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1.  The influence of tuberculosis treatment on efavirenz clearance in patients co-infected with HIV and tuberculosis 
Purpose
Drug interactions are of concern when treating patients co-infected with human immunodeficiency virus (HIV) and tuberculosis. Concomitant use of efavirenz (EFV) with the enzyme inducer rifampicin might be expected to increase EFV clearance. We investigated the influence of concomitant tuberculosis treatment on the plasma clearance of EFV.
Methods
Fifty-eight patients were randomized to receive their EFV-containing antiretroviral therapy either during or after tuberculosis treatment. Steady-state EFV plasma concentrations (n=209 samples) were measured, 83 in the presence of rifampicin. Data were analyzed using a non-linear mixed effects model, and the model was evaluated using non-parametric bootstrap and visual predictive checks.
Results
The patients had a median age of 32 (range 19–55) years and 43.1% were women. There was a bimodal distribution of apparent clearance, with slow EFV metabolizers accounting for 23.6% of the population and having a metabolic capacity 36.4% of that of the faster metabolizers. Apparent EFV clearance after oral administration in fast metabolizers was 12.9 L/h/70 kg whilst off tuberculosis treatment and 9.1 L/h/70 kg when on tuberculosis treatment. In slow metabolizers, the clearance estimates were 3.3 and 4.7 L/h/70 kg in the presence and absence of TB treatment, respectively. Overall there was a 29.5% reduction in EFV clearance during tuberculosis treatment.
Conclusion
Unexpectedly, concomitant rifampicin-containing tuberculosis treatment reduced apparent EFV clearance with a corresponding increase in EFV exposure. While the reasons for this interaction require further investigation, cytochrome P450 2B6 polymorphisms in the population studied may provide some explanation.
doi:10.1007/s00228-011-1166-5
PMCID: PMC3888951  PMID: 22108776
Pharmacokinetics; Tuberculosis; HIV; Efavirenz; Rifampicin
2.  Implementing microbicides in low income countries 
The magnitude of the global HIV epidemic is determined by women from lower income countries, specifically sub-Saharan Africa. Microbicides offer women who are unable to negotiate safe sex practices a self-initiated HIV prevention method. Of note, is its potential to yield significant public health benefits even with relatively conservative efficacy, coverage and user adherence estimates, making microbicides an effective intervention to invest scarce health care resources. Existing health care delivery systems provide an excellent opportunity to identify women at highest risk for infection and to also provide an access point to initiate microbicide use. Innovative quality improvement approaches, which strengthen existing sexual reproductive health services and include HIV testing, and linkages to care and treatment services provide an opportunity to lay the foundations for wide-scale provision of microbicides. The potential to enhance health outcomes in women and infants and potentially impact rates of new HIV infection may soon be realised.
doi:10.1016/j.bpobgyn.2012.02.004
PMCID: PMC3467713  PMID: 22498040
microbicides; implementation; low income countries; HIV prevention
3.  A drug evaluation of 1% tenofovir gel and tenofovir disoproxil fumarate tablets for the prevention of HIV infection 
Introduction
More than a million people acquire HIV infection annually. Pre-exposure prophylaxis (PrEP) using antiretrovirals is currently being investigated for HIV prevention. Oral and topical formulations of tenofovir have undergone pre-clinical and clinical testing to assess acceptability, safety and effectiveness in preventing HIV infection.
Areas covered
The tenofovir drug development pathway from compound discovery; pre-clinical animal model testing and human testing were reviewed for safety, tolerability, and efficacy. Tenofovir is well tolerated and safe when used both systemically or applied topically for HIV prevention. High drug concentrations at the site of HIV transmission and concomitant low systemic drug concentrations are achieved with vaginal application. Coitally applied gel may be the favoured prevention option for women compared to the tablets which may be more suitable for prevention in men and sero-discordant couples. However, recent contradictory effectiveness outcomes in women need to be better understood.
Expert opinion
Emerging evidence has brought new hope that antiretrovirals can potentially change the course of the HIV epidemic when used as early treatment for prevention, as topical or oral PrEP. Although some trial results appear conflicting, behavioral factors, adherence to dosing, and pharmacokinetic properties of the different tenofovir formulations and dosing approaches offer plausible explanations for most of the variations in effectiveness observed in different trials.
doi:10.1517/13543784.2012.667072
PMCID: PMC3460694  PMID: 22394224
ART; NtRTI; tenofovir; tenofovir disoproxil fumarate; HIV prevention; microbicide; PMPA – [9-R-(2-Phosphonomethoxypropyl) adenine]
4.  Co-enrollment in multiple HIV prevention trials – Experiences from the CAPRISA 004 Tenofovir gel trial 
Contemporary clinical trials  2011;32(3):333-338.
