Tenofovir disoproxil fumarate and an optimized background regimen of antiretroviral agents as salvage therapy: impact on bone mineral density in HIV-infected children

Antiretroviral treatment in pregnancy: a six-year perspective on recent trends in prescription patterns, viral load suppression, and pregnancy outcomes

The aim of the study was to describe the recent trends in antiretroviral treatment in late pregnancy and the sociodemographic changes among pregnant women with HIV over the last 6 years. Data from the National Program on Surveillance on Antiretroviral Treatment in Pregnancy in Italy were grouped per calendar year, and changes in antiretroviral treatment, population characteristics, maternal immunovirologic status and newborn clinical parameters were analyzed. A total of 981 HIV-infected mothers who delivered between 2002 and 2008 were evaluated. The proportion of women receiving at least three antiretroviral drugs at delivery increased significantly from 63.0% in 2002 to 95.5% in 2007-2008, paralleled by a similar upward trend in the proportion of women who achieved complete viral suppression at third trimester (from 37.3 in 2002 to 80.9 in 2007-2008; p < 0.001). The co-formulation of zidovudine plus lamivudine remained the most common nucleoside backbone in pregnancy, even if a significant increase in the use of tenofovir plus emtricitabine was observed in more recent years. Starting from 2003, nevirapine prescription declined, paralleled by a significant rise in the use of protease inhibitors (PI), which were present in more than 60% of regimens administered in 2007-2008. Nelfinavir was progressively replaced by ritonavir-boosted PIs, mainly lopinavir. No significant changes in preterm delivery, Apgar score, birth weight, and birth defects were observed during the study period, and the rate of HIV transmission remained below 2%. These data demonstrate a significant evolution in the treatment of HIV in pregnancy. Constant improvements in the rates of HIV suppression were observed, probably driven by the adoption of stronger and more effective regimens and by the increasing options available for combination treatment.

Incidence of persistent renal dysfunction in human immunodeficiency virus-infected children: associations with the use of antiretrovirals, and other nephrotoxic medications and risk factors

BACKGROUND

Survival of HIV-infected children continues to increase and the use of antiretrovirals (ARVs) is expanding; however there are few data regarding the incidence of renal dysfunction and associated risk factors among HIV-infected children and youth.

METHODS

A total of 2102 children enrolled in Pediatric AIDS Clinical Trials Group Study 219/219C, were followed and assessed prospectively for >30 months. Occurrence of clinical events and laboratory abnormalities were recorded using standardized criteria and forms. Therapeutic decisions were made by clinicians at each site. Occurrence of persistent renal laboratory abnormalities was the main outcome measure.

RESULTS

Four hundred forty-six (22%) enrollees exhibited at least one persistent renal laboratory abnormality. Elevated serum creatinine (Cr) was more common than persistent proteinuria (15% vs. 8%). The incidence of new renal laboratory abnormalities was 3.7 events per 100 person-years with rates increasing between 1993 and 2005. Older age (>or=6 years vs. <6 years), Hispanic ethnicity, and Black non-Hispanic race were associated with increased risk of renal dysfunction, but CDC clinical class and plasma HIV RNA levels were not. Subjects exposed to ARV regimens containing tenofovir and/or indinavir had approximately twice the risk of developing renal dysfunction compared with persons exposed to other ARVs. The risk of renal dysfunction was also elevated for other antivirals (hazard ratio = 5.4) and amphotericin B (hazard ratio = 28).

CONCLUSIONS

Persistent renal function abnormalities occur frequently in HIV-infected children. Improved survival, Black race and Hispanic ethnicity, and exposure to tenofovir, indinavir, and other antimicrobial agents increase the risk for renal dysfunction. All HIV-infected children should be monitored closely for evidence of renal disease.

Pharmacotherapy of pediatric and adolescent HIV infection

Significant advances have been made in the treatment of human immunodeficiency virus (HIV) infection over the past two decades. Improved therapy has prolonged survival and improved clinical outcome for HIV-infected children and adults. Sixteen antiretroviral (ART) medications have been approved for use in pediatric HIV infection. The Department of Health and Human Services (DHHS) has issued "Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection", which provide detailed information on currently recommended antiretroviral therapies (ART). However, consultation with an HIV specialist is recommended as the current therapy of pediatric HIV therapy is complex and rapidly evolving.

