Lactic acidemia in human immunodeficiency virus-uninfected infants exposed to perinatal antiretroviral therapy

High levels of zidovudine (AZT) and its intracellular phosphate metabolites in AZT- and AZT-lamivudine-treated newborns of human immunodeficiency virus-infected mothers

Newborns from human immunodeficiency virus-infected mothers are given antiretroviral prophylaxis against mother-to-child transmission, including predominantly nucleoside reverse transcriptase inhibitors. Pharmacological monitoring of these drugs in newborns has so far been limited to plasma and cord blood. In this study, samples from newborns (up to 45 days old) treated with zidovudine (AZT) alone (n = 29) or in combination with lamivudine (3TC) (n = 20) were analyzed for both intracellular concentrations of phosphate metabolites in peripheral blood mononuclear cells and levels of parent drugs in plasma. Plasma AZT and intracellular AZT-monophosphate and AZT-triphosphate (TP) concentrations were significantly higher during the first 15 days of life (199 versus 52.7 ng/ml [P < 0.0001], 732 versus 282 fmol/10(6) cells [P < 0.0001], and 170 versus 65.1 fmol/10(6) cells [P < 0.0001], respectively) and then became comparable to those of adults. No difference in intracellular AZT metabolite concentrations was found when AZT- and AZT-3TC-treated groups were compared. Plasma 3TC levels (lower limit of quantification [LLOQ], 1,157 ng/ml; median, 412.5 ng/ml) were not associated with the newborn's age, gender, or weight. Intracellular 3TC-TP concentrations (LLOQ, 40.4 pmol/10(6) cells; median, 18.9 pmol/10(6) cells) determined for newborns receiving the AZT-3TC combination were associated with neither the age nor weight of the newborns. Concentrations in females were significantly higher (1.8-fold [P = 0.0415]) than those in males. Unexpectedly, newborns on AZT monotherapy whose mothers' treatment included 3TC displayed residual plasma 3TC and intracellular 3TC-TP levels up to 1 week after birth.

Spongiform encephalopathy following allogeneic cord blood transplant

A 6 year old boy developed a fatal, rapidly progressive encephalopathy 5 months after a matched unrelated cord blood transplant. Autopsy findings revealed spongiform changes in his brain. The clinical course of this child's illness had many findings consistent with that of a transmissible spongiform encephalopathy (TSE). Pre-mortem and post-mortem studies failed to definitively determine an etiology. Spongiform encephalopathies include the TSEs and mitochondrial encephalopathies. Both should be considered in a post-hematopoietic stem cell transplant patient who develops a progressive encephalopathy when more common etiologies are not found.

Mitochondrial disorders among infants exposed to HIV and antiretroviral therapy

Although antiretroviral therapy (ART) is critical for preventing mother-to-child transmission of HIV, concern has been raised about the possibility that it may cause mitochondrial dysfunction in infants. There is adequate evidence for a mechanism by which exposure to nucleoside reverse transcriptase inhibitors (NRTIs) could lead to mitochondrial dysfunction; animal studies have shown evidence of mitochondrial dysfunction in the offspring of animals treated with NRTIs and mitochondrial disorders occur in adults treated with NRTIs. This systematic review synthesises the published research on mitochondrial dysfunction and disorders in infants exposed to HIV and antiretrovirals. We found conflicting evidence regarding the possible association of in utero ART exposure with mortality and morbidity due to mitochondrial dysfunction. ART exposure in utero or postpartum was associated with persistent decreases in lymphocytes, neutrophils and platelets as well as an increased risk of transient lactic acidaemia, anaemia and mitochondrial DNA depletion, although these laboratory findings were generally not associated with clinical symptoms. We conclude that large, prospective studies of HIV-exposed infants are needed to resolve the discrepant results regarding morbidity and mortality related to mitochondrial disorders, to ascertain the clinical significance of effects on laboratory values, to determine whether or not the incidence of mitochondrial disorders differs by regimen and to develop predictive models that might identify which infants are at the greatest risk. The challenges that remain to be addressed include the development of a sensitive but affordable screening algorithm in combination with specific diagnostic criteria; consistent collection of data on ART exposure and other risk factors, long-term follow-up of HIV-exposed but uninfected children and implementation in resource-limited settings.

