Adverse events experienced by three children taking tenofovir and didanosine in combination

Didanosine-induced Retinopathy: New Insights with Long-term Follow-up

INTRODUCTION

Didanosine is an adenosine analog, part of the nucleoside reverse-transcriptase inhibitor family. Since the description of didanosine-induced retinopathy in the early 1990s, little is known about the progression of this toxic retinopathy and the putative underlying mitochondrial defect.

OBJECTIVES

We report long-term follow-up for cases of didanosine-induced retinopathy and discuss a new hypothesis for pathophysiology based on the alteration of endogenous adenosine on the photoreceptor outer segment turnover and phagocytosis by the retinal pigment epithelium.

METHODS

Ophthalmic data from six cases (12 eyes) of didanosine-induced retinopathy from a single institution were retrospectively analyzed.

RESULTS

All patients displayed bilateral retinal alterations in the mid-periphery. Despite didanosine discontinuation, patients with advanced areas of patchy chorioretinal atrophy appeared to have a faster progression than those with limited lesions. Full-field electroretinogram revealed generalized rod-cone dysfunction in most cases that remained stable over time.

CONCLUSION

We propose new guidelines including early screening and long-term observations.

Renal and Bone Adverse Effects of a Tenofovir-Based Regimen in the Treatment of HIV-Infected Children: A Systematic Review

INTRODUCTION

Tenofovir disoproxil fumarate (TDF)-containing regimens in the treatment of HIV-infected children have safety concerns with respect to renal and bone toxicity.

OBJECTIVE

The aim of this study was to systematically review and critically appraise the literature relating to the reported renal and bone adverse effects of TDF-based regimens in the treatment of HIV-infected children from 2 to 19 years old.

METHODS

Searches were performed using the Cochrane Central Register of Controlled Trials (CENTRAL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, OvidSP, ScienceDirect and Web of Science databases and platforms. All primary studies involving tenofovir use in HIV-infected children were sought. Studies that involved the use of TDF for pre- and post-exposure prophylaxis, and treatment of chronic hepatitis B virus infection were excluded. Data on study characteristics, participant's characteristics, therapeutic intervention and adverse effects were extracted using a piloted tool. In addition, pharmacovigilance data from the WHO Adverse Reaction database were included.

RESULTS

We identified 19 studies that reported the presence of renal and bone adverse effects of TDF and these included a total of 1100 study participants. The reports were in distinctly heterogeneous participant groups. A total of 287 renal and bone adverse effects were reported (250 renal and 37 bone adverse effects). Approximately 238 (21.6 %) participants were affected by these adverse effects. Of these, 15 participants stopped their TDF-containing regimen due to these adverse effects. In addition, the pharmacovigilance data from the WHO Adverse Reaction database reported 101 renal and bone adverse effects for patients whose indication was HIV/AIDS.

CONCLUSION

This systematic review summarises the reports of renal and bone adverse effects of a TDF-containing regimen in the treatment of HIV-infected children. Our findings suggest that the benefits of using TDF in children need to be balanced against the potential risk of toxicity.

Long-term renal effects of tenofovir-disoproxil-fumarate in vertically HIV-infected children, adolescents, and young adults: a 132-month follow-up study

BACKGROUND AND OBJECTIVES

The introduction of highly active anti-retroviral therapy has led to a significant decline in morbidity and mortality. Although several studies in adult populations have shown that tenofovir-disoproxil-fumarate (TDF) use is associated with a significant loss of renal function, there is still uncertainty on the long-term TDF safety profile in pediatric HIV populations, mostly in vertically HIV-infected patients. The aim of this study was to evaluate the long-term TDF renal safety profile, during a ten-year follow up.

METHODS

Twenty-six vertically HIV-infected patients were evaluated for a total of 132 months of follow up, monitoring anthropometric parameters, renal function, viral load and CD4+ count. Generalized estimating equations were used to evaluate the changes in anthropometric and laboratory variables. Multivariable fractional polynomials were used to test for the existence of non-linear relationships of outcomes with time and other continuous covariates. In all patients, weight, height and body mass index increased linearly with time. CD4+ count and glomerular filtration rate decreased linearly with time (p < 0.01).

