Browsing by Author "Fehr, Jan"

Now showing 1 - 6 of 6
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    Antiretroviral concentration measurements as an additional tool to manage virologic failure in resource limited settings: a case control study
    (AIDS research and therapy, 2019) Buzibye, Allan; Musaazi, Joseph; Braun, Amrei von; Nanzigu, Sarah; Sekaggya‑Wiltshire, Christine; Kambugu, Andrew; Fehr, Jan; Lamorde, Mohammed; Gutteck, Ursula; Muller, Daniel; Sowinski, Stefanie; Reynolds, Steven J.; Castelnuovo, Barbara
    Several studies demonstrate a correlation between sub-therapeutic concentrations of antiretroviral drugs and virologic failure. We examined the sensitivity, specificity and predictive values of sub-therapeutic drug levels in predicting viralogic failure. Methods: This was a case control study with cases being samples of participants with virologic failure, and controls samples of participants with virologic suppression. We analyzed samples obtained from participants that had been on antiretroviral treatment (ART) for at least 6 months. Virologic failure was defined as HIV-RNA viral load ≥ 1000 copies/ ml. Sub-therapeutic drug levels were defined according to published reference cutoffs. The diagnostic validity of drug levels for virologic failure was assessed using plasma viral loads as a gold standard. Results: Sub-therapeutic ART concentrations explained only 38.2% of virologic failure with a probability of experiencing virologic failure of 0.66 in a patient with low drug levels versus 0.25 for participants with measurements within or above the normal range. Approximately 90% of participants with ART concentrations above the lower clinical cut off did not have virologic failure. Conclusions: These results support prior indication for therapeutic drug monitoring in cases of suspected virologic failure.
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    Baseline Xpert MTB/RIF ct values predict sputum conversion during the intensive phase of anti-TB treatment in HIV infected patients in Kampala, Uganda: a retrospective study
    (BMC Infectious Diseases, 2021) Namugenyi, Juliet; Musaazi, Joseph; Katamba, Achilles; Kalyango, Joan; Sendaula, Emmanuel; Kambugu, Andrew; Fehr, Jan; Castelnouvo, Barbara; Manabe, Yukari C.; Ssengooba, Willy; Sekaggya-Wiltshire, Christine
    In resource-limited settings, sputum smear conversion is used to document treatment response. Many People living with HIV (PLHIV) are smear-negative at baseline. The Xpert MTB/RIF test can indirectly measure bacterial load through cycle threshold (ct) values. This study aimed to determine if baseline Xpert MTB/RIF could predict time to culture negativity in PLHIV with newly diagnosed TB. Methods: A subset of 138 PLHIV from the ‘SOUTH’ study on outcomes related to TB and antiretroviral drug concentrations were included. Bacterial load was estimated by Mycobacterium Growth Indicator Tubes (MGIT) culture time-to-positivity (TTP) and Lowenstein Jensen (LJ) colony counts. Changes in TTP and colony counts were analyzed with Poisson Generalised Estimating Equations (GEE) and multilevel ordered logistic regression models, respectively, while time to culture negativity analysed with Cox proportional hazard models. ROC curves were used to explore the accuracy of the ct value in predicting culture negativity. Results: A total of 81 patients (58.7%) were males, median age 34 (IQR 29 ̶ 40) years, median CD4 cell count of 180 (IQR 68 ̶345) cells/μL and 77.5% were ART naive. The median baseline ct value was 25.1 (IQR 21.0 ̶ 30.1). A unit Increase in the ct value was associated with a 5% (IRR = 1.05 95% CI 1.04 ̶ 1.06) and 3% (IRR = 1.03 95% CI 1.03 ̶ 1.04) increase in TTP at week 2 and 4 respectively. With LJ culture, a patient’s colony grade was reduced by 0.86 times (0R = 0.86 95% CI 0.74 ̶ 0.97) at week 2 and 0.84 times (OR = 0.84 95% CI 0.79 ̶ 0.95 P = 0.002) at week 4 for every unit increase in the baseline ct value. There was a 3% higher likelihood of earlier conversion to negativity for every unit increase in the ct value. A ct cut point ≥28 best predicted culture negativity at week 4 with a sensitivity of 91. 7% & specificity 53.7% while a cut point ≥23 best predicted culture negativity at week 8. Conclusion: Baseline Xpert MTB/RIF ct values predict sputum conversion in PLHIV on anti-TB treatment. Surrogate biomarkers for sputum conversion in PLHIV are still a research priority.
