Hyperlactatemia and antiretroviral therapy: the Swiss HIV Cohort Study

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.

Lactic Acidosis International Study Group. Risk factors for lactic acidosis and severe hyperlactataemia in HIV-1-infected adults exposed to antiretroviral therapy

BACKGROUND

Severe hyperlactataemia and lactic acidosis are rare serious complications of antiretroviral therapy (ART).

METHODS

Lactic acidosis was defined as pH < 7.35, bicarbonate < 20 mmol/l and raised lactate; hyperlactataemia as two consecutive lactates > 5 mmol/l. The case-control study of 110 cases and 220 controls(two randomly selected from treated patients by centre and calendar year) from centres in 10 countries included 40 (36.4%) female cases and 40 female controls (18.2%) (P < 0.001). Median age was 42.4 years [interquartile range (IQR, 36.0-52.5] for cases and 40 (IQR, 35.0-47.1) for controls (P = 0.013). More cases were nonwhite (41.9%) than controls (31.2%) (P = 0.032). Cases had a shorter duration of exposure to dideoxynucleosides.

RESULTS

After adjusting for age, gender and current CD4 cell count, hyperlactataemia/lactic acidosis remained associated with exposure to didanosine in every category of exposure duration but was most strongly associated with exposure < 12 months. In a separate multivariable model, apart from exposure to stavudine, didanosine, or even more strongly both, age above 40 years [odds ratio (OR), 2.6; 95% confidence interval (CI), 1.08-6.29], female gender (OR, 5.97; 95% CI, 1.92-18.5) and advanced immunosuppression were independent associations (CD4 cell count 200-349, 100-199 and < 100 cells/mul: OR, 3.89, 7.58 and 8.11, respectively).

INTERPRETATION

Hyperlactataemia/lactic acidosis was associated with exposure to dideoxynucleosides, female gender, advanced immunosuppression and possibly ethnicity. This has important consequences for choice of ART in resource-limited settings. The association with shorter duration of exposure may support the hypothesis of susceptibility in a small proportion of patients.

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.

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.

Usage of stavudine (D4T) - a retrospective analysis in a South London hospital

British HIV Association (BHIVA) guidelines are updated on a regular basis with emergence of new clinical evidence. In June 2003, the BHIVA guidelines recommended that stavudine (D4T)-containing regimens are less preferred if other viable options are available. A retrospective analysis was conducted to establish whether local prescribing practice reflects national guidance offered by BHIVA. This study identifies 28 patients on D4T combinations, which represents 2% of the total treated group in our clinic population. In all, 89% (25/28) of patients had a viral load of <50 copies/mL and CD4 counts ranged from 122 to 1016 cells/mm(3). In this study, 12/28 patients had documented lipodystrophy. Seventeen out of 28 patients had no clear documented reasons for remaining on D4T, eight patients preferred to continue and three patients continued because of genotypic findings. This study shows that a small proportion of patients are still on D4T-containing regimen for the following reason - patient's choice, side-effects, toxicities and interaction. The majority of patients remaining on D4T had documented lipodystrophy changes. Therefore, clinicians continuing to prescribe D4T should document the precise reason for its continued use. If patients prefer to continue D4T, this should be well documented to circumvent any medicolegal consequences, should toxicity develop later.

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.

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.

Glucose production, oxidation and disposal correlate with plasma lactate levels in HIV-infected patients on HAART

OBJECTIVES

Hyperlactatemia is prevalent in HIV-infected patients on highly active antiretroviral therapy (HAART) and may be associated with depletion of mitochondrial DNA. However, the correlation between fasting lactate and mitochondrial DNA may be weak or absent, implicating that other factors e.g. glucose turnover may contribute to hyperlactatemia.

METHODS

HIV-infected patients receiving HAART who had lipodystrophy (LIPO, n=18) or were without lipodystrophy (NONLIPO, n=18) were investigated. Insulin sensitivity (M-value), glucose oxidation rate (GOX) and fasting endogenous glucose production (EGP) were determined by hyperinsulinemic euglycemic clamp, indirect calorimetry and glucose tracer technique, respectively.