Background
In settings where multiple HIV prevention trials are conducted in close proximity, trial participants may attempt to enroll in more than one trial simultaneously. Co-enrollment impacts on participant’s safety and validity of trial results. We describe our experience, remedial action taken, inter-organizational collaboration and lessons learnt following the identification of co-enrolled participants.
Experiences
Between February and April 2008, we identified 185 of the 398 enrolled participants as ineligible. In violation of the study protocol exclusion criteria, there was simultaneous enrollment in another HIV prevention trial (ineligible co-enrolled, n=135), and enrollment of women who had participated in a microbicide trial within the past 12 months (ineligible not co-enrolled, n=50). Following a complete audit of all enrolled participants, ineligible participants were discontinued via study exit visits from trial follow-up. Custom-designed education program on co-enrollment impacting on participants’ safety and validity of the trial results were implemented. Shared electronic database between research units were established to enable verification of each volunteer’s trial participation and to prevent future co-enrollments.
Lessons Learnt
Interviews with ineligible enrolled women revealed that high-quality care; financial incentives; altruistic motives; preference for sex with gel; wanting to increase their likelihood of receiving active gel; perceived low risk of discovery and peer pressure as the reasons for their enrolment in the CAPRISA 004 trial.
Conclusion
Instituting education programs based on the reasons reported by women for seeking enrolment in more than one trial and using a shared central database system to identify co-enrollments have effectively prevented further co-enrollments.
doi:10.1016/j.cct.2011.01.005
PMCID: PMC3616246  PMID: 21278001
HIV prevention trials; co-enrollment; young women
5.  Integration of Antiretroviral Therapy with Tuberculosis Treatment 
The New England journal of medicine  2011;365(16):1492-1501.
Background
We previously reported that integrating antiretroviral therapy (ART) with tuberculosis treatment reduces mortality. However, optimal time to initiate ART during tuberculosis treatment remains contentious.
Methods
To address this, we conducted a 3-arm, open-label randomized controlled trial in South Africa in acid-fast bacilli smear positive patients (n=642) with HIV and CD4+ counts <500 cells/mm3. Findings on the early therapy group (ART initiated within 4 weeks of tuberculosis treatment initiation, n=214) and late therapy group (ART initiated within the first 4 weeks of the continuation phase of tuberculosis treatment, n=215) are presented here.
Results
Median CD4+ count and viral load at baseline was 150 cells/mm3 and 161000 copies/ml, being similar in both groups. Incidence rate of AIDS or death was 6.9 (18/259.4) and 7.8 (19/244.2) per 100 person-years in the early and late therapy groups respectively (Incidence Rate Ratio (IRR)=0.89; 95%Confidence Interval (95%CI): 0.44,1.79; P=0.73). However, in patients with CD4+ counts <50 cells/mm3, the incidence rates of AIDS or death were 8.5 (early) and 26.3 (late) per 100 person-years (IRR=0.32; 95%CI: 0.07,1.13; P=0.06). Immune reconstitution inflammatory syndrome (IRIS) incidence rates were 20.2 (early) and 7.7 (late) per 100 person-years (IRR=2.62; 95%CI: 1.48,4.82; P<0.001). Adverse events requiring antiretroviral drug switches occurred in 10 (early) and 1 (late) patients (P=0.006).
Conclusions
The benefits of AIDS-free survival balanced against the risks of IRIS and ART-related adverse events, support early ART initiation in patients with CD4+ counts <50 cells/mm3 and deferred ART initiation to the continuation phase of tuberculosis treatment when CD4+ counts are higher.
doi:10.1056/NEJMoa1014181
PMCID: PMC3233684  PMID: 22010915
6.  Initiating antiretrovirals during tuberculosis treatment: a drug safety review 
Expert opinion on drug safety  2011;10(4):559-574.
Introduction
Integrating HIV and 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 anti-retrovirals 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.
doi:10.1517/14740338.2011.546783
PMCID: PMC3114264  PMID: 21204737
Tuberculosis; HAART; toxicity; drug interactions; safety HIV; rifamycins

Results 1-6 (6)