Side effects of long-term oral antiviral therapy for hepatitis B

The aim of this review is to summarize the safety profile of the five approved oral nucleoside analogs used to treat chronic hepatitis B virus (HBV) infection, focusing on both the class adverse effects and those that have been reported with individual agents, as well as their safety in pregnancy. All nucleoside analogs have a "Black Box" warning because of their potential for inhibition of human DNA polymerase gamma involved in mitochondrial DNA replication. A reduction in intracellular mitochondrial DNA levels can lead to varying clinical manifestations of mitochondrial toxicity (i.e., neuropathy, myopathy, lactic acidosis), but these side effects are rarely reported with the oral antiviral agents active against HBV. Adefovir and tenofovir are associated with a dose-dependent but usually reversible proximal renal tubular toxicity. For these reasons, patients receiving these agents should be monitored for renal toxicity and the dose modified for renal insufficiency. Prolonged use of tenofovir has also been reported to lead to reduced bone mineral density in patients with human immunodeficiency virus infection, but prospective studies in patients with HBV infection are lacking. Telbivudine treatment is associated with moderate serum creatine phosphokinase elevations in up to 12% of patients. There have been few prospective studies on the safety of nucleoside analogs during pregnancy. According to the Antiretroviral Pregnancy Registry, the incidence of birth defects associated with lamivudine and tenofovir use during pregnancy is not increased. Studies on the safety of long-term therapy with the nucleoside analogs, alone and in combination, are needed as are further studies of children, the elderly, pregnant women, and patients with renal insufficiency.

Tenofovir use in human immunodeficiency virus-1-infected children in the United kingdom and Ireland

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is neither licensed for use nor extensively studied in HIV-infected children. The only available formulation is an adult tablet, introducing the possibility of dosing errors in children. TDF interacts with other antiretrovirals and has been associated with decline in renal function and CD4 count. We describe the use of TDF in a cohort of HIV-1-infected children in the United Kingdom and Ireland.

METHODS

Children ever prescribed TDF and followed in the Collaborative HIV Pediatric Study cohort since 2001 were included in analyses of dosing, adverse events, and virologic and immunologic response. Suspected adverse drug reactions to TDF reported to the Medicines and Healthcare products Regulatory Agency during the same time were also reviewed.

RESULTS

One hundred fifty-nine of 1253 children had taken TDF. They were older and had clinically more advanced disease than the rest of the cohort. Eighteen percent received >120% and 37% received <80% of the suggested pediatric dose (8 mg/kg). Thirty-seven percent of new TDF regimens contained didanosine (ddI), though few since 2005. Twelve of 159 (7.5%) children experienced serious adverse events and stopped TDF permanently, 11 taking concurrent lopinavir-ritonavir, and 10 ddI; 5 had renal toxicity. Viral load suppressed to < or =50 copies/mL at 12 months in 38% of those starting TDF. Median increase in CD4 count at 12 months was +110 cells/mL (interquartile range, 9-270), but only 3 cells/mL in those taking concurrent ddI.

CONCLUSIONS

TDF seems to be an effective antiretroviral drug in this pediatric cohort, although considerable underdosing and overdosing occurs. A small number of children experienced serious adverse events while taking TDF; half were renal toxicity, most associated with concurrent ddI and lopinavir-ritonavir use.

Pharmacologic and nonpharmacologic options for the management of HIV infection during pregnancy

Over the past decade, significant advances have been made in the treatment of HIV-1 infection using both pharmacologic and nonpharmacologic strategies to prevent mother-to-child transmission (MTCT). Optimal prevention of the MTCT of HIV requires antiretroviral drugs (ARV) during pregnancy, during labor, and to the infant. ARVs reduce viral replication, lowering maternal plasma viral load and thus the likelihood of MTCT. Postexposure prophylaxis of ARV agents in newborns protect against infection following potential exposure to maternal HIV during birth. In general, the choice of an ARV for treatment of HIV-infected women during pregnancy is complicated by the need to consider the effectiveness of the therapy for the maternal disease as well as the teratogenic or teratotoxic potential of these drugs. Clinicians managing HIV in pregnancy need to discuss the potential risks and benefits of available therapy options so that mothers can make informed decisions in choosing the best treatment regimen for themselves and for their children.

