Effect of Metformin on Plasma Exposure of Rifampicin, Isoniazid, and Pyrazinamide in Patients on Treatment for Pulmonary Tuberculosis

BACKGROUND

To evaluate the effect of metformin on the plasma levels of rifampicin, isoniazid, and pyrazinamide in patients with drug-sensitive pulmonary tuberculosis being treated with first-line antituberculosis treatment (ATT) and to assess the influence of gene polymorphisms on the metabolic pathway of metformin and plasma levels of antitubercular drugs.

METHODS

Nondiabetic adults aged 18-60 years with pulmonary tuberculosis were randomized to either the standard ATT (ATT group) or ATT plus metformin (METRIF group) groups in a phase IIB clinical trial. An intensive pharmacokinetic study with blood collection at 0 hour (predosing), followed by 1, 2, 4, 6, 8, and 12 hours after dosing was conducted during the first month of treatment in a subset of 60 study participants after a minimum of 14 doses. Plasma concentrations of rifampicin, isoniazid, pyrazinamide, and metformin were measured by high-performance liquid chromatography using validated methods, and pharmacokinetic parameters and OCT1 and MATE1 gene polymorphisms were compared between the groups.

RESULTS

Significant increases in the clearance of rifampicin, isoniazid, and pyrazinamide were observed in patients in the METRIF group (n = 29) compared with those in the ATT group (n = 31). The AA genotypes of the single-nucleotide polymorphism of rs2289669 ( MATE1 ) in the METRIF group showed a significantly decreased area under the concentration-time curve to the last observation point and increased clearance of rifampicin.

CONCLUSIONS

Metformin altered rifampicin and isoniazid plasma concentrations in patients receiving antituberculosis treatment for pulmonary tuberculosis with little effect on sputum conversion at the end of treatment. Studies with larger sample sizes are needed to understand host drug-drug interactions.

Effect of Bedaquiline and Delamanid Pharmacokinetics on Sputum Culture Conversion and Adverse Events in Drug-Resistant Tuberculosis

BACKGROUND

Pharmacokinetic studies of bedaquiline and delamanid in patients with pre-extensively drug-resistant tuberculosis (pre-XDR TB) will help in the optimization of these drugs for both culture conversion and adverse events.

METHODS

A prospective cohort of 165 adult patients (56% male with mean [SD] age 29 [9.7] years) with pre-XDR TB was treated with bedaquiline, delamanid, clofazimine, and linezolid for 24 weeks at 5 sites in India. Bedaquiline was administered at 400 mg daily for 2 weeks followed by 200 mg thrice weekly for 22 weeks, whereas delamanid was administered at 100 mg twice daily. In 23 consenting participants at 8 and 16 weeks of treatment, blood was collected at 0, 2, 4, 5, 6, 8, 12, and 24 hours postdosing for an intense pharmacokinetic study. Pharmacokinetic parameters were correlated with sputum culture conversion and adverse events.

RESULTS

The mean (SD) age and weight of patients were 30 (10) years and 54 kg, respectively. The median minimum concentration (C min ) and time-concentration curve (AUC) for bedaquiline, respectively, were 0.6 mcg/mL and 27 mcg/mL·h at week 8 and 0.8 mcg/mL and 36 mcg/mL·h at week 16, suggesting drug accumulation over time. The median C min and AUC of delamanid, respectively, were 0.17 mcg/mL and 5.1 mcg/mL·h at week 8 and 0.20 mcg/mL and 7.5 mcg/mL·h at week 16. Delay in sputum conversion was observed in patients with drug concentrations lower than the targeted concentration. At weeks 8 and 16, 13 adverse events were observed. Adverse events were resolved through symptomatic treatment. Body mass index was found to be significantly associated with drug-exposure parameters.

CONCLUSIONS

Bedaquiline and delamanid when co-administered exhibit plasma drug levels within the targeted concentrations, showing an exposure-response relationship.

Linezolid Pharmacokinetics and Its Association with Adverse Drug Reactions in Patients with Drug-Resistant Pulmonary Tuberculosis

We evaluated the relationship between the pharmacokinetic parameters of linezolid (LZD) and development of adverse drug reactions (ADRs) in patients with pulmonary drug-resistant tuberculosis. A prospective cohort of adults with pulmonary multidrug-resistant tuberculosis with additional resistance to fluoroquinolone (MDR-TB_FQ+) received treatment with bedaquiline, delamanid, clofazimine, and LZD. Blood samples were collected during weeks 8 and 16 at eight time points over 24 h. The pharmacokinetic parameters of LZD were measured using high-performance liquid chromatography and associated with ADRs. Of the 165 MDR-TB_FQ+ patients on treatment, 78 patients developed LZD-associated anemia and 69 developed peripheral neuropathy. Twenty-three patients underwent intense pharmacokinetic testing. Plasma median trough concentration was 2.08 µg/mL and 3.41 µg/mL, (normal <2 µg/mL) and AUC_0-24 was 184.5 µg/h/mL and 240.5 µg/h/mL at weeks 8 and 16, respectively, showing a linear relationship between duration of intake and plasma levels. Nineteen patients showed LZD-associated ADRs-nine at week 8, twelve at week 16, and two at both weeks 8 and 16. Thirteen of the nineteen had high plasma trough and peak concentrations of LZD. A strong association between LZD-associated ADRs and plasma LZD levels was noted. Trough concentration alone or combinations of trough with peak levels are potential targets for therapeutic drug monitoring.

