Pharmacokinetics of antiretroviral therapy in HIV-1-infected children

Challenges to achieving and maintaining viral suppression among children living with HIV

OBJECTIVES

The objective of this study was to determine the time to, and durability of, viral suppression, among Canadian children living with HIV after initiation of combination antiretroviral therapy (cART).

DESIGN

Prospective, multicenter Canadian cohort study (Early Pediatric Initiation Canada Child Cure Cohort), using both prospective and retrospectively collected data.

METHODS

Kaplan-Meir survival estimates with Cox regression were used to determine the time to and risk factors for viral suppression, defined as two consecutive undetectable viral loads (<50 copies/ml) at least 30 days apart after initiation of cART.

RESULTS

A total of 228 children were enrolled between December 2014 and December 2018. The time to viral suppression was significantly shorter among children initiating cART after 5 ≤ 5 vs. years or less of age [adjusted hazard ratio (aHR) 1.57, 95% confidence interval (CI) 1.13-2.20], among those born after 2010 vs. prior (aHR 1.71, 95% CI 1.04-2.79), and among those without child protection services involvement (aHR 1.44, 95% CI 1.03-2.01). Overall, 27% of children had a viral rebound within 3 years of achieving viral suppression; the risk of viral rebound was significantly lower among children initiating cART after 5 vs. 5 years or less of age [adjusted odds ratio (aOR): 0.32, 95% CI 0.13-0.81], those whose families had not received social assistance (aOR 0.16, 95% CI 0.06-0.46), and females vs. males (aOR 0.51, 95% CI 0.26-0.99).

CONCLUSION

Only 73% of the children in the Early Pediatric Initiation Canada Child Cure Cohort had maintained viral suppression 3 years after it was first achieved. Age at cART initiation, and socioeconomic factors were predictors of both time to viral suppression and risk of viral rebound in this cohort.

The Transition of Care From Pediatric to Adult Health-Care Services of Vertically HIV-Infected Adolescents: A Pilot Study

Objective: Clinical and psychological HIV-related problems peak during adolescence, which coincides with transition of children and adolescents infected from mothers from pediatric to adult reference centers for HIV infection. Transition often is done without specific programs. We wanted to explore transition as an opportunity to increase the efficacy of care and the psychological well-being through a specific program. Methods: Thirteen vertically infected patients aged 13-20 years were followed up for 24 months by pediatricians, infectious disease specialists, a psychologist, and a nurse. Interventions consisted in joint clinic, simplification of therapy, patient group discussions, HIV infection explanations, and psychological support, lasting 12 months. Efficacy was measured by viro-immunological outcomes and adherence to therapy and psychological tests. Clinical, viro-immunological, and psychological evaluations were performed at 0 (T0) and 12 months (T12) and 6 months after transition to an adult center (T18). Psychological outcomes were assessed using standardized questionnaires for quality of life and self-esteem. Results: In 11/13 participants, pills administrations/day were significantly reduced. Patients with undetectable viral load and CD4+ >25% increased from 61 to 77% and from 61 to 74%, respectively. Six months after transition, all patients exhibited an undetectable viral load. Adolescents' awareness of the severity of the disease and the risk of sexual transmission was generally poor. Patients classified with "severe" psychological distress according to the quality of life index decreased from 38 to 15% and well-being increased. Similar results were observed 6 months after the transition to adult care. No effect was observed on self-esteem index. Conclusions: Specific protocols for transition should be developed to optimize resilience and psychological well-being, including routine psychological support for adolescents with HIV infection transiting from pediatric to adult centers for HIV infection.

The physical and psychological effects of HIV infection and its treatment on perinatally HIV-infected children

INTRODUCTION

As highly active antiretroviral therapy (HAART) transforms human immunodeficiency virus (HIV) into a manageable chronic disease, new challenges are emerging in treating children born with HIV, including a number of risks to their physical and psychological health due to HIV infection and its lifelong treatment.

