High-performance liquid chromatographic determination of ribavirin in serum and urine and of its urinary metabolite 1,2,4-triazole-3-carboxamide

Determination of ribavirin in chicken muscle by quick, easy, cheap, effective, rugged and safe method and liquid chromatography-tandem mass spectrometry

A new analytical method for the determination of ribavirin in chicken muscle using a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method and liquid chromatography-tandem mass spectrometry (LC-MS-MS) was developed and validated. Samples were extracted with acidified methanol (methanol:acetic acid, 99:1, v/v). The extract was further purified by QuEChERS method using primary-secondary amine (PSA) and C18. Finally, the extract was dried by nitrogen under 45°C and reconstituted in water. The separation was performed on a Hypercarb analytical column under a gradient elution. The mobile phase was composed of water buffered with ammonium acetate (2.0mM) and acetonitrile. The proposed method was validated according to the European Commission Decision 2002/657/EC. The values of the decision limit (CCα) and the detection capability (CCβ) were 1.1 and 1.5μg/kg, respectively. The mean recoveries of ribavirin ranged from 94.2% to 99.2%. The repeatability (expressed as coefficient of variation, CVr) of the method ranged from 4.5% to 4.9% and the reproducibility (CVR) of the method ranged from 4.8% to 5.4%. The method is demonstrated to be suitable for the determination of ribavirin in chicken muscle in conformity with the current EU performance requirements through validation. The total time required for the analysis of one sample, including sample preparation, was about 45min.

The utility of therapeutic drug monitoring for ribavirin in patients with chronic hepatitis C--a critical review

OBJECTIVE

To evaluate the utility of therapeutic drug monitoring (TDM) for ribavirin in chronic hepatitis C.

DATA SOURCES

Literature searches were conducted through PubMed (1949-June 2009), EMBASE (1980-June 2009), BIOSIS Previews (1969-June 2009), International Pharmaceutical Abstracts (1970-June 2009), Google, and www.clinicaltrials.gov using the terms ribavirin, therapeutic monitoring, hepatitis C, and drug levels. In addition, pertinent reference citations from identified publications were reviewed. Studies were limited to English language, adult age, and human subjects.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated. Studies that measured ribavirin concentrations or dose and treatment response were included in the review.

DATA SYNTHESIS

While monitoring of ribavirin plasma concentrations to improve treatment response in patients with chronic hepatitis C has been described in the literature, the utility of TDM for ribavirin in this group of patients has not been systematically studied. Thus, a previously published 9-step decision-making algorithm was employed to help determine whether TDM is warranted, based on currently available evidence. Thirty articles involving patients with chronic hepatitis C mono-infection, 12 for hepatitis C-HIV coinfection, 5 for renal dysfunction, and 5 for post-liver transplant patients were reviewed. In all subpopulations, studies exist that either support or refute the usefulness of ribavirin TDM. Additionally, the majority of the included studies had methodologic limitations, such as small sample size, retrospective analyses, and lack of p value adjustment for multiple analyses. Large randomized controlled trials would help to definitively answer this question.

CONCLUSIONS

There is conflicting evidence about the existence of a correlation between ribavirin concentrations and virologic response or development of toxicity. This inconsistent evidence, coupled with the currently employed effective strategies that maximize sustained virologic response and minimize development of anemia, precludes the utility of TDM for ribavirin.