RESULTS

No significant increase of serum creatinine was registered. An inverse linear relationship between time and plasma phosphate was found. Hypophosphatemia was detected in 17 patients, mostly mild. In 14 out of 17 we also genotyped single nucleotide polymorphisms rs717620 mapping in ABCC2, a gene encoding for a renal transporter.

CONCLUSIONS

Our study demonstrates the relative safety of prolonged use of TDF in vertically HIV-infected children and young adults. The most relevant alteration that emerged was hypophosphatemia, appearing after 72 months of TDF therapy, mostly mild and without clinical significance.

Tenofovir-Associated Nephrotoxicity in Children with Perinatally-Acquired HIV Infection: A Single-Centre Cohort Study

BACKGROUND AND OBJECTIVE

In 2012, tenofovir disoproxil fumarate (TDF) was approved for use in children over 2 years of age at a dose of 8 mg/kg/day, and is the WHO recommended first-line therapy for children over 10 years of age or 35 kg in weight, at 300 mg daily. Whilst postmarketing experience of paediatric TDF is limited, prior off-licence use has occurred at our centre due to its tolerability, efficacy and resistance profiles. In this article we describe a single-centre experience of TDF nephrotoxicity in children aged <16 years.

METHODS

We conducted a retrospective case-note audit of children with perinatally-acquired HIV who ever received TDF-based antiretroviral therapy.

RESULTS

From 2001 to December 2013, 70 children [39 (56 %) females] ever received TDF. Median age at the start of TDF treatment was 12 years (interquartile range 10-14). Seven (10 %) children developed asymptomatic renal tubular leak with associated hypophosphataemia (3) and hypokalaemia (1), all resulting in TDF withdrawal and biochemical resolution. Comparison of the nephrotoxic group versus the rest of the cohort showed no significant differences for age, sex, antiretroviral regimen or CD4 count. Lower weight (p = 0.05) and initial dose of TDF received (p = 0.0048) were significantly associated with TDF-induced nephrotoxicity: median dose of TDF (7.8 mg/kg/day) compared with the remainder of the cohort (6.5 mg/kg/day). Concurrent use of protease inhibitors (PIs) with TDF may be a contributing factor to the development of nephrotoxicity (odds ratio 6; 95 % CI 0.7-54; p = 0.111).

CONCLUSION

Although all children with TDF-associated nephrotoxicity had biochemical resolution on drug withdrawal, renal monitoring of children receiving TDF is important, especially with the co-administration of PIs. Postmarketing surveillance is essential in the paediatric setting.

Metabolic and renal adverse effects of antiretroviral therapy in HIV-infected children and adolescents

Worldwide, the benefits of combined antiretroviral (ARV) therapy in morbidity and mortality due to perinatally acquired human immunodeficiency virus infection are beyond question and outweigh the toxicity these drugs have been associated with in HIV-infected children and adolescents to date. In puberty, abnormal body fat distribution is stigmatizating and leads to low adherence to ARV treatment. The other metabolic comorbidities (mitochondrial toxicity, dyslipidemias, insulin resistance and low bone mineral density) and renal toxicity, albeit nonsymptomatic in most children, are increasingly being reported and potentially put this population at risk for early cardiovascular or cerebrovascular atherosclerotic disease, diabetes, pathologic fractures or premature renal failure in the third and fourth decades of life. Evidence from available studies is limited because of methodological limitations and also because of several HIV-unrelated factors influencing, to some degree, the development of these conditions. Current recommendations for the prevention, diagnosis, monitoring and treatment of metabolic and renal adverse effects in HIV-children and adolescents are based on adult studies, observational pediatric studies and experts' consensus. Healthy lifestyle habits (regarding diet, exercise and refraining from toxic substances) and wise use of ARV options are the only preventive tools for the majority of patients. Should abnormal findings arise, switches in one or more ARV drugs have proved useful. Specific therapies are also available for some of these comorbidities, although the experience in the pediatric age is still very scarce. We aim to summarize the epidemiological, clinical and therapeutic aspects of metabolic and renal adverse effects in vertically HIV-infected children and adolescents.

