Evidence for Implementation: Management of TB in HIV and Pregnancy

PURPOSE OF REVIEW

Pregnant people living with HIV (PLWH) are at especially high risk for progression from latent tuberculosis infection (LTBI) to active tuberculosis (TB) disease. Among pregnant PLWH, concurrent TB increases the risk of complications such as preeclampsia, intrauterine fetal-growth restriction, low birth weight, preterm-delivery, perinatal transmission of HIV, and admission to the neonatal intensive care unit. The grave impact of superimposed TB disease on maternal morbidity and mortality among PLWH necessitates clear guidelines for concomitant therapy and an understanding of the pharmacokinetics (PK) and potential drug-drug interactions (DDIs) between antitubercular (anti-TB) agents and antiretroviral therapy (ART) in pregnancy.

RECENT FINDINGS

This review discusses the currently available evidence on the use of anti-TB agents in pregnant PLWH on ART. Pharmacokinetic and safety studies of anti-TB agents during pregnancy and postpartum are limited, and available data on second-line and newer anti-TB agents used in pregnancy suggest that several research gaps exist. DDIs between ART and anti-TB agents can decrease plasma concentration of ART, with the potential for perinatal transmission of HIV. Current recommendations for the treatment of LTBI, drug-susceptible TB, and multidrug-resistant TB (MDR-TB) are derived from observational studies and case reports in pregnant PLWH. While the use of isoniazid, rifamycins, and ethambutol in pregnancy and their DDIs with various ARTs are well-characterized, there is limited data on the use of pyrazinamide and several new and second-line antitubercular drugs in pregnant PLWH. Further research into treatment outcomes, PK, and safety data for anti-TB agent use during pregnancy and postpartum is urgently needed.

Reasons for Antiretroviral Treatment Change Among Adult HIVAIDS Patients at Nedjo General Hospital, Western Ethiopia

Background:

Frequent change of Antiretroviral Treatment (ART) regimen is a challenging problem especially in a resource-limited setting like Ethiopia where treatment options are limited. This study was aimed to identify reasons for ART regimen change among adult HIV patients at Nedjo General Hospital (NGH).

Methods:

An institutional-based retrospective cross-sectional study was conducted at NGH by reviewing patient information cards from 2006 to 2016.

Results:

From a total of 117 included patients, 50.4% were females and the median (IQR) age of the patients was 28 (24-47) years. Majority of patients, 63 (53.9%) started their treatment at world health organization (WHO) clinical stage III (53.9%) and CD4 count of between 200-350 cells/mm3 (44.54%). At the beginning of ART, 56 (47.9%) patients were on a fixed-dose combination of stavudine-lamivudine-nevirapine (D4T/3TC/NVP). The single-drug substitutions were D4T (n = 63), NVP (n = 34), AZT (n =5), EFV (n = 2), and TDF (n = 1). Majority of the patients, 35(29.9%) switched their initial ART regimen after 3 years of regimen commencement. The common reasons reported for initial regimen change was availability of new drug 46 (39.3%) followed by toxicity/side effects 34 (29.2%). From all toxicities, peripheral neuropathy (47.1%) was the most common toxicity followed by rash (20.6%). After regimen change, 47 (40.2%) were received AZT+3TC+NVP.

Conclusion:

Availability of new drug and toxicity were the common reasons for regimen modifications. There should be updated guidelines, sustainable supply of affordable ART drugs, and effective laboratory materials to increase treatment success and minimize the toxicity of the drugs.

State-of-the-Art Review of HIV-TB Coinfection in Special Populations

Children and pregnant and postpartum women experience an undue burden of HIV-associated tuberculosis (TB), but data are lacking on key aspects of their complex management. Often excluded from clinical trials, they are left with limited options for HIV-TB cotreatment. This review will focus on pharmacologic aspects of the treatment of HIV-TB coinfection in the special populations of children and pregnant and postpartum women. Pharmacogenomic considerations, rational dosing, drug-drug interactions, safety, immune reconstitution inflammatory syndrome, and ethical and policy aspects of the inclusion of special populations in research will be surveyed. Considerations related to the treatment of both HIV-associated TB disease and HIV-associated latent TB infection will be summarized. Relevant knowledge gaps and research priorities in special populations will be outlined.

The pharmacological challenges of treating tuberculosis and HIV coinfections

INTRODUCTION

Tuberculosis (TB) is the most prevalent opportunistic infection among HIV patients, and the leading cause of death among HIV patients worldwide. Simultaneous treatment of both diseases is recommended by current guidelines, but can be challenging due to the potential for drug-drug interactions, overlapping toxicities, difficulty adhering to medications, and an increased risk for immune reconstitution inflammatory syndrome (IRIS). Clinical manifestations of TB can also vary between HIV-infected patients and uninfected patients, which can increase the risk for delayed diagnosis. Areas covered: Topics covered in this review include the following: the inter-related pathophysiology of HIV and TB; clinical manifestations and diagnosis; drug-drug interactions, particularly the rifamycins with the antiretrovirals; IRIS presentation and treatment, as well as a discussion on overlapping toxicity between the two disease states. Expert commentary: The complexity of managing these two disease states simultaneously requires a multidisciplinary approach to care and dedicated resources. If properly funded, TB/HIV co-infection will continue to decline over the coming years.

Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals

Neurological complications associated with the human immunodeficiency virus (HIV) are a matter of great concern. While antiretroviral (ARV) drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity.

Current trends and intricacies in the management of HIV-associated pulmonary tuberculosis

Human immunodeficiency virus (HIV) epidemic has undoubtedly increased the incidence of tuberculosis (TB) globally, posing a formidable global health challenge affecting 1.2 million cases. Pulmonary TB assumes utmost significance in the programmatic perspective as it is readily transmissible as well as easily diagnosable. HIV complicates every aspect of pulmonary tuberculosis from diagnosis to treatment, demanding a different approach to effectively tackle both the diseases. In order to control these converging epidemics, it is important to diagnose early, initiate appropriate therapy for both infections, prevent transmission and administer preventive therapy. Liquid culture methods and nucleic acid amplification tests for TB confirmation have replaced conventional solid media, enabling quicker and simultaneous detection of mycobacterium and its drug sensitivity profile Unique problems posed by the syndemic include Acquired rifampicin resistance, drug-drug interactions, malabsorption of drugs and immune reconstitution inflammatory syndrome or paradoxical reaction that complicate dual and concomitant therapy. While the antiretroviral therapy armamentarium is constantly reinforced by discovery of newer and safer drugs every year, only a few drugs for anti tuberculosis treatment have successfully emerged. These include bedaquiline, delamanid and pretomanid which have entered phase III B trials and are also available through conditional access national programmes. The current guidelines by WHO to start Antiretroviral therapy irrespective of CD4+ cell count based on benefits cited by recent trials could go a long way in preventing various complications caused by the deadly duo. This review provides a consolidated gist of the advancements, concepts and updates that have emerged in the management of HIV-associated pulmonary TB for maximizing efficacy, offering latest solutions for tackling drug-drug interactions and remedial measures for immune reconstitution inflammatory syndrome.

HAART, DOTS and renal disease of patients co-infected with HIV/AIDS and TB in the South West Region of Cameroon

Background

Tuberculosis is the commonest infection among HIV/AIDS patients. This co-infection constitutes a major death threat in the world. There is paucity of data about renal disease amongst patients on HAART and DOTS therapy in Cameroon.

Methods

This was a hospital-based cross-sectional study in the Buea, Limbe and Kumba government Hospitals. Spectrophotometric method was used for the quantitative determination of serum creatinine, urea, albumin and total protein levels. Glomerular filtration rate was estimated using the MDRD method. The student’s t test, ANOVA and logistic regression were used to analyse the data.

Results

Out of 200 participants, 101 (50.5 %) were males. The ages ranged from 21 to 65 years with a mean age of 38.04 ± 10.52 years. Compared to adults on DOTS alone, adults on HAART alone had a significantly higher prevalence of eGFR <60 ml/min/1.73 m² (10/70 (14.3 %) vs. 1/70 (1.4 %), OR = 11.5 [1.4–92.5], p = 0.02) while more participants on HAART/DOTS had significantly higher serum creatinine (18/60 (30 %) vs 10/70 (14.3) OR = 2.57 [1.08–6.12], p = 0.033). Though participants on HAART/DOTS combined therapy had low eGFR, the association was not statistically significant (OR = 6.27, 95 % CI;0.71–55.27, p = 0.098). Participants on the Zidovudine, Lamivudine, Nevirapine regimen showed a statistically significant difference in the mean serum creatinine and albumin levels between the HAART/DOTS combined therapy and HAART group (p = 0.0219 and 0.0001 respectively).

Conclusion

Compared to adults on DOTS, adults on HAART were more likely to have renal dysfunction (eGFR <60 ml/min per 1.73 m²). Adult on a combination of HAART and DOTS had a similar prevalence of renal dysfunction as those on HAART alone. This study showed that the use of the HAART regimen (Tenofovir, Lamivudine and Efavirenz combination) among the HAART treated adults was nephrotoxic. However, other combined HAART and DOTS regimens had no nephrotoxic effect. Abnormal kidney function can be associated with HAART use.

Population pharmacokinetics of nevirapine in combination with rifampicin-based short course chemotherapy in HIV- and tuberculosis-infected South African patients

OBJECTIVE

The aim was to develop a model to describe the population pharmacokinetics of nevirapine in South African human immunodeficiency virus (HIV)-infected patients who were taking nevirapine-based antiretroviral therapy concomitantly or in the absence of rifampicin-based tuberculosis therapy.

METHODS

Patients were divided into two groups: (1) patients receiving nevirapine-containing antiretroviral regimen (200 mg twice daily) and continuation phase rifampicin-containing tuberculosis therapy (n = 27) in whom blood samples were obtained before and not less than 14 days after they completed tuberculosis therapy; (2) patients without tuberculosis who were receiving a nevirapine-containing antiretroviral regimen for at least 3 weeks (n = 26). The population pharmacokinetics of nevirapine was described using nonlinear mixed effects modelling with NONMEM software. Based on the developed model, plasma concentration profiles after 300, 400 and 500 mg of nevirapine twice daily were simulated.