RESULTS

Fasting p-lactate (median 1.2 mmol/L; range 0.6-4.3, n=36) tended to be increased in LIPO (P=0.12); 6 patients (4 LIPO) had lactate > or =2.0 mmol/L. Fasting lactate correlated inversely with M-value (P<0.001) and positively with fasting EGP (P<0.05) and fasting GOX (P<0.05), together explaining 51% (R2, n=36) of the variation in fasting lactate. Lactate increased in NONLIPO (P<0.05) but not in LIPO (P>0.5) during clamp. Incremental (clamp minus fasting value) GOX (P<0.01) was decreased and incremental insulin (P<0.01) was increased in LIPO.

CONCLUSIONS

Fasting EGP, GOX and insulin resistance may be major determinants of fasting lactate levels in HIV-infected patients on HAART. Insulin levels per se may not determine plasma lactate in such patients.

Antiretroviral therapy: a primer for dermatologists

Combination antiretroviral therapy (ART) has transformed the care of individuals who have HIV infection. Effective ART has resulted in dramatic reductions in mortality, hospitalization rates, and the development of AIDS-defining illnesses. This article discusses the variety of agents that can comprise an effective ART regimen, focusing on the basic principles of ART, the indications for initiating ART in treatment-naive individuals who have established HIV infection, and the challenges associated with the use of antiretroviral medications.

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.

Current concepts in the diagnosis and management of metabolic complications of HIV infection and its therapy

Changes in fat distribution, dyslipidemia, disordered glucose metabolism, and lactic acidosis have emerged as significant challenges to the treatment of human immunodeficiency virus (HIV) infection. Over the past decade, numerous investigations have been conducted to better define these conditions, identify risk factors associated with their development, and test potential therapeutic interventions. The lack of standardized diagnostic criteria, as well as disparate study populations and research methods, have led to conflicting data regarding the diagnosis and treatment of metabolic and body shape disorders associated with HIV infection. On the basis of a review of the medical literature published and/or data presented before April 2006, we have prepared a guide to assist the clinician in the detection and management of these complications.

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.

Risk factors for osteonecrosis in HIV-infected patients: impact of treatment with combination antiretroviral therapy

BACKGROUND

Osteonecrosis was increasingly associated with HIV infection in the 1990s. It is unclear whether its risk increases with the duration of HIV infection, the duration of combination antiretroviral therapy (cART) or both.

OBJECTIVE

To analyse factors associated with the rate of symptomatic osteonecrosis, particularly the relative impacts of the duration of HIV infection and the duration of cART, using the French Hospital Database on HIV, which comprises a large number of subjects with substantial follow-up.

METHODS

Poisson regression model was used to identify factors associated with the rate of osteonecrosis among patients enrolled in 1996-2002.

RESULTS

The study involved 56,393 subjects with a total follow-up of 229,031 person-years. Symptomatic osteonecrosis was diagnosed in 104 subjects with an incidence rate of 4.5/10,000 person-years. Multivariate analysis identified three factors associated with the rate of osteonecrosis: prior AIDS-defining illnesses [adjusted relative rate (RR), 3.1; 95% confidence interval (CI), 2.0-4.9], the CD4 cell nadir [RR, 1.6 (95% CI, 0.9-2.9) for CD4 cell count 50-199 cells/microl; RR, 1.8 (95% CI, 1.0-3.3) for CD4 cell count < 50 cells/microl; both relative to CD4 cell count > or = 200 cells/microl] and exposure to cART. Compared with unexposed patients, the RR of osteonecrosis ranged from 2.6 (95% CI, 1.2-5.9) in patients treated with cART for < 12 months to 5.1 (95% CI, 2.1-12.6) in patients treated for > or = 60 months.

CONCLUSIONS

Osteonecrosis appears to be a complication of both HIV infection and cART.

Hepatic steatosis is associated with fibrosis, nucleoside analogue use, and hepatitis C virus genotype 3 infection in HIV-seropositive patients

BACKGROUND

We conducted a study to determine the prevalence and factors associated with hepatic steatosis in human immunodeficiency virus (HIV)-seropositive patients with hepatitis C and to investigate whether steatosis is associated with liver fibrosis.

METHODS

Retrospective chart reviews were conducted in 4 hospitals that serve community-based and incarcerated HIV-infected patients who had undergone a liver biopsy for evaluation of hepatitis C virus (HCV) infection during the period of 2000-2003. Demographic characteristics and medication and laboratory data were collected from the time of the biopsy. A pathologist blinded to all clinical data evaluated the specimens. The primary outcome was presence or absence of steatosis.

