Drug–drug interactions and tolerance in combining antituberculosis and antiretroviral therapy

Disease extent and anti-tubercular treatment response correlates with Mycobacterium tuberculosis-specific CD4 T-cell phenotype regardless of HIV-1 status

Objectives

The development of non‐sputum‐based assays for tuberculosis (TB) diagnosis and treatment monitoring is a key priority. Recent data indicate that whole blood‐based assays to assess the phenotype of Mycobacterium tuberculosis (Mtb)‐specific CD4 T cells hold promise for this purpose and require further investigation in well‐characterised TB cohorts. In this study, we investigated the relationship between the phenotypic signature of Mtb‐specific CD4 responses, TB disease extent and treatment response.

Methods

Using flow cytometry, we measured the expression of phenotypic and functional markers (HLA‐DR, CD27, CD153, KLRG1, IL‐2, MIP‐1β, TNF‐α and IFN‐γ) on Mtb‐specific CD4 T‐cells in whole blood from 161 participants of varying TB and HIV status. TB disease extent was graded as a continuum using the Xpert_ct value, C‐reactive protein, Timika radiographic score and monocyte/lymphocyte ratio.

Results

The phenotypic profile of Mtb‐specific CD4 T cells pre‐anti‐tubercular treatment (ATT) strongly correlated with disease extent, irrespective of HIV status. ATT associated with major changes in the phenotype of Mtb‐specific CD4 T cells, with decreased expression of HLA‐DR and increased CD27 and CD153 expression. Principal component analysis showed an almost complete separation between latent TB infection (LTBI) and active TB (aTB) pre‐ATT groups, whereas the profile of the aTB post‐ATT group overlapped with the LTBI group. However, in patients experiencing treatment failure or relapse, no significant changes were observed in Mtb‐specific CD4 T‐cell phenotype pre‐ and post‐ATT.

Conclusion

Whole blood‐based assays of Mtb‐specific CD4 T‐cell activation and maturation markers can be used as non‐sputum‐based biomarkers of disease extent and treatment monitoring in TB, regardless of HIV‐1 status.

ChemDIS-Mixture: an online tool for analyzing potential interaction effects of chemical mixtures

The assessment of bioactivity and toxicity for mixtures remains a challenging work. Although several computational models have been developed to accelerate the evaluation of chemical-chemical interaction, a specific biological endpoint should be defined before applying the models that usually relies on clinical and experimental data. The development of computational methods is desirable for identifying potential biological endpoints of mixture interactions. To facilitate the identification of potential effects of mixture interactions, a novel online system named ChemDIS-Mixture is proposed to analyze the shared target proteins, and common enriched functions, pathways, and diseases affected by multiple chemicals. Venn diagram tools have been implemented for easy analysis and visualization of interaction targets and effects. Case studies have been provided to demonstrate the capability of ChemDIS-Mixture for identifying potential effects of mixture interactions in clinical studies. ChemDIS-Mixture provides useful functions for the identification of potential effects of coexposure to multiple chemicals. ChemDIS-Mixture is freely accessible at http://cwtung.kmu.edu.tw/chemdis/mixture .

Identification of 1-[4-Benzyloxyphenyl)-but-3-enyl]-1H-azoles as New Class of Antitubercular and Antimicrobial Agents

A series of 1-[(4-benzyloxyphenyl)-but-3-enyl]-1H-azoles has been identified as potent antitubercular agents against Mycobacterium tuberculosis. Synthesis of compounds involved acid catalyzed ring-opening of cyclopropyl ring of phenyl cyclopropyl methanols followed by nucleophilic attack of the azoles on the carbocation intermediates. Several of the compounds 26, 34, and 36 exhibited significant antitubercular activities with MIC value as low as 1.56, 1.56, and 0.61 μg/mL, respectively, comparable to many standard drugs. These compounds were also screened against other strains of bacteria and fungi, and few of them showed good antifungal activity against A. fumigatus, responsible for lung infection.

Discovery of new inhibitors of Mycobacterium tuberculosis InhA enzyme using virtual screening and a 3D-pharmacophore-based approach

Mycobacterium tuberculosis InhA (MtInhA) is an attractive enzyme to drug discovery efforts due to its validation as an effective biological target for tuberculosis therapy. In this work, two different virtual-ligand-screening approaches were applied in order to identify new InhA inhibitors' candidates from a library of ligands selected from the ZINC database. First, a 3-D pharmacophore model was built based on 36 available MtInhA crystal structures. By combining structure-based and ligand-based information, four pharmacophoric points were designed to select molecules able to satisfy the binding features of MtInhA substrate-binding cavity. The second approach consisted of using four well established docking programs, with different search algorithms, to compare the binding mode and score of the selected molecules from the aforementioned library. After detailed analyses of the results, six ligands were selected for in vitro analysis. Three of these molecules presented a satisfactory inhibitory activity with IC50 values ranging from 24 (±2) μM to 83 (±5) μM. The best compound presented an uncompetitive inhibition mode to NADH and 2-trans-dodecenoyl-CoA substrates, with Ki values of 24 (±3) μM and 20 (±2) μM, respectively. These molecules were not yet described as antituberculars or as InhA inhibitors, making its novelty interesting to start efforts on ligand optimization in order to identify new effective drugs against tuberculosis having InhA as a target. More studies are underway to dissect the discovered uncompetitive inhibitor interactions with MtInhA.

