Severe nucleoside-associated lactic acidosis in human immunodeficiency virus-infected patients: report of 12 cases and review of the literature

Safety of stavudine in the treatment of HIV infection with a special focus on resource-limited settings

BACKGROUND

Western randomized trials and prospective cohorts in resource-limited settings have proven virological success with stavudine-based highly active antiretroviral therapy. However, stavudine is no longer recommended in first-line treatments in these two settings due to its intrinsic toxicities and side effects. Yet it remains a cornerstone of treatment in resource-limited settings, due to lack of alternatives and its availability in generic fixed-dose combinations.

OBJECTIVE

To review the toxic effects of stavudine and their prevention and management strategies, especially in resource-limited settings.

METHODS

Data from clinical and pharmacological trials in Western countries, as well as prospective cohorts in resource-limited settings, were reviewed.

CONCLUSION

Initiating or switching to less toxic nucleoside analogues whenever possible, or lowering stavudine doses to 30 mg b.i.d., is strongly recommended.

The impact of episodic CD4 cell count-guided antiretroviral therapy on quality of life

OBJECTIVE

To evaluate the effect of episodic antiretroviral therapy on quality of life (QOL).

DESIGN

This was a substudy of the Strategies of Management of Antiretroviral Therapy study, in which patients were randomized to continuous versus CD4 cell count-guided episodic antiretroviral therapy. QOL assessments included an analog scale for current health and the Short-Form 12 Item Survey, a standard abbreviated QOL instrument.

RESULTS

A total of 1225 patients had QOL assessments over a mean follow-up time of 2.4 years. Most (76%) were on antiretroviral therapy at enrollment; the median CD4 lymphocyte count was 575 (interquartile range: 455 to 784) cells/mm3; and mean current health was 75 on a scale from 0 to 100, and 50% reported very good or excellent general health. Through follow-up, whenever QOL outcomes differed, the results were inferior among patients in the episodic therapy group compared with the continuous therapy group (current health, Physical Health Component Score [both P = 0.05], general health perceptions, physical functioning, and energy [all P = 0.03]). HIV disease progression (opportunistic disease or death) was more common in the episodic therapy arm and was preceded by marked declines in QOL, but excluding participants with disease progression had minimal effect on QOL comparisons.

CONCLUSION

CD4 count-guided episodic use of antiretroviral therapy resulted in inferior QOL compared with continuous therapy.

Risk factors for mortality in symptomatic hyperlactatemia among HIV-infected patients receiving antiretroviral therapy in a resource-limited setting

OBJECTIVES

To determine the mortality rate and risk factors after experiencing symptomatic hyperlactatemia in HIV-infected patients receiving antiretroviral therapy (ART).

METHODS

A retrospective cohort study was conducted among patients who were diagnosed with symptomatic hyperlactatemia (lactate >2.5mmol/l) between January 2004 and April 2006. All patients were followed until 3 months after the diagnosis.

RESULTS

One hundred and twenty-five patients were included in the study. The mean+/-standard deviation (SD) age was 39.9+/-10.1 years and body weight was 58.2+/-16.9kg; 60.8% were male. Symptomatic hyperlactatemia in 114 (91.2%) was associated with receiving d4T, in five (4.0%) with d4T+ddI, in four (3.2%) with ZDV+ddI, and in two (1.6%) with ddI (d4T, stavudine; ddI, didanosine; ZDV, zidovudine). The median duration of ART was 13 months. Nine (7.2%) patients died. Patients who died had a higher mean lactate level (8.0 vs. 5.1mmol/l) and mean alanine aminotransferase (ALT; 164 vs. 48U/l) at the time of diagnosis when compared to those who survived (p<0.05). Patients who died had a lower mean weight than those who survived (48 vs. 59kg, p=0.008). By logistic regression, mortality was associated with patients whose body weight was <45kg (p=0.014, odds ratio (OR) 9.090, 95% confidence interval (CI) 1.575-52.632) and whose serum lactate was >10mmol/l (p=0.004, OR 20.372, 95% CI 2.610-159.001).

CONCLUSIONS

The mortality rate of symptomatic hyperlactatemia among HIV-infected patients receiving ART is substantial. Almost all patients received d4T. Patients who have a low body weight and high serum lactate level are at a higher risk of mortality.

Higher-than-expected rates of lactic acidosis among highly active antiretroviral therapy-treated women in Botswana: preliminary results from a large randomized clinical trial

BACKGROUND

The ability of nucleoside reverse transcriptase inhibitors (NRTIs) to inhibit human mitochondrial polymerase-gamma results in impaired synthesis of mitochondrial enzymes that generate adenosine triphosphate (ATP) by oxidative phosphorylation. This has been associated with several long-term mitochondrial toxicities, which include lactic acidosis and pancreatitis, peripheral neuropathy, and lipoatrophy.

METHODS

Enrolled highly active antiretroviral therapy (HAART)-treated adults have completed nearly 2 years of follow-up as part of the ongoing randomized clinical trial Adult Antiretroviral Treatment and Drug Resistance (Tshepo) study. All patients were intensively screened for the presence of ARV-related toxicities.

RESULTS

Six hundred fifty adults (69% female) were initiated on NRTI-based HAART. Overall, 2.0% of patients developed moderate to severe symptomatic hyperlactatemia, with 7 (1.0%), all female, diagnosed with lactic acidosis. Female gender (P = 0.008) and being overweight, namely having a body mass index (BMI) of greater than 25 (P = 0.001), were predictive for the development of moderate to severe symptomatic hyperlactatemia or lactic acidosis. Older age (age >40 years) showed a statistical trend (P = 0.053) as a predictor for the development of toxicity, whereas exposure to d4T and/or ddI for 6 or more months was not predictive (P = 0.102). Those diagnosed with lactic acidosis had a mean BMI of 32.38 (interquartile range [IQR] = 29.4 to 35) at the time of toxicity and had been receiving HAART for a mean of 12.1 months (IQR = 7 to 20.8). Four of the 7 (57%) died of lactic acidosis and/or hemorrhagic pancreatitis; these 4 patients also had a comorbid diagnosis of severe clinical pancreatitis with grade 3/4 lipase elevations and abdominal symptoms at the time of their demise.

CONCLUSIONS

Rates of lactic acidosis appear to be higher in southern Africa when compared with rates previously described elsewhere. Risk factors for the development of moderate to severe symptomatic hyperlactatemia or lactic acidosis appear to be multifactorial but include female gender and having a BMI of greater than 25. Additional studies are ongoing to evaluate for other possible risk factors, such as host genetic differences.

Limitation of exercise capacity in nucleoside-treated HIV-infected patients with hyperlactataemia

BACKGROUND

Inhibition of DNA polymerase gamma by nucleoside reverse transcriptase inhibitors (NRTIs) can cause mitochondrial dysfunction and cellular toxicity. Hyperlactataemia, which is a consequence of a shift in the metabolism of pyruvate, is an indicator of nucleoside-related mitochondrial toxicity.