RESULTS

Concomitant administration of rifampicin increased nevirapine oral clearance (CL/F) by 37.4% and reduced the absorption rate constant (k(a)) by almost sixfold. Rifampicin reduced the nevirapine average minimum concentration by 39%. Simulated doses of 300 mg twice daily elevated nevirapine concentrations above subtherapeutic levels in most patients, with minimum exposure above the recommended maximum concentration. The area under the concentration-time curve of 12-hydroxynevirapine was not different in the presence of rifampicin. 2-, 3- and 8-Hydroxynevirapine were not detectable (LLOQ = 0.025 mg/L).

CONCLUSION

The developed model adequately describes nevirapine population pharmacokinetics in a South African population when taken with/and in the absence of rifampicin treatment. The simulations suggest that an increased dose of 300 mg twice daily would achieve adequate nevirapine concentrations in most patients during rifampicin-containing treatment for tuberculosis.

Factors Influencing Efavirenz and Nevirapine Plasma Concentration: Effect of Ethnicity, Weight and Co-Medication

Background

The aim of this study was to examine factors influencing plasma concentration of efavirenz and nevirapine.

Methods

Data from the Liverpool Therapeutic Drug Monitoring (TDM) registry were linked with the UK Collaborative HIV Cohort (CHIC) Study. For each patient, the first measurement of efavirenz (600 or 800 mg/day) or nevirapine (400 mg/day) plasma concentration was included. Linear regression was used to evaluate the association of dose, gender, age, weight, ethnicity and concomitant antiretroviral drugs or rifampicin with log-transformed drug concentration, adjusted for time since last intake.

Results

Data from 339 patients on efavirenz (34% black, 17% rifampicin) and 179 on nevirapine (27% black, 6% rifampicin) were included. Multivariable models revealed the following predictors for efavirenz concentration: black ethnicity (59% higher; P<0.001), weight (10% lower per additional 10 kg; P=0.002), 800 mg/day (52% higher; P=0.027), rifampicin (35% lower; P=0.039), and zidovudine (25% lower; P=0.010). Notably, without adjustment for other factors, patients on rifampicin had 48% higher efavirenz concentration, as these patients were mostly black and on 800 mg/day. For nevirapine the predictors were black ethnicity (39% higher; P=0.002), rifampicin (40% lower; P=0.002), protease inhibitor (28% higher; P=0.008) and tenofovir (22% higher; P=0.024).

Conclusions

We observed clear associations between ethnicity and concentrations of nevirapine and efavirenz. Our analyses confirm that concomitant rifampicin substantially decreases concentration of both efavirenz and nevirapine; however, for efavirenz this effect was more than counterbalanced by the effect of ethnicity and increased efavirenz dose. There was also an additional impact of weight, which should be considered when determining optimal dosage. Other associations from our analysis (between tenofovir or protease inhibitor and nevirapine, and zidovudine and efavirenz), require confirmation in formal pharmacokinetic studies.

Pharmacokinetics and 48-Week Efficacy of Nevirapine: 400 mg Versus 600 mg per day in HIV–Tuberculosis Coinfection Receiving Rifampicin

Background

We aim here to determine the appropriate dose of nevirapine (NVP) in Thai HIV–tuberculosis (TB)-coinfected patients receiving rifampicin.

Methods

Thirty-two HIV-infected adults with CD4+ T-cell counts <200 cells/mm3 and active TB, receiving rifampicin for 2–6 weeks were randomized to receive either NVP 400 mg (NVP400) or 600 mg (NVP600) per day plus two nucleoside reverse transcriptase inhibitors; a 2-week NVP lead-in was performed at 200 mg once daily (OD) and 200 mg twice daily, respectively. Plasma NVP levels were determined at weeks 2, 4 and 12. Twelve-hour pharmacokinetics (PK) were obtained ( n=20) at week 4.

Results

Baseline body weight was comparable. There were more patients with NVP plasma concentration at 12 h (C12) <3.1 mg/l at week 2 in NVP400 than in NVP600 (79% versus 19%, respectively; P=0.002). However, the proportions were comparable at weeks 4 and 12. From week 4, 12 h PK studies showed that NVP400 had lower median NVP area under the plasma concentration-0–12 h (AUC0–12 h), maximum concentration in plasma (Cmax) and C12 than NVP600 ( P<0.05). Four patients in NVP600 developed NVP hypersensitivity. At week 48, the median CD4+ T-cell count rise and proportion with viral load <50 copies/ml (intention-to-treat analysis 56% versus 50% and as-treated analysis 75% versus 89%) were comparable.

Conclusions

In rifampicin-treated patients, 200 mg NVP OD lead-in led to a significant short-term suboptimal NVP C12 level, while NVP 400 mg lead-in then 600 mg/day was associated with a high rate of NVP hypersensitivity. Forty-eight week efficacy was comparable. Thus, NVP 600 mg/day in rifampicin-treated patients is not recommended.