Mitochondrial disease in the offspring as a result of antiretroviral therapy

Nucleoside analogue reverse transcriptase inhibitors (NRTIs) have substantially lowered the risk of the mother-to-child transmission of HIV. Evidence of mitochondrial toxicity in vitro, in animal models and in adult HIV-infected patients, has raised concern about the perinatal safety of these antiretrovirals. In zidovudine-exposed, but HIV-uninfected infants, transient anaemia and additional long-term blood abnormalities (neutropenia, thrombopenia and lymphopenia) and hyperlactatemia have been documented. The overall risk of mortality and congenital abnormalities does not appear to be increased, but rare mitochondrial events cannot be excluded for lack of statistical power. French data suggest an above background incidence of mitochondrial symptomatology. Preclinical data demonstrate zidovudine also to be a carcinogen. Long-term systematic follow-up of exposed babies in large cohorts is needed, as are randomised trials with NRTIs carrying a lower risk of mitochondrial toxicity.

International perspectives, progress, and future challenges of paediatric HIV infection

Paediatric HIV infection is a growing health challenge worldwide, with an estimated 1500 new infections every day. In developed countries, well established prevention programmes keep mother-to-child transmission rates at less than 2%. However, in developing countries, where transmission rates are 25-40%, interventions are available to only 5-10% of women. Children with untreated natural infection progress rapidly to disease, especially in resource-poor settings where mortality is greater than 50% by 2 years of age. As in adult infection, antiretroviral therapy has the potential to rewrite the natural history of HIV, but is accessible only to a small number of children needing therapy. We focus on the clinical and immunological features of HIV that are specific to paediatric infection, and the formidable challenges ahead to ensure that all children worldwide have access to interventions that have proved successful in developed countries.

Clinical mitochondrial dysfunction in uninfected children born to HIV-infected mothers following perinatal exposure to nucleoside analogues

Clinical and biological observations of mitochondrial dysfunction in children exposed to zidovudine (azidothymidine, AZT) during the perinatal period rapidly followed similar observations in animal experiments. To date, two different disorders have been identified. The first, asymptomatic hyperlactatemia, is observed during treatment in one third of exposed newborns, and is reversible with treatment cessation. In rare cases, it is associated with symptomatic acidosis. Regression may be slow, taking up to several months after the end of the treatment. The long-term clinical consequences of this biochemical disturbance are unknown. The second disorder involves severe neurological symptoms, which become clinically detectable during the first 2 years of life. These symptoms are associated with a series of biochemical and ultrastructural changes consistent with persistent mitochondrial dysfunction. This latter phenomenon is rare, and affects only 0.3-0.5% of exposed children in the French pediatric cohort, in which observations continue. Despite initial controversy, several similar observations in other cohorts have since confirmed its occurrence. The pathophysiology of these two mitochondrial dysfunctions may differ. Continued efforts to identify and understand clinical mitochondrial toxicities are essential, given the intensification and diversification of perinatal prophylaxis strategies, and the number of pregnant women potentially involved.

Safety of Agents Used to Prevent Mother-to-Child Transmission of HIV

Antiretroviral drugs have been used routinely to reduce the risk of mother-to-child transmission of HIV infection since 1994, following the AIDS Clinical Trials Group 076 trial, which demonstrated the efficacy of zidovudine in reducing the risk of in utero and intrapartum transmission. The use of antiretroviral drugs in pregnancy varies geographically, with widespread use of highly active antiretroviral therapy (HAART) in resource-rich settings for delaying maternal HIV disease progression as well as the prevention of mother-to-child transmission; however, in low- and middle-income settings, abbreviated prophylactic regimens focus on the perinatal period, with very limited access to HAART to date. The potential risks associated with antiretroviral exposure for pregnant women, fetuses and infants depend on the duration of this exposure as well as the number and type of drugs. As the benefits of HAART regimens in reducing the risk of mother-to-child transmission and in delaying disease progression are so great, their widespread use has been accepted, despite the relative lack of safety data from human pregnancies. Animal studies have suggested an increased risk of malformations associated with exposure to specific antiretroviral drugs, although evidence to support this from human studies is limited. Trials, cohorts and surveillance studies have shown no evidence of an increased risk of congenital malformations associated with in utero exposure to zidovudine, or other commonly used antiretroviral drugs, with an estimated 2-3% prevalence of birth defects (i.e. similar to that seen in the general population). Exposure to prophylactic zidovudine for prevention of mother-to-child transmission is associated with a usually mild and reversible, but rarely severe, anaemia in infants. However, a medium-term impact on haematological parameters of antiretroviral-exposed infants has been reported, with small but persistent reductions in levels of neutrophils, platelets and lymphocytes in children up to 8 years of age; the clinical significance of this remains uncertain. To date, there is no evidence to suggest that exposure to antiretroviral drugs in utero or neonatally is associated with an increased risk of childhood cancer, but the potential for mutagenic and carcinogenic effects at older ages cannot be excluded. Nucleoside analogue-related mitochondrial toxicity is well recognised from studies in non-pregnant individuals, whilst animal studies have provided evidence of mitochondrial toxicity resulting from in utero antiretroviral exposure. Clinically evident mitochondrial disease in children with antiretroviral exposure has only been described in Europe, with an estimated 18-month incidence of 'established' mitochondrial dysfunction of 0.26% among exposed children. Regarding pregnancy-related adverse effects, increased risks of prematurity, pre-eclampsia and gestational diabetes mellitus have been reported by a variety of observational studies with varying strengths of evidence and with conflicting results. Based on current knowledge, the immense benefits of antiretroviral prophylaxis in prevention of mother-to-child transmission far outweigh the potential for adverse effects. However, these potential adverse effects require further and longer term monitoring because they are likely to be rare and to occur later in childhood.

