Zidovudine in asymptomatic human immunodeficiency virus infection. A controlled trial in persons with fewer than 500 CD4-positive cells per cubic millimeter. The AIDS Clinical Trials Group of the National Institute of Allergy and Infectious Diseases

Repurposing of biologics and biopharmaceuticals

The field of drug repurposing is gaining attention as a way to introduce pharmaceutical agents with established safety profiles to new patient populations. This approach involves finding new applications for existing drugs through observations or deliberate efforts to understand their mechanisms of action. Recent advancements in bioinformatics and pharmacology, along with the availability of extensive data repositories and analytical techniques, have fueled the demand for novel methodologies in pharmaceutical research and development. To facilitate systematic drug repurposing, various computational methodologies have emerged, combining experimental techniques and in silico approaches. These methods have revolutionized the field of drug discovery by enabling the efficient repurposing of screens. However, establishing an ideal drug repurposing pipeline requires the integration of molecular data accessibility, analytical proficiency, experimental design expertise, and a comprehensive understanding of clinical development processes. This chapter explores the key methodologies used in systematic drug repurposing and discusses the stakeholders involved in this field. It emphasizes the importance of strategic alliances to enhance the success of repurposing existing compounds for new indications. Additionally, the chapter highlights the current benefits, considerations, and challenges faced in the repurposing process, which is pursued by both biotechnology and pharmaceutical companies. Overall, drug repurposing holds great promise in expanding the use of existing drugs and bringing them to new patient populations. With the advancements in computational methodologies and the collaboration of various stakeholders, this approach has the potential to accelerate drug development and improve patient outcomes.

Repurposing Drugs: An Empowering Approach to Drug Discovery and Development

Drug discovery and development is a time-consuming and costly procedure that necessitates a substantial effort. Drug repurposing has been suggested as a method for developing medicines that takes less time than developing brand new medications and will be less expensive. Also known as drug repositioning or re-profiling, this strategy has been in use from the time of serendipitous drug discoveries to the modern computer aided drug designing and use of computational chemistry. In the light of the COVID-19 pandemic too, drug repurposing emerged as a ray of hope in the dearth of available medicines. Data availability by electronic recording, libraries, and improvements in computational techniques offer a vital substrate for systemic evaluation of repurposing candidates. In the not-too-distant future, it could be possible to create a global research archive for us to access, thus accelerating the process of drug development and repurposing. This review aims to present the evolution, benefits and drawbacks including current approaches, key players and the legal and regulatory hurdles in the field of drug repurposing. The vast quantities of available data secured in multiple drug databases, assisting in drug repurposing is also discussed.

Why there are so many contradicted or exaggerated findings in highly cited clinical research?

It is not uncommon that clinical studies of the same intervention contradicted with each other, e.g., one study produced positive results, while the other produced negative results. Ioanndis (2005a) found that among 49 highly-cited original clinical research studies, published in New England Journal of Medicine, Journal of the American Medical Association, Lancet or in a high-impact medical specialty journal, 32% of them were contradicted in subsequent large-scale studies, or were shown to have potentially overestimated the efficacy of the experimental intervention. This finding is disturbing and of serious concern given the widespread impact of these highly-cited studies and the rigorous standards used to design and conduct the studies. We perform Bayesian analysis of these highly-cited clinical studies based on Bayesian factor. We identified one cause of the issue: p values strongly overstated the experimental evidence. For the highly-cited studies, when the p value was 0.05, there was a 74.4% percentage chance that the null hypothesis was true. The use of a p value of 0.05 as the criterion for significance caused many researchers to mistakenly draw conclusions of positive findings, which were then contradicted by subsequent large-scale studies.

Evaluating Neurodevelopmental Consequences of Perinatal Exposure to Antiretroviral Drugs: Current Challenges and New Approaches

