Browsing by Author "Pahirko, Leonora"

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    Effect of NAT2, GSTM1 and CYP2E1 genetic polymorphisms on plasma concentration of isoniazid and its metabolites in patients with tuberculosis, and the assessment of exposure-response relationships
    (2024-03) Ulanova, Viktorija; Kivrane, Agnija; Viksna, Anda; Pahirko, Leonora; Freimane, Lauma; Sadovska, Darja; Ozere, Iveta; Cirule, Andra; Sevostjanovs, Eduards; Grinberga, Solveiga; Bandere, Dace; Ranka, Renate; Research Professor (Tenured Professor) Group at the Faculty of Pharmacy; Department of Pharmaceutical Chemistry
    Objectives: Isoniazid is a key drug in the chemotherapy of tuberculosis (TB), however, interindividual variability in pharmacokinetic parameters and drug plasma levels may affect drug responses including drug induced hepatotoxicity. The current study investigated the relationships between isoniazid exposure and isoniazid metabolism-related genetic factors in the context of occurrence of drug induced hepatotoxicity and TB treatment outcomes.  Methods: Demographic characteristics and clinical information were collected in a prospective TB cohort study in Latvia ( N = 34). Time to sputum culture conversion (tSCC) was used as a treatment response marker. Blood plasma concentrations of isoniazid (INH) and its metabolites acetylisoniazid (AcINH) and isonicotinic acid (INA) were determined at three time points (pre-dose (0 h), 2 h and 6 h after drug intake) using liquid chromatography-tandem mass spectrometry. Genetic variations of three key INH-metabolizing enzymes (NAT2, CYP2E1, and GSTM1) were investigated by application PCR- and Next-generation sequencing-based methods. Depending on variables, group comparisons were performed by Student's t-test, one-way ANOVA, Mann-Whitney-Wilcoxon, and Kruskal-Wallis tests. Pearson correlation coefficient was calculated for the pairs of normally distributed variables; model with rank transformations were used for non-normally distributed variables. Time-to-event analysis was performed to analyze the tSCC data. The cumulative probability of tSCC was obtained using Kaplan-Meier estimators. Cox proportional hazards models were fitted to estimate hazard rate ratios of successful tSCC.  Results: High TB treatment success rate (94.1%) was achieved despite the variability in INH exposure. Clinical and demographic factors were not associated with either tSCC, hepatotoxicity, or INH pharmacokinetics parameters. Correlations between plasma concentrations of INH and its metabolites were NAT2 phenotype-dependent, while GSTM1 genetic variants did not showed any effects. CYP2E1*6 (T > A) allelic variant was associated with INH pharmacokinetic parameters. Decreased level of AcINH was associated with hepatotoxicity, while decreased values of INA/INH and AcINH/INH were associated with month two sputum culture positivity. Conclusion: Our findings suggest that CYP2E1, but not GSTM1, significantly affects the INH pharmacokinetics along with NAT2. AcINH plasma level could serve as a biomarker for INH-related hepatotoxicity, and the inclusion of INH metabolite screening in TB therapeutic drug monitoring could be beneficial in clinical studies for determination of optimal dosing strategies.
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    Identification of Factors Determining Patterns of Serum C-Reactive Protein Level Reduction in Response to Treatment Initiation in Patients with Drug-Susceptible Pulmonary Tuberculosis
    (2024-12) Kivrāne, Agnija; Ulanova, Viktorija; Grinberga, Solveiga; Sevostjanovs, Eduards; Vīksna, Anda; Ozere, Iveta; Bogdanova, Ineta; Simanovica, Ilze; Norvaisa, Inga; Pahirko, Leonora; Bandere, Dace; Ranka, Renāte; Research Professor (Tenured Professor) Group at the Faculty of Pharmacy; Department of Infectology; Department of Pharmaceutical Chemistry
    Background: Serum C-reactive protein (CRP) levels vary depending on radiological and bacteriological findings at the time of tuberculosis (TB) diagnosis. However, the utility of this biomarker in monitoring response to anti-TB treatment and identifying patients at risk of treatment failure is not well established. Objectives: This study evaluated the impact of patients’ baseline characteristics and anti-TB drug plasma exposure on the early reduction in serum CRP levels and its relationship with treatment response. Methods: We enrolled 42 patients with drug-susceptible pulmonary TB, who received a standard six-month regimen. The plasma concentrations of four anti-TB drugs were analysed using LC-MS/MS. Clinically relevant data, including serum CRP levels before and 10–12 days after treatment initiation (CRP10–12d), were obtained from electronic medical records and patient questionnaires. Results: In 10–12 days, the median serum CRP level decreased from 21.9 to 6.4 mg/L. Lower body mass index, positive sputum-smear microscopy results, and lung cavitations at diagnosis were related to higher biomarker levels at both time points; smoking had a more pronounced effect on serum CRP10–12d levels. Variability in anti-TB drug plasma exposure did not significantly affect the reduction in serum CRP levels. The serum CRP10–12d levels, or fold change from the baseline, did not predict the time to sputum culture conversion. Conclusions: Disease severity and patient characteristics may influence the pattern of early CRP reduction, while anti-TB drug plasma exposure had no significant effect at this stage. These early changes in serum CRP levels were not a predictor of response to anti-TB therapy.