Feasibility of ribavirin therapeutic drug monitoring in hepatitis C

Ribavirin, a nucleoside analog, is administered in combination with interferon to patients with chronic hepatitis C. To evaluate the feasibility of ribavirin therapeutic drug monitoring, we investigated the influence of blood collection and preanalytical conditions on ribavirin concentrations and compared the results obtained from interlaboratory blind tests by 3 laboratories using different analytical techniques. On 3 occasions, blank serum samples spiked with ribavirin and pooled serum samples from patients on ribavirin were sent to the 3 laboratories. Two analytical techniques were based on liquid chromatography with tandem mass spectrometry (LC-MS/MS) and 1 on high-performance liquid chromatography with UV detection (HPLC-UV), with protein precipitation or solid-phase extraction, all validated according to international guidelines. Inter- and intra-batch mean relative errors ranged from -7.4% to +10.3% and from -10.3% to +7.4%, respectively. Relative standard deviations were <13.5% and <10.6%, respectively. Linearity, assessed blindly, between 125 and 4550 ng/mL was excellent (r > 0.991) for all 3 methods. The 2 LC-MS/MS techniques were slightly less precise and accurate than HPLC-UV, perhaps because the internal standard used was not a ribavirin isotope. Accurate and precise LC-MS/MS and HPLC-UV methods developed in 3 different laboratories provided excellent and consistent results to blind tests for ribavirin determination in spiked serum samples and pools of serum samples from patients with chronic hepatitis C virus infection.

Immunological and mutagenic actions of ribavirin monotherapy preceding combination therapy with interferon for patients with chronic hepatitis C

Background

We aimed to investigate the effects of ribavirin on hepatitis C virus (HCV). Immunological and virological effects were analysed in patients undergoing treatment with ribavirin monotherapy prior to the initiation of combination therapy with interferon-α.

Methods

A total of 25 patients with chronic HCV infection were enrolled in this study. All patients received ribavirin for 4 weeks during monotherapy; subsequently, interferon-α2b was additionally given as combined therapy. Patients were divided into two groups according to virological response. A rapid viral responder (RVR) was defined as a patient in whom HCV RNA became undetectable within 4 weeks after combination therapy. The changes of the T-helper (Th)1/Th2 subset of peripheral blood CD4+ T-cells, serum cytokine levels and the alignment of the interferon sensitivity- determining region (ISDR) during ribavirin monotherapy were analysed by flow cytometry, ELISAs and sequencing methods.

Results

A total of 17 patients were classed as RVR. In the RVR group, the mean ±sd serum alanine aminotransferase levels significantly decreased (before treatment 103 ±92 IU/l and after treatment 57 ±46 IU/l; P<0.05) during ribavirin monotherapy. The mean ±sd Th1/Th2 ratio significantly increased (before treatment 13.9 ±5.1 and after treatment 16.7 ±6.2; P<0.05), but did not change in the non-RVR group. The levels of Th2 cytokines (interleukin-10 and soluble CD30) significantly decreased, especially in the RVR group. The mean ±sd mutation rates of ISDR at the nucleotide level increased in the RVR group (before treatment 2.6 ±0.9 sites/clone and after treatment 3.9 ±1.6 sites/clone; P<0.05), but did not change in the non-RVR group.

Conclusions

Ribavirin administration might increase the efficacy of interferon therapy for patients with chronic hepatitis C by stimulating the host immune system and promoting HCV gene mutation.

HPLC-MS/MS method for the intracellular determination of ribavirin monophosphate and ribavirin triphosphate in CEM ss cells

A sensitive and specific method using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the determination of ribavirin monophosphate (RBV-MP) and ribavirin triphosphate (RBV-TP) in cells has been developed and validated. In this method, ribavirin phosphorylated metabolites were extracted and separated by anion exchange solid phase extraction (SPE). The RBV-MP and RBV-TP fractions were dephosphorylated using acid phosphatase and further purified by phenyl boronate SPE prior to HPLC-MS/MS analysis. (13)C(5)-uridine was added as internal standard to obtain better accuracy and precision of the analysis. The MS/MS detector was optimized at multiple reaction monitoring (MRM) using positive electrospray ionization to detect 245-->113 and 250-->133 transitions for ribavirin and internal standard, respectively. The calibration curve was linear over a concentration range of 0.01-10 microg/mL with a limit of quantitation of 0.01 microg/mL. Mean inter-assay accuracy and precision for RBV-MP and RBV-TP quality control samples at 0.03, 0.3 and 8 microg/mL were 5% and 10%, respectively. This method was successfully used for the in vitro determination of RBV-MP and RBV-TP in CEM(ss) cells cultured with RBV.