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    Building clinical pharmacology laboratory capacity in low- and middle-income countries: Experience from Uganda
    (African Journal of Laboratory Medicine, 2023) Omali, Denis; Buzibye, Allan; Kwizera, Richard; Byakika-Kibwika, Pauline; Namakula, Rhoda; Matovu, Joshua; Mbabazi, Olive; Mande, Emmanuel; Sekaggya-Wiltshire, Christine; Nakanjako, Damalie; Gutteck, Ursula; McAdam, Keith; Easterbrook, Philippa; Kambugu, Andrew; Fehr, Jan; Castelnuovo, Barbara; Manabe, Yukari C.; Lamorde, Mohammed; Mueller, Daniel; Merry, Concepta
    Research and clinical use of clinical pharmacology laboratories are limited in low- and middle-income countries. We describe our experience in building and sustaining laboratory capacity for clinical pharmacology at the Infectious Diseases Institute, Kampala, Uganda. Intervention: Existing laboratory infrastructure was repurposed, and new equipment was acquired. Laboratory personnel were hired and trained to optimise, validate, and develop in-house methods for testing antiretroviral, anti-tuberculosis and other drugs, including 10 high-performance liquid chromatography methods and four mass spectrometry methods. We reviewed all research collaborations and projects for which samples were assayed in the laboratory from January 2006 to November 2020. We assessed laboratory staff mentorship from collaborative relationships and the contribution of research projects towards human resource development, assay development, and equipment and maintenance costs. We further assessed the quality of testing and use of the laboratory for research and clinical care. Lessons learnt: Fourteen years post inception, the clinical pharmacology laboratory had contributed significantly to the overall research output at the institute by supporting 26 pharmacokinetic studies. The laboratory has actively participated in an international external quality assurance programme for the last four years. For clinical care, a therapeutic drug monitoring service is accessible to patients living with HIV at the Adult Infectious Diseases clinic in Kampala, Uganda. Recommendations: Driven primarily by research projects, clinical pharmacology laboratory capacity was successfully established in Uganda, resulting in sustained research output and clinical support. Strategies implemented in building capacity for this laboratory may guide similar processes in other low- and middle-income countries.
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    Cohort profile of a study on outcomes related to tuberculosis and antiretroviral drug concentrations in Uganda: design, methods and patient characteristics of the SOUTH study
    (BMJ open, 2017) Sekaggya-Wiltshire, Christine; Castelnuovo, Barbara; Braun, Amrei von; Musaazi, Joseph; Muller, Daniel; Buzibye, Allan; Gutteck, Ursula; Henning, Lars; Ledergerber, Bruno; Corti, Natascia; Lamorde, Mohammed; Fehr, Jan; Kambugu, Andrew
    Tuberculosis (TB) is a leading cause of death among people living with HIV in sub-Saharan Africa. Several factors influence the efficacy of TB treatment by leading to suboptimal drug concentrations and subsequently affecting treatment outcome. The aim of this cohort is to determine the association between anti-TB drug concentrations and TB treatment outcomes. Participants Patients diagnosed with new pulmonary TB at the integrated TB-HIV outpatient clinic in Kampala, Uganda, were enrolled into the study and started on firstline anti-TB treatment. Findings to date Between April 2013 and April 2015, the cohort enrolled 268 patients coinfected with TB/HIV ; 57.8% are male with a median age of 34 years (IQR 29–40). The median time between the diagnosis of HIV and the diagnosis of TB is 2 months (IQR 0–22.5). The majority of the patients are antiretroviral therapy naive (75.4%). Our population is severely immunosuppressed with a median CD4 cell count at enrolment of 163 cells/μL (IQR 46–298). Ninety-nine per cent of the patients had a diagnosis of pulmonary TB confirmed by sputum microscopy, Xpert/RIF or culture and 203 (75.7%) have completed TB treatment with 5099 aliquots of blood collected for pharmacokinetic analysis. Future plans This cohort provides a large database of well-characterised patients coinfected with TB/HIV which will facilitate the description of the association between serum drug concentrations and TB treatment outcomes as well as provide a research platform for future substudies including evaluation of virological outcomes.