As antiretroviral therapy (ART) becomes increasingly affordable and accessible to women of childbearing age across the globe, the number of children who are exposed to Human Immunodeficiency Viruses (HIV) but remain uninfected is on the rise, almost all of whom were also exposed to ART perinatally. Although ART has successfully aided in the decline of mother-to-child-transmission of HIV, the long-term effects of in utero exposure to ART on fetal and postnatal neurodevelopment remain unclear. Evaluating the safety and efficacy of therapeutic drugs for pregnant women is a challenge due to the historic limitations on their inclusion in clinical trials and the dynamic physiological states during pregnancy that can alter the pharmacokinetics of drug metabolism and fetal drug exposure. Thus, much of our data on the potential consequences of ART drugs on the developing nervous system comes from preclinical animal models and clinical observational studies. In this review, we will discuss the current state of knowledge and existing approaches to investigate whether ART affects fetal brain development, and describe novel human stem cell-based strategies that may provide additional information to better predict the impact of specific drugs on the human central nervous system. Graphical Abstract Approaches to evaluate the impact of drugs on the developing brain. Dysregulation of the developing nervous system can lead to long-lasting changes. Integration of data from animal models, clinical observations, and cell culture studies is needed to predict the safety of therapeutic antiretroviral drugs during pregnancy. New approaches include human induced pluripotent stem cell (iPSC)-based 2D and 3D models of neuronal networks and brain regions, as well as single cell profiling in response to drug exposure.

Drug-drug interactions and clinical considerations with co-administration of antiretrovirals and psychotropic drugs

Psychotropic medications are frequently co-prescribed with antiretroviral therapy (ART), owing to a high prevalence of psychiatric illness within the population living with HIV, as well as a 7-fold increased risk of HIV infection among patients with psychiatric illness. While ART has been notoriously associated with a multitude of pharmacokinetic drug interactions involving the cytochrome P450 enzyme system, the magnitude and clinical impact of these interactions with psychotropics may range from negligible effects on plasma concentrations to life-threatening torsades de pointes or respiratory depression. This comprehensive review summarizes the currently available information regarding drug-drug interactions between antiretrovirals and pharmacologic agents utilized in the treatment of psychiatric disorders-antidepressants, stimulants, antipsychotics, anxiolytics, mood stabilizers, and treatments for opioid use disorder and alcohol use disorder-and provides recommendations for their management. Additionally, overlapping toxicities between antiretrovirals and the psychotropic classes are highlighted. Knowledge of the interaction and adverse effect potential of specific antiretrovirals and psychotropics will allow clinicians to make informed prescribing decisions to better promote the health and wellness of this high-risk population.

How to construct an optimal interim report: What the data monitoring committee does and doesn’t need to know

Background:

Data monitoring committees for randomized clinical trials have the responsibility of safeguarding interests of trial participants. To do so, the data monitoring committee must receive reports on safety and efficacy to assess risk/benefit and on trial conduct to ensure that the study can achieve its goals. This article outlines the key components of reports to the data monitoring committee and the important role of the unblinded statistician in preparing those reports.

Methods:

Most data monitoring committee meetings include open and closed sessions. For each session, there is a report of interim results. The open session is attended by the sponsor and lead investigators, including the statistician(s) responsible for the trial design. These investigators are blinded to the interim treatment comparisons. The closed session is attended by the data monitoring committee members and by the statistician(s) who prepared the closed report. These individuals are unblinded to interim treatment comparisons and therefore are not involved in study design changes. The optimal content of data monitoring committee reports and qualifications of the unblinded statistician(s) are discussed.

Reports:

Open reports should include responses to data monitoring committee recommendations, a synopsis of the protocol, a review of the protocol history and amendments, and information on enrollment, baseline characteristics, completeness of follow-up, and data quality. The open report is also a vehicle through which the sponsor and investigators should inform the data monitoring committee of relevant external information. Data in the open report are pooled over the treatment groups. The open report should not include data summaries by treatment group. The closed report should include a written summary with references to key tables and figures and methods used to prepare them. Tables and figures should summarize baseline characteristics, follow-up completeness, treatment adherence, and major safety and efficacy outcomes by treatment group. Text summaries should accompany the tables and figures. The data monitoring committee monitoring history (e.g. treatment differences at previous meetings) should be summarized. The unblinded statistician preparing the closed report should be familiar with the protocol and data collection plan and be capable of customizing the report to the current stage of the trial. This includes anticipating questions that may arise during the data monitoring committee review and pro-actively including data summaries to address these questions.

Conclusions:

There is considerable variation in the quality of open and closed data monitoring committee reports. Open and closed data monitoring committee reports should be concise, up to date, and informative. To achieve this, unblinded statisticians responsible for preparing closed data monitoring committee reports should be familiar with the statistical methods, the trial protocol, and the data collection plan. They should be capable of anticipating questions from the data monitoring committee and responding to requests for additional analyses.