RESULTS

Of 260 HIV-HCV-coinfected patients, 183 met inclusion criteria and had a biopsy specimen adequate for review. Steatosis was present in 69% of patients (graded as minimal in 31%, mild in 27%, moderate in 18%, and severe in 1%). Factors associated with steatosis included use of dideoxynucleoside analogues, such as didanosine and stavudine (odds ratio [OR], 4.63; 95% confidence interval [CI], 1.55-13.82). There was a trend toward presence of steatosis and use of other nucleoside analogues or infection with HCV genotype 3 (OR, 2.65 [95% CI, 0.95-7.41] and 3.38 [95% CI, 0.86-13.28], respectively). The presence of steatosis was associated with fibrosis (OR, 1.37; 95% CI, 1.03-1.81).

CONCLUSIONS

In this multiracial population of HIV-HCV-coinfected patients, steatosis was prevalent and was associated with severity of liver fibrosis. Use of nucleoside analogues (particularly didanosine and stavudine) and HCV genotype 3 infection were associated with hepatic steatosis. The development of steatosis is multifactorial in nature and may play a contributory role in the progression of liver disease in HIV-infected patients.

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.

[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.

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.

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.

The Relationship between Nucleoside Analogue Treatment Duration, Insulin Resistance, and Fasting Arterialized Lactate Level in Patients with HIV Infection

BACKGROUND

Treatment with nucleoside reverse-transcriptase inhibitors (NRTIs) is associated with hyperlactatemia, presumably as a result of NRTI-induced mitochondrial toxicity. We examined the association of NRTI treatment duration and lactate level in human immunodeficiency virus (HIV)-infected patients and assessed the relationship of treatment duration and lactate level with insulin resistance.

METHODS

Fasting arterialized venous lactate levels, routine blood chemistry findings, insulin resistance (determined by homeostasis model assessment [HOMA-IR]), percentage of body fat (determined by dual-energy radiographic absorptiometry), and detailed histories of antiretroviral therapy were obtained for 95 HIV-infected individuals. The independent association of NRTI treatment duration and lactate level was examined using multivariable linear regression.

RESULTS

Among 95 subjects with a mean age (+/- standard deviation [SD]) of 44 +/- 8 years), 95% had NRTI exposure, with current NRTI use in 83%. The mean (+/- SD) lactate level was 1.24 +/- 0.46 mmol/L (6% had a lactate level > 2 mmol/L). Longer duration of NRTI use was positively associated with lactate level (beta = 0.047; P < .01), as were age, duration of protease inhibitor treatment, and HOMA-IR. Female sex and percentage of body fat were negatively associated with lactate level. After adjustment for age, sex, diabetes, percentage of body fat, and duration of protease inhibitor therapy, an increased duration of NRTI therapy remained significantly associated with lactate level (beta = 0.035; P = .04). However, the addition of HOMA-IR to the adjusted model attenuated the relation between duration of NRTI therapy and lactate level (beta = 0.024; P = .14), whereas HOMA-IR was significantly associated with lactate level (beta = 0.206; P < .01). Furthermore, HOMA-IR was also associated with NRTI treatment duration in adjusted analyses.

CONCLUSION

NRTI treatment duration was independently associated with higher lactate level, but this relationship was attenuated after adjusting for HOMA-IR. These data raise the possibility that insulin resistance may be an additional mechanism through which NRTI therapy is related to lactate level.

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.

Risk Factors for and Outcome of Hyperlactatemia in HIV-Infected Persons: Is There a Need for Routine Lactate Monitoring?

BACKGROUND

Lactic acidosis is a rare but life-threatening complication of combination antiretroviral therapy (CART). Asymptomatic or mildly symptomatic episodes of hyperlactatemia are more frequent, but their clinical relevance is unknown.

METHODS

The incidences of, risk factors for, and courses of hyperlactatemia and lactic acidosis were prospectively assessed in the following 3 groups at the Zurich center of the Swiss HIV Cohort Study: persons already receiving CART at baseline, treatment-naive persons who initiated CART during the observation period, and persons who received no CART before or during the observation period.