Serum lactate levels in infants exposed peripartum to antiretroviral agents to prevent mother-to-child transmission of HIV: Agence Nationale de Recherches Sur le SIDA et les Hépatites Virales 1209 study, Abidjan, Ivory Coast

BACKGROUND

Mitochondrial toxicity was described in infants exposed to long-term antiretroviral regimens containing nucleoside analogues for the prevention of mother-to-child transmission of HIV. We measured the serum lactate levels in children born to HIV-1 infected African women receiving short-term antiretroviral prevention of mother-to-child transmission of HIV regimens.

METHODS

A prospective study was conducted in women-child pairs from the third trimester of pregnancy to 3 months of life. The exposed group was formed by children exposed in utero to nucleoside analog antiretroviral regimens, zidovudine or zidovudine + lamivudine from 32 to 36 weeks of amenorrhea until delivery. All of these women received nevirapine single dose at the beginning of labor. The children received zidovudine during the first 7 days of life and a nevirapine single dose at day 3. The control group was formed by infants born to HIV-1-infected women who had received nevirapine single dose only and who were not exposed to nucleoside analog antiretroviral regimens. Serum lactate levels were measured at 4, 6, and 12 weeks of life by Cobas Integra 400.

RESULTS

A total of 836 blood samples from 338 infants was collected (262 exposed and 76 controls). Median lactacidemia was 1.8 mmol/L (interquartile range: 1.2-2.7 mmol/L). Overall serum lactate levels > or = 2.5 mmol/L, defining hyperlactatemia, were observed in 39 of the 292 infants who had > or = 2 serum lactate measurements. The 3-month period prevalence of hyperlactatemia did not differ between the exposed group and the control group. All of the serum lactate levels returned to normal values in all of the subsequent samples. No case of symptomatic hyperlactatemia was detected during the study period.

CONCLUSIONS

Increased lactate levels were identified equally in infants whose mother received short-term nucleoside analogs or nevirapine single dose for prevention of mother-to-child transmission of HIV. Although not rare, hyperlactatemia was not related to short-term exposure to nucleoside analog antiretroviral regimens.

A prospective controlled study of neurodevelopment in HIV-uninfected children exposed to combination antiretroviral drugs in pregnancy

OBJECTIVE

Our intent was to investigate the neurodevelopment of HIV-uninfected children exposed to combination highly active antiretroviral therapy in pregnancy compared with children not exposed to highly active antiretroviral therapy but with similar socioeconomic backgrounds.

PATIENTS AND METHODS

A prospective controlled cross-sectional study of the neurodevelopment of children exposed to highly active antiretroviral therapy versus those not exposed was performed by using the Bayley Scales of Infant Development and Vineland Adaptive Behavior Scales at 18 to 36 months of age. The highly active antiretroviral therapy-exposed children were born to HIV-infected women but were uninfected themselves. The control children were born to HIV-uninfected women with similar anticipated socioeconomic background (hepatitis C infected and high proportion of substance use). Sociodemographic, clinical, highly active antiretroviral therapy (antenatal, intrapartum, neonatal), and substance-use histories were collected. Results were compared by using analyses of covariance and chi2 analysis.

RESULTS

Thirty-nine highly active antiretroviral therapy-exposed and 24 control children were assessed. All mean scores were lower for those in the highly active antiretroviral therapy-exposed group than those in the control group (Bayley Mental Development Index: 85.4 vs 94.3; Bayley Psychomotor Development Index: 93.4 vs 96.6; Vineland mean communication score: 90.1 vs 94.4; Vineland mean daily-living score: 91.2 vs 93.6; Vineland mean socialization score: 97.1 vs 98.4). However, when maternal substance use during pregnancy was controlled for, there were no significant differences between the groups in any domains assessed. Children in both groups exposed to maternal substance use scored significantly lower than children not exposed in all domains except communication skills. It is important to note that there were no differences between the highly active antiretroviral therapy-exposed children with no substance exposure and the control children with no substance exposure in any of the scores.