Drug repurposing from the perspective of pharmaceutical companies

Drug repurposing holds the potential to bring medications with known safety profiles to new patient populations. Numerous examples exist for the identification of new indications for existing molecules, most stemming from serendipitous findings or focused recent efforts specifically limited to the mode of action of a specific drug. In recent years, the need for new approaches to drug research and development, combined with the advent of big data repositories and associated analytical methods, has generated interest in developing systematic approaches to drug repurposing. A variety of innovative computational methods to enable systematic repurposing screens, experimental as well as through in silico approaches, have emerged. An efficient drug repurposing pipeline requires the combination of access to molecular data, appropriate analytical expertise to enable robust insights, expertise and experimental set-up for validation and clinical development know-how. In this review, we describe some of the main approaches to systematic repurposing and discuss the various players in this field and the need for strategic collaborations to increase the likelihood of success in bringing existing molecules to new indications, as well as the current advantages, considerations and challenges in repurposing as a drug development strategy pursued by pharmaceutical companies.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Translational Pharmacology in Glaucoma Neuroprotection

Glaucoma is both the most common optic neuropathy worldwide and the most common cause of irreversible blindness in the world. The only proven treatment for glaucomatous optic neuropathy is lowering the intraocular pressure, achieved with a variety of pharmacological, laser, and surgical approaches. Over the past 2 decades there has been much basic and clinical research into achieving treatment of the underlying optic nerve damage with neuroprotective approaches. However, none has resulted in regulatory approval based on successful phase 3 studies. This chapter discusses the reasons for this "lost in translation" aspect of glaucoma neuroprotection, and outlines issues at the laboratory and clinical trial level that need to be addressed for successful development of neuroprotective therapies.

Discovery and Development of the Anti-Human Immunodeficiency Virus Drug, Emtricitabine (Emtriva, FTC)

The HIV/AIDS epidemic, which was first reported on in 1981, progressed in just 10 years to a disease afflicting 10 million people worldwide including 1 million in the US. In 1987, AZT was approved for treating HIV/AIDS. Unfortunately, its clinical usefullness was severly limited by associated toxicities and the emergence of resistance. Three other drugs that were approved in the early 1990s suffered from similar liabilities. In 1990, the Liotta group at Emory University developed a highly diastereoselective synthesis of racemic 3'-thia-2',3'-dideoxycytidine and 3'-thia-2',3'-5-fluorodideoxycytidine and demonstrated that these compounds exhibited excellent anti-HIV activity with no apparent cytotoxicity. Subsequently, the enantiomers of these compounds were separated using enzyme-mediated kinetic resolutions and their (-)-enantiomers (3TC and FTC, respectively) were found to have exceptionally attractive preclinical profiles. In addition to their anti-HIV activity, 3TC and FTC potently inhibit the replication of hepatitis B virus. The development of FTC, which was being carried out by Burroughs Wellcome, had many remarkable starts and stops. For example, passage studies indicated that the compound rapidly selected for a single resistant mutant, M184V, and that this strain was 500-1000-fold less sensitive to FTC than was wild-type virus. Fortunately, it was found that combinations of AZT with either 3TC or FTC were synergistic. The effectiveness of AZT-3TC combination therapy was subsequently demonstrated in four independent clinical trials, and in 1997, the FDA approved Combivir, a fixed dose combination of AZT and 3TC. In phase 1 clinical trials, FTC was well tolerated by all subjects with no adverse events observed. However, the development of FTC was halted by the aquistition of Wellcome PLC by Glaxo PLC in January 1995. In 1996, Triangle Pharmaceuticals licensed FTC from Emory and initiated a series of phase I/II clinical studies that demonstrated the safety and efficacy of the drug. In August 1998, FTC was granted "Fast Track" status, based primarily on its potential for once daily dosing. While the outcomes of two subsequent phase III trials were positive, a third phase III clinical trial involving combinations of 3TC or FTC with stavudine and neviripine had to be terminated due to serious liver-related adverse events. Although analysis of the data suggested that the liver toxicity was due to neviripine, the FDA decided that the study could not be used for drug registration. Ultimately, in January 2003, Gilead Sciences acquired Triangle Pharmaceuticals and completed the development of FTC (emtricitabine), which was approved for once a day, oral administration in July 2003. A year later, Truvada, a once a day, oral, fixed dose combination of emtricitabine and tenofovir disoproxyl fumarate received FDA approval and quickly became the accepted first line therapy when used with a third antiretroviral agent. In July 2006, the FDA approved Atripla, a once a day, oral, fixed dose combination of emtricitabine, tenofovir disoproxyl fumarate, and efavirenz, which represented the culmination of two decades of research that had transformed AIDS from a death sentence to a manageable chronic disease.