Ribavirin: Analytical determinations since the origin until today

Ribavirin (RV) (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), is a synthetic purine nucleoside analog with a broad spectrum of antiviral activity. To better understand the mechanism of action of RV, as well as its pharmacokinetic characteristics, an assay that can allow specific, sensitive, and accurate measurement of RV in biologic samples is critical. In this way, diverse analytical methods have been established. In this work, we have recompiled these methods with the aim to present the different options for the RV determination.

Simultaneous determination of ribavirin and ribavirin base in monkey plasma by high performance liquid chromatography with tandem mass spectrometry

For the first time, a liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the simultaneous determination of ribavirin and rabavirin base was developed and validated over the concentration range of 10-5,000 ng/ml, respectively, using a 0.025 ml monkey plasma sample. Ribavirin, ribavirin base, and the internal standards were extracted from monkey plasma via protein precipitation. After evaporation of the supernatant, the extract was reconstituted with 5% methanol (containing 0.1% formic acid) and injected onto the LC-MS/MS system. Optimum chromatographic separation was achieved on a Waters Atlantis dc18 (150 mm x 2.1mm, 5 microm) column with mobile phase run in gradient with 100% water containing 0.5% formic acid (A) and 90% acetonitrile (containing 0.5% formic acid (B). The flow rate was 0.4-0.6 ml/min with total cycle time of approximately 7.0 min. Post-column addition of acetonitrile (containing 0.1% formic acid) at 0.3 ml/min was used to increase the ionization efficiency in the MS source. The method was validated for sensitivity, linearity, reproducibility, stability and recovery. Lack of adverse matrix effect and carry-over was also demonstrated. The intra-day and inter-day precision and accuracy of the quality control (QC) samples were <9.0% relative standard deviation (R.S.D.) and 10.8% bias for ribavirin, and 10.3% R.S.D. and 11.3% bias for ribavirin base. The current specific, accurate and precise assay is useful in support of the toxicokinetic and pharmacokinetic studies of these compounds.

Ribavirin quantification in combination treatment of chronic hepatitis C

Ribavirin in combination with alpha 2 interferon is the consensus treatment for chronic hepatitis C. However, recent preliminary pharmacological studies have suggested that the bioavailability of ribavirin displays great interindividual variability. In order to monitor serum ribavirin levels during combination treatment, we developed and validated a quantitative assay using an approach adaptable for routine hospital laboratories. The method involved solid-phase extraction on phenyl boronic acid cartridges followed by high-performance liquid chromatography with a C(18)-bonded silica column and a mobile phase containing 10 mM ammonium phosphate buffer (with the pH adjusted to 2.5) and UV detection (207 nm). The sensitivity, recovery, linearity of the calibration curve, intra- and interassay accuracies, precision, and stability at 4 degrees C were consistent with its use in the laboratory routine. In addition, other nucleoside analogues sometimes used with ribavirin in patients coinfected with hepatitis C virus (HCV) and human immunodeficiency virus did not interfere with the quantification of ribavirin levels. The ribavirin concentration was quantified in 24 serum samples from patients with chronic hepatitis C treated with a combination of ribavirin and alpha 2 interferon. The mean serum ribavirin concentration was 2.67 +/- 1.06 micro g/ml (n = 24) at week 12 of treatment (W12) and 3.24 +/- 1.35 micro g/ml (n = 24) at week 24 of treatment (W24). In addition, ribavirin concentrations displayed high interindividual variabilities: the coefficients of variation of the serum ribavirin concentrations adjusted to the administered dose were 44 and 48% at W12 and W24, respectively. Moreover, the ribavirin concentration was higher in patients with a sustained virological response (n = 11) than in patients with treatment failure (n = 13), with significant intergroup differences at W12 (P = 0.030) and W24 (P = 0.049). The present study describes a simple analytical method for the quantification of ribavirin in human serum that could be a useful tool for the monitoring of ribavirin concentrations in HCV-infected patients in order to improve the efficacy and safety of therapy with ribavirin plus interferon.