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    High efavirenz serum concentrations in TB/HIV-coinfected Ugandan adults with a CYP2B6 516 TT genotype on anti-TB treatment
    (Journal of Antimicrobial Chemotherapy, 2019) Braun, Amrei von; Castelnuovo, Barbara; Ledergerber, Bruno; Cusato, Jessica; Buzibye, Allan; Kambugu, Andrew; Fehr, Jan; Calcagno, Andrea; Lamorde, Mohammed; Sekaggya-Wiltshire, Christine
    To report the efavirenz serumconcentrations in TB/HIV-coinfected Ugandan adults on concomitant anti-TB treatment and analyse factors associated with elevated concentrations in this specific population. Methods: Serum efavirenz concentrations in TB/HIV-coinfected Ugandan adults on efavirenz-based ART (600mg daily) were measured onsite at 2, 8, 12 and 24 weeks of concomitant anti-TB treatment, including rifampicin. Genetic analysis was done retrospectively through real-time PCR by allelic discrimination (CYP2B6 516G.T, rs3745274). Univariable and multivariable logistic regression analyses were done to assess factors potentially associated with elevated efavirenz serum concentrations. Results: A total of 166 patients were included in the analysis. The median age was 34 (IQR"30–40) years, 99 (59.6%) were male, the median CD4 cell count was 195 (IQR"71–334) cells/mm3 and the median BMI was 19 (IQR"17.6–21.5) kg/m2. Almost half of all patients (82, 49.4%) had at least one efavirenz serum concentration above the reference range of 4 mg/L. The serum efavirenz concentrations of patients with genotype CYP2B6 516 TT were consistently above 4 mg/L and significantly higher than those of patients with GG/GT genotypes: CYP2B6 516 TT 9.6 mg/L (IQR"7.3–13.3) versus CYP2B6 516 GT 3.4 mg/L (IQR"2.1–5.1) and CYP2B6 516 GG 2.6 mg/L (IQR"1.3–4.0) (Wilcoxon rank-sumtest: P,0.0001). Conclusions: A large proportion of our study participants had at least one efavirenz serum concentration .4 mg/L. The CYP2B6 516 TT genotype was the strongest predictor of high concentration. Physicians should be vigilant that efavirenz serum concentrations may be elevated in patients on concomitant anti-TB treatment and that individualized care is warranted whenever possible.
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    Low isoniazid and rifampicin concentrations in TB/HIV co-infected patients in Uganda
    (Journal of the International AIDS Society, 2014) Sekaggya Wiltshire, Christine; Lamorde, Mohammed; Scherrer, Alexandra; Musaazi, Joseph; Corti, Natascia; Allan, Buzibye; Nakijoba, Rita; Nalwanga, Damalie; Henning, Lars; Von Braun, Amrei; Okware, Solome; Kambugu, Andrew; Fehr, Jan; Castelnuovo, Barbara
    There is limited data available on exposure to anti-tuberculosis (TB) drugs in this region. Peloquin has described reference ranges [1] however some studies have demonstrated that patients actually achieve concentrations below these ranges [2]. There is limited data about exposure to anti-TB drugs in the HIV/TB co-infected population in Sub-Saharan Africa. Our objective is to describe the concentration of anti-TB drug levels in a well characterized prospective cohort of adult patients starting treatment for pulmonary TB. Methods: This study is an ongoing study carried out in the TB/HIV integrated clinic at the Infectious Diseases Institute in Kampala, Uganda. Sputum culture and microscopy was done for all patients. We performed pharmacokinetic blood sampling of anti-TB drugs for 1 hour, 2 hours and 4 hours post dose at 2 weeks, 8 weeks and 24 weeks after initiation of anti-TB treatment using ultraviolet high-performance liquid chromatography (UV-HPLC). We described the maximum concentration (Cmax) of isoniazid (H), rifampicin (R), ethambutol (E) and pyrazinamide (Z) and compare them with the values observed by Peloquin et al. referenced in other studies. Results: We started 113 HIV infected adults on a fixed dose combination of HREZ. The median age of our population was 33 years, of which 52% were male with a median BMI of 19 kg/m2 and a median CD4 cell count of 142 cells/mL. In 90% of the participants, the diagnosis of TB was based on microscopy and or cultures. The boxplot graph shows the median Cmax and IQR of H and R. Levels of H were found to be below the reference ranges (3 6 mg/mL) in 54/77(70.1%), 38/59(64.4%) and 15/24(62.5%) participants at weeks 2, 8 and 24. Rif levels were also found to be below the reference ranges (8 24 mg/mL) in 41/66(62.1%), 26/48(54.2%) and 8/10(8%) participants at weeks 2, 8 and 24, respectively. The mean Cmax of E and Z were within the reference range at week 2 and 8; mean Cmax of 3.29SD2.1 mg/mL and 4.09SD3.1 mg/mL for E and 41.69SD13.1 mg/mL and 42.69SD16.4 mg/mL for Z. Conclusion: We observed lower concentrations of isoniazid and rifampicin in our study population of HIV/TB co-infected patients. The implications of these findings are not yet clear.We therefore need to correlate our findings with the response to TB treatment.