Thirty-five years of CD4 T-cell counting in HIV infection: From flow cytometry in the lab to point-of-care testing in the field

CD4 T-cell counting was introduced in clinical laboratories shortly after the discovery of the human immune deficiency virus (HIV) in the early eighties. In western clinical laboratories, improvements in the CD4 T-cell counting methods were mainly driven by progress in the field of flow cytometry and immunology. In contrast, the development of dedicated CD4 T-cell counting technologies were needs driven. When antiretroviral treatment (ART) was made available on a large scale by international Acquired Immune Deficiency Syndrome (AIDS) relief programs to HIV+ patients living in low income countries in 2003, there was a distinct need for simplified and affordable CD4 T-cell counting technologies. The first decade of 2000, several compact flow cytometers appeared on the market, mainly to the benefit of low income countries with limited resources. More recently, however, portable point-of-care (POC) CD4 T-cell counting devices have been developed especially to improve access to affordable monitoring of HIV+ patients in low income countries. The accuracy of these POC instruments is not yet very well documented as many are still under development and clinical validation but preliminary evidence is encouraging. The new HIV treatment guidelines released by the World Health Organization in 2016 give CD4 T-cell counting a less central role in the management of HIV infection. It is, therefore, to be expected that CD4 T-cell counting will be phased out as a tool to assess eligibility of HIV+ patients for ART in the future. However, CD4 T-cell counting will remain a valuable tool for directing treatment against opportunistic infections. © 2016 International Clinical Cytometry Society.

HIV-1 Infection In The Correctional Setting

HIV infection is a major public health problem in prisons and jails. In several correctional systems, AIDS has become the leading cause of death. Seroprevalence estimates for different systems in the United States and Europe range form 0 percent to 18 percent among inmates entering prison, indicating geographic variation. Reported HIV rates are higher among females compared to males, among inmates over 25 years, and among racial/ethnic minorities. The major established risk behavior for HIV infection among prison inmates is a history of pre-incarceration intravenous drug use. The prison and jail setting provides an opportunity to educate, counsel, test, and treat individuals at risk for HIV infection who otherwise might have a very limited access to care. Services to this population must be voluntary and confidential.

Didanosine

OBJECTIVE:

To review the chemistry, intracellular metabolism, pharmacokinetics, and clinical experience with didanosine (2',3'-dideoxyinosine [ddI]).

DATA SOURCES:

English-language articles and conference proceedings (indexing terms were didanosine, 2′,3′-dideoxyinosine, and ddI).

STUDY SELECTION:

Available Phase I studies and abstracts determined to have clinical significance were included.

DATA EXTRACTION:

Clinical experience with ddI is limited to uncontrolled Phase I studies and a large “expanded-access” program. The primary outcome parameters used to evaluate ddI were the HIV surrogate markers: CD4+ lymphocytes and p24 antigen. Thus, the clinical data reviewed here must be evaluated critically and be considered preliminary until the results of studies comparing ddI with zidovudine (ZDV) and combination studies are available.

DATA SYNTHESIS:

Didanosine has been approved for the treatment of HIV infection in patients who are unable to tolerate ZDV because of adverse effects (e.g., anemia and neutropenia) or who experience clinical or immunologic deterioration while receiving ZDV. Compared with ZDV, ddI has a long intracellular half-life and negligible bone-marrow toxicity. It also has in vitro activity against ZDV-resistant strains of HIV. Phase I studies indicate that ddI has a beneficial effect on the CD4+ cell counts and HIV p24 antigen concentrations. As a result of the acid-labile nature of ddI, oral formulations are buffered or must be mixed with antacid to neutralize gastric pH. Bioavailability then averages 20–40 percent, depending on the dose and formulation given. The plasma half-life, total body clearance, and volume of distribution of ddI are one to two hours, 0.7–1 L/kg/h, and 0.8–1 L/kg, respectively. Painful peripheral neuropathy and pancreatitis (dose-limiting toxicities of ddI) occurred in 34 and 9 percent of patients in Phase I studies, respectively.

CONCLUSIONS:

Didanosine has demonstrated preliminary efficacy in the treatment of late-stage HIV infection; however, its effect on patient survival, its efficacy relative to ZDV, and its utility in combination with other agents are still under evaluation.

Drug Combination of AZT and ddl: Synergism of Action and Prevention of Appearance of AZT-Resistance

Both 3′-azido-3′-deoxythymidine (AZT) and 2′,3′-dideoxynosine (ddl) strongly inhibit the replication of human immunodeficiency virus type 1 (HIV-1). Here, it is shown that combination of AZT and ddl at concentrations that are readily achievable in vivo synergistically inhibit HIV-1 replication in C8166 cells and peripheral blood mononuclear cells. The synergism is significant even when the effect of AZT and ddl alone was negligible.