BCG vaccination induces enhanced humoral responses in elderly individuals

BACKGROUND

Studies have reported the beneficial effects of Bacillus Calmette Guerin (BCG) vaccination, including non-specific cross-protection against other infectious diseases.

METHODS

We investigated the impact of BCG vaccination on the frequencies of B cell subsets as well as total antibody levels in healthy elderly individuals at one month post vaccination. We also compared the above-mentioned parameters in post-vaccinated individuals to unvaccinated controls.

RESULTS

Our results demonstrate that BCG vaccination induced enhanced frequencies of immature, classical and activated memory B cells and plasma cells and diminished frequencies of naïve and atypical memory B cells. BCG vaccination induced significantly increased levels of total IgG subclass isotypes compared to baseline. Similarly, all of the above parameters were significantly higher in vaccinated individuals compared to unvaccinated controls.

CONCLUSION

BCG vaccination was associated with enhanced B cell subsets, suggesting its potential utility by enhancing heterologous immunity.

Bedaquiline, Delamanid, Linezolid and Clofazimine for Treatment of Pre-extensively Drug-Resistant Tuberculosis

BACKGROUND

Treatment success rates for multidrug-resistant tuberculosis (MDR-TB) remain low globally. Availability of newer drugs has given scope to develop regimens that can be patient-friendly, less toxic, with improved outcomes. We proposed to determine the effectiveness of an entirely oral, short-course regimen with Bedaquiline and Delamanid in treating MDR-TB with additional resistance to fluoroquinolones (MDR-TBFQ+) or second-line injectable (MDR-TBSLI+).

METHODS

We prospectively determined the effectiveness and safety of combining two new drugs with two repurposed drugs - Bedaquiline, Delamanid, Linezolid, and Clofazimine for 24-36 weeks in adults with pulmonary MDR-TBFQ+ or/and MDR-TBSLI+. The primary outcome was a favorable response at end of treatment, defined as two consecutive negative cultures taken four weeks apart. The unfavorable outcomes included bacteriologic or clinical failure during treatment period.

RESULTS

Of the 165 participants enrolled, 158 had MDR-TBFQ+. At the end of treatment, after excluding 12 patients due to baseline drug susceptibility and culture negatives, 139 of 153 patients (91%) had a favorable outcome. Fourteen patients (9%) had unfavorable outcomes: four deaths, seven treatment changes, two bacteriological failures, and one withdrawal. During treatment, 85 patients (52%) developed myelosuppression, 69 (42%) reported peripheral neuropathy, and none had QTc(F) prolongation >500msec. At 48 weeks of follow-up, 131 patients showed sustained treatment success with the resolution of adverse events in the majority.

CONCLUSION

After 24-36 weeks of treatment, this regimen resulted in a satisfactory favorable outcome in pulmonary MDR-TB patients with additional drug resistance. Cardiotoxicity was minimal, and myelosuppression, while common, was detected early and treated successfully.

BCG vaccination induces enhanced frequencies of dendritic cells and altered plasma levels of type I and type III interferons in elderly individuals

OBJECTIVE

BCG can improve the response to vaccines directed against viral infections, and also, BCG vaccination reduces all-cause mortality, most likely by protecting against unrelated infections. However, the effect of BCG vaccination on dendritic cell (DC) subsets is not well characterized.

METHODS

We investigated the impact of BCG vaccination on the frequencies of DC subsets and type I and III interferons (IFNs) using whole blood and plasma samples in a group of elderly individuals (age 60-80 years) at one-month post-vaccination as part of our clinical study to examine the effect of BCG on COVID-19.

RESULTS

Our results demonstrate that BCG vaccination induced enhanced frequencies of plasmacytoid DC (pDC) and myeloid DC (mDC). BCG vaccination also induced diminished plasma levels of type I IFNs, IFNα and IFNβ but increased levels of type III IFNs, IL-28A and IL-29.

CONCLUSIONS

Thus, BCG vaccination was associated with enhanced DC subsets and IL-28A/IL-29 in elderly individuals, suggesting its ability to induce non-specific innate immune responses.