Browsing by Author "Weiner, Marc."

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Evaluation of time to detection of mycobacterium tuberculosis in broth culture as a determinant for end points in treatment trials.
(American Society for Microbiology., 2010) Weiner, Marc.; Prihoda, Thomas J.; Burman, William.; Johnson, John L.; Goldberg, Stefan.; Padayatchi, Nesri.; Duran, Paula.; Engle, Melissa.; Muzanye, Grace.; Mugerwa, Roy D.; Sturm, Adriaan Willem.
Development of new treatments for tuberculosis is hampered by the lack of an accurate surrogate end point and the high degree of efficacy of current 6-month regimens. Sputum culture status after 2 months of therapy, a binary test, is widely used for phase IIB trials but has only moderate accuracy for predicting failure/relapse (12) and requires large sample sizes (4, 8). Changes in the number of colonies found in dilutions of sputum applied to solid medium is an end point that has been used to assess activities of single drugs and doses in phase IIA (early-bactericidal-activity) studies (10) and has also been suggested as an end point for phase IIB trials (15). Though promising, quantitative culture on solid medium involves prolonged sputum collections and intensive laboratory techniques and has been difficult to standardize at multiple sites. Time to detection in broth culture (TTD) is a potential end point that has a good correlation with quantitative culture on solid medium (11, 13). An initial small study had suggested a correlation between a shorter time to detection (an indication of higher numbers of viable bacilli) and poor treatment outcomes (9). In this study, TTD was evaluated as a marker of regimen potency. Preliminary results have been reported elsewhere (16).
Lessons from a randomised clinical trial for multidrug-resistant tuberculosis.
(International Union against Tuberculosis and Lung Disease., 2012) Padayatchi, Nesri.; MacKenzie, William R.; Hirsch-Moverman, Yael.; Feng, P-J.; Villarino, E.; Saukkonen, J.; Heilig, Charles M.; Weiner, Marc.; El-Sadr, Wafaa M.
BACKGROUND: The treatment of multidrug-resistant tuberculosis (MDR-TB) is currently based upon expert opinion and findings from case series, rather than upon randomised clinical trials (RCTs). OBJECTIVE: To describe the challenges encountered during an RCT for the treatment of MDR-TB. METHODS: Tuberculosis Trials Consortium Study 30 was a pilot, Phase I/II, double-blind, placebo-controlled, RCT of the safety and tolerability of 16 weeks of daily, low-dose linezolid treatment for MDR-TB. RESULTS: A total of 36 patients, 56% of the target of 64 patients, consented to participate, for an average of 0.69 enrolments per week. Of the 36 patients enrolled, only 25 (69%) completed at least 90 doses of study treatment. Among the 12 (33%) patients who did not complete all 112 doses of the study treatment, the median time to study withdrawal was 15 days (range 0-92). After the study, we discovered discordance between treatment assignment and study drug for at least 9 (25%) of the 36 patients. CONCLUSIONS: Recruitment and retention in this MDR-TB clinical trial posed substantial challenges, suggesting the need for a large, multidisciplinary group of study staff to support the participants. Withdrawal tended to occur early in study treatment. The discrepancy in assigned study medication reflects the need for stronger administrative controls for study drugs.
Population pharmacokinetics and pharmacodynamics of Ofloxacin in South African patients with multidrug-resistant tuberculosis.
(American Society for Microbiology., 2012) Chigusta, Emmanuel.; Meredith, Sandra.; Wiesner, Lubbe.; Padayatchi, Nesri.; Harding, Joe.; Moodley, Prashini.; MacKenzie, William R.; Weiner, Marc.; McIlleron, Helen.; Kirkpatrick, Carl M. J.
Despite the important role of fluoroquinolones and the predominant use of ofloxacin for treating multidrug-resistant tuberculosis in South Africa, there are limited data on ofloxacin pharmacokinetics in patients with multidrug-resistant tuberculosis, no ofloxacin pharmacokinetic data from South African patients, and no direct assessment of the relationship between ofloxacin pharmacokinetics and the MIC of ofloxacin of patient isolates. Our objectives are to describe ofloxacin pharmacokinetics in South African patients being treated for multidrug-resistant tuberculosis and assess the adequacy of ofloxacin drug exposure with respect to the probability of pharmacodynamic target attainment (area under the time curve/MIC ratio of at least 100). Sixty-five patients with multidrug-resistant tuberculosis were recruited from 2 hospitals in South Africa. We determined the ofloxacin MICs for the Mycobacterium tuberculosis isolates from baseline sputum specimens. Patients received daily doses of 800 mg ofloxacin, in addition to other antitubercular drugs. Patients underwent pharmacokinetic sampling at steady state. NONMEM was used for data analysis. The population pharmacokinetics of ofloxacin in this study has been adequately described. The probability of target attainment expectation in the study population was 0.45. Doubling the dose to 1,600 mg could increase this to only 0.77. The currently recommended ofloxacin dose appeared inadequate for the majority of this study population. Studies to assess the tolerability of higher doses are warranted. Alternatively, ofloxacin should be replaced with more potent fluoroquinolones.