Our findings show that AZT-resistance is less likely to occur when a combination of AZT and ddl is used. Particularly, generation of AZT-resistant strains by in vitro selection is prevented, or delayed, by the combination of AZT plus ddl.

Taken together these observations provide a rationale for combination of AZT and ddl in the therapy of AIDS patients.

Anti-HIV Activities of Anionic Metalloporphyrins and Related Compounds

Various water-soluble polysulphonated and polycarboxylated porphyrins and some of their metallated derivatives have been prepared and their antiviral properties against human immunodeficiency virus (HIV-1, HIV-2), simian immunodeficiency virus and other viruses are reported. Besides these polyanionic compounds, two new series of porphyrins were included and studied from the perspective of bio-availability modulation: (i) acefylsulphonamido derivatives endowed with weak acidity properties (deprotonation gives the corresponding anionic derivatives in a pH range 4.5-8.5) and (ii) compounds with the anionic charge transiently masked by esterification (acetoxymethyl- and pivaloyloxymethylesters). Among the more active compounds in inhibiting HIV-induced cytopathic effects, the sulphonated and carboxylated porphyrin complexes were found to interact directly with the HIV protein gp 120 and not with the CD4 cellular receptor.

Proton Spectroscopy in a Cross-Section of HIV-Positive Asymptomatic Patients Receiving Immediate Compared with Deferred Zidovudine (Concorde Study)

The purpose of this study was to examine by proton spectroscopy for any difference in cerebral metabolites in patients taking part in the Concorde study (comparing the efficacy of immediate versus deferred treatment with zidovudine on asymptomatic HIV infected individuals). Forty seven HIV positive male patients [29 immediate, 18 deferred zidovudine] were examined in the last 9 months of the therapeutic trial. Magnetic resonance imaging and proton spectroscopy were performed at 1.5 Tesla using a single voxel placed in the parieto-occipital white matter. No significant difference was found in metabolite ratios comparing immediate versus deferred zidovudine (NA/NA+Cho+Cr 0.52 vs. 0.52). High quality spectra were acquired in relatively large numbers of patients and logistically spectroscopy may be applied to clinical therapeutic studies.

Efficient quantile marginal regression for longitudinal data with dropouts

In many biomedical studies independent variables may affect the conditional distribution of the response differently in the middle as opposed to the upper or lower tail. Quantile regression evaluates diverse covariate effects on the conditional distribution of the response with quantile-specific regression coefficients. In this paper, we develop an empirical likelihood inference procedure for longitudinal data that accommodates both the within-subject correlations and informative dropouts under missing at random mechanisms. We borrow the matrix expansion idea of the quadratic inference function and incorporate the within-subject correlations under an informative working correlation structure. The proposed procedure does not assume the exact knowledge of the true correlation structure nor does it estimate the parameters of the correlation structure. Theoretical results show that the resulting estimator is asymptotically normal and more efficient than one attained under a working independence correlation structure. We expand the proposed approach to account for informative dropouts under missing at random mechanisms. The methodology is illustrated by empirical studies and a real-life example of HIV data analysis.

Backbones versus core agents in initial ART regimens: one game, two players

The advances seen in ART during the last 30 years have been outstanding. Treatment has evolved from the initial use of single agents as monotherapy. The ability to use HIV RNA as a surrogate marker for clinical outcomes allowed the more rapid evaluation of new therapies. This led to the understanding that triple-drug regimens, including a core agent (an NNRTI or a boosted PI) and two NRTIs, are optimal. These combinations have demonstrated continued improvements in their efficacy and toxicity as initial therapy. However, the need for pharmacokinetic boosting, with potential drug-drug interactions, or residual issues of efficacy or toxicity have persisted for some agents. Most recently, integrase strand transfer inhibitors, particularly dolutegravir, have shown unparalleled safety and efficacy and are currently the core agents of choice. Regimens that included only core agents or only backbone agents have not been as successful as combined therapy in antiretroviral-naive patients. It appears that at least one NRTI is needed for optimal performance and lamivudine and emtricitabine may be the ideal candidates. Several studies are ongoing of agents with longer dosing intervals, lower cost and new NRTI-saving strategies to address unmet needs.