Tenofovir-associated nephrotoxicity in two HIV-infected adolescent males

We report two cases of tenofovir (TDF)-associated nephrotoxicity in perinatally HIV-infected adolescents. The first case, a 16-year-old African American male with an absolute CD4+ cell count of 314 cells/mm(3), presented with an abrupt rise in serum creatinine leading to irreversible renal failure while on TDF-containing highly active antiretroviral therapy (HAART). While the patient had evidence of underlying kidney disease, the timing of his renal failure indicates that TDF played a central role. The second case, a 16-year-old African-American male with an absolute CD4+ cell count of 895 cells/mm3, presented with rickets and hypophosphatemia while receiving TDF-based HAART. To our knowledge, these cases represent the first reports of TDF-associated irreversible renal failure and rickets in pediatric patients. We believe these cases highlight important and potentially irreversible side effects of this agent and emphasize the need for further studies of the renal safety of TDF in pediatric patients.

Tenofovir use is Associated with an Increase in Serum Alkaline Phosphatase in the Swiss HIV Cohort Study

Background

Tenofovir (TDF) use has been associated with proximal renal tubulopathy, reduced calculated glomerular filtration rates (cGFR) and losses in bone mineral density. Bone resorption could result in a compensatory osteoblast activation indicated by an increase in serum alkaline phosphatase (sAP). A few small studies have reported a positive correlation between renal phosphate losses, increased bone turnover and sAP.

Methods

We analysed sAP dynamics in patients initiating ( n=657), reinitiating ( n=361) and discontinuing ( n=73) combined antiretroviral therapy with and without TDF and assessed correlations with clinical and epidemiological parameters.

Results

TDF use was associated with a significant increase of sAP from a median of 74 U/l (interquartile range 60–98) to a plateau of 99 U/l (82–123) after 6 months ( P<0.0001), with a prompt return to baseline upon TDF discontinuation. No change occurred in TDF-sparing regimes. Univariable and multivariable linear regression analyses revealed a positive correlation between sAP and TDF use ( P≤0.003), but no correlation with baseline cGFR, TDF-related cGFR reduction, changes in serum alanine aminotransferase (sALT) or active hepatitis C.

Conclusions

We document a highly significant association between TDF use and increased sAP in a large observational cohort. The lack of correlation between TDF use and sALT suggests that the increase in sAP is because of the bone isoenzyme and indicates stimulated bone turnover. This finding, together with published data on TDF-related renal phosphate losses, this finding raises concerns that TDF use could result in osteomalacia with a loss in bone mineral density at least in a subset of patients. This potentially severe long-term toxicity should be addressed in future studies.

Adverse effects of tenofovir use in HIV-infected pregnant women and their infants

BACKGROUND

Data regarding use of tenofovir disoproxil fumarate in HIV-infected pregnant women are limited.

OBJECTIVE

To identify adverse effects of tenofovir use during pregnancy in HIV-infected women and their infants.

METHODS

In a retrospective case series, the charts of 127 pregnant HIV-infected women who received highly active antiretroviral therapy (HAART) between 2001 and 2005 were reviewed. Those who received tenofovir during pregnancy were selected for this study. Each woman's chart was reviewed for clinical data and adverse events during the pregnancy; each infant's chart was reviewed for growth parameters from birth to 12 months.

RESULTS

Fifteen HIV-infected women with limited treatment options were prescribed HAART containing tenofovir during 16 pregnancies. In utero tenofovir exposure was a median of 127 days (range 6-259). Tenofovir was well tolerated by all women throughout pregnancy. There were 15 successful deliveries occurring at a median (range) of 36 weeks (30-40), with a median birth weight of 3255 g (1135-3610). Complications, including 1 spontaneous abortion, occurred in 9 pregnancies and were not attributed to tenofovir. Eleven (73%) women had abnormal laboratory results, including 6 who experienced grade 1 hemoglobin abnormalities; 4 of these women had preexisting anemia. Calculated glomerular filtration rate (calculated by Modification of Diet in Renal Disease equation) remained above 90 mL/min/1.73 m(2) in all women, except one who had a transient decline. Fourteen infants demonstrated normal growth and development for weight and height at birth, as well as during the 12-month follow-up period; no congenital malformations were documented. Mother-to-child transmission of HIV was not observed in this cohort.

CONCLUSIONS

Tenofovir was found to be a well-tolerated component of HAART in this small cohort. Longer-term assessment of tenofovir effects on childhood growth and larger prospective studies of tenofovir use in pregnant women are warranted.

