz University hospital, Jeddah, 279 patients were included in the present study. They were primarily male (152, 54.5%), with a mean age of 50.41 ± 1.72 years. The majority of patients were either Saudi (108, 38.7%) or Egyptian (60, 21.5%). A total of 61 patients received combination treatment with pegylated interferon and ribavirin, and one patient with sickle-cell anemia received pegylated INF monotherapy. Demographic, clinical and laboratory features of the CHC patients, and their responses to treatment were studied.

RESULTS

Decompensated cirrhosis was documented in 60 patients (21.5%), and hepatocellular carcinoma in 14 (5%). The mean level of serum alanine aminotransferase was 83.6 ± 231 u/L. The predominant genotype among the 70 patients tested, was genotype 4, followed by genotype 1 (39 and 18 patients, respectively). The sustained viral response (SVR) rate was 82.99%. The main predictive factors for SVR were baseline HCV viral load and rapid virologic response (RVR). The mean duration of follow-up was 4.2 ± .85 years. There were 24 patients who had liver disease-related mortality.

CONCLUSIONS

our data showed that 22% of CHC patients progress to cirrhosis and another 22% had treatment. Liver related mortality was more common in patients with advanced cirrhosis.

A new tool to study ribavirin-induced haemolysis

BACKGROUND

Today, treatment of chronic hepatitis C is based on a synergistic combination of pegylated interferon and ribavirin with antiprotease inhibitors. Haemolytic anaemia, which is the major side effect of ribavirin treatment, disrupts ribavirin treatment compliance and varies significantly from one patient to another. There is an individual susceptibility to ribavirin haemolysis. With a view to studying haemolysis, and thus optimizing the treatment response, we have developed a new in vitro tool for analysing the ribavirin-induced lysis of red blood cells.

METHODS

Resuspended red blood cells were incubated with isotonic buffer and a range of concentrations of ribavirin. Haemolysis was quantified by spectrophotometric measurement of the supernatant at 540 nm. The assay was used to test the effects of various compounds and to investigate the susceptibility of patients to haemolytic anaemia.

RESULTS

In our assay, the degree of haemolysis is dependent on the ribavirin concentration used and can be inhibited by the addition of dipyridamole (50% inhibitory concentration [IC(50)] 30 μM), ATP or glutathione (IC(50) 1.63 mM and 767 μM, respectively). We observed a strong decrease in red blood cell haemolysis in the presence of the ribavirin prodrug viramidine (Taribavirin(®)). When testing the performance of this assay with blood from 24 patients before treatment, we observed a strong correlation between in vitro haemolysis before treatment and the decrease in haemoglobin levels seen in vivo during subsequent treatment (P<0.001).

CONCLUSIONS

With this new tool it is possible to better evaluate individual susceptibility to ribavirin-induced haemolysis before the start of treatment. In addition, this model will enable the mechanism of ribavirin-induced anaemia to be further explored and allow molecules that could reduce ribavirin haemolysis to be screened and tested in vitro. This approach could help optimize current and future therapeutic strategies involving ribavirin in the treatment of chronic hepatitis C.

A formula to estimate the optimal dosage of ribavirin for the treatment of chronic hepatitis C: influence of ITPA polymorphisms

BACKGROUND

Greater cumulative exposure to ribavirin increases response to interferon-ribavirin combination therapy for hepatitis C but also induces more severe anaemia. Polymorphisms in the ITPA gene protect against ribavirin-induced anaemia. The maximum dosage of ribavirin that can be tolerated by patients with different ITPA polymorphisms remains unknown.

METHODS

We developed a mathematical model of haemoglobin (Hb) decline in patients undergoing combination therapy. Using it to analyse published patient data, we estimated the average erythrocyte lifespan in patients with different ITPA polymorphisms. Coupled with a previous population pharmacokinetic study, we derived a formula for predicting the optimal ribavirin dosage, D(opt), above which anaemia becomes intolerable (Hb<10 g/dl).

RESULTS

Our model provided good fits to patient data of ribavirin accumulation in erythrocytes and the ensuing Hb decline during therapy. With the current treatment protocol, the average erythrocyte lifespan was approximately 36 days in patients with wild-type ITPA activity, and approximately 43 days and 55 days, respectively, in patients with mild and moderate ITPA deficiency. Our model yielded a facile formula for estimating D(opt) given a patient's weight, creatinine clearance, pretreatment Hb and ITPA polymorphism. Patients with moderate ITPA deficiency are predicted to tolerate twice the ribavirin dosage as patients with wild-type ITPA.

CONCLUSIONS

Our formula for D(opt) presents an avenue for personalizing ribavirin dosage. By keeping anaemia tolerable, the predicted optimal dosage may improve adherence, reduce the need for drug monitoring, and increase response rates. Response rates may be increased further by the higher dosages recommended for patients with ITPA deficiency.