A Brief Chronicle of CD4 as a Biomarker for HIV/AIDS: A Tribute to the Memory of John L. Fahey

Foundational cellular immunology research of the 1960s and 1970s, together with the advent of monoclonal antibodies and flow cytometry, provided the knowledge base and the technological capability that enabled the elucidation of the role of CD4 T cells in HIV infection. Research identifying the sources and magnitude of variation in CD4 measurements, standardized reagents and protocols, and the development of clinical flow cytometers all contributed to the feasibility of widespread CD4 testing. Cohort studies and clinical trials provided the context for establishing the utility of CD4 for prognosis in HIV-infected persons, initial assessment of in vivo antiretroviral drug activity, and as a surrogate marker for clinical outcome in antiretroviral therapeutic trials. Even with sensitive HIV viral load measurement, CD4 cell counting is still utilized in determining antiretroviral therapy eligibility and time to initiate therapy. New point of care technologies are helping both to lower the cost of CD4 testing and enable its use in HIV test and treat programs around the world.

Reduced darunavir dose is as effective in maintaining HIV suppression as the standard dose in virologically suppressed HIV-infected patients: a randomized clinical trial

OBJECTIVES

Maximizing ART efficiency is of growing interest. This study assessed the efficacy, safety, pharmacokinetics and economics of a darunavir dose-reduction strategy.

METHODS

This was a multicentre, randomized, open-label clinical trial in HIV-infected patients with plasma HIV-1 RNA <50 copies/mL while receiving triple ART including 800 mg of darunavir once daily. Participants were randomized to continue 800 mg of darunavir (DRV800) or to 600 mg of darunavir (DRV600), both once daily. Treatment failure was defined as two consecutive HIV-1 RNA determinations >50 copies/mL or discontinuation of study treatment by week 48. The study was registered at https://www.clinicaltrialsregister.eu (trial number 2011-006272-39).

RESULTS

Fifty participants were allocated to each arm. The mean (SD) CD4+ T cell count at baseline was 562 (303) cells/mm(3) and HIV-1 RNA had been <50 copies/mL for a median (IQR) of 106.9 (43.4-227.9) weeks before enrolment. At week 48 no treatment failure had occurred in 45/50 (90%) DRV600 patients and in 47/50 (94%) DRV800 patients (difference -4%; 95% CI lower limit, -12.9%). When only patients with virological data were considered, that endpoint was met by 45/48 (94%) in the DRV600 arm and 47/49 (96%) in the DRV800 arm (difference -2.2%; 95% CI lower limit, -9.6%). Darunavir exposure was similar in the two arms. The average reduction in annual cost per successfully treated DRV600-arm patient was US$7273.

CONCLUSIONS

The efficacy of a darunavir daily dose of 600 mg seemed to be similar to the efficacy of the standard 800 mg dose in virologically suppressed HIV-infected patients on triple ART. This strategy can potentially translate to substantial savings in the cost of care of HIV-infected patients.

Maternal anaemia and duration of zidovudine in antiretroviral regimens for preventing mother-to-child transmission: a randomized trial in three African countries

BACKGROUND

Although substantiated by little evidence, concerns about zidovudine-related anaemia in pregnancy have influenced antiretroviral (ARV) regimen choice for preventing mother-to-child transmission of HIV-1, especially in settings where anaemia is common.

METHODS

Eligible HIV-infected pregnant women in Burkina Faso, Kenya and South Africa were followed from 28 weeks of pregnancy until 12-24 months after delivery (n = 1070). Women with a CD4 count of 200-500 cells/mm(3) and gestational age 28-36 weeks were randomly assigned to zidovudine-containing triple-ARV prophylaxis continued during breastfeeding up to 6-months, or to zidovudine during pregnancy plus single-dose nevirapine (sd-NVP) at labour. Additionally, two cohorts were established, women with CD4 counts: <200 cells/mm(3) initiated antiretroviral therapy, and >500 cells/mm(3) received zidovudine during pregnancy plus sd-NVP at labour. Mild (haemoglobin 8.0-10.9 g/dl) and severe anaemia (haemoglobin < 8.0 g/dl) occurrence were assessed across study arms, using Kaplan-Meier and multivariable Cox proportional hazards models.

RESULTS

At enrolment (corresponded to a median 32 weeks gestation), median haemoglobin was 10.3 g/dl (IQR = 9.2-11.1). Severe anaemia occurred subsequently in 194 (18.1%) women, mostly in those with low baseline haemoglobin, lowest socio-economic category, advanced HIV disease, prolonged breastfeeding (≥ 6 months) and shorter ARV exposure. Severe anaemia incidence was similar in the randomized arms (equivalence P-value = 0.32). After 1-2 months of ARV's, severe anaemia was significantly reduced in all groups, though remained highest in the low CD4 cohort.