CONCLUSIONS

HIV- and highly active antiretroviral therapy-exposed HIV-uninfected children had lower development and adaptive behavior scores when compared with children who had not been exposed. However, these differences were not significant after correcting for maternal substance use, which had a greater impact on neurodevelopment than highly active antiretroviral therapy exposure. These results suggest that perinatal highly active antiretroviral therapy exposure is not associated with altered development and behavior at 18 to 36 months of age.

Antiviral Activity of Nucleoside Analogues During Short-Course Monotherapy or Dual Therapy

BACKGROUND

This is the first report on the preliminary efficacy of 4 different short-course nucleoside analogue regimens (stavudine [d4T], didanosine [ddI], d4T+ddI, and zidovudine [ZDV]) for the prevention of mother-to-child transmission of HIV-1 (MTCT) in a resource-limited setting.

DESIGN

This prospective open-label, randomized 4-arm study (May 1999 to May 2000) conducted in South Africa enrolled 373 women from 34 weeks of gestation; medication was continued through delivery and for 6 weeks to infants. MTCT rates were ascertained at birth, 6, 12, and 24 weeks of age.

RESULTS

Mean maternal HIV-1 RNA levels decreased rapidly on treatment in all groups. At week 4, the mean decrease was 1.91 log10 copies/mL (c/mL) in the d4T+ddI group, 1.33 log10 c/mL in the ddI group, 1.12 log10 c/mL in the d4T group, and 0.76 log10 c/mL in the ZDV group. Among the 362 evaluable mother-infant pairs, 11 infants in the d4T group, 10 in the ddI group, 5 in the ZDV group, and 4 in the d4T+ddI group were infected by 24 weeks of age. Eleven infections occurred in utero. Treatment with d4T and ddI was not associated with lactic acidosis or hepatic steatosis.

CONCLUSIONS

The abbreviated use of nucleoside analogues for the prevention of MTCT appears safe and effective.

Growth of human immunodeficiency virus-uninfected children exposed to perinatal zidovudine for the prevention of mother-to-child human immunodeficiency virus transmission

BACKGROUND

Perinatal human immunodeficiency virus (HIV) prevention programs have been implemented in several countries, and many children have been or will be exposed to antiretrovirals in utero and during their first weeks of life. Although reducing substantially the number of infected children, the potential adverse consequences of these treatments on the health of HIV-uninfected children need to be assessed.

OBJECTIVE

To investigate the impact of in utero and postnatal zidovudine exposure on the growth of HIV-uninfected children born to HIV-infected women.

METHODS

We used data prospectively collected in 1408 live born children participating in a clinical trial comparing zidovudine regimens of different durations to prevent perinatal transmission in Thailand (PHPT-1). We used a linear mixed model to analyze the anthropometric measurements (weight for age, height for age and weight for height Z-scores) until 18 months of age according to zidovudine treatment duration (mothers, <7.5 weeks versus more; infants, 3 days versus >4 weeks).

RESULTS

Children exposed in utero for >7.5 weeks had a slightly lower birth weight (Z-score difference, 0.08; P = 0.003). However, zidovudine exposure had no effect on the evolution of Z-scores from 6 weeks to 18 months of age.

CONCLUSIONS

Although a longer in utero zidovudine exposure may have had a negative impact on birth weight, the magnitude of this effect was small and faded over time. Neither the total nor the postnatal duration of exposure was associated with changes in infant Z-scores from 6 weeks to 18 months of age.

Mitochondrial toxicity of nucleoside analogues: mechanism, monitoring and management

Nucleoside analogues (NRTIs) are potent antiretroviral medications and are central to effective highly active antiretroviral therapy (HAART). Their intended action is to inhibit HIV reverse transcriptase. Nucleoside analogues also inhibit replication of mitochondrial DNA, and the pathogenesis of many of the toxicities associated with HAART is thought to be NRTI-induced mitochondrial dysfunction. Individuals with HIV infection may be particularly susceptible to clinically significant mitochondrial toxicity due to possible effects of HIV itself on mitochondria. At present there is no reliable method of detecting subclinical mitochondrial toxicity in patients exposed to NRTIs. Clinical awareness of this problem is therefore important to ensure the early detection of significant side effects and to allow timely consideration of changing therapy in those affected. There is no proven, effective therapy for NRTI-associated mitochondrial toxicity other than ceasing the implicated agent, and even with this strategy, resolution of symptoms may be incomplete. Similarly, there are no established methods for preventing mitochondrial toxicity in those on therapy including NRTIs. Micronutrients may have a role, but further study is needed to clarify optimal prevention as well as monitoring strategies.