RESULTS

During 4788 person-years of follow-up, a total of 22,678 lactate assessments were performed for 1566 persons; 662 (42.3%) had at least 1 lactate level measurement of > 2.4 mmol/L, and 49 (3.1%) had severe hyperlactatemia (lactate level of > 5.0 mmol/L). The incidence of hyperlactatemia was 227 cases (95% confidence interval [CI], 210-245) and 59 cases (95% CI, 38-93) per 1000 person-years of follow-up among persons with and persons without CART, respectively. During the observation period, the incidence decreased from 459 cases (95% CI, 415-508) to 85 cases (95% CI, 76-107) per 1000 person-years of follow-up, respectively, because of changing CART prescription patterns. Severe hyperlactatemia occurred in treated persons only. In multivariable Cox proportional hazards models, significant risk factors for severe hyperlactatemia were regimens containing stavudine and didanosine (hazard ratio [HR], 6.65; 95% CI, 2.70-16.3) and regimens containing efavirenz (HR, 2.85; 95% CI, 1.31-6.21). Lactic acidosis was diagnosed in 4 of 1566 persons, all of whom were receiving stavudine and didanosine.

CONCLUSIONS

Hyperlactatemia was frequently observed in all 3 groups, but severe hyperlactatemia and lactic acidosis were rarely observed among persons who received CART. Lactate monitoring appears to be indicated primarily for persons receiving stavudine and didanosine and for persons who are symptomatic. Long-term follow-up is needed to investigate the risk of novel treatment regimens for hyperlactatemia.

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.

Incidence and Risk Factors for Mitochondrial Toxicity in Treated HIV/HCV-Coinfected Patients

Background

Coinfection with hepatitis C virus (HCV) and HIV is not uncommon and therapies for both infections are currently available. A major drawback, however, could be a potentially higher risk for mitochondrial toxicity (MT), defined as the elevation of pancreatic enzymes or lactate levels due to the nucleoside analogue reverse transcriptase inhibitors contained in both therapies.

Methods

Prospective analyses of clinical and laboratory data, including plasma lactate levels and pancreatic enzymes, of 113 consecutive HIV/HCV-coinfected patients were assigned to receive ribavirin (RBV) plus interferon (IFN)-α.

Results

Fourteen patients (12%) showed increased levels of amylase/lipase and/or hyperlactataemia. No patient developed clinical pancreatitis. Four patients with hyperlactataemia had clinical symptoms of lactic acidosis and recovered uneventfully by 2 weeks after treatment withdrawal. The variables significantly associated with MT in the univariate analysis were: therapy with didanosine (ddI), ddI plus stavudine (d4T), previous history of diabetes and the baseline lactate level. However, ddI use was the only independent risk factor for MT identified in the multivariate analysis. MT was not associated with gender, age, alcohol consumption, type of IFN, degree of steatosis and fibrosis in liver biopsy, presence of lipodystrophy, CD4+ cell count, HCV or HIV viral load, mitochondrial DNA and COXII-expression in liver tissue, or antiretroviral therapy containing d4T or protease inhibitors.

Conclusions

12% of HIV/HCV-coinfected patients receiving IFN plus RBV concomitantly with highly active antiretroviral therapy developed laboratory markers of MT. Although most of cases were asymptomatic, our study suggests that concomitant use of RBV plus ddI should be avoided, and that routine monitoring of lactate and pancreatic enzymes may be recommended.

Tolérance et interactions médicamenteuses des traitements anti-VIH et anti-VHC

Treating Hepatitis C among HIV patients under antiretroviral drug therapy requires a high degree of vigilance and continuous monitoring because of frequent problems with intolerance and/or drug interactions. Recent studies, including three therapeutic trials, on Ribavic, APRICOT, and ACTG A5671, have given some insights on following these patients up. The adverse effects are relatively similar in HCV-HIV-co-infected patients and patients infected by HCV only. Their frequency is, on the other hand, higher among HCV-HIV-Co-infected patients. The adverse-effects are consistent, in a non-exhaustive way, with pseudo influenza-like symptoms, fever, myalgia, cephalgia, with psychiatric disorders (irritability, depression, etc.); endocrine disorders (thyroid dysfunction, diabetes...); and with hematological anomalies especially anemia and leucopenia. But the percentage of lymphocyte T CD4 is not modified, therefore there is no risk of opportunistic infection. Pharmacokinetic interactions between antiretroviral drugs and treatment for HCV infection including ribavirin plus interferon alpha (IFN-alpha) or pegylated IFN are described. They are almost exclusively due to the combination of ribavirin and of nucleoside analogue reverse transcriptase inhibitors. One of the principal consequences is the emergence of mitochondrial toxicity defined by the occurrence of hyperlactatemia, or acute pancreatitis). Thus, some combinations should be avoided such as ddI+ribavirin and ddI+d4T+ribavirin. The d4T+ribavirin combination must also be used with caution.