METHODS

We evaluated exercise and oxidative capacities as well as circulatory and ventilatory responses to exercise in 24 HIV-infected patients on NRTIs presenting hyperlactataemia [mean (+/-standard deviation) fasted lactate=3.5+/-1.1 mmol/L]; 27 NRTI-treated patients with normal baseline lactate concentrations were used as controls (mean fasted lactate=1.6+/-0.3 mmol/L).

RESULTS

In the patients with hyperlactataemia, the average peak work capacity (1.7+/-0.6 W/kg) and peak oxygen consumption (VO(2)) (21+/-4 mL/kg/min) were significantly lower (P<0.01) than in control subjects (work, 2.1+/-0.4 W/kg; VO(2), 25+/-4 mL/kg/min). The capacity to increase oxygen extraction during exercise was significantly diminished in the hyperlactataemia group, as shown by a low peak systemic arteriovenous oxygen difference (a-vO(2)) difference compared with controls (11+/-3 vs 14+/-3 mL/dL; P=0.008), and as indicated by a linear correlation between VO(2) and systemic a-vO(2) difference (r(2)=0.76). During exercise, the increases in cardiac output relative to VO(2) (mean Delta cardiac output (Q)/DeltaVO(2)=8+/-3.6) and ventilation (mean Delta ventilation (VE)/DeltaVO(2)=48.6+/-13.2) were significantly higher in hyperlactataemia patients compared with controls (mean cardiac output Delta(Q)/DeltaVO(2)=6+/-2; mean DeltaVE/DeltaVO(2)=42+/-12.7; P=0.03).

CONCLUSIONS

The degree of exercise limitation in patients with nucleoside-related mitochondrial toxicity correlates directly with the severity of impaired muscle oxidative phosphorylation, as indicated by the capacity for muscle oxygen extraction. Exaggerated circulatory and ventilatory responses to exercise are direct consequences of the level of impaired muscle oxidative phosphorylation.

Didanosine enteric-coated capsule: current role in patients with HIV-1 infection

Didanosine, which is a synthetic nucleoside analogue intracellularly phosphorylated to the active metabolite, inhibits the activity of HIV-1 reverse transcriptase by competing with the natural substrate. Currently, didanosine is mainly provided as an enteric-coated capsule. In vitro, the molecule is active against laboratory strains and clinical isolates of HIV-1 in resting and activated T cells and monocyte/macrophages. Didanosine may select for resistance mutations that may render the drug inactive against the virus; L74V and K65R remain as the main didanosine-related mutations. In vitro, phenotypic susceptibility to didanosine was decreased beyond a defined fold change clinical cut-off (1.7), and it is considered that genotypic resistance exists when five thymidine-associated mutations or four plus M184V are present. In vivo, clinical studies have shown that didanosine retains significant antiviral activity in patients who have up to five nucleoside analogue mutations at baseline. Didanosine is useful in patients with no previous therapy, as well as in experienced patients in whom one or more antiretroviral regimens has failed.Enteric-coated didanosine is taken once daily, its co-administration with food has been recently evaluated and a reduction of the efficacy of the antiretroviral treatment was not observed. Administered with lamivudine (or emtricitabine), it can be considered a good alternative for use in the nucleoside analogue backbone included in combination therapies for antiretroviral-naive patients. Didanosine could be used in initial treatments for patients intolerant of zidovudine, abacavir or tenofovir. It can be included in once-daily combination regimens, which are more convenient and patient friendly.Prospective, observational and open-label studies, as well as clinical trials (with durations between 24 and 96 weeks), have demonstrated the safety and efficacy of didanosine plus lamivudine (or emtricitabine) plus efavirenz (or nevirapine) in previously untreated HIV-1-infected patients. The administration of didanosine to treatment-experienced patients has been evaluated in two different contexts: patients in whom previous therapies have failed (rescue therapy) and those with controlled viraemia who are switched to a didanosine-containing regimen for simplification.Adverse events associated with the administration of didanosine have been well known since the initial clinical trials with the drug. Gastrointestinal intolerance, peripheral neuropathy and hyperamylasaemia/pancreatitis were the most frequently reported. In the highly active antiretroviral therapy (HAART) era, the rate of adverse events has decreased. The tolerability of didanosine has been clearly improved with the development of the enteric-coated capsule. Severe manifestations of mitochondrial toxicity, including lactic acidosis and abnormal fat distribution, are rare complications, and occur most frequently when didanosine is used in combination with stavudine.

Symptomatic Hyperlactatemia Associated with Nucleoside Analogue Reverse-Transcriptase Inhibitor Use in HIV-Infected Patients: A Report of 24 Cases in a Resource-Limited Setting (Uganda)

We describe 24 Ugandan patients with human immunodeficiency virus infection who developed symptomatic hyperlactatemia associated with the use of nucleoside analogues. All patients were receiving combination therapy that contained stavudine. The median serum lactate level was 6.6 mmol/L. All patients had their antiretroviral treatment regimen discontinued. Hospital admission was required for 5 patients. Five patients died.

A High Incidence of Lactic Acidosis and Symptomatic Hyperlactatemia in Women Receiving Highly Active Antiretroviral Therapy in Soweto, South Africa

BACKGROUND

Lactic acidosis and symptomatic hyperlactatemia may complicate nucleoside reverse-transcriptase inhibitor use. Females may be at increased risk for such complications. Our study evaluated the incidence of lactic acidosis and symptomatic hyperlactatemia by sex, analyzed clinical features, and described the safety of reintroducing highly active antiretroviral therapy (HAART) with zidovudine replacing stavudine.

METHODS

A retrospective cohort analysis was performed for 1735 adults (63% of whom were female) who initiated HAART from April 2004 through August 2005 in Soweto, South Africa, with follow-up until February 2006. Patients with lactate levels > or =4.5 mmol/L and no potential cause of elevated lactic acidosis other than receipt of HAART were included in the study.

RESULTS

A total of 23 patients (22 of whom were female) experienced lactic acidosis. The overall incidence was 10.6 cases per 1000 patient-years; the incidence was 16.1 cases per 1000 patient-years in female patients and 1.2 cases per 1000 patient-years in male patients. Seven (30.4%) of the patients died. Eight (34.8%) of the patients were obese (body mass index [calculated as weight in kilograms divided by the square of height in meters], >30) at HAART initiation. Forty-four patients (37 of whom were female) had symptomatic hyperlactatemia. The overall incidence was 20.2 cases per 1000 patient-years, with an incidence of 27.0 cases per 1000 patient-years in female patients and 8.7 cases per 1000 patient-years in male patients. None of the patients died. Nine (20.4%) of the patients were obese at HAART initiation. Sixty-six of 67 patients were receiving stavudine, and 5 patients were receiving didanosine. Among 56 patients who restarted HAART with zidovudine for a cumulative nucleoside reverse-transcriptase inhibitor reexposure of 44.6 patient-years--including 41 patients who received treatment for > or =9 months--there were no relapses.