Chronic administration of tenofovir to rhesus macaques from infancy through adulthood and pregnancy: summary of pharmacokinetics and biological and virological effects

The reverse transcriptase (RT) inhibitor tenofovir (TFV) is highly effective in the simian immunodeficiency virus (SIV) macaque model of human immunodeficiency virus infection. The current report describes extended safety and efficacy data on 32 animals that received prolonged (>or=1- to 13-year) daily subcutaneous TFV regimens. The likelihood of renal toxicity (proximal renal tubular dysfunction [PRTD]) correlated with plasma drug concentrations, which depended on the dosage regimen and age-related changes in drug clearance. Below a threshold area under the concentration-time curve for TFV in plasma of approximately 10 microg x h/ml, an exposure severalfold higher than that observed in humans treated orally with 300 mg TFV disoproxil fumarate (TDF), prolonged TFV administration was not associated with PRTD based on urinalysis, serum chemistry analyses, bone mineral density, and clinical observations. At low-dose maintenance regimens, plasma TFV concentrations and intracellular TFV diphosphate concentrations were similar to or slightly higher than those observed in TDF-treated humans. No new toxicities were identified. The available evidence does not suggest teratogenic effects of prolonged low-dose TFV treatment; by the age of 10 years, one macaque, on TFV treatment since birth, had produced three offspring that were healthy by all criteria up to the age of 5 years. Despite the presence of viral variants with a lysine-to-arginine substitution at codon 65 (K65R) of RT in all 28 SIV-infected animals, 6 animals suppressed viremia to undetectable levels for as long as 12 years of TFV monotherapy. In conclusion, these findings illustrate the safety and sustained benefits of prolonged TFV-containing regimens throughout development from infancy to adulthood, including pregnancy.

Pediatric HIV infection: the state of antiretroviral therapy

Pediatric HIV/AIDS has become less of a problem in resource-rich countries as the number of perinatal infections has reduced dramatically since the advent of antiretrovirals, resulting in the effective prevention of mother-to-child transmission. In resource-limited settings, however, pediatric HIV infection remains a colossal problem; a separate review in this same issue of Expert Review of Anti-Infective Therapy examines the international aspects of pediatric HIV/AIDS. Treatment of HIV infection in children differs from that in adults in the use of immunologic markers and owing to drug pharmacokinetics and age-related adherence issues. This review, geared for the general pediatrician or family practitioner who may see the HIV-positive child in the clinic or the hospital, summarizes the most recent pediatric data and guidelines for the testing and treatment of HIV, including the US NIH guidelines released in February 2008. Treatment-experienced patients, who should be cared for by pediatric HIV specialists, are not addressed here specifically. Adolescents, infected either perinatally or sexually, with their own unique issues, deserve a separate review.

Global challenges in the development and delivery of paediatric antiretrovirals

By the end of 2006, compared with 28% coverage for adults, only 15% of children with HIV that needed antiretroviral treatment were receiving it. Major challenges in delivering treatment include the lack of paediatric antiretrovirals that can be dosed in small children and limited studies examining safety and efficacy for existing antiretroviral formulations. The high costs of treatment have been reduced through the use of generic, fixed-dose combination drugs. Evidence-based strategies for managing resistance and the scale-up of pharmacological trials for children in low- and middle-income countries are crucial to the success and future development of paediatric antiretrovirals.

Metabolic complications of antiretroviral therapy in HIV-infected children

The purpose of this review is to describe the metabolic complications associated with antiretroviral therapy in HIV-infected children. As a result of extensive research over the last 10 years, there is a greater awareness and understanding of these conditions. However, in resource-limited settings, where the majority of HIV-infected children live, the prevalence and risk factors of metabolic complications are largely unknown. Limited diagnostic resources contribute to this impediment. Therapies for these conditions are still under investigation, including prevention and optimal treatment of reduced bone mineral density, osteopaenia and osteoporosis. Future research goals should be directed towards closing the diagnostic and treatment gaps between rich and poor settings.

Decreased bone mineral density with off-label use of tenofovir in children and adolescents infected with human immunodeficiency virus

5 of 6 children infected with human immunodeficiency virus (HIV) receiving Tenofovir disoproxil fumarate (TDF) experienced absolute decreases in bone mineral density (BMD). 2 pre-pubertal subjects experienced >6% BMD decreases. 1 subject was the smallest child and experienced a 27% decrease, necessitating withdrawal of TDF. Subsequently, her BMD recovered. Monitoring of children infected with HIV who require treatment with TDF is warranted.

Alendronate with calcium and vitamin D supplementation is safe and effective for the treatment of decreased bone mineral density in HIV

BACKGROUND

Decreased bone mineral density (BMD) is prevalent in HIV-infected patients. Bisphosphonates are currently the mainstay of treatment for postmenopausal and male osteoporosis in HIV-uninfected individuals; however, their efficacy and safety in HIV-infected patients remains unclear.