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.

Possible Ways Nucleoside Analogues Can Affect Mitochondrial Dna Content and Gene Expression during HIV Therapy

In recent years, research into nucleoside reverse transcriptase inhibitor (NRTI)-related mitochondrial (mt) toxicity in HIV therapy has led to conflicting results and many unanswered questions regarding the molecular mechanisms that lead to such toxicity. From the early hypothesis that inhibition of the human mt polymerase γ by NRTIs was responsible for the drugs’ mt toxicity, an increasingly complex picture is emerging that probably involves multiple mt pathways. Results have been presented suggesting that NRTIs affect not only mtDNA but also mtRNA, nucleotide phosphorylation and the mt respiratory chain. Based on the current level of knowledge, this overview addresses some of the potential mechanisms through which NRTIs could affect mitochondria and ultimately cause the toxicity symptoms observed in HIV patients receiving NRTI-containing antiretroviral therapy.

[13C]Methionine breath test: a novel method to detect antiretroviral drug-related mitochondrial toxicity

OBJECTIVES

A major side effect of antiretroviral drugs is nucleoside reverse transcriptase inhibitor (NRTI)-related mitochondrial toxicity, the in vivo diagnosis of which is difficult and not yet standardized. We used the [(13)C]methionine breath test to investigate hepatic mitochondrial oxidation in HIV-1-infected patients receiving antiretroviral therapy.

PATIENTS AND METHODS

The [(13)C]methionine breath test was performed in healthy subjects (n=10), HIV-infected patients on antiretroviral therapy with (n=6) and without (n=15) hyperlactataemia and naive HIV-infected patients (n=11). After oral administration of [(13)C]methionine (2 mg/kg body weight), hepatic methionine metabolism was measured by breath (13)CO(2) enrichment, expressed as delta over baseline (DOB) every 15 min for 120 min by mass spectrometry.

RESULTS

The four study groups showed a significant difference in (13)CO(2) exhalation (P=0.001). HIV-infected patients on antiretroviral therapy with normal serum lactate had reduced exhalation of (13)CO(2) compared with healthy subjects (DOB mean peak: 8.82+/-0.62 versus 11+/-0.9, P<0.05). HIV patients with hyperlactataemia had even lower values when compared with patients with normal lactataemia (DOB mean peak: 4.98+/-0.68 versus 8.82+/-0.62, P<0.05).

CONCLUSIONS

The [(13)C]methionine breath test possibly showed mitochondrial impairment in antiretroviral-treated HIV-positive patients, particularly with hyperlactataemia. This non-invasive test can be used to monitor drug-related mitochondrial toxicity in vivo and to discover early and asymptomatic damage of the respiratory chain.

Depleted skeletal muscle mitochondrial DNA, hyperlactatemia, and decreased oxidative capacity in HIV-infected patients on highly active antiretroviral therapy

The nucleoside reverse transcriptase inhibitors (NRTIs), especially stavudine, may deplete mitochondrial (mt) DNA in human tissues by inhibiting the mitochondrial polymerase gamma, a setting, which is associated with hyperlactatemia. The aim of the present study was to examine whether hyperlactatemia is associated with depletion of skeletal muscle (sm)-mtDNA and decreased oxidative capacity in HIV-infected patients on NRTI based highly active antiretroviral therapy (HAART) and whether HIV infection itself is associated with sm-mtDNA depletion. Sm-mtDNA was determined in 42 HIV-infected patients (35 patients on HAART including at least one NRTI (HIV-NRTI) and 7 patients never treated with antiretroviral drugs (NAIVE)) and 14 healthy controls. Whole body oxidative capacity (DeltaGOX) was estimated in HIV-infected patients by indirect calorimetry. Hyperlactatemia (>or=2.0 mM) was detected in six HIV-NRTI, who all used Stavudine (P < 0.01), displayed depleted sm-mtDNA (P < 0.02) and decreased DeltaGOX (P < 0.01) compared with normolactatemic HIV-NRTI (n = 29). NAIVE displayed decreased sm-mtDNA (P < 0.05), increased HIV-RNA (P < 0.01) and increased plasma TNF-alpha (P < 0.05) compared to all HIV-NRTI (n = 35), in turn displaying decreased sm-mtDNA (P < 0.01) compared to healthy controls. Thus, hyperlactatemia in HIV-NRTI may be associated with pronounced depletion of sm-mtDNA, decreased oxidative capacity and current stavudine therapy. Further, HIV may deplete sm-mtDNA of NAIVE, which in part could be mediated through an enhanced pro-inflammatory response.