CONCLUSION

Women in Soweto, South Africa, have a higher frequency of symptomatic hyperlactatemia and lactic acidosis than has been reported for patients in other study groups. In cases associated with stavudine use, restarting HAART with zidovudine seemed to be safe and effective for patients with limited nucleoside reverse-transcriptase inhibitor alternatives.

The Impact of Reducing Stavudine dose versus switching to tenofovir on plasma lipids, body composition and mitochondrial function in HIV-infected patients

Background

Stavudine (d4T)-containing regimens are associated with a potential for lipoatrophy and dyslipidaemia. We assessed the safety and efficacy of reducing the dose of stavudine compared with switching to tenofovir or maintaining the standard dose of d4T.

Methods

Clinically stable HIV-infected patients receiving antiretroviral therapy containing stavudine 40 mg twice daily with a plasma HIV RNA <200 copies/ml for at least 6 months were randomized to maintain stavudine 40 mg twice daily (d4T40 arm), to reduce to 30 mg twice daily (d4T30 arm), or to switch from d4T to tenofovir (TDF arm).

Results

Fifty-eight (93% male) patients were included: 22 in the d4T40 arm, 19 in the d4T30 arm and 17 in TDF arm. At baseline, median time on d4T was 6 years (interquartile range [IQR] 2.6–7.1), median age 43 years (IQR 36–51) and median CD4+ T-cell count was 587/mm3 (IQR 329–892). At week 24, median limb fat changes (g) were as follows: d4T40=-182 (95% CI: -469—5); d4T30=527 (95% CI: -343–694); and TDF=402 (95% CI: 130–835; d4T40 versus TDF, P=0.0003). Significant differences between median values of laboratory parameters were detected: triglycerides (mg/dl): d4T40=19; d4T30=-23 and TDF=-79 (d4T40 versus TDF, P=0.03); and total cholesterol (mg/dl): d4t40=22, d4T30=-4, and TDF=-28 (d4T40 versus TDF, P=0.04). No significant difference was observed in mitochondrial function assessed in peripheral blood mononuclear cells.

Conclusions

Although both strategies were associated with a trend toward a decrease in plasma lipids and an increase in body fat, the only significant changes were observed among those who switched to tenofovir.

Tratamiento antirretroviral y toxicidad mitocondrial

The introduction of highly active antiretroviral therapy for the treatment of human immunodeficiency virus (HIV) infection has led to substantial reduction in morbidity and near-complete suppression of HIV-1 replication. This progress has been tempered by a growing number of new adverse effects. Mitochondrial toxicity is one aspect of these long-term toxicities of antiretroviral drugs, with the role of nucleoside analogs being particularly underlined. Some cases of impaired mitochondrial function have been clearly identified, such as pancreatitis, neuropathy, miopathy and lactic acidosis. Beyond the inhibition of DNA polymerase-g using nucleoside analogs, it appears that several physiopathologic mechanisms interact to explain the observed toxicity. At present there is no reliable method to detect subclinical mitochondrial toxicity. There is no proven effective therapy for antiretroviral therapy-associated mitochondrial toxicity other than ceasing the implicated agent, and even with this strategy, resolution of symptoms may be incomplete. Therefore, investigation of mitochondrial toxicity of new compounds or new combinations is of growing interest for the clinical application of antiretroviral agents.

Lactic acidosis in an HIV-infected patient receiving highly active antiretroviral therapy

BACKGROUND

A 51-year-old man with HIV infection on highly active antiretroviral therapy presented with abdominal pain and exertional dyspnea. Physical examination revealed increased respiration and cachexia. Laboratory tests showed a lactic acid concentration elevated to 6.4 mM.

INVESTIGATION

Physical examination, blood chemistry, arterial blood gas, urine analysis, chest X-ray, and ultrasound of liver.

DIAGNOSIS

Nucleoside reverse transcriptase inhibitor (NRTI)-induced lactic acidosis, hepatitis and chemical pancreatitis. Proximal renal tubular acidosis with Fanconi's syndrome, secondary to treatment with tenofovir.

MANAGEMENT

The patient was supported on intravenous and oral bicarbonate, riboflavin and phosphorus supplementation. Highly active antiretroviral therapy was discontinued. The patient's lactate level decreased about 2 weeks after discharge.

Antiretroviral medication considerations for individuals coinfected with HIV and hepatitis C virus

There is great need to treat HIV/hepatitis C virus (HCV)-coinfected individuals with both antiretroviral and anti-HCV pharmacotherapy. However, treatment for HIV may lead to hepatotoxicity, and there are potential interactions and synergistic effects between antiretrovirals and anti-HCV medications. The ideal antiretroviral therapy options for coinfected patients, in the setting of anti-HCV treatment, are unclear and present important challenges to clinicians. We review the current data on the use of antiretrovirals in HIV/HCV-coinfected patients and offer evidence-based recommendations on optimal selection and dosing of antiretroviral agents for this population.

[Antiretroviral treatment associated life-threatening adverse events]

The primary goal of the highly active antiretroviral treatment is to improve HIV-infected patient immune function through maintaining viral suppression. However, this treatment may lead to adverse events, some of them potentially serious. This article emphasizes on the antiretroviral therapy associated adverse events and their management recommendations, especially for serious or potentially life-threatening cases. Adverse events analyzed in this article include side effects derived from mitochondrial toxicity, abacavir hypersensitivity reaction, hepatotoxicity, skin rash and Stevens-Johnson syndrome, increased bleeding episodes in hemophilic patients and nephrotoxicity. In some cases, a high suspicion is needed because the onset symptoms may be unspecific.

Current therapy for human immunodeficiency virus infection and acquired immunodeficiency syndrome

Antiretroviral treatments with highly active antiretroviral therapy (HAART) have shown remarkable progress in the past decade and resulted in impressive improvements in life expectancy and quality of life for patients infected with human immunodeficiency virus 1 (HIV-1). Despite the clinical benefits, the management of HIV infection faces many problems. Although HAART is able to suppress the viral load in the plasma, it is unable to eradicate it, and once HAART is initiated, treatment needs to be continued over a lifetime. The side effects of long-term HAART, such as lipodystrophy, lactic acidosis, insulin resistance, and hyperlipidemia, are negative impacts for patients who receive HAART. In addition, patients need to demonstrate high adherence to the therapy to achieve viral suppression and prevent the development of a drug-resistant virus. This review discusses currently recommended antiretroviral treatment strategies, the difficulties with antiretroviral treatments, and current issues regarding HIV management.