Treating HIV During Pregnancy

The expanded use of multiple antiretroviral drugs during pregnancy has led to a reduction in the occurrence of perinatal transmission of HIV to <2%, but has led to concerns regarding both short-term toxicity and the long-term impact on the woman and her child. Enhanced toxicity of nevirapine has been noted among women with CD4+ lymphocyte counts >250 cells/microL at treatment initiation and among pregnant women on long-term didanosine and stavudine. These drugs should be avoided in such situations if alternatives are available. Efavirenz has been associated with birth defects in monkeys, and several cases of neural tube defects have been reported in humans after first trimester exposure, so treatment with this drug should be avoided during the first trimester. Protease inhibitors have been associated with an increased risk of maternal glucose intolerance, pre-eclampsia and preterm birth in some, but not all, studies. Pregnancies exposed to antiretroviral therapy should be registered with the Antiretroviral Pregnancy Registry as early in pregnancy as possible in order to provide data on the risk of birth defects after exposure. The pharmacokinetics of nucleoside and non-nucleoside reverse transcriptase inhibitors are not significantly changed in pregnancy, so standard dosing may be used. However, concentrations of several protease inhibitors are lower in pregnancy, so ritonavir-boosting or increased doses are required. Of great theoretical concern is the impact of resistance mutations that develop following single-dose nevirapine therapy on the response to later therapy among women and their infected infants. The use of dual nucleoside therapy for 3-7 days after single-dose nevirapine in the mother reduces but does not eliminate the risk of nevirapine resistance; alternative regimens for prevention of resistance are under study, as are the subsequent responses of the mother and her infant to therapy. Short courses of prophylactic zidovudine and nevirapine have been well tolerated in neonates. Concern has been raised, however, that these exposures may lead to persistent mitochondrial dysfunction or later cancers, underscoring the need for long-term surveillance of antiretroviral-exposed, HIV-uninfected infants.

HIV in pregnancy

PURPOSE OF REVIEW

This review discusses recent articles on various aspects of the prevention of mother-to-child transmission during pregnancy and delivery.

RECENT FINDINGS

Rapid human immunodeficiency virus (HIV) testing of women in labour whose status is not known allows the prompt treatment of mother and baby to reduce transmission risk. The feared clinical resistance in the mother after treatment with a single dose of nevirapine has been confirmed. Strategies are required to minimize this resistance and allow the use of nevirapine for treatment of the mother. There are new findings of mitochondrial toxicity in babies who have been exposed to anti-retroviral medicines during pregnancy or delivery, but the clinical implications are not clear. Long-term follow-up of exposed children is required. Resource-poor countries are starting to use multiple drugs to further reduce transmission to the infant. These efforts are reducing the rates of transmission to the level found in affluent countries.

SUMMARY

Improvements in treatment continue to reduce the risk of HIV transmission from mother to child in resource-poor countries, but subsequent maternal resistance continues to be a problem since treatment for the mother's health is now possible. The long-term effects on the infant are still not understood.

Fetal and neonatal exposure to AZT and low-protein diet affects glucose homeostasis: a model with implications for AIDS prevention

Zidovudine (AZT) lowers the perinatal transmission of HIV but can impair mitochondrial function by depleting mitochondrial DNA (mtDNA). AZT therapy and perinatal nutritional deprivation affect the body fat distribution, which influences glucose tolerance. We sought to model intrauterine exposure to AZT in humans to determine whether it interacts with low-protein diet (LPD) to impact on birth weight and glucose homeostasis in the offspring. Pregnant dams and their offspring were given AZT, an LPD, or AZT and an LPD (LPD + AZT). AZT reduced mtDNA copy number in liver and birth weight in the offspring and increased their fasting glucose and insulin (P = 0.021, 0.03, 0.001, and 0.011 respectively) at 6-8 wk of age. LPD decreased litter size and birth weight (P = 0.01 and 0.012). In the LPD + AZT group, birth weight and litter size were reduced compared with untreated controls, and fasting blood glucose and insulin were raised. There was a significant interaction between LPD and AZT on fasting insulin levels (P = 0.025). Islet size was not significantly affected, but the mean beta-cell area/islet was reduced in the LPD + AZT group compared with controls (P < 0.05). Early exposure to AZT interacts with LPD to impair fetal development in this model. This combination appeared to impair the supply of insulin and, hence, glucose homeostasis, perhaps as a result of impaired mitochondrial function. Although it is not certain that this can be extrapolated to humans, maternal nutritional deprivation combined with AIDS therapy could influence both birth weight and onset of diabetes.

Increased incidence of necrotizing enterocolitis in premature infants born to HIV-positive mothers

OBJECTIVE

To examine if being born to an HIV-positive mother may increase the risk of necrotizing enterocolitis in premature infants.