METHODS

We conducted a literature review to evaluate the evidence on the physical and psychological effects of perinatal HIV (PHIV+) infection and its treatment in the era of HAART, including major chronic comorbidities.

RESULTS AND DISCUSSION

Perinatally infected children face concerning levels of treatment failure and drug resistance, which may hamper their long-term treatment and result in more significant comorbidities. Physical complications from PHIV+ infection and treatment potentially affect all major organ systems. Although treatment with antiretroviral (ARV) therapy has reduced incidence of severe neurocognitive diseases like HIV encephalopathy, perinatally infected children may experience less severe neurocognitive complications related to HIV disease and ARV neurotoxicity. Major metabolic complications include dyslipidaemia and insulin resistance, complications that are associated with both HIV infection and several ARV agents and may significantly affect cardiovascular disease risk with age. Bone abnormalities, particularly amongst children treated with tenofovir, are a concern for perinatally infected children who may be at higher risk for bone fractures and osteoporosis. In many studies, rates of anaemia are significantly higher for HIV-infected children. Renal failure is a significant complication and cause of death amongst perinatally infected children, while new data on sexual and reproductive health suggest that sexually transmitted infections and birth complications may be additional concerns for perinatally infected children in adolescence. Finally, perinatally infected children may face psychological challenges, including higher rates of mental health and behavioural disorders. Existing studies have significant methodological limitations, including small sample sizes, inappropriate control groups and heterogeneous definitions, to name a few.

CONCLUSIONS

Success in treating perinatally HIV-infected children and better understanding of the physical and psychological implications of lifelong HIV infection require that we address a new set of challenges for children. A better understanding of these challenges will guide care providers, researchers and policymakers towards more effective HIV care management for perinatally infected children and their transition to adulthood.

Measuring adherence to antiretroviral therapy in children and adolescents in western Kenya

Introduction

High levels of adherence to antiretroviral therapy (ART) are central to HIV management. The objective of this study was to compare multiple measures of adherence and investigate factors associated with adherence among HIV-infected children in western Kenya.

Methods

We evaluated ART adherence prospectively for six months among HIV-infected children aged ≤14 years attending a large outpatient HIV clinic in Kenya. Adherence was reported using caregiver report, plasma drug concentrations and Medication Event Monitoring Systems (MEMS^®). Kappa statistics were used to compare adherence estimates with MEMS^®. Logistic regression analyses were performed to assess the association between child, caregiver and household characteristics with dichotomized adherence (MEMS^® adherence ≥90% vs. <90%) and MEMS^® treatment interruptions of ≥48 hours. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

Results

Among 191 children, mean age at baseline was 8.2 years and 55% were female. Median adherence by MEMS^® was 96.3% and improved over the course of follow-up (p<0.01), although 49.5% of children had at least one MEMS^® treatment interruption of ≥48 hours. Adherence estimates were highest by caregiver report, and there was poor agreement between MEMS^® and other adherence measures (Kappa statistics 0.04–0.37). In multivariable logistic regression, only caregiver-reported missed doses in the past 30 days (OR 1.25, 95% CI 1.14–1.39), late doses in the past seven days (OR 1.14, 95% CI 1.05–1.22) and caregiver-reported problems with getting the child to take ART (OR 1.10, 95% CI 1.01–1.20) were significantly associated with dichotomized MEMS^® adherence. The caregivers reporting that ART made the child sick (OR 1.12, 95% CI 1.01–1.25) and reporting difficulties in the community that made giving ART more difficult (e.g. stigma) (OR 1.14, 95% CI 1.02–1.27) were significantly associated with MEMS^® treatment interruptions in multivariable logistic regression.

Conclusions

Non-adherence in the form of missed and late doses, treatment interruptions of more than 48 hours and sub-therapeutic drug levels were common in this cohort. Adherence varied significantly by adherence measure, suggesting that additional validation of adherence measures is needed. Few factors were consistently associated with non-adherence or treatment interruptions.