Impact of antiretroviral treatment-related toxicities on hospital admissions in HIV-infected patients

While classical opportunistic infections have decreased as the main cause of hospital admission of HIV-infected patients, other conditions including drug-related toxicities seem to have increased. We assessed the proportion of patients with hospital admission due to antiretroviral (ARV)-related toxicities over the last 7 years at a single HIV/AIDS reference institution located in Madrid. A total of 1981 consecutive hospital admissions in 1581 different HIV-infected patients were analyzed. Nearly half of them (45%) were on ARV therapy. Overall, ARV-related toxicities were the main or secondary reason for hospital admission in 141 patients (7%). Liver toxicity was the most frequent complication (n = 42; 30%), of which one-third were associated with NVP use and 80% occurred in subjects with underlying chronic hepatitis C virus (HCV) infection. Other main ARV-related toxicities were bone marrow toxicity due to zidovudine (17%), pancreatitis (13%), and indinavirassociated nephrolithiasis (6%). Eight patients presented with symptomatic hyperlactatemia, two of them with lactic acidosis. All subjects with ARV-related toxicities had a favorable outcome, except one with prior HCVrelated end-stage liver disease, who died after experiencing hepatic decompensation following initiation of a protease inhibitor-based regimen.

Differentiating the causes of metabolic acidosis in the poisoned patient

Numerous drugs and toxins may induce the development of a metabolic acidosis. The treating physician should be cognizant of the many compounds that can produce metabolic acidosis following an overdose or an accidental exposure, or with therapeutic use. Knowledge and comprehension of the substances associated with metabolic acidosis will facilitate the diagnosis and treatment of poisoned patients.

Antiretroviral therapy: an update for the non-AIDS specialist

PURPOSE OF REVIEW

The treatment of HIV infection has been transformed by the introduction of highly active antiretroviral therapy. For patients who respond and can tolerate lifelong therapy, HIV infection may become a chronic disease requiring long-term ambulatory care follow-up. The current management of antiretrovirals is increasingly complex because of the large number of agents, wide spectrum of toxicities, adherence issues, and drug interactions. This review summarizes the currently available agents, recommended and alternative combinations, commonly encountered adverse events, and viral resistance issues.

RECENT FINDINGS

Twenty antiretroviral medications are commercially available in the United States. Six new agents have been introduced since 2000, including one drug in a novel class of HIV fusion inhibitors. The adverse effects of antiretrovirals are well characterized and include lactic acidosis related to nucleoside reverse transcription inhibitors; metabolic and body habitus changes, primarily attributed to protease inhibitors; and concern about the long-term vascular consequences of elevated lipids and insulin resistance associated with treatment. The recommended antiretroviral therapy by an expert panel as of October 2004 is summarized.

SUMMARY

The benefits of antiretroviral therapy are clear: reduced morbidity and mortality related to advanced HIV infection. Managing antiretroviral therapy, along with their adverse effects and drug interactions, is complex. Modern treatment mandates a thorough understanding of the agents. Consultation with an HIV-experienced clinician should be considered in most circumstances.

Antiviral hepatitis and antiretroviral drug interactions

More and more HIV-infected patients are treated for viral hepatitis, increasing interactions. HEPATITIS C: The concomitant use of didanosine and ribavirin increases the risk of mitochondrial toxicity, responsible for pancreatitis and/or lactic acidosis. Lactic acidosis is characterized by a high mortality rate. Thus, didanosine, but also stavudine, should not be co-administered with ribavirin. Cases of hepatic decompensation have been reported in cirrhotics concomitantly receiving ribavirin and didanosine. Thus, this co-admininistration should be contraindicated in patients with advanced liver fibrosis. Anemia is a frequent side effect of ribavirin. In patients with zidovudine-related anemia, this drug should be discontinued before prescribing ribavirin. Erythropoietin may help to improve the haemoglobin level. HEPATITIS B: Adefovir significantly decreases the plasma levels of saquinavir. Pancreatitis may occur with the co-administration of didanosine and tenofovir. Thus this co-administration should be avoided. Atazanavir concentrations are decreased when tenofovir is co-administered. Thus, atazanavir should be boosted with ritonavir, when combined with tenofovir. Atazanavir increases the concentrations of tenofovir, with the potential risk of increasing the adverse events of tenofovir, including renal disorders. Tenofovir area under the curve is increased if lopinavir-ritonavir are co-administered. The main interactions, with a fatal risk, are observed with didanosine, when co-administered with ribavirin (hepatitis C) or with tenofovir (hepatitis B). Anemia is frequent, but usually moderate, when zidovudine is co-administered with ribavirin. Other interactions are usually easy to manage.

Symptomatic hyperlactataemia precipitated by the addition of tetracycline to combination antiretroviral therapy

Hyperlactataemia in the setting of combination antiretroviral therapy for HIV infection occurs on a spectrum ranging from common, asymptomatic laboratory abnormalities to rare, potentially life-threatening lactic acidosis. Some other medications, including the biguanides, tetracycline, and even linezolid, have rarely been reported to cause lactic acidosis. Recently, cases of lactic acidosis or hyperlactataemia have been reported in patients receiving combination antiretroviral therapy that have been precipitated by the addition of other medications-eg, metformin or ribavirin. We report a case of symptomatic hyperlactataemia in a patient on combination antiretroviral therapy that was likely precipitated by the addition of tetracycline and discuss the broader implications of other medications with the potential to cause hyperlactataemia in the setting of combination antiretroviral therapy.

Recomendaciones de GEAM/SPNS sobre el tratamiento de las alteraciones metabólicas y morfológicas en el paciente con infección por VIH

OBJECTIVE

To provide an update of the metabolic and morphologic alterations in patients infected with HIV with an in-depth analysis of their clinical management and treatment.

METHODS

These recommendations were agreed by consensus by a committee of experts in metabolic alterations and HIV patient care, under the auspices of the Secretariat for the National AIDS Plan. To do this, the latest clinical, epidemiological and physiopathological advances described in studies published in the scientific literature and/or presented in congresses were reviewed.

RESULTS

The most frequent metabolic alterations in HIV patients and in antiretroviral treatment (ART) are dyslipidemia with an atherogenic profile and alterations in carbohydrate metabolism/insulin resistance. A high prevalence of cardiovascular risk factors, especially smoking, has been described. The same criteria for their management as those used in the general population have been employed, with specific nuances. Diet and exercise should be the first therapeutic recommendation. In patients with dyslipidemia who require drug treatment, statins and/or fibrates are indicated. Glitazones have demonstrated efficacy in the treatment of insulin resistance. The approach to anomalous fat distribution continues to be controversial. The main approaches at present are a switch of ART, reparative surgery, psychological support and lifestyle changes. Lactic acidosis is an infrequent but highly serious complication, and the first step is withdrawal of ART. In bone metabolism alterations, prevention and early detection are essential, especially in children and perimenopausal women. Sexual dysfunction is a frequent problem in both men and women; because the causes are highly varied, treatment should be individualized.

CONCLUSIONS

The prevalence of metabolic and morphologic alterations has increased since the introduction of highly active antiretroviral treatment (HAART). Knowledge of the various aspects involved in their diagnosis and treatment is essential for the appropriate care of patients with HIV infection.