DESIGN

Case-control study.

SETTING

Neonatal unit of a level 3 perinatal centre.

METHODS

: Over a period of 8.5 years, all cases of necrotizing enterocolitis occurring in premature infants admitted to the neonatal unit were identified. For each case, two controls were retrospectively chosen that matched for postmenstrual age at birth, intrauterine growth and year of birth. Perinatal characteristics were studied in all infants.

MAIN RESULTS

There were 79 cases of necrotizing enterocolitis, which were compared with 158 controls. Using multivariate analysis, multiple pregnancy [odds ratio (OR), 2.29; 95% confidence interval (CI), 1.23-4.25; P = 0.009], abnormal umbilical artery velocity (OR, 2.21; 95% CI, 1.08-4.54; P = 0.030), abnormal fetal heart rate (OR, 2.14; 95% CI, 1.05-4.36; P = 0.036) and HIV-positive mother (OR, 6.63; 95% CI, 1.26-34.8; P = 0.025) were significantly more frequent in fetuses who subsequently developed necrotizing enterocolitis.

CONCLUSIONS

This preliminary report suggests an association, not previously reported, between maternal HIV-positive status and an increased risk of necrotizing enterocolitis in premature infants. Despite the limitations of this study, we suggest that premature newborn infants of HIV-positive mothers should be monitored very carefully for a possible increased risk of necrotizing enterocolitis.

Zidovudine Administration during Pregnancy and Mitochondrial Disease in the offspring

Prophylactic administration of zidovudine (ZDV) to mother–child pairs reduces HIV transmission. ZDV can impair mitochondrial (mt) DNA polymerase γ, leading to mtDNA depletion. Signs of mitochondrial dysfunction have been observed in a few children with prenatal exposure to nucleoside analogues, although no mtDNA depletion was demonstrated. Other studies failed to confirm mitochondrial disorders in children who were exposed to antiretroviral agents in utero. A child, whose HIV-infected mother received ZDV from the fourth month of pregnancy, developed neonatal encephalomyopathy, anaemia and hyperlactataemia. At 2 weeks of age, a muscle biopsy exhibited red-ragged-like fibres, proliferation of abnormal mitochondria and a 90% depletion of mtDNA without qualitative abnormalities. At 6 months, the depletion was less profound (about 50% of normal values). Severe psychomotor delay and visual disturbances persisted at 30 months, but they were greatly reduced at 5-year follow-up. These laboratory and clinical findings clearly demonstrated that mtDNA alteration was acquired and not consequent to an inherited disorder. Fetal exposure to ZDV may have caused the mtDNA depletion, which, although temporary, led to irreversible but not progressive brain damage.

The safety of antiretroviral drugs in pregnancy

Advances in HIV therapy and mother-to-child transmission (MTCT) prophylaxis have led to increasing use of antiretroviral drugs in pregnancy. Highly active antiretroviral therapy in pregnancy has been associated with prematurity, pre-eclampsia and gestational diabetes. Women may be at increased risk of nevirapine-associated hepatotoxicity but whether or not pregnancy is an additional risk is uncertain. Although animal studies suggest a possibility of congenital abnormalities with specific antiretrovirals, such as efavirenz, results from registries and cohort studies do not support an excess of congenital malformations associated with in utero antiretroviral exposure. Concerns regarding the health of uninfected, antiretroviral-exposed children include the potential for cancers, mitochondrial disease and haematological abnormalities. However, the absence of any excess mortality in large observational cohort studies of uninfected, antiretroviral therapy-exposed children born to HIV-infected women is reassuring. Based on current knowledge, the immense benefits of antiretroviral prophylaxis in reducing the risk of MTCT, far outweigh the potential for adverse effects.

Pharmacotherapy of perinatal HIV

Continued spread of HIV infection among women has led to the use of antiretrovirals in pregnant women and their newborns. Regional strategies to prevent mother-to-child transmission are evolving. Altered drug disposition during pregnancy may require altered dosing or 'boosted' therapies to avoid treatment failure. Maturing drug elimination pathways in newborns must also be considered for effective therapy. Potential teratogenic effects and increased sensitivity to antiretroviral toxicities might be encountered in this population. Use of highly active antiretroviral therapy (HAART) to suppress viral replication combined with formula feeding can reduce the rate of mother-to-child HIV transmission to less than 2%. In resource-limited settings, less intensive regimens including zidovudine, lamivudine and nevirapine still substantially reduce mother-to-child transmission. Although difficult to perform, clinical trials to determine the safety, pharmacokinetics and optimal dosing of antiretroviral in pregnant women and their newborns are urgently needed.