Raltegravir: a review of its use in the management of HIV-1 infection in children and adolescents

Raltegravir (ISENTRESS(®)) is an HIV-1 integrase strand transfer inhibitor that is well established as a component of highly active antiretroviral therapy regimens for the treatment of adults with HIV-1 infection, and has recently been approved for the treatment of HIV-1-infected children and adolescents aged 2-18 years. A new chewable formulation has been introduced and results of a pharmacokinetic study have led to the establishment of dosages for this formulation for children. In a phase I/II, open-label, multicentre, clinical trial, raltegravir (administered as the chewable or the film-coated tablet) in combination with optimized background antiretroviral therapy was an effective treatment for treatment-experienced children and adolescents with HIV-1 infection, in terms of virologic measures of efficacy (i.e. a decrease of in HIV-1 RNA levels of ≥1 log(10), or an HIV-1 RNA level of <400 copies/mL at the 24-week primary efficacy assessment), with virologic efficacy sustained at the 48-week assessment. Immunologic improvements (increases from baseline in CD4+ cell counts) were also observed. As a component of combination therapy, raltegravir was generally well tolerated over a period of up to 48 weeks. Raltegravir is an important new option for the treatment of children and adolescents with HIV-1 infection, and the introduction of a new chewable formulation (allowing dosage flexibility) extends its benefits to the treatment of younger children.

Children with HIV are not small adults: what is different in pharmacology?

PURPOSE OF REVIEW

The pharmacokinetics of antiretroviral drugs are highly variable among HIV-infected children. This review describes pharmacokinetic processes in children and recent pharmacokinetic data in children with HIV. The general lack of pharmacokinetic data and the potential role of therapeutic drug monitoring are discussed.

RECENT FINDINGS

It was found unexpectedly that exposure to lopinavir is decreased in the first 6 months of life. Recent findings of subtherapeutic efavirenz concentrations in children suggest that pediatric dose recommendations should be re-evaluated. In addition, recommended dosing of lamivudine leads to lower exposure in children younger than 6 years of age. Preliminary results of pediatric fixed-dose combination tablets for HIV-infected children with a higher nevirapine to stavudine and lamivudine ratio than adult fixed-dose combinations suggest adequate drug exposure. As an alternative to plasma sampling, concentrations of nevirapine can be determined in saliva.

SUMMARY

There is a shortage of pharmacokinetic data in the highly variable population of HIV-infected children. Selected pharmacology studies should be undertaken to improve pediatric dose guidance of existing antiretroviral drugs. Therapeutic drug monitoring is a useful tool to optimize treatment in HIV-infected children. More data are needed, however, to establish child-specific reference values.

Influence of CYP2B6 516G>T polymorphism and interoccasion variability (IOV) on the population pharmacokinetics of efavirenz in HIV-infected South African children

OBJECTIVE

To investigate the influence of CYP2B6 516G>T polymorphism, as a covariate, and of interoccasion variability (IOV) on the oral clearance (CL/F) of efavirenz (EFV) in treatment-naïve black South African children over a period of 24 months post-antiretroviral therapy (ART) initiation.

METHODS

HIV-infected black children (n = 60, aged 3-16 years), with no prior exposure to ART, eligible to commence ART and attending an outpatient clinic were enrolled into this study. Blood samples were taken at mid-dose interval at 1, 3, 6, 12, 18 and 24 months post-ART initiation. EFV plasma samples were determined with an adapted and validated LC/MS/MS method. Genotyping of the CYP2B6 G516T single nucleotide polymorphism (SNP) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). NONMEM was used for the population pharmacokinetic modelling.

RESULTS

EFV concentrations below 1 μg/mL accounted for 18% (116/649), EFV concentrations >4 μg/mL accounted for 29.5% (192/649) and concentrations within the therapeutic range (1-4 μg/mL) represented 52.5% (341/649) of all the samples determined. The covariates age, weight and CYP2B6 G516Tgenotype were included in the final model with population estimates for CL/F determined as 2.46, 4.60 and 7.33 L/h for the T/T, G/T and G/G genotype groups respectively.