[Mitochondrial cytopathies associated with HIV infection]

The tremendous progress achieved during the last few years with the use of highly active antiretroviral therapy in suppressing HIV replication together with improvements in immunity have been tempered by a growing number of new adverse effects. Mitochondrial toxicity is one aspect of these long-term toxicities of antiretroviral drugs, with the role of nucleoside analogs particularly underlined. Some cases of impaired mitochondrial function have been clearly identified, such as pancreatitis due to didanosine, neuropathy due to zalcitabine, myopathy due to zidovudine, and lactic acidosis due to stavudine. These mitochondrial toxicities can affect several organs, presenting different patterns of symptoms: from asymptomatic to states with few symptoms despite huge metabolic abnormalities whose prognosis is immediately life-threatening. Beyond the inhibition of DNA polymerase gamma using nucleoside analogs, responsible for decreasing mitochondrial DNA in certain targeted organs, it appears that several physiopathologic mechanisms interact to explain this observed toxicity, HIV itself plays a role, and the underlying genetic pool needs to be better identified. Such cases mean that, it is imperative to avoid cumulated toxicities caused by associated treatments. With serious cases, or persistent symptoms despite discontinuing the nucleoside analogs responsible for such toxicity, one must propose vitamins, mitochondrial co-factors, or anti-oxidants. However, the future lies in the use of potent, less toxic nucleoside analogs, and in developing compounds belonging to other classes of antiretrovirals.

Lopinavir/ritonavir as single-drug therapy for maintenance of HIV-1 viral suppression: 48-week results of a randomized, controlled, open-label, proof-of-concept pilot clinical trial (OK Study)

OBJECTIVE

This study evaluated maintenance with lopinavir/ritonavir monotherapy vs. continuing lopinavir/ritonavir and 2 nucleosides in HIV-infected patients with suppressed HIV replication.

DESIGN

Randomized, controlled, open-label, multicenter, pilot clinical trial.

METHODS

Adult patients were eligible if they had no history of virologic failure while receiving a protease inhibitor, were receiving 2 nucleosides + lopinavir/ritonavir (400/100 mg b.i.d.) for >1 month and had maintained serum HIV RNA <50 copies/mL for >6 months prior to enrollment.

RESULTS

Forty-two patients were randomly assigned 1:1 to continue or stop the nucleosides. At baseline there were no significant differences between groups in median CD4 cells/muL (baseline or nadir), pre-HAART (highly active antiretroviral therapy) HIV log10 viremia, or time with HIV RNA <50 copies/mL prior to enrollment. After 48 weeks of follow-up, percentage of patients remaining at <50 HIV RNA copies/mL (intention to treat, M = F) was 81% for the monotherapy group (95% CI: 64% to 98%) vs. 95% for the triple-therapy group (95% CI: 86% to 100%); P = 0.34. Patients in whom monotherapy failed had significantly worse adherence than patients who remained virally suppressed on monotherapy. Monotherapy failures did not show primary resistance mutations in the protease gene and were successfully reinduced with prerandomization nucleosides. Mean change in CD4 cells/microL: +70 (monotherapy) and +8 (triple) (P = 0.27). Mean serum fasting lipids remained stable in both groups. No serious adverse events were observed.

CONCLUSION

Most of the patients maintained with lopinavir/ritonavir monotherapy remain with undetectable viral load after 48 weeks. Failures of lopinavir/ritonavir monotherapy were not associated with the development of primary resistance mutations in the protease gene and could be successfully reinduced adding back prior nucleosides.

Mitochondrial dysfunction: patient monitoring and toxicity management

Mitochondrial toxicity has been implicated in the development of a variety of nucleoside reverse transcriptase inhibitor-associated syndromes. Mitochondrial damage and decreases in mitochondrial DNA levels have been demonstrated in various tissues of patients treated with NRTIs, especially in conjunction with exposure to stavudine. Clinical syndromes that may be mediated by mitochondrial toxicity include hyperlactatemia and lactic acidosis, hepatic steatosis, lipoatrophy, peripheral neuropathy, HIV-associated neuromuscular weakness syndrome, pancreatitis, skeletal myopathies, and cardiomyopathy. Early recognition of these syndromes in their mild forms involves close monitoring and a high index of suspicion. This may allow prompt discontinuation of the causative agent(s) and initiation of appropriate therapeutic measures, thereby increasing the chances of reversibility of the syndrome.

HIV and liver diseases: recent clinical advances

Because the life expectancy of patients infected with HIV has been prolonged, liver diseases have assumed far greater importance as a cause of morbidity and mortality in these patients. Given the shared risks of transmission, patients who have HIV often are coinfected with hepatotrophic viruses such as hepatitis C and hepatitis B. Further, antiretroviral therapy (ART) used by patients who have HIV is often hepatotoxic, contributing to liver damage. With increasing immunosuppression caused by AIDS, patients who have HIV have to deal with these issues and the increased risk of infection with opportunistic viral, fungal, bacterial, and protozoal pathogens. In addition, steatosis and lipodystrophy now are recognized more commonly in patients who have HIV, particularly in the setting of ART. Thus, understanding of liver diseases in the setting of HIV infection becomes an important focus in caring these individuals. There have been numerous advances in the treatment of liver disease in patients who have HIV, particularly in treating viral hepatitis C and B. This article reviews various liver manifestations in patients who have HIV and the recent advances in diagnostic and therapeutic options.

Metabolic acidosis: differentiating the causes in the poisoned patient

Metabolic acidosis may arise from several drugs and toxins through a variety of mechanisms. Differentiating the causes of metabolic acidosis in the poisoned patient is an indispensable skill in clinical practice. Comprehension of toxin-induced metabolic acidosis, combined with a thorough history, physical examination, appropriate use of laboratory tests, and a stepwise approach, should aid the clinician in determining the cause of metabolic acidosis in the poisoned patient. When confronted with such a patient, it is imperative that one administer appropriate antidotal therapy, when necessary, and provide the patient with exceptional supportive care.

Highly active antiretroviral therapy and the kidney: an update on antiretroviral medications for nephrologists

Highly active antiretroviral therapy has dramatically altered the treatment and life expectancy of individuals who are infected with HIV. More than 20 antiretroviral drugs and drug combinations now are available in the United States. Nephrologists need to have an understanding of the pharmacokinetics of antiretroviral medications and the proper dosing of these medications in patients with impaired kidney function. It is also important for nephrologists to be aware of drug-drug interactions that can occur between antiretroviral medications and other medications that they may prescribe, including immunosuppressive medications that are used for renal transplantation, as this becomes more common in HIV-infected patients. Adverse reactions that affect the kidneys and cause fluid-electrolyte complications occur with certain antiretroviral agents, although most are relatively free of nephrotoxicity. This article reviews the clinical pharmacology and dosing modifications of the newer antiretroviral medications in patients with reduced kidney function; important drug-drug interactions involving these medications, particularly with other medications that are likely to be prescribed by nephrologists; and renal toxicities of antiretroviral agents.