The effect of long-term storage on measured plasma lactate concentrations and prospective lactate results from a multicenter trial of antiretroviral therapy

Plasma lactate measurements are typically performed in real time, limiting their usefulness in multicenter or longitudinal studies. To determine the stability of lactate specimens, blood was drawn in sodium fluoride/potassium oxalate tubes from 13 volunteers before and after 5min of handgrip exercise to intentionally increase lactate concentrations. Plasma was stored at −70°C. Aliquots were assayed in real time and after 1, 3, 6, 9, 12, 18, and 24months. Real-time lactate concentrations measured at baseline ranged from 0.52 to 2.23mmol/L before and from 2.91 to 11.04mmol/L after handgrip exercise. Using a linear mixed model, the estimated change from baseline at month 24 was 1.67% (95% confidence interval, −0.70% to 4.03%) for pre-exercise samples and 0.39% (95% CI, −1.13% to 1.91%) for post-exercise samples. Stored serial specimens from 232 HIV-infected subjects in a multicenter trial of antiretroviral therapy were also assayed centrally. Among those, median plasma lactate increased from baseline to 64weeks by 0.4mmol/L with zidovudine+lamivudine treatment and by 0.6mmol/L with didanosine+stavudine (each p<0.001 from baseline; p=0.04 for difference between groups over time). When performed as in this study, frozen storage with central batch lactate analysis is appropriate for prospectively collected samples in multicenter trials.

Hyperlactatemia in human immunodeficiency virus-uninfected infants who are exposed to antiretrovirals

OBJECTIVE

Exposure to nucleoside analogues in fetal or early life has been associated with rare clinically significant mitochondrial toxic effects, mainly neurologic symptoms. Lactate (LA) measurements have been used to monitor nucleoside-related mitochondrial toxicity. Our aim was to determine the prevalence, clinical evolution, and risk factors for hyperlactatemia in our cohort of human immunodeficiency virus (HIV)-uninfected children who were exposed to antiretrovirals.

METHODS

We conducted a prospective observational study of 127 HIV-uninfected infants who were born to HIV-infected women. Clinical symptoms suggesting mitochondrial dysfunction were analyzed in routine follow-up, and LA and alanine plasma levels were obtained at 6 weeks, 3 months, 6 months, and 12 months in all patients. Elevated alanine levels, together with hyperlactatemia, suggest chronic mitochondrial injury.

RESULTS

Most (85%) women received highly active antiretroviral therapy (HAART) during pregnancy (mean duration: 31 weeks) and zidovudine during labor (93%). Most (96%) children received zidovudine alone. Hyperlactatemia with hyperalaninemia was detected in 63 children in at least 1 of the measurements. Mean LA levels were significantly higher in children who were exposed to nucleoside analogue reverse transcriptase inhibitors than in control subjects (2.88 vs 1.61 at 6 weeks, 2.78 vs 1.49 at 3 months, 1.89 vs 1.39 at 6 months, and 1.71 vs 1.24 at 12 months; peak levels: 8.06, 10.1, 7.28, and 4.48 mmol/L, respectively). In 44 patients, LA levels progressed spontaneously to normality within the first year of life. Three girls presented a slight and self-limited delay in psychomotor development, with LA peak levels of 7.3, 4.0, and 4.6 mmol/L. Only the gestational use of didanosine was associated with a higher risk of hyperlactatemia.

CONCLUSIONS

In our series, almost half of the children (63 of 127) who were exposed to nucleoside analogues developed benign and self-limited hyperlactatemia. When symptomatic, nucleoside analogue-induced toxicity affected neurologic development.

PENTA guidelines for the use of antiretroviral therapy, 2004

There have been few major advances in paediatric HIV management over the last 2 years. Decisions about starting antiretroviral therapy can now be based on a recent large meta-analysis of the predictive value of CD4 and HIV RNA viral load (VL) in nearly 4000 untreated children, which is discussed in these updated guidelines. Risk estimates for progression to AIDS and death using surrogate markers can now be broken down by age, allowing more accurate discussion with families. In addition, there is increasing recognition of the problems of long-term adherence, drug resistance and cumulative toxicity in adults and children. The controversy over whether to treat asymptomatic infants continues. For older children more data on the efficacy of ritonavir boosted protease inhibitor (PI) regimens suggests that these may be the PI option of first choice. There is still no adult or paediatric trial evidence on which to base decisions about whether to start with PI- or non-nucleoside reverse transcriptase inhibitor (NNRTI)- based regimens, but the PENPACT 1 trial, which is addressing this question, is ongoing. There are increasing moves to provide simpler antiretroviral therapy (ART) regimens, including once daily dosing, but these lag behind adult regimens because of the paucity of pharmacokinetic data. Resistance assays should now be performed in all HIV-infected infants exposed to ART in pregnancy. Therapeutic drug monitoring may be very important in children because of high between- and within-child variability in drug absorption and metabolism. A trial to evaluate this should start shortly in Europe (PENTA 14 trial). The value of resistance tests for choice of second-line and subsequent choices of ART regimens remain unproven (the PERA trial will report late in 2004), but resistance assays are increasingly being used. The issue of when to switch therapy also remains unanswered and is being addressed within the PENPACT 1 trial. Regular formal assessment of adherence is now the standard of care, and routine monitoring in the clinic for lipodystrophy syndrome (LDS) and other ART toxicities is increasingly important. These guidelines will be updated again in 2006.

