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at time of writing, PharmD Student, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada; now, Clinical Pharmacist/Educator, Alberta Health Services, Edmonton, Alberta, Canada
Clinical Coordinator and Pharmacotherapeutic Specialist (Transplant/Immunology), Vancouver Coastal Health Authority; Clinical Professor, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver
Professor and Director, Doctor of Pharmacy Program, Faculty of Pharmaceutical Sciences, and Distinguished University Scholar, The University of British Columbia; Clinical Pharmacy Specialist, Children's and Women's Health Centre of British Columbia, Vancouver
Reprints: Dr. Ensom, Department of Pharmacy (0B7), Children's and Women's Health Centre of British Columbia, 4500 Oak St., Vancouver V6H 3N1, British Columbia, Canada, fax 604/875-3735, ensom{at}interchange.ubc.ca
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.
Key Words: clinical pharmacokinetic monitoring, drug levels, hepatitis C, ribavirin, therapeutic monitoring
Published Online, November 17, 2009. www.theannals.com, DOI 10.1345/aph.1M225
THIS ARTICLE IS APPROVED FOR CONTINUING EDUCATION CREDIT
ACPE
UNIVERSAL PROGRAM NUMBER: 407-000-09-022-H01-P
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