CONCLUSIONS

The inclusion of both age and weight to predict accurate EFV CL values for the respective genotype groups within this paediatric population was required, whereas the addition of gender and body surface area did not improve the predictions. The importance of introducing IOV in a PK model for a longitudinal study with sparsely collected data was again highlighted by this investigation.

The role of therapeutic drug monitoring in the management of patients with human immunodeficiency virus infection

Therapeutic drug monitoring (TDM) is a well-established method to optimize dosing regimens in individual patients for drugs that are characterized by a narrow therapeutic range and large interindividual pharmacokinetic variability. For some antiretroviral drugs, mainly nonnucleoside reverse transcriptase inhibitors and protease inhibitors, TDM has been proposed as a means to improve the response in human immunodeficiency virus-infected patients. In contrast, nucleoside reverse transcriptase inhibitors do not show a predictable plasma concentration-response (toxicity, efficacy) relationship, and intracellular analyses are expensive. Therefore, TDM is generally not recommended for this class of drugs. TDM has been successfully applied in the clinical practice for certain antiretroviral drugs, but there are ongoing research efforts on the use and refinement of TDM for human immunodeficiency virus treatment, and convincing data from randomized trials are still needed. The best pharmacokinetic measures of drug exposure such as trough and peak concentrations or concentration ratios have not been unambiguously established.

Immunovirological response to combined antiretroviral therapy and drug resistance patterns in children: 1- and 2-year outcomes in rural Uganda

Background

Children living with HIV continue to be in urgent need of combined antiretroviral therapy (ART). Strategies to scale up and improve pediatric HIV care in resource-poor regions, especially in sub-Saharan Africa, require further research from these settings. We describe treatment outcomes in children treated in rural Uganda after 1 and 2 years of ART start.

Methods

Cross-sectional assessment of all children treated with ART for 12 (M12) and 24 (M24) months was performed. CD4 counts, HIV RNA levels, antiretroviral resistance patterns, and non-nucleoside reverse transcriptase inhibitor (NNRTI) plasma concentrations were determined. Patient adherence and antiretroviral-related toxicity were assessed.

Results

Cohort probabilities of retention in care were 0.86 at both M12 and M24. At survey, 71 (83%, M12) and 32 (78%, M24) children remained on therapy, and 84% participated in the survey. At ART start, 39 (45%) were female; median age was 5 years. Median initial CD4 percent was 11% [IQR 9-15] in children < 5 years old (n = 12); CD4 count was 151 cells/mm³ [IQR 38-188] in those ≥ 5 years old (n = 26). At M12, median CD4 gains were 11% [IQR 10-14] in patients < 5 years old, and 206 cells/mm³ [IQR 98-348] in ≥ 5 years old. At M24, median CD4 gains were 11% [IQR 5-17] and 132 cells/mm³ [IQR 87-443], respectively. Viral suppression (< 400 copies/mL) was achieved in 59% (M12) and 33% (M24) of children. Antiretroviral resistance was found in 25% (M12) and 62% (M24) of children. Overall, 29% of patients had subtherapeutic NNRTI plasma concentrations.

Conclusions

After one year of therapy, satisfactory survival and immunological responses were observed, but nearly 1 in 4 children developed viral resistance and/or subtherapeutic plasma antiretroviral drug levels. Regular weight-adjustment dosing and strategies to reinforce and maintain ART adherence are essential to maximize duration of first-line therapy in children in resource-limited countries.