CONCLUSIONS

Severe anaemia occurs at a similar rate in women receiving longer triple zidovudine-containing regimens or shorter prophylaxis. Pregnant women with pre-existing anaemia and advanced HIV disease require close monitoring.

TRIAL REGISTRATION NUMBER

ISRCTN71468401.

An update on oxidative stress-mediated organ pathophysiology

Exposure to environmental pollutants and drugs can result in pathophysiological situations in the body. Research in this area is essential as the knowledge on cellular survival and death would help in designing effective therapeutic strategies that are needed for the maintenance of the normal physiological functions of the body. In this regard, naturally occurring bio-molecules can be considered as potential therapeutic targets as they are normally available in commonly consumed foodstuffs and are thought to have minimum side effects. This review article describes the detailed mechanisms of oxidative stress-mediated organ pathophysiology and the ultimate fate of the cells either to survive or to undergo necrotic or apoptotic death. The mechanisms underlying the beneficial role of a number of naturally occurring bioactive molecules in oxidative stress-mediated organ pathophysiology have also been included in the review. The review provides useful information about the recent progress in understanding the mechanism(s) of various types of organ pathophysiology, the complex cross-talk between these pathways, as well as their modulation in stressed conditions. Additionally, it suggests possible therapeutic applications of a number of naturally occurring bioactive molecules in conditions involving oxidative stress.

Population pharmacokinetics study of recommended zidovudine doses in HIV-1-infected children

The aims of this study were to describe the pharmacokinetics of zidovudine (ZDV) and its biotransformation to its metabolite, 3*-azido-3*-deoxy-5*-glucuronylthymidine (G-ZDV), in HIV-infected children, to identify factors that influence the pharmacokinetics of ZDV, and to compare and evaluate the doses recommended by the World Health Organization (WHO) and the Food and Drug Administration (FDA). ZDV concentrations in 782 samples and G-ZDV concentrations in 554 samples from 247 children ranging in age from 0.5 to 18 years were retrospectively measured. A population pharmacokinetic model was developed with NONMEM software (version 6.2), and the pharmacokinetics of ZDV were best described by a one-compartment model with first-order absorption and elimination. The effect of body weight on the apparent elimination clearance and volume of distribution was significant. The mean population parameter estimates were as follows: absorption rate, 2.86 h(-1); apparent elimination clearance, 89.7 liters · h(-1) (between-subject variability, 0.701 liters · h(-1)); apparent volume of distribution, 229 liters (between-subject variability, 0.807 liters); metabolic formation rate constant, 12.6 h(-1) (between-subject variability, 0.352 h(-1)); and elimination rate constant of G-ZDV, 2.27 h(-1). On the basis of simulations with FDA and WHO dosing recommendations, the probabilities of observing efficient exposures (doses resulting in exposures of between 3 and 5 mg/liter · h) with less adverse events (doses resulting in exposures below 8.4 mg/liter · h) were higher when the FDA recommendations than when the WHO recommendations were followed. In order to improve the FDA recommendations, ZDV doses should be reconsidered for the weight band (WB) of 20 to 40 kg. The most appropriate doses should be decreased from 9 to 8 mg/kg of body weight twice a day (BID) for the WB from 20 to 29.9 kg and from 300 to 250 mg BID for the WB from 30 to 39.9 kg. The highest dose, 300 mg BID, should be started from body weights of 40 kg.

Clinical significance and characterization of AZT-resistant strains of HIV-1

A number of laboratories have now independently confirmed that zidovudine (AZT)-resistant strains of human immunodeficiency virus type 1 (HIV-1) may be isolated from patients undergoing prolonged therapy with this drug. In certain instances, such drug-resistant viral isolates have been obtained from patients with clinical acquired immune deficiency syndrome (aids), while in others, isolation of drug-resistant strains has been achieved in the case of HIV seropositive, asymptomatic subjects. Most of the evidence points to a series of mutations within the polymerase gene of HIV-1, which encodes viral reverse transcriptase, as being responsible for development of the drug-resistant phenotype. It further appears that over 50% of patients treated with AZT for periods longer than six months are likely to yield drug-resistant strains of HIV-1 in their circulation. Furthermore, the development of drug resistance soon after initiation of AZT therapy may potentially be correlated with the likelihood of AZT treatment failure. In several instances, cross resistance has been observed between AZT and other nucleosides being considered for potential therapy of HIV-1-associated disease.