Tratamiento de la hiperlactatemia sintomática y de la acidosis láctica en pacientes con infección por el virus de la inmunodeficiencia humana en tratamiento con inhibidores de la transcriptasa inversa análogos de los nucleósidos

BACKGROUND AND OBJECTIVE

We intended to find out the effectiveness of lactic acidosis therapy for mitochondrial toxicity.

PATIENTS AND METHOD

HIV-patients receiving nucleoside reverse transcriptase inhibitors (NRTIs), hospitalized with lactic acidosis or symptomatic hyperlactatemia. Venous hyperlactatemia was considered at > 2.2 mmol/l. Treatment consisted of a daily vitamin regime of L-carnitine, thiamine, vitamin B6, hydroxicobalamine, and vitamin C; any glucose intake was discontinued. NRTIs treatment was stopped immediately.

RESULTS

Nine patients on current therapy were identified who had symptomatic hyperlactatemia (n = 4) or lactic acidosis (n = 5) from 1/2001 to 9/2002. All were patients with AIDS, receiving NRTIs with a mean duration of 5 years: ddI (n = 7), d4T (n = 5), AZT(n = 3), 3TC (n = 2), abacavir (n = 1). Most common symptoms were tachypnea, slight fever, abdominal pain, nausea, vomiting and diarrhea. All patients had a favourable prognosis after administration of L-carnitine and vitamin complexes, with discontinuation of NRTIs and glucose intake. Clinical features lasted 7 days. After 15 (5) months of follow up, none had a recurrence of the syndrome.

CONCLUSION

The application of this therapy could play a role in the treatment of NRTI - related lactic acidosis.

Muscle and Liver Lactate Metabolism in Haart-Treated and Naive HIV-Infected Patients: The Mitovir Study

Objective

To assess the impact of nucleoside analogue reverse transcriptase inhibitor (NRTI) combination therapy on muscle and liver lactate metabolism in HIV-infected patients.

Methods

This cross-sectional study involved HIV-infected patients who were either antiretroviral-naive (Group 1) or were receiving either a stable triple-drug combination including at least one d-drug (zidovudine, zalcitabine, stavudine, didanosine; Group 2) or a backbone of abacavir and lamivudine (Group 3). Lactataemia was measured at rest. Muscle lactate metabolism was assessed during a standardized exercise test and liver lactate metabolism during intravenous lactate infusion. Mitochondrial DNA was quantified in peripheral blood mononuclear cells.

Results

A total of 65 patients were enrolled (16, 31 and 18 patients in Group 1, Group 2 and Group 3, respectively). None of the patients had symptoms of hyperlactataemia. Patients in Group 3 had received d-drugs for a median of seven years before switching to abacavir and lamivudine. Median baseline lactataemia, although within the normal range, was significantly higher in both treatment groups than in the naive patients (Group 2: 1.4, Group 3: 1.5, and Group 1: 1.0 mmol/l, P=0.005). Muscle lactate clearance was significantly lower in both treatment groups than in naive patients (Group 2: 1.6, Group 3: 1.8, and Group 1: 2.1, P=0.01). Lactate liver metabolism and mitochondrial DNA levels did not differ among the three groups.

Conclusions

In HIV-infected patients without symptomatic hyperlactataemia, all NRTI-containing HAART regimens appear to cause muscle mitochondrial damage but to spare the liver. Absence of difference between Group 2 and Group 3 raises questions about the potential reversibility of muscle mitochondrial dysfunction, and/or the ability of abacavir and lamivudine to induce such mitochondrial damage.

Hyperlactataemia and lactic acidosis in HIV-infected patients receiving antiretroviral therapy

Nucleoside reverse-transcriptase inhibitors (NRTIs) have been associated with functional and structural mitochondrial abnormalities, leading to several adverse events, such as increased serum lactic acid levels and lactic acidosis. Mild-to-moderate, asymptomatic hyperlactataemia has been frequently reported in human immunodeficiency virus (HIV)-infected patients treated with NRTIs, with an estimated prevalence between 15% and 35%. On the contrary, symptomatic, severe hyperlactataemia and lactic acidosis are less common, with an incidence ranging from 1.7 to 25.2 cases per 1000 person-years of antiretroviral treatment, and are associated with a remarkable mortality rate, which varies from 30% to 60% in different studies. The clinical presentation of lactic acid syndrome is non-specific and includes asthenia, malaise, nausea, vomiting, abdominal pain, weight loss, tachypnoea, dyspnoea, liver steatosis and increased transaminase levels, and risk factors include previous or concurrent therapy with stavudine or didanosine. Management of symptomatic lactic acid alterations involves NRTI-therapy interruption and supportive care, while natural history of hyperlactataemia is still unknown, and it is uncertain whether asymptomatic patients with increased lactate concentrations are at increased risk of developing lactic acidosis.

Nucleoside Analogue-Sparing Strategy for the Treatment of Chronic HIV Infection: Potential Interest and Clinical Experience

Nucleoside analogue-sparing antiretroviral combinations may be interesting as first-line therapies as they spare a complete class of drugs that will remain fully active for later use and prevent the risk of mitochondrial toxicity related to exposure to nucleoside reverse transcriptase inhibitors (NRTIs). This strategy is also used in patients failing NRTIs with cross-resistance to compounds in this class. Different combinations of antiretroviral drugs are theoretically available. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) associated with protease inhibitor (PI) and boosted double-PI combinations have been studied through small, non-comparative clinical studies and preliminary results suggest that they are efficient and often well-tolerated. However, NNRTIs and PIs are extensively metabolized in the liver through cytochrome P450, leading to pharmacokinetic interactions; a good knowledge of the interactions between NNRTIs and PIs, or between PIs, is helpful in assisting physicians in clinical practice in choosing drugs and doses. Access to a therapeutic drug monitoring service to confirm that appropriate drug exposures are achieved is useful when using such regimens. Some negative kinetic interactions may lead to complicated combinations with a high pill burden that reduces their applicability. Gastrointestinal toxicity often remains a limiting factor in the use of boosted double-PI combinations. Non-comparative studies have allowed selection of NRTI-sparing options that now need to be compared with the current standard of care in comparative clinical trials before being considered as valuable options. Other NRTI-sparing therapeutic strategies are emerging: PI monotherapy with lopinavir/ritonavir has been evaluated in a small group of naive patients and appears promising. Drugs belonging to new classes currently under investigation, such as entry inhibitors, might be included early in the antiretroviral treatment of patients as soon as compounds with a convenient route of administration are available, increasing the number of therapeutic combinations without NRTIs.

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.

Complications Associated with Nrti Therapy: Update on Clinical Features and Possible Pathogenic Mechanisms

The availability of durable, effective antiretroviral therapy for HIV-infected patients has fundamentally altered the prognosis of this disease and has also increased awareness that long-term drug toxicities have the potential to cause significant morbidity and even mortality in this patient population. The long-term use of nucleoside analogue reverse transcriptase inhibitor (NRTI) drugs has been associated with a number of clinically relevant toxicities including hyperlactataemia and lactic acidosis, neuropathy, pancreatitis and, more recently, a syndrome of pathological loss of subcutaneous fat tissue (lipoatrophy). Importantly, the toxicity profile of each NRTI drug within this class is unique in terms of the overall risk of long-term complications, as well as the tissue specificity of its toxic effects. In this review, the clinical manifestations, risk factors and pathological basis for NRTI-associated toxicity syndromes are explored, with an emphasis on clinical assessment and management.

