1983. Ethambutol is a Dialysable Drug, and Drug Monitoring Ensures Safety and Therapeuticity
Session: Poster Abstract Session: Antimicrobial Pharmacokinetics and Pharmacodynamics
Saturday, October 29, 2016
Room: Poster Hall
Posters
  • IDWeek Poster 1.pdf (210.8 kB)
  • Background: Ethambutol is renally cleared, but whether it is removed by haemodialysis is uncertain. No consensus guidelines exist on dosing ethambutol in the haemodialysis-dependent patient despite the potential for toxicity, in particular optic neuritis. To address this problem and ascertain if ethambutol is dialysable, we measured serum ethambutol levels in such a patient. We aimed for a trough (pre-dialysis) level of <1000 µg/l, and a peak level of 2000-6000 µg/l.

    Methods: A 79-year old Caucasian male was diagnosed with delayed disseminated Bacille Calmette-Guérin infection (BCG) secondary to intravesical BCG immunotherapy for bladder cancer 12 months prior. He was on thrice-weekly haemodialysis. Rifampicin, isoniazid and ethambutol were commenced for 6 months, with cessation of ethambutol after 2 months. Ethambutol was dosed post-dialysis. Levels were taken at 0, 1, 2, and 3 hours into a 4-hour dialysis session, and at 1 hour post-dialysis, once weekly for 5 weeks. Additionally, a random dialysate level was measured during dialysis in week 2. Regular assessments of colour vision were undertaken during the period of treatment with ethambutol.

    Results: A clear decline in ethambutol concentration during each dialysis session was observed (Figure 1). There was a significant concentration of ethambutol in the dialysate fluid (274 μg/l; pre-dialysis level 1496 µg/l). The target trough and peak levels were, in the main, achieved. As there were concerns regarding patient compliance, directly-observed therapy immediately after dialysis was commenced in week 3, and levels measured 1 hour post-dialysis showed clear peaks (Figure 1). No abnormalities of colour vision were detected, and the patient did not complain of any visual symptoms.

    Conclusion: Ethambutol is a dialysable drug. Therapeutic drug monitoring, at the very least with pre- and post-dialysis levels, aids in dosing the drug so as to maintain concentrations in the therapeutic range. Finally, because ethambutol should be dosed after dialysis, directly-observed therapy may help patient compliance.   

    Figure 1. Serum ethambutol concentrations before, during, and 1 hour after, haemodialysis.

    Rusheng Chew, BMedSci MBBChir DTM&H DRCOG DHMSA FRACP1,2, Sarah Jongbloed, MBBS PhD1, Dev Jegatheesan, MBBS3, Helen Healy, MBBS PhD FRACP3, Kim Ta, BPharm4, Jacobus Ungerer, MBChB MMed MBL FRCPA5, Peter Donovan, BAppSc MBBS FRACP6 and Marion L. Woods II, MD MPH FRACP FACP FAFPHM1,2, (1)Department of Infectious Diseases, Royal Brisbane and Women's Hospital, Herston, Australia, (2)Mayne Medical School, University of Queensland, Herston, Australia, (3)Department of Renal Medicine, Royal Brisbane and Women's Hospital, Herston, Australia, (4)Department of Pharmacy, Royal Brisbane and Women's Hospital, Herston, Australia, (5)Department of Chemical Pathology, Pathology Queensland, Herston, Australia, (6)Department of Clinical Pharmacology, Royal Brisbane and Women's Hospital, Herston, Australia

    Disclosures:

    R. Chew, None

    S. Jongbloed, None

    D. Jegatheesan, None

    H. Healy, None

    K. Ta, None

    J. Ungerer, None

    P. Donovan, None

    M. L. Woods II, None

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