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.

Mitochondrial Effects of a 24-Week Course of Pegylated-Interferon plus Ribavirin in Asymptomatic HCV/HIV Co-Infected Patients on Long-Term Treatment with Didanosine, Stavudine or Both

Background

It has been suggested that the addition of ribavirin (RBV) as a part of the treatment for chronic hepatitis C virus (HCV) in HIV co-infected patients on didanosine (ddI) or stavudine (d4T) might increase the nucleoside-induced impairment of mitochondrial function. Design: Comparative study to investigate the impact on mitochondrial function of adding RBV to a long-term treatment with ddI, d4T or both in HCV/HIV non-cirrhotic, asymptomatic patients. We included 26 patients: 16 continued with their current antiretroviral therapy (control group) and 10 patients received a concomitant 24-week course of RBV plus pegylated interferon (PEG-IFN) α-2b therapy (HCV-treated group).

Methods

We assessed peripheral blood mononuclear cells mitochondrial DNA (mtDNA) content and mitochondrial respiratory chain (MRC) function at baseline and at 24 weeks of follow-up. In the HCV-treated group we performed additional determinations at 12 weeks during anti-HCV therapy and 24 weeks after finishing anti-HCV therapy.

Results

Times on ddI or d4T exposure were 194 ±54.9 and 131 ±66.5 weeks in the HCV-treated and control groups, respectively. There were no differences either in mtDNA content, the enzyme activity of MRC complexes or clinical parameters at baseline. Throughout the study, mitochondrial measurements remained stable within groups and without differences when we compared HCV-treated and control groups.

Conclusions

In our study, the addition of RBV and PEG-IFN during a 24-week period in HCV/HIV non-cirrhotic, asymptomatic patients on long-term ddI, d4T or both had no impact on mitochondrial function. These findings could suggest that additional triggers are required to achieve a critical threshold in the degree of mitochondrial damage needed for symptoms to develop.

Lack of Recurrence of Hyperlactatemia in HIV-Infected Patients Switched From Stavudine to Abacavir or Zidovudine

Stavudine (d4T) has been observed in clinical trials and cohort studies to be more often implicated in cases of hyperlactatemia than other nucleoside reverse transcriptase inhibitors, possibly because of its relatively greater propensity to induce mitochondrial toxicity. The ESS40010 study was a 48-week, open-label, switch study that assessed changes in serum lactate levels and signs/symptoms of hyperlactatemia after substitution of abacavir (n = 86) or zidovudine (n = 32) for d4T in 118 virologically suppressed HIV-infected patients (HIV-1 RNA <400 copies/mL) who had developed serum lactate concentrations > or =2.2 mmol/L (n = 16) or had remained normolactatemic (n = 102) after receiving > or =6 months of d4T-based treatment. Median serum lactate decreased significantly below baseline at week 24 (-0.15 mmol/L, P = 0.0002) and week 48 (-0.15 mmol/L, P = 0.0015). In 10 hyperlactatemic patients in whom d4T was discontinued, serum HIV-1 RNA levels rebounded over the ensuing 31 days, but virologic suppression (HIV-1 RNA <400 copies/mL) was regained when treatment using abacavir or zidovudine was subsequently instituted. In the group with elevated lactate at baseline, symptoms of hyperlactatemia improved in 8% to 23% of patients, did not change in 69%, and worsened in 8%. Serum transaminases, which had been elevated while patients received d4T, normalized after d4T discontinuation and remained in the normal range after the switch to abacavir or zidovudine. Overall, in patients with d4T-associated hyperlactatemia, stopping d4T results in normalization of lactate and a rebound in viral load; restarting treatment using abacavir or zidovudine subsequently maintains normal lactate levels and rapidly leads to a return of virologic suppression.