Evidence-based guideline: Antiepileptic drug selection for people with HIV/AIDS: report of the Quality Standards Subcommittee of the American Academy of Neurology and the Ad Hoc Task Force of the Commission on Therapeutic Strategies of the International League Against Epilepsy

OBJECTIVE

To develop guidelines for selection of antiepileptic drugs (AEDs) among people with HIV/AIDS.

METHODS

The literature was systematically reviewed to assess the global burden of relevant comorbid entities, to determine the number of patients who potentially utilize AEDs and antiretroviral agents (ARVs), and to address AED-ARV interactions.

RESULTS AND RECOMMENDATIONS

AED-ARV administration may be indicated in up to 55% of people taking ARVs. Patients receiving phenytoin may require a lopinavir/ritonavir dosage increase of ~50% to maintain unchanged serum concentrations (Level C). Patients receiving valproic acid may require a zidovudine dosage reduction to maintain unchanged serum zidovudine concentrations (Level C). Coadministration of valproic acid and efavirenz may not require efavirenz dosage adjustment (Level C). Patients receiving ritonavir/atazanavir may require a lamotrigine dosage increase of ∼50% to maintain unchanged lamotrigine serum concentrations (Level C). Coadministration of raltegravir/atazanavir and lamotrigine may not require lamotrigine dosage adjustment (Level C). Coadministration of raltegravir and midazolam may not require midazolam dosage adjustment (Level C). Patients may be counseled that it is unclear whether dosage adjustment is necessary when other AEDs and ARVs are combined (Level U). It may be important to avoid enzyme-inducing AEDs in people on ARV regimens that include protease inhibitors or nonnucleoside reverse transcriptase inhibitors, as pharmacokinetic interactions may result in virologic failure, which has clinical implications for disease progression and development of ARV resistance. If such regimens are required for seizure control, patients may be monitored through pharmacokinetic assessments to ensure efficacy of the ARV regimen (Level C).

Paediatric use of second-line anti-tuberculosis agents: a review

Childhood multidrug-resistant tuberculosis (MDR-TB) is an emerging global epidemic. With the imminent roll-out of rapid molecular diagnostic tests, more children are likely to be identified and require treatment. As MDR-TB is resistant to the most effective first-line drugs, clinicians will have to rely on second-line medications which are less effective and often associated with more pronounced adverse effects than first-line therapy. Despite the fact that most of these agents were discovered many years ago, robust information is lacking regarding their pharmacokinetic and pharmacodynamic properties, adverse effects and drug interactions, especially in children. Children differ from adults in the way that drugs are administered, the manner in which they are metabolised and in the adverse effects experienced. The interaction of these drugs with human immunodeficiency virus infection and antiretroviral therapy is also poorly documented. This article reviews the available second-line drugs currently used in the treatment of MDR-TB in children and discusses medication properties and adverse effects while potential interactions with antiretroviral therapy are explored.

Initiating antiretrovirals during tuberculosis treatment: a drug safety review

INTRODUCTION

Integrating HIV and tuberculosis (TB) treatment can reduce mortality substantially. Practical barriers to treatment integration still exist and include safety concerns related to concomitant drug use because of drug interactions and additive toxicities. Altered therapeutic concentrations may influence the chances of treatment success or toxicity.

AREAS COVERED

The available data on drug-drug interactions between the rifamycin class of anti-mycobacterials and the non-nucleoside reverse transcriptase inhibitor and the protease inhibitor classes of antiretrovirals are discussed with recommendations for integrated use. Additive drug toxicities, the impact of immune reconstitution inflammatory syndrome (IRIS) and the latest data on survival benefits of integrating treatment are elucidated.

EXPERT OPINION

Deferring treatment of HIV to avoid drug interactions with TB treatment or the occurrence of IRIS is not necessary. In the integrated management of TB-HIV co-infection, rational drug combinations aimed at reducing toxicities while effecting TB cure and suppressing HIV viral load are possible.