METHODS

In this prospective, randomized, placebo-controlled multicenter trial, we studied the effectiveness of calcium and vitamin D supplementation with or without alendronate in improving BMD in HIV-infected subjects receiving stable antiretroviral therapy. Subjects with secondary causes of osteoporosis were excluded. The study was powered to detect differences of 3.5% between arms and to detect a moderate sex effect in percentage change in lumbar spine BMD. All dual-energy X-ray absorptiometry scans were analysed centrally, blinded by arm.

RESULTS

The 82 subjects enrolled were 71% men, 77% white, with a baseline median age of 48 years, CD4 cell count of 469 cells/mul, and lumbar spine t-score of less than 2.1; 91% had HIV-RNA levels less than 400 copies/ml, and 99% were taking antiretroviral drugs. Compared with calcium/vitamin D alone, alendronate plus calcium/vitamin D resulted in significant improvements in BMD at the lumbar spine, total hip, and trochanter, but not at the femoral neck, compared with baseline. There were trends towards significant increases in BMD values in the calcium/vitamin D group at the lumbar spine, total hip, and femoral neck. There were no apparent sex differences in the responses to therapy. Alendronate was well tolerated, without significant adverse events.

CONCLUSION

Once-weekly alendronate is safe and effective in the treatment of decreased BMD in HIV-infected patients.

Treatment of children with HIV infection

The treatment of pediatric HIV infection has seen vast improvements in terms of better long-term suppression of HIV replication and subsequent improvements in the longevity and quality of life in children. This has been realized, in part, by development of newer antiretroviral medications, better knowledge about the pharmaco-kinetics of these drugs in children, and improved insight on drug toxicities in children. This review will discuss some of the newer agents that may be available for children in the near future, in addition to new pharmacokinetic and toxicity data that are specific to the pediatric patient. New information on key vaccines that should be administered to children with HIV infection is also discussed.

Increased beta-2 microglobulinuria in human immunodeficiency virus-1-infected children and adolescents treated with tenofovir

A single-center cross sectional evaluation of beta-2 micro-globinuria as a marker of proximal renal tubule damage in 92 HIV-infected children showed that tenofovir treatment was significantly associated with very high abnormal values. In view of the very long duration of treatments for HIV infection, their possible consequences for the child's growing body should be carefully evaluated.

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.

Alterations in circulating osteoimmune factors may be responsible for high bone resorption rate in HIV-infected children and adolescents

OBJECTIVES

Bone metabolism derangements have been reported in HIV-infected children and adolescents. Nuclear factor kappa B ligand (RANKL) and osteoprotegerin potently stimulate and inhibit, respectively, osteoclast formation and activity. We investigated the possible role of RANKL and osteoprotegerin on bone metabolism alterations in paediatric patients.

DESIGN

A prospective controlled longitudinal study. Measurements were obtained before and 6 months after switching antiretroviral regimen.

METHODS

We studied 27 vertically HIV-infected children and adolescents (aged 4.9-17.3 years) on long-term HAART (70.1 +/- 1.5 months). All patients received lamivudine, stavudine and one protease inhibitor (PI). During follow-up, the PI was replaced with efavirenz and stavudine with tenofovir. We also enrolled 336 healthy children, aged 4.8-17.9 years. Concentrations of bone-specific alkaline phosphatase (BALP), N-terminal telopeptide of type I collagen (NTx), RANKL, and osteoprotegerin were measured at baseline and 6 months after switching.

RESULTS

BALP serum concentrations and NTx urine levels of HIV-infected patients were significantly higher than those of healthy children both at baseline and after 6 months (P < 0.001). Baseline osteoprotegerin and RANKL concentrations of HIV-infected patients were significantly higher than in healthy children (P < 0.0001). Both concentrations decreased after 6 months, and RANKL levels were no longer different to controls. At baseline the RANKL/osteoprotegerin ratio was significantly higher (P = 0.02) in HIV-infected children (0.27 +/- 0.07) compared with healthy children (0.078 +/- 0.01).

CONCLUSION

A marked alteration in the RANKL/osteoprotegerin system is present in patients receiving PI-based HAART. Short-term data indicate that replacing stavudine and PI with tenofovir and efavirenz restores the RANKL/osteoprotegerin equilibrium, and may thus lead to a reduction in the bone resorption rate.