Gene expression profiles associated with anaemia and ITPA genotypes in patients with chronic hepatitis C (CH-C)

Anaemia is a common side effect of ribavirin (RBV) which is used for the treatment of hepatitis C. Inosine triphosphatase gene polymorphism (C to A) protects against RBV-induced anaemia. The aim of our study was to genotype patients for inosine triphosphatase gene polymorphism rs1127354 SNP (CC or CA) and associate treatment-induced anaemia with gene expression profile and genotypes. We used 67 hepatitis C patients with available gene expression, clinical, laboratory data and whole-blood samples. Whole blood was used to determine inosine triphosphatase gene polymorphism rs1127354 genotypes (CC or CA). The cohort with inosine triphosphatase gene polymorphism CA genotype revealed a distinct pattern of protection against anaemia and a lower drop in haemoglobin. A variation in the propensity of CC carriers to develop anaemia prompted us to look for additional predictors of anaemia during pegylated interferon (PEG-IFN) and RBV. Pretreatment blood samples of patients receiving a full course of PEG-IFN and RBV were used to assess expression of 153 genes previously implicated in host response to viral infections. The gene expression data were analysed according to presence of anaemia and inosine triphosphatase gene polymorphism genotypes. Thirty-six genes were associated with treatment-related anaemia, six of which are involved in the response to hypoxia pathway (HIF1A, AIF1, RHOC, PTEN, LCK and PDGFB). There was a substantial overlap between sustained virological response (SVR)-predicting and anaemia-related genes; however, of the nine JAK-STAT pathway-related genes associated with SVR, none were implicated in anaemia. These observations exclude the direct involvement of antiviral response in the development of anaemia associated with PEG-IFN and RBV treatment, whereas another, distinct component within the SVR-associated gene expression response may predict anaemia. We have identified baseline gene expression signatures associated with RBV-induced anaemia and identified its functional pathways. In particular, we identified the hypoxia response pathway and the apoptosis/survival-related gene network, as differentially expressed in chronic hepatitis C patients with anaemia.

A pharmacological profile of ribavirin and monitoring of its plasma concentration in chronic hepatitis C infection

Chronic hepatitis C (CHC) infection, usually an asymptomatic infection, has long-term serious complications such as cirrhosis, hepatocellular carcinoma, and end-stage liver disease requiring liver transplantation (LT). Several novel drugs against hepatitis C which form part of 'specifically targeted antiviral therapy for hepatitis C' (STAT-C) have been developed. These include NS3/4A protease inhibitors telaprevir, boceprevir, and nucleoside/non-nucleoside polymerase inhibitors (NS5A) which hold promise for future therapy. Despite the development of new anti-hepatitis C virus (HCV) drugs, ribavirin (RBV) remains the single most important drug to prevent relapse and is frequently included among newer regimens being developed with novel small molecule anti-HCV drugs. The current approved treatment is a combination therapy of once weekly subcutaneous pegylated-interferon (PEG-IFN)-α plus body-weight-based oral RBV regimen. The most significant dose-dependent side effect of RBV is hemolytic anemia warranting dose reduction or discontinuation in severe cases compromising sustained virological response (SVR). Monitoring RBV plasma concentration has been challenging due to its peculiar pharmacokinetics and has been done to predict both efficacy and toxicity. Herein, we review the pharmacological profile of RBV and the monitoring of its plasma concentration, monitoring in renal impairment, post-LT, and human immunodeficiency virus (HIV)-HCV co-infection in patients being treated with combination therapy of PEG-IFN-α and RBV.

Anemia is not predictive of sustained virological response in liver transplant recipients with hepatitis C virus who are treated with pegylated interferon and ribavirin

In the immunocompetent setting, antiviral therapy-related anemia has recently been shown to be associated with a sustained virological response (SVR). Our goal was to assess whether this is also true for liver transplantation (LT). We included 160 LT patients with recurrent hepatitis C virus (HCV) who were treated with pegylated interferon and ribavirin (RBV) between 2002 and 2010; 76% of the patients were men, the median age of the patients was 56 years (range = 33-75 years), 63% had advanced fibrosis, and 86% were infected with HCV genotype 1a or 1b. The baseline immunosuppression was tacrolimus in 56% of the patients. Mycophenolate mofetil (MMF) was used in 15%. Anemia was defined as a hemoglobin (Hb) level < 10 g/dL. Significant anemia was present when the Hb decline was >5 g/dL. Anemia and significant anemia developed in 67% and 41% of the patients, respectively. Erythropoietin was used in 60%. Factors independently associated with significant anemia included low estimated creatinine clearance [relative risk (RR) = 0.951, 95% confidence interval (CI) = 0.925-0.978, P = 0.0001], a longer time from LT to therapy (RR = 1.001, 95% CI = 1.000-1.001, P = 0.002), high baseline viremia (RR = 3.2, 95% CI = 1.3-8.1, P = 0.01), cyclosporine A (CSA)-based immunosuppression (RR: 3.472, 95% CI: 1.386-8.695; P = 0.008), and the use of MMF (RR: 5.346, 95% CI: 1.398-20.447; P = 0.014). An SVR occurred in 43% of the patients; the factors associated with an SVR included baseline variables (younger recipient age, younger donor age, infections with non-1 HCV genotypes, body mass index, and mild fibrosis) and on-treatment factors related to adherence or viral kinetics. Anemia resulted in RBV dose reductions but was not associated with the virological response at any time. In conclusion, anemia is a very frequent complication in LT patients during antiviral therapy and is associated with increased RBV dose reduction but not with an SVR. Predictors of anemia include MMF or CSA immunosuppression, high viremia, and renal insufficiency.