Determination of ribavirin in serum using highly selective solid-phase extraction and high-performance liquid chromatography

A rapid assay for determination of ribavirin in serum using solid-phase extraction (SPE), high-performance liquid chromatography (HPLC), and UV-detection was developed. The SPE uses phenylboronic acid columns with an approximately 100% recovery for ribavirin. The concentration-peak area relation was linear (r > 0.995), from 1 to 64 microM in 100 microL serum. The limit of detection was 0.1 microM. The intraassay CV was 3.2% at treatment levels (9.7 microM) and 11.5% at 0.4 microM. The method is used to monitor patients undergoing ribavirin treatment for hepatitis C (HCV). Samples from HCV-infected patients with and without renal dysfunction have been analyzed without interference of endogenous compounds. It is concluded that the method is useful for routine therapeutic drug monitoring.

High-performance liquid chromatographic determination of ribavirin in whole blood to assess disposition in erythrocytes

Ribavirin is an antiviral agent used in the treatment of chronic hepatitis C virus infection. One of the limitations associated with the use of ribavirin is a reversible anemia caused by its accumulation in erythrocytes. Therefore, it is of interest to determine ribavirin levels in erythrocytes, as well as in plasma, as these measurements may be predictive of hematotoxicity. In the present study, we describe a high-performance liquid chromatographic (HPLC) assay for ribavirin in whole blood to estimate concentrations of free ribavirin and phosphorylated anabolites in erythrocytes. Since ribavirin exists primarily as phosphorylated anabolites (mono-, di-, and triphosphates) in erythrocytes, whole-blood extracts were initially dephosphorylated with acid phosphatase. The enzyme-treated samples were subjected to phenyl boronic acid column extraction for cleanup. The purified fraction was analyzed by reversed-phase HPLC, which was optimized for determination of ribavirin levels in whole blood. The recoveries of ribavirin from whole blood ranged from 63.1 to 90.7% at concentrations ranging from 1.67 to 40.0 microM. Intra- and interassay variations estimated at these concentrations were 3.2 to 10.4 and 4.7 to 11.7%, respectively. This method was used to quantitate ribavirin in samples both treated and untreated with acid phosphatase to estimate the extent of intracellular phosphorylation in erythrocytes. The method was also used to evaluate the effects of dipyridamole, a nucleoside transporter inhibitor, on ribavirin disposition in erythrocytes in in vitro experiments.

Chromatographic methods for the bioanalysis of antiviral agents

The present review has concentrated on chromatographic techniques for the quantitative determination of antiviral drugs in biological samples. Special attention has been paid to the elements of chromatographic assays that are essential to ensure selectivity, sensitivity, accuracy and precision of the various methods. Wherever possible, attempts have been made to determine the suitability of the methods for application to investigations in pharmacokinetics in man and experimental animals, biopharmaceutics, therapeutic drug monitoring, metabolism and pharmacology. Because of the serious consequences of infection from material contaminated with viruses, special consideration has been given to the handling of contaminated samples. It was convenient to divide the antiviral drugs for the purpose of this review into two groups, the nucleoside and the non-nucleoside antiviral drugs. The nucleosides discussed are vidarabine, cytarabine, ribavirin, riboxamide, acyclovir, ganciclovir, desciclovir, carbovir, 2',3'-dideoxyadenosine, 2',3'-dideoxycytidine, zidovudine, 2',3'-dideoxyinosine, 2',3'-didehydro-3'-deoxythymidine, idoxuridine, 5-(2-bromovinyl)-2'-deoxyuridine, 2'-fluoro-5-iodoaracytidine and 5-iodo-2'-deoxycytidine. The non-nucleoside antiviral drugs discussed are arildone, amantidine, rimantidine, moroxydine, enviroxime, foscarnet and ampligen.