Ultra-fast analysis of plasma and intracellular levels of HIV protease inhibitors in children: a clinical application of MALDI mass spectrometry

HIV protease inhibitors must penetrate into cells to exert their action. Differences in the intracellular pharmacokinetics of these drugs may explain why some patients fail on therapy or suffer from drug toxicity. Yet, there is no information available on the intracellular levels of HIV protease inhibitors in HIV infected children, which is in part due to the large amount of sample that is normally required to measure the intracellular concentrations of these drugs. Therefore, we developed an ultra-fast and sensitive assay to measure the intracellular concentrations of HIV protease inhibitors in small amounts of peripheral blood mononuclear cells (PBMCs), and determined the intracellular concentrations of lopinavir and ritonavir in HIV infected children. An assay based on matrix-assisted laser desorption/ionization (MALDI) - triple quadrupole mass spectrometry was developed to determine the concentrations of HIV protease inhibitors in 10 µL plasma and 1×10⁶ PBMCs. Precisions and accuracies were within the values set by the FDA for bioanalytical method validation. Lopinavir and ritonavir did not accumulate in PBMCs of HIV infected children. In addition, the intracellular concentrations of lopinavir and ritonavir correlated poorly to the plasma concentrations of these drugs. MALDI-triple quadrupole mass spectrometry is a new tool for ultra-fast and sensitive determination of drug concentrations which can be used, for example, to assess the intracellular pharmacokinetics of HIV protease inhibitors in HIV infected children.

Efavirenz plasma concentrations at 1, 3, and 6 months post-antiretroviral therapy initiation in HIV type 1-infected South African children

The aim of this study was to quantify the plasma efavirenz concentrations over 6 months in black HIV-1-infected South African children (3-14 years), from resource-limited households, attending an outpatient clinic. The children were antiretroviral treatment (ART) naive and received efavirenz in combination with two nucleoside reverse transcriptase inhibitors according to South African national guidelines. Two blood samples were taken between 12 and 20 h after the last efavirenz dose at 1 (n = 58), 3 (n = 54), and 6 (n = 54) months post-ART initiation. A total of 328 efavirenz mid-dose plasma samples from 58 patients was determined with a validated liquid chromatography tandem mass spectrometry method. Viral suppression (<25 copies/ml) was achieved in 95% of the children after 6 months on ART. The median (range) plasma concentration at time points 1 and 2 were 2.06 (0.10-11.14) and 1.80 (0.14-10.70) microg/ml with respective mean (+/-SD) blood sampling times of 15.24 (2.03) and 16.91 (2.03) h post-evening dose. Efavirenz plasma samples within the therapeutic range of 1-4 microg/ml accounted for 58%; 17% were <1 microg/ml and 25% were >4 microg/ml over the 6 months. Efavirenz levels persistently >4 microg/ml were recorded for 13 (23%) children and 3 (5%) children had persistent efavirenz levels <1 microg/ml. Possible reasons for efavirenz plasma levels outside the accepted therapeutic range include genetic variation in drug metabolism, incorrect dosing, drug-drug interactions, and nonadherence. However, these need to be further explored and the importance of sequential plasma levels has been highlighted in this study.

Comparison of levels of antiretroviral drugs with efficacy in children with HIV infection

OBJECTIVE

To determine the prevalence of low and high antiretroviral (ARV) plasma levels and to analyze correlation between ARV concentrations and the appearance of therapeutic failure and toxicity.

METHODS

The authors present here a study evaluating antiretroviral plasma concentrations in HIV infected children on nonnucleoside reverse transcriptase inhibitors and protease inhibitors based therapy. The authors carried out a multicentre, cross-sectional study, including HIV-infected children from five large Hospitals in Madrid, Spain. Clinical, haematological, biochemical and immuno-virological parameters were assessed. Antiretroviral plasma trough levels were performed using a validated high performance liquid chromatography method.