Daily quality control in CD3+ and CD4+ T cell estimation by the FACSCount system at a tertiary care center in south India

CD4(+) T cell count estimations are subject to high variations; hence, in this study, the previous day's tested samples were included routinely as the internal quality controls. The percentages of variation of the 2-day values were analyzed for 280 observations and the mean variation for CD4(+) and CD3(+) T cell counts ranged from 5.21% to 9.66%. This method is a good internal quality control (IQC) procedure for the estimation of CD3(+) and CD4(+) T cell counts in resource-poor settings.

The history of antiretroviral therapy and of its implementation in resource-limited areas of the world

HIV/AIDS not only represents the most severe epidemic in modern times, but also the greatest public health challenge in history. The response of the scientific community has been impressive and in just a few years, turned an inevitably fatal disease into a chronic manageable although not yet curable condition. The development of antiretroviral therapy is not only the history of scientific advancements: it is the result of the passionate 'alliance' towards a common goal between researchers, doctors and nurses, pharmaceutical industries, regulators, public health officials and the community of HIV-infected patients, which is rather unique in the history of medicine. In addition, the rapid and progressive development of antiretroviral therapy has not only proven to be life-saving for many millions but has been instrumental in unveiling the inequities in access to health between rich and poor countries of the world. Optimal benefits indeed, are not accessible to all people living with HIV, with challenges to coverage and sustainability in low and middle income countries. This paper will review the progress made, starting from the initial despairing times, till the current battle towards universal access to treatment and care for all people living with HIV.

CD4 lymphocyte count as predictor of drug expenditure in a cohort of anti-HIV seropositive haemophiliacs

The CD4 lymphocyte counts of 76 haemophilic patients who acquired HIV infection from unsterilised clotting factor concentrate were measured and the cost of all drugs used to treat each patient calculated. A rapid rise in drug costs was seen as patients' CD4 counts approached 0.2×109/L, the level at which zidovudine treatment and prophylaxis against Pneumocystis carinii are started. The relationship between decline in CD4 counts and cost of drugs was found to be linear. The authors conclude that it is possible to use CD4 counts to predict future drug costs.

When to start antiretroviral therapy

Antiretrovirals perform superbly in combating HIV infection. But when to initiate therapy in asymptomatic, nonpregnant, hepatitis-free, HIV-infected persons is not securely established. Of two completed randomized trials using modern therapy, a Haitian trial demonstrated a benefit to initiating therapy between 200 and 350 CD4 cells/mm(3) as compared with less than 200 CD4 cells/mm(3) and an international trial demonstrated a benefit to starting at greater than 350 CD4 cells/mm(3) as compared with less than 250 CD4 cells/mm(3). Many observational cohorts support initiating treatment at less than 350 CD4 cells/mm(3). Of these, three large studies supported initiation at less than 350 cells/mm(3), less than 450 CD4 cells/mm(3), and less than 500 CD4 cells/mm(3), respectively, but only the last supported starting at higher counts. Such studies are not probative, given the problem of confounding. No conventional antiretroviral regimen is free of long-term adverse effects, especially over decades of use. All are expensive and require expensive monitoring. When resources are restricted, initiation of antiretrovirals for persons with high CD4 count diverts treatment from more needy persons. Pathophysiological considerations favor universal treatment because antiretrovirals mitigate systemic inflammation, which aggravates atherosclerosis. There are suggestions that HIV hastens the natural decline of cognitive, renal, and pulmonary function as well as bone mineral loss; the mechanism(s) are uncertain, as is the ability of antiretrovirals to counteract the probable acceleration. The four major guideline panels, although all have issued updates in the past year, are not consistent in recommendations for treatment of HIV-infected persons with counts greater than 350 CD4 cells/mm(3).

Statistical decisions and the interim analyses of clinical trials

This paper analyzes statistical decisions during the interim analyses of clinical trials. After some general remarks about the ethical and scientific demands of clinical trials, I introduce the notion of a hard-case clinical trial, explain the basic idea behind it, and provide a real example involving the interim analyses of zidovudine in asymptomatic HIV-infected patients. The example leads me to propose a decision analytic framework for handling ethical conflicts that might arise during the monitoring of hard-case clinical trials. I use computer simulations to show how the framework can assist in reconciling certain ethical conflicts. The framework is partial, lacking the precision of a complete systematization of statistical monitoring procedures in practice.