Pharmacokinetic interaction study of ritonavir-boosted saquinavir in combination with rifabutin in healthy subjects

The effect of multiple doses of rifabutin (150 mg) on the pharmacokinetics of saquinavir-ritonavir (1,000 mg of saquinavir and 100 mg of ritonavir [1,000/100 mg]) twice daily (BID) was assessed in 25 healthy subjects. Rifabutin reduced the area under the plasma drug concentration-time curve from 0 to 12 h postdose (AUC(0-12)), maximum observed concentration of drug in plasma (C(max)), and minimum observed concentration of drug in plasma at the end of the dosing interval (C(min)) for saquinavir by 13%, 15%, and 9%, respectively, for subjects receiving rifabutin (150 mg) every 3 days with saquinavir-ritonavir BID. No effects of rifabutin on ritonavir AUC(0-12), C(max), and C(min) were observed. No adjustment of the saquinavir-ritonavir dose (1,000/100 mg) BID is required when the drugs are administered in combination with rifabutin. The effect of multiple doses of saquinavir-ritonavir on rifabutin pharmacokinetics was evaluated in two groups of healthy subjects. In group 1 (n = 14), rifabutin (150 mg) was coadministered every 3 days with saquinavir-ritonavir BID. The AUC(0-72) and C(max) of the active moiety (rifabutin plus 25-O-desacetyl-rifabutin) increased by 134% and 130%, respectively, compared with administration of rifabutin (150 mg) once daily alone. Rifabutin exposure increased by 53% for AUC(0-72) and by 86% for C(max). In group 3 (n = 13), rifabutin was coadministered every 4 days with saquinavir-ritonavir BID. The AUC(0-96) and C(max) of the active moiety increased by 60% and 111%, respectively, compared to administration of 150 mg of rifabutin once daily alone. The AUC(0-96) of rifabutin was not affected, and C(max) increased by 68%. Monitoring of neutropenia and liver enzyme levels is recommended for patients receiving rifabutin with saquinavir-ritonavir BID.

Treatment strategies for HIV-infected patients with tuberculosis: ongoing and planned clinical trials

Currently, there are limited data to guide the management of highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 (HIV-1)-infected patients with active tuberculosis (TB), the leading cause of death among individuals with acquired immunodeficiency syndrome (AIDS) in resource-limited areas. Four trials to take place in Southeast Asian, African, and South American countries will address the unresolved question of the optimal timing for initiation of HAART in patients with AIDS and TB: (1) Cambodian Early versus Late Introduction of Antiretrovirals (CAMELIA [ANRS 1295/NIH-CIPRA KH001]), (2) Adult AIDS Clinical Trials Group A5221, (3) START, and (4) a trial sponsored by the World Health Organization/Special Programme for Research and Training in Tropical Diseases. Two other clinical questions regarding patients with TB and HIV-1 coinfection are also undergoing evaluation: (1) the benefits of short-term HAART when CD4 cell counts are >350 cells/mm(3) (PART [NIH 1 R01 AI051219-01A2]) and (2) the efficacy of a once-daily HAART regimen in treatment-naive patients (BKVIR [ANRS 129]). Here, we present an overview of these ongoing or planned clinical studies, which are supported by international agencies.

Co-infection with human immunodeficiency virus and tuberculosis in Asia

Asia has the highest numbers of tuberculosis cases (60% of the global total) and has experienced a marked rise in HIV seroprevalence (22% of the global total) in key subpopulations of these highly populous nations. Thus, co-infected patients are a challenge for practitioners and public health workers alike. The U.S.-Japan Cooperative Medical Science Program is spearheading interdisciplinary collaborations in Asia to address the many outstanding research priorities for HIV-tuberculosis co-infection. There is an urgency to this agenda for many reasons, including the frequency with which tuberculosis accounts for the death of HIV-infected persons in Asia, and the continued rise of multiple drug-resistant Mycobacterium tuberculosis. We review briefly the public health situation in Asia, highlighting research questions from US-Japan-Asian partner joint meetings, and cite salient studies to indicate trends and challenges.

Correlates for disease progression and prognosis during concurrent HIV/TB infection

Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) are both life-threatening pathogens in their own right, but their synergic effects on the immune system during co-infection markedly enhance their effect on the host. This review focuses on the bidirectional interaction between HIV and Mtb and discusses the relevance of sputum smear examination, CD4+ counts, viral load at baseline and after initiation of anti-retroviral therapy, as well as additional existing and new potential immune correlates of disease progression and prognosis. These markers include beta2-microglobulin, neopterin, tumor necrosis factor receptor II (TNFRII), CD8+/CD38+, soluble urokinase plasminogen activator receptor (suPAR) and CXCL10 (or IP-10).

An Update on Therapeutic Drug Monitoring for Antiretroviral Drugs

There is an increasing uptake of TDM of antiretroviral drugs, particularly in Europe. There is consensus that current antiretroviral drugs meet most of the criteria of drugs that can be considered as candidates for a TDM strategy. This review examines the pharmacokinetic-pharmacodynamic relationship for protease inibitors and non nucleoside reverse transcriptase inhibitor, give an overview of the published randomised clinical trials and then summarises the scenarios for use of TDM. Finally the development of the inhibitory quotient (IQ) concept is discussed.