Evaluation and treatment of the human immunodeficiency virus-1--exposed infant

In developed countries, care and treatment are available for pregnant women and infants that can decrease the rate of perinatal human immunodeficiency virus type 1 (HIV-1) infection to 2% or less. The pediatrician has a key role in prevention of mother-to-child transmission of HIV-1 by identifying HIV-exposed infants whose mothers' HIV infection was not diagnosed before delivery, prescribing antiretroviral prophylaxis for these infants to decrease the risk of acquiring HIV-1 infection, and promoting avoidance of HIV-1 transmission through human milk. In addition, the pediatrician can provide care for HIV-exposed infants by monitoring them for early determination of HIV-1 infection status and for possible short- and long-term toxicities of antiretroviral exposure, providing chemoprophylaxis for Pneumocystis pneumonia, and supporting families living with HIV-1 infection by providing counseling to parents or caregivers.

Evaluation and treatment of the human immunodeficiency virus-1-exposed infant

In developed countries, care and treatment are available for pregnant women and infants that can decrease the rate of perinatal human immunodeficiency virus type 1 (HIV-1) infection to 2% or less. The paediatrician has a key role in the prevention of mother-to-child transmission of HIV-1 by identifying HIV-exposed infants whose mothers' HIV infection was not diagnosed before delivery, prescribing antiretroviral prophylaxis for these infants to decrease the risk of acquiring HIV-1 infection, and promoting avoidance of HIV-1 transmission through human milk. In addition, the paediatrician can provide care for HIV-exposed infants by monitoring them for early determination of HIV-1 infection status and for possible short- and long-term toxicities of antiretroviral exposure, providing chemoprophylaxis for Pneumocystis pneumonia, and supporting families living with HIV-1 infection by providing counselling to parents or caregivers.

Mitochondrial damage and DNA depletion in cord blood and umbilical cord from infants exposed in utero to Combivir

OBJECTIVE

Although most uninfected infants born to women infected with HIV-1 show no clinical evidence of mitochondrial compromise, mitochondrial dysfunction has been reported in children born to women receiving zidovudine and/or lamivudine during pregnancy. In this pilot study we examined mitochondrial integrity in HIV-1-uninfected infants born to HIV-1-infected women receiving Combivir during pregnancy.

DESIGN

: Samples of umbilical cord and cord blood were obtained from HIV-1-uninfected infants born to either HIV-1-infected women receiving Combivir therapy during pregnancy (n = 10) or HIV-1-uninfected women (n = 9).

METHODS

Mitochondrial morphological integrity was examined in umbilical cords (n = 16) by electron microscopy and mtDNA quantity was determined in DNA from cord blood (n = 18) and umbilical cord (n = 18) by PCR-chemiluminescence immunoassay detection.

RESULTS

In umbilical cords from six of nine infants born to HIV-1-infected mothers taking Combivir moderate to severe mitochondrial morphological damage was observed (P = 0.011), while none of seven unexposed infants showed similar damage. Compared to unexposed infants, statistically significant mtDNA depletion was observed in umbilical cord (P = 0.006) and cord blood (P = 0.003) from drug-exposed infants.

CONCLUSIONS

A cohort of HIV-1-uninfected Combivir-exposed infants with no clinical symptoms showed morphological and molecular evidence of mitochondrial damage.

Severe lactic acidosis in association with reverse transcriptase inhibitors with potential response to L-carnitine in a pediatric HIV-positive patient

We report a case of life-threatening lactic acidosis in a 10-year-old male with HIV stage B2 infection, presumed to be vertically acquired. This occurred after several months of therapy with d4t, ddl, and nevirapine. His most recent CD4 count was 347 cells per microliter and viral load 16,000 copies per milliliter 3 weeks prior to admission. The peak lactic acid level was 12.4 mmol/L. Although multiple therapeutic interventions took place, the patient showed rapid improvement and resolution temporally associated with the administration of levocarnitine.