HIV-associated neuromuscular weakness syndrome

OBJECTIVE

To investigate progressive, severe neuromuscular weakness associated with lactic acidosis in some HIV-infected patients after exposure to nucleoside reverse transcriptase inhibitors (NRTI).

METHODS

HIV-associated neuromuscular weakness syndrome (HANWS) was retrospectively identified and classified based on the level of diagnostic certainty: possible (progressive weakness owing to neuromuscular disease), probable (progressive neuromuscular weakness with documented exclusion of confounding causes), or definite (progressive weakness and electrophysiological or pathological evidence of neuromuscular pathology).

RESULTS

Of 69 patients identified with HANWS, 27 had definite HANWS, 19 probable, and 23 possible. In 44 patients with documented follow-up, 16 required intubation and nine died. There was a marginal association between death and hyperlactatemia (P = 0.061). At onset of neurological symptoms, 68 were receiving antiretroviral therapy, including stavudine for 61 (89.7%). Serum lactate level was elevated (> 2.2 mmol/l) in 30/37 (81%), with a trend towards an association between hyperlactatemia and stavudine usage (P = 0.087). In 25, neurological symptoms occurred after antiretroviral therapy discontinuation (median, 14 days). Electrophysiological studies (n = 24) indicated sensorimotor neuropathy in 20 patients and myopathy in three. Nerve biopsy (n = 9) revealed axonal degeneration and inflammation in three, mixed axonal and demyelinating lesions in three, and primary axonal neuropathy in three. Of 15 muscle biopsies, three revealed inflammation and four mitochondrial abnormalities.

CONCLUSIONS

A severe neuromuscular weakness syndrome may occur in HIV-infected individuals. The association with hyperlactatemia and NRTI exposure supports mitochondrial toxicity as a pathogenesis. In some, the onset of neurological symptoms lagged significantly after discontinuation of antiretroviral therapy, suggesting that different etiological mechanisms may underlie these cases.

Prognostic factors in lactic acidosis syndrome caused by nucleoside reverse transcriptase inhibitors: report of eight cases and review of the literature

We conducted a retrospective study to identify prognostic factors in the lactic acidosis syndrome (LAS) caused by nucleoside reverse transcriptase inhibitors (NRTIs) in patients with HIV/AIDS. Fifty-eight cases of LAS were included in our analysis, 8 from our hospital spanning the years 1992-2002, and 50 reported in the English language literature from 1986 through 2002. Peak venous lactate level was the best predictor of mortality. Zidovudine was associated with higher lactate levels and higher mortality than stavudine and lamuvidine. Mortality declined progressively after 1986 when the first cases of NRTI-related LAS were described. Increased mortality with zidovudine in this study appears due in part to its greater use prior to 1990 when LAS was not widely recognized as a potential complication of NRTI therapy.

Bench-to-bedside review: treating acid-base abnormalities in the intensive care unit - the role of buffers

The recognition and management of acid-base disorders is a commonplace activity for intensivists. Despite the frequency with which non-bicarbonate-losing forms of metabolic acidosis such as lactic acidosis occurs in critically ill patients, treatment is controversial. This article describes the properties of several buffering agents and reviews the evidence for their clinical efficacy. The evidence supporting and refuting attempts to correct arterial pH through the administration of currently available buffers is presented.

Mitochondrial toxicity associated with HAART following liver transplantation in an HIV-infected recipient

Antiretroviral therapy is not uncommonly associated with drug toxicities, and hepatotoxicity occurs in approximately 20% of individuals prescribed antiretroviral therapy. Mitochondrial toxicity causing lactic acidosis is a rare but fatal complication that has been described in some HIV-infected patients treated with nucleoside analogue reverse transcriptase inhibitors. In this report, we describe the course of an HIV-infected patient receiving antiretroviral therapy who developed lactic acidosis after liver transplantation for HCV-induced liver disease.

Absence of Sustained Hyperlactatemia in HIV-Infected Patients With Risk Factors for Mitochondrial Toxicity

BACKGROUND

The prevalence of asymptomatic hyperlactatemia among HIV-infected individuals has been reported to be 4% to 36%. This variability may reflect differences in the definition of and risk factors for hyperlactatemia and/or techniques for venous lactate collection.

METHODS

We examined the prevalence of elevated venous lactate collected in accordance with Adult AIDS Clinical Trials Group (AACTG) guidelines among HIV-infected and nucleoside analogue-treated subjects with risk factors associated with hyperlactatemia. Sustained hyperlactatemia was defined as 2 consecutive levels >or=1.5 but <or=4 times the upper limit of normal (ULN) within 30 days.

RESULTS

Eighty-three subjects were enrolled. Two thirds had >or=2 risk factors, with 11% having >4 risk factors. The median entry venous lactate level was 1.2 mmol/L (range: 0.7-5.1 mmol/L). Two subjects had a lactate level >1.5 times the ULN: 1 with a value of 2.1 times the ULN at entry and a week 2 level of 1.2 times the ULN and a second subject with a week 2 value of 1.9 times the ULN but an entry level of 1.4 times the ULN. The latter subject developed symptomatic lactic acidosis 3 weeks following study discontinuation.

CONCLUSIONS

Sustained asymptomatic hyperlactatemia among subjects with risk factors associated with hyperlactatemia was not observed when venous lactate was measured in a standardized fashion. One case of hyperlactatemia that evolved into symptomatic lactic acidosis was diagnosed soon after the completion of the study, however. Our findings indicate that asymptomatic hyperlactatemia is either very rare or an artifact of collection technique.

High Rate of Didanosine-Related Mitochondrial Toxicity in HIV/HCV-Coinfected Patients Receiving Ribavirin

Background

Nucleoside analogues may induce mitochondrial toxicity, particularly didanosine. Ribavirin increases didanosine exposure, which might be clinically relevant when coadministered in HIV/HCV-coinfected patients.

Objective

To evaluate, among 89 patients receiving highly active antiretroviral therapy (HAART) and therapy for chronic hepatitis C, clinically relevant mitochondrial toxicity in those treated with concomitant ribavirin and didanosine ( n=35, 39%).

Methods

From January 2000 to July 2002 longitudinal analysis of the incidence and clinical course of didanosine-related hyperamylasaemia, pancreatitis, hyperlactataemia/lactic acidosis or neuropathy. Risk factors were evaluated using univariate and multivariate Cox's proportional hazards model.