RESULTS

Between April 2006 and April 2008, 129 children were enrolled in the present study, with median treatment duration of 39.2 months. 25.5% of the non-nucleoside reverse transcriptase inhibitors levels were low and 17.6%, high. 27.9% percent of the protease inhibitors levels were low and 12.5%, high. A correlation was found among adequate or high levels of antiretrovirals and normal CD4 percentage and low viral load. Lopinavir/ritonavir plasma levels were correlated with an increase in lipodystrophy. Patients with Tanner stage 1 presented the lowest ARV plasma levels. Full adherence was reported for all the participants by a questionnaire.

CONCLUSION

Many HIV-infected children show ARV plasma levels out of the therapeutic range which demands a child-adjusted approach. However, larger studies are urgently needed in pediatric populations to define optimal reference values.

Long-term effectiveness of highly active antiretroviral therapy (HAART) in perinatally HIV-infected children in Denmark

The long-term impact of highly active antiretroviral therapy (HAART) on HIV-1 infected children is not well known. The Danish Paediatric HIV Cohort Study includes all patients <16 y of age with HIV-1 infection in Denmark. We report the complete follow-up from 1996 to 2005 of 49 perinatally infected children treated with HAART. Initial HAART included 2 nucleoside reverse-transcriptase inhibitors in combination with either a protease inhibitor (n =38) or a non-nucleoside reverse-transcriptase inhibitor (n =12). 19 (39%) patients were previously treated with mono- or dual therapy. Baseline characteristics were median CD4 percentage 14% and HIV-RNA viral load 4.9 log(10). Within the first 12 weeks of therapy approximately 60% achieved HIV-RNA viral load <500 copies/ml, and this remained stable for up to 8 y, although many children changed the components of HAART. The proportion of children with CD4 percentage >25% increased to 60-70% over the y of treatment. For the total cohort, 245 patient-y of observation were available with only 1 death. During our observation period there were no signs of a waning impact. The challenge remains to maintain a high adherence to therapy as the children grow into adolescence and develop more independence from family and health care staff.

Practical therapeutic drug management in HIV-infected patients: use of population pharmacokinetic models supplemented by individualized Bayesian dose optimization

Individualized, model-based, target-oriented optimal concentration-controlled dosing of HIV medications can be beneficial to patients for whom there are limited dosing guidelines, such as children, adolescents, or patients with altered physiologic function. Barriers to this approach include lack of training, expertise, and access to appropriate software to assist the clinician. The authors present 4 illustrative clinical cases of HIV-infected patients whose therapy was optimized using population pharmacokinetic models (here generated from published studies) and supplemented by individualized Bayesian adaptive control of dosage regimens as implemented in the MM-USCPACK software. These 4 cases illustrate how clinicians can maximize therapeutic success in (1) patients with reduced drug clearance, (2) young adolescents transitioning to adult physiology, (3) patients with dose-dependent toxicity, and (4) adolescents with limited therapeutic options.

Indinavir/low-dose ritonavir containing HAART in HIV-1 infected children has potent antiretroviral activity, but is associated with side effects and frequent discontinuation of treatment

We here present the study results of 21 HIV-1 infected children who were treated with indinavir plus low-dose ritonavir and two nucleoside reverse transcriptase inhibitors (NRTIs) for 48 weeks. Although this q12h HAART regimen had potent antiretroviral activity, it was frequently associated with side effects and discontinuation of therapy.

Treatment of pediatric HIV infection

HIV-infected children require a peculiar management when compared to infected adults. Antiretroviral therapy has been quite well adapted to children, but new studies are needed to answer many unsolved questions, such as when to start therapy in asymptomatic infected children. Recently, several guidelines have been updated. In this review, we compare these recommendations together with the latest studies concerning the treatment of HIV in children. A triple-drug combination therapy based either on nonnucleoside reverse transcriptase inhibitors or protease inhibitors is the recommended initial therapy. After treatment failure, a second-line therapy should be based on switching between these two regimens. Antiretroviral therapy should be managed by an expert in pediatric and adolescent HIV infection. The importance of children's adherence to therapy is a crucial point, particularly in adolescents.