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.

Prospective evaluation of blood concentration of mitochondrial DNA as a marker of toxicity in 157 consecutively recruited untreated or HAART-treated HIV-positive patients

Highly active antiretroviral therapy (HAART) can cause mitochondrial toxicity. The concentration of mitochondrial DNA (mtDNA) in peripheral blood cells has been reported to be a marker of this toxicity. However, these observations are controversial and were drawn from small series. Thus, we analysed the value of blood mtDNA as a marker of mitochondrial toxicity in a large cohort of human immunodeficiency virus (HIV)-infected out-patients during routine clinical evaluations. Real-time quantitative PCR was used to determine the mtDNA to nuclear DNA (nDNA) ratio in peripheral blood mononuclear cells from 157 consecutive HIV-1-infected patients (13 naive, 144 receiving HAART) and 30 HIV-1-uninfected patients. The mtDNA to nDNA ratio was significantly lower in both groups of HIV-infected patients than in the control group. No significant difference was observed between treated and naive HIV-infected patients. Lactataemia was significantly lower in controls than in the group of HIV-treated patients. None of the treated patients had lactataemia >5 mmol/l or bicarbonates <20 mmol/l. Triglyceride levels were significantly higher in the HAART-treated patients than in the nontreated patients. Clinical symptoms of lipodystrophy were observed in 62 HAART-treated patients. These symptoms were not associated with an abnormal mtDNA to nDNA ratio or plasma triglyceride concentration. The mtDNA to nDNA ratio was lower in DDI/D4T-treated patients than in AZT/3TC-treated patients. In conclusion, there are no obvious links between the mtDNA to nDNA ratio in peripheral mononuclear cells and any clinical symptoms or lactate level. Thus, the mtDNA to nDNA ratio in leukocytes does not seem to be an accurate marker of mild and/or long-term mitochondrial toxicity.

Nucleoside-related mitochondrial toxicity among HIV-infected patients receiving antiretroviral therapy: insights from the evaluation of venous lactic acid and peripheral blood mitochondrial DNA

Nucleoside analogues inhibit human DNA polymerase gamma. As a result, they can produce mitochondrial toxicity. We evaluated the possible role of random venous lactic-acid determinations as a screening tool for mitochondrial toxicity among patients receiving nucleoside therapy. More recently, we have developed an assay that can detect changes in mitochondrial DNA (mtDNA) levels in peripheral blood cells. Using this assay, we have characterized changes in mtDNA relative to nuclear DNA (nDNA) in peripheral blood cells from patients with symptomatic nucleoside-induced hyperlactatemia. Our results demonstrated that symptomatic hyperlactatemia was associated with markedly low mtDNA : nDNA ratios. A statistically significant increase in the mtDNA : nDNA ratio was observed after the discontinuation of antiretroviral therapy. Full validation of monitoring the mtDNA : nDNA ratio is currently under way.

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.

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.

A case of lactic acidosis caused by stavudine in an AIDS patient

Nucleoside reverse transcriptase inhibitors (NRTIs), which are used for the treatment of human immunodeficiency virus (HIV) infection have been associated with a wide spectrum of clinical manifestations, including hepatic steatosis, lipodystrophy, myopathy, and lactic acidosis. Such adverse effects are postulated to result from the inhibition of mitochondrial DNA gamma polymerase, which causes the depletion of mitochondrial DNA and eventual the disruption of oxidative phosphorylation. Although cases of severe decompensated lactic acidosis are rare, this syndrome is associated with a high mortality rate. We report upon the first Korean case, of severe lactic acidosis in an acquired immunodeficiency syndrome (AIDS) patient receiving stavudine, an anti-HIV drug.

Asymptomatic Hyperlactataemia: Predictive Value, Natural History and Correlates

Background

The significance of asymptomatic hyperlactataemia is unknown.

Methods

We measured serial lactate levels in a group of HIV-infected subjects. Objectives were to identify covariates associated with hyperlactataemia, and to explore the natural history of hyperlactataemia.

Results

Overall, 1487 lactate measurements were performed on 396 subjects; 299 subjects had serial lactate testing, with a median of four performed per patient (range: 2–16). At study entry, lactate was >2.4 mmol/l in 6% of subjects and >3.6 mmol/l in 1%. A multiple logistic regression analysis revealed that