Results

Among 35 patients who received concomitant didanosine (400 mg/day in 86%) and ribavirin (≥10 mg/kg/day in 91%), 20 (57%) developed one or more adverse events after a mean of 87 days. Most frequent laboratory abnormalities were hyperamylasaemia (18 patients, 51%) and hyperlactataemia (eight patients, 23%). Acute pancreatitis and symptomatic hyperlactataemia developed in 10 (28%) and six (17%) patients, respectively. Two patients (6%) with pancreatitis and severe lactic acidosis died; the other patients recovered uneventfully despite continuation of anti-HCV therapy in 83% after didanosine withdrawal in 40%. In the Cox's model higher baseline amylase levels (HR: 1.04, 95% CI: 1.02–1.06, P=0.001) and three nucleoside reverse transcriptase inhibitor-based HAART (HR: 5.3, 95% CI: 1.73–16.24, P=0.003) were significantly associated to toxicity.

Conclusions

The coadministration of didanosine and ribavirin should be avoided in HIV/HCV-coinfected patients, due to a high rate of clinically significant toxicity, particularly in triple nucleoside-based HAART. Amylase levels should be strictly monitored, especially if elevated at baseline.

Serum l-lactate and pyruvate in HIV-infected patients with and without presumed NRTI-related adverse events compared to healthy volunteers

BACKGROUND

Nucleoside reverse transcriptase inhibitors (NRTIs) used in antiretroviral therapy may cause mitochondrial toxicity. Mitochondrial dysfunction leads to disturbance of the glucose metabolism, resulting in an accumulation of L-lactate (L) and pyruvate (P), with an enhanced L/P ratio.

OBJECTIVES

We analysed lactate and pyruvate blood samples of patients of our outpatient department. Aim of the analysis was to detect preliminary mitochondrial toxicity in patients on antiretroviral nucleoside analogues, which might result in disturbances of L, P, L/P ratio, bicarbonate (Bic) or beta-hydroxybutyrate/aceto-acetate (beta-HB/AA) ratios.

STUDY DESIGN

Blood samples of L, P, Bic, beta-HB and AA were analysed in four groups of subjects. The first group (A) consisted of patients with presumed NRTI-related adverse events (n=21), the second group (B) consisted of patients without adverse events (n=28), the third group (C) were HIV-infected patients without antiretroviral therapy (n=6) and the last group (D) were healthy controls (n=12). The mean duration of NRTI-treatment was 18 months (range 0-78 months).

RESULTS

The mean lactate level in group A was 2319 micromol/l (S.D. +/-1231, median 1741 micromol/l), in group B 1257 micromol/l (S.D. +/-607, median 1087), Group C 1285 (S.D. +/-451, median 1245 micromol/l) and 951 micromol/l (S.D. +/-270, median 979) in the healthy controls. No significant differences in pyruvate, L/P, Bic and beta-HB/AA were seen in the four groups. The mean lactate level in patients on stavudine was 1980 micromol/l (S.D. +/-1197) versus 1051 micromol/l (S.D. +/-395, P=0.01) in patients on zidovudine. All patients with lactate values above 2700 micromol/l (eight) experienced adverse events.

CONCLUSION

Lactate levels were higher in patients with presumed NRTI-related adverse events. Furthermore, HIV patients receiving a stavudine containing antiretroviral therapy had higher lactate values than patients without stavudine. Although routine lactate measurement in all patients on antiretroviral therapy is not recommended, lactate measurement might be useful for follow up of patients with presumed NRTI-related adverse events and in patients with lactate levels above 2500 micromol/l. These patients require extra surveillance to evaluate if discontinuation of the current antiretroviral therapy is needed.

Neuromuscular complications in HIV

HIV affects many organs of the body, including the nervous system. As a result, a series of neurologic complications have created challenges for scientists and clinicians alike. Among these, HIV-associated neuropathy and myopathy may occur at all stages of the disease process. Of the neuropathies, distal symmetrical polyneuropathy is the most common form. The pathogenesis of primary HIV neuropathy is unknown. Other types of neuropathy seen in HIV-infected subjects include toxic neuropathy, inflammatory demyelinating polyneuropathy, progressive polyradiculopathy, and mononeuritis multiplex. In this review, we present the clinical manifestations, pathogenesis, diagnosis, and management of different types of neuropathy in HIV infection. Myopathy, another complication of HIV, is not associated with any particular stage of immunosuppression. Symptoms include symmetrical weakness of the proximal muscles in the extremities. Serum creatine kinase levels are often moderately elevated. Electromyography and muscle biopsy are helpful tests for diagnosis. Treatment of HIV myopathy includes corticosteroids, nonsteroidal anti-inflammatory agents, and intravenous immunoglobulin.

Critical issues in nephrology

Renal and electrolyte problems are common in patients in the ICU. Several advances that occurred in the recent past have been incorporated in the diagnosis and management of these disorders and were reviewed in this article. Unfortunately, many important questions remain unanswered, especially in the area of ARF, where new therapies are anxiously awaited to make the transition from bench to bedside. Better studies are sorely needed to define the best approach to dialysis in patients who have ARF.

Safety and efficacy of switching to alternative nucleoside analogues following symptomatic hyperlactatemia and lactic acidosis

OBJECTIVE

To evaluate the safety and efficacy of rechallenging patients who have recovered from nucleoside reverse transcriptase inhibitor (NRTI)-induced symptomatic hyperlactatemia or lactic acidosis with alternative NRTI-containing regimens.

METHODS

Data in this case series was collected from patients followed at the UCSD Owen Clinic from July 1998 through September 2002. Cases of symptomatic hyperlactatemia were HIV-infected adults receiving NRTI who had symptoms compatible with hyperlactatemia and two lactates > 2 times the upper normal limit. Lactic acidosis was defined as lactate > 5 mmol/l with bicarbonate < 20 mmol/l. The suspected offending NRTI in the prior regimen were replaced with other NRTI thought to have equivalent antiviral potency but less mitochondrial toxicity.

RESULTS

Ten patients diagnosed with symptomatic hyperlactatemia and two with lactic acidosis were later restarted on antiretrovirals that included new NRTI. The NRTI that patients were receiving when symptomatic hyperlactatemia or lactic acidosis was diagnosed included stavudine and lamivudine (n = 6), stavudine and didanosine (n = 4), and stavudine and abacavir (n = 2). The median (range) peak lactate was 5.4 (4.7-19.1) mmol/l. Five patients were rechallenged with abacavir and lamivudine, five with zidovudine, abacavir and lamivudine, and two with zidovudine and lamivudine. Among the 12 patients contributing over 22 years of cumulative reexposure to NRTI-containing therapy, one developed symptomatic hyperlactatemia again yielding a recurrence rate of 45.5 cases/1000 patient-years. Virologic control was maintained in all patients.

CONCLUSIONS

This data supports the strategy that in cases of symptomatic hyperlactatemia or lactic acidosis in which the toxicity is associated with stavudine, didanosine or both, it is safe and efficacious to reintroduce NRTI that are less potent inhibitors of mitochondria.