Review of tenofovir use in HIV-infected children

Tenofovir disoproxil fumarate (TDF) is approved by the Food and Drug Administration for use in children ages 2 years and older and is recommended by the World Health Organization for use as a preferred first-line nucleotide reverse transcriptase inhibitor in adults and adolescents ages 10 years and older. The simplicity of once daily dosing, few metabolic side effects and efficacy against hepatitis B virus make TDF suitable for use in a large scale program. Unlike thymidine analoge nucleoside reverse transcriptase inhibitors (NRTIs); tenofovir does not induce multi-NRTI resistance mutations, so more NRTI options are available for future second-line-regimens. Fixed-dose combinations of TDF with other ARVs as a single tablet regimen are now widely available for adults and adolescents, but none are available for young children. Current information on TDF including the pharmacokinetics, safety and tolerability in children and adolescents was reviewed. A dosing regimen according to body-weight-band has been established for pediatric use. Safety concerns of TDF mainly relate to its effects on renal function and bone mineral density. Regular monitoring of renal function in high-risk patients, including those on other nephrotoxic drugs, may be warranted to detect adverse renal effects. Long-term-data on renal and bone outcomes among HIV-infected children is needed. Lessons learned from clinical studies will help clinicians balance the risks and benefits of TDF and design appropriate antiretroviral regimens for children in different circumstances.

Update on tenofovir toxicity in the kidney

Tenofovir (TFV) is a widely used and effective treatment for HIV infection. Numerous studies have shown that TFV exposure is associated with small but significant declines in estimated glomerular filtration rate (eGFR). However, TFV toxicity is targeted mainly at the proximal tubule (PT), and in severe cases can cause the renal Fanconi syndrome or acute kidney injury. Severe toxicity occurs in a minority of patients, but milder PT dysfunction is more common; the long-term significance of this on kidney and bone health is uncertain. Recent work suggests that changes in eGFR on TFV therapy might be explained by inhibition of PT creatinine secretion rather than actual alterations in glomerular function. Risk factors for nephrotoxicity include pre-existing kidney disease, increased age, and low body mass. Mitochondria in the PT are the targets of TFV toxicity, but the exact mechanisms remain unclear. Substantial improvement of renal function occurs in many patients with TFV toxicity upon stopping therapy, but function does not always return to baseline. In recent years, TFV usage has been extended to new clinical spheres, including pediatrics, resource-poor settings and treatment of hepatitis B infection; theoretical reasons exist as to why some of these patients might be at higher or lower risk of TFV toxicity. Finally, strategies have been proposed to prevent TFV toxicity or enhance recovery.

Long-term renal safety of tenofovir disoproxil fumarate in vertically HIV-infected children, adolescents and young adults: a 60-month follow-up study

BACKGROUND AND OBJECTIVE

Sporadic cases of renal toxicity have been reported in HIV-infected children treated with tenofovir disoproxil fumarate (TDF). We assessed the long-term renal safety of TDF in a cohort of vertically HIV-infected children, adolescents and young adults.

METHODS

We evaluated 26 HIV-infected children, adolescents and young adults, aged 4.9-17.4 years at baseline, every 6 months for 60 consecutive months. At the baseline visit, they had an undetectable viral load and a good immune reconstitution and were being treated with lamivudine, stavudine and a protease inhibitor (PI). At the same visit, stavudine was replaced with TDF and the PI with efavirenz. Serum creatinine, estimated glomerular filtration rate (GFR), urine protein to creatinine ratio, serum phosphate, ratio of the maximum rate of tubular phosphate reabsorption to the GFR (TmPO(4)/GFR), urine glucose, and urine α(1)-microglobulin to creatinine ratio were used as markers of renal function. The outcome-time relationships were studied using generalized estimating equations (GEEs). In addition to time (continuous, ten equally spaced intervals), sex, age at baseline and CD4+ T-cell count were used as covariates.

RESULTS

A moderate reduction in GFR was observed only once in an underweight female patient. There was no occurrence of proteinuria, hypophosphataemia or glycosuria. Moreover, TmPO(4)/GFR was stable and the urine α(1)-microglobulin to creatinine ratio was always within normal limits.

CONCLUSION

TDF had an excellent renal safety profile in HIV-infected children, adolescents and young adults regularly followed up for 60 months.

Secondary complications and co-infections in the HIV-infected adolescent in the antiretroviral era

PURPOSE OF REVIEW

The number of HIV-infected adolescents is increasing dramatically. With combination antiretroviral therapy, they are expected to live well into adulthood. However, complications are emerging at a higher rate in the HIV-infected population compared to the general population. HIV-infected adolescents are also at a high risk of sexually transmitted co-infections. This article reviews the main secondary complications and co-infections in the HIV-infected adolescent.