Nucleoside and nucleotide reverse transcriptase inhibitors in children

By the end of 2006, approximately 2.3 million children worldwide were living with HIV infection, representing about 15% of all HIV-infected individuals but only 5-7% of the total population of treated patients worldwide. Despite a general increase in the use of antiretroviral therapy (ART) in resource-limited settings, appropriate care and ART remain inaccessible for most of the world's HIV-infected children. ART of children is challenging because of a general lack of paediatric formulations (including tablets in paediatric strengths), limited options of drugs available for children (some have been approved only for use in adults), different viral and immunological responses, dependency on caregivers for administration of the therapy, and specific issues of toxicity in long-term therapy related to maturation and development. As in adults, nucleoside reverse transcriptase inhibitors (NRTIs) are a key component of any ART schedule in children, being the recommended 'backbone' treatment in US, European and WHO guidelines, and, indeed, NRTIs have been extensively studied in children. NRTIs are the class of antiretroviral drugs that have more drugs licensed for paediatric use and more paediatric formulations.Generally, the dual NRTI backbone treatment of combination with a non-NRTI (NNRTI) or protease inhibitor (PI) should comprise a cytidine analogue (lamivudine, emtricitabine) and a thymidine analogue (stavudine, zidovudine), guanosine analogue (i.e. abacavir), or nucleotide RTI (NtRTI; i.e. tenofovir). European and US guidelines recommend the use of triple NRTI therapy (abacavir/lamivudine/zidovudine) in children with anticipated poor adherence to other treatment regimens because of tablet burden. In conclusion, while use of ART in children needs to be dramatically increased, selecting and administering the best drug combination for children is still limited by a lack of paediatric formulations and knowledge of drug metabolism, safety and efficacy in children. NRTIs are already a key component of paediatric ART, but fixed-dose combinations and specific research in children are needed to optimise their use. In this article we review the available information to facilitate selection of the best NRTI for backbone treatment in combination ART for HIV-infected children.

Clinical management of HIV infection in children

PURPOSE OF REVIEW

The aim of this article is to review recent advances in the clinical care of HIV-infected children.

RECENT FINDINGS

Obstacles to diagnosing HIV in children and providing clinical care to those HIV infected relate to a number of technical and operational factors. Most countries now have antiretroviral treatment guidelines and have incorporated co-trimoxazole prophylaxis for infected and exposed infants and children. Implementation lags behind policy and technical recommendations. Optimal early infant feeding remains difficult and, while breastfeeding remains the safest feeding option for child survival, it carries with it the risk of HIV acquisition. Recent data suggest HIV-free survival at 18 months is comparable in infants who are replacement-fed or exclusively breastfed for the first 6 months of life. Antiretroviral treatment efficacy in children is now well documented. Optimal timing of initiation of antiretroviral treatment remains uncertain; in general it is started earlier, especially in infants. Children starting treatment in infancy are surviving and reaching adulthood; new problems of managing the highly treatment-experienced and adolescents are emerging.

SUMMARY

New antiretroviral drugs and classes will be needed for the future; research is urgently required to characterize optimal nutritional interventions, interpretation of immunological and virological parameters, and develop diagnostic tools for use in health services with limited infrastructure and capacity.

Increasing antiretroviral drug access for children with HIV infection

Although there have been great gains in the prevention of pediatric HIV infection and provision of antiretroviral therapy for children with HIV infection in resource-rich countries, many barriers remain to scaling up HIV prevention and treatment for children in resource-limited areas of the world. Appropriate testing technologies need to be made more widely available to identify HIV infection in infants. Training of practitioners in the skills required to care for children with HIV infection is required to increase the number of children receiving antiretroviral therapy. Lack of availability of appropriate antiretroviral drug formulations that are easily usable and inexpensive is a major impediment to optimal care for children with HIV. The time and energy spent trying to develop liquid antiretroviral formulations might be better used in the manufacture of smaller pill sizes or crushable tablets, which are easier to dispense, transport, store, and administer to children.