RECENT FINDINGS

HIV-infected adolescents are at a high risk of sexually transmitted infections. A careful, age-appropriate and developmentally appropriate inquiry into the individual's sexual behavior to assess risk is paramount, in addition to regular screening at medical visits. Treating co-infections is not only important for HIV-infected individuals, but also limits HIV transmission to others. In addition, monitoring and addressing modifiable secondary risk factors for complications such as renal disease, osteopenia or osteoporosis, and cardiovascular disease are critical, well before the onset of clinically apparent disease. Using antiretroviral therapy to suppress viral replication and inflammation appears to be a promising strategy for decreasing secondary complication risk, and likely overshadows the toxicities associated with the long-term use of certain antiretrovirals.

SUMMARY

Assessing and addressing the risk of secondary complications and co-infections in the HIV-infected adolescent is crucial for optimal length and quality of life.

Prospective study of renal function in HIV-infected pediatric patients receiving tenofovir-containing HAART regimens

AIM

to describe the impact of tenofovir disoproxil fumarate (TDF) use on renal function in HIV-infected pediatric patients.

DESIGN

it is a prospective, multicenter study. The setting consisted of five third-level pediatric hospitals in Spain. The study was conducted on patients aged 18 years and younger who had received TDF for at least 6 months. The intervention was based on the study of renal function parameters by urine and serum analyses. The main outcome measures were renal function results following at least 6 months of TDF therapy.

RESULTS

forty patients were included (32 were white and 26 were diagnosed with AIDS). Median (range) duration of TDF treatment was 77 months (16-143). There were no significant changes in the estimated creatinine clearance. Urine osmolality was abnormal in eight of 37 patients, a decrease in tubular phosphate absorption was documented in 28 of 38 patients, and 33 of 37 patients had proteinuria. A statistically significant decrease in serum phosphate and potassium concentrations was observed during treatment (P = 0.005 and P = 0.003, respectively), as well as a significant relationship between final phosphate concentration and tubular phosphate absorption (P = 0.010). A negative correlation was found between phosphate concentration and time on TDF.

CONCLUSIONS

TDF use showed a significant association with renal tubular dysfunction in HIV-infected pediatric patients. Periodic assessment of tubular function may be advisable in the follow-up of this population.

Effect of tenofovir disoproxil fumarate on risk of renal abnormality in HIV-1-infected children on antiretroviral therapy: a nested case-control study

OBJECTIVE

To investigate the association between tenofovir disoproxil fumarate (TDF) use and renal abnormality in a large cohort of HIV-1-infected children on antiretroviral therapy (ART).

DESIGN

Nested case-control study.

METHODS

Patients were from the Collaborative HIV Paediatric Study, a cohort of approximately 95% of HIV-1-infected children in the UK/Ireland. Serum (but not urine) biochemistry results for 2002-2008 were obtained for 456 ART-exposed children (2-18 years) seen at seven hospitals. Cases had either confirmed hypophosphataemia DAIDS grade at least 2 or estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m; three controls per case were matched by hospital. Conditional logistic regression identified risk factors for renal abnormality.

RESULTS

Twenty of 456 (4.4%) had hypophosphataemia, and one had eGFR less than 60 ml/min per 1.73 m. Ten of 20 (50%) cases versus 11 of 60 (18%) controls had taken TDF-containing ART for a median [interquartile range (IQR)] of 18 [17-20] months, as part of second-line or salvage therapy. The hypophosphataemia incidence rate was 4.3/100 person-years in the TDF group versus 0.9/100 person-years in those not exposed to TDF. In multivariable analysis, only TDF exposure in the previous 6 months was associated with hypophosphataemia [odds ratio (OR) = 4.81, 95% confidence interval (CI) 1.45-16.0, P = 0.01]. In six of 10 children with hypophosphataemia and at least four subsequent phosphate measurements, phosphate values returned to normal when TDF was stopped; in four with three measures or less, values rose but remained subnormal.

CONCLUSIONS

Hypophosphataemia was uncommon (4%), but was associated with prolonged TDF use, and was generally reversible following TDF withdrawal. Findings highlight the importance of continuing to monitor longer-term renal function, in particular tubular function, especially in those taking TDF. Further studies assessing urine biochemistry measures which more accurately indicate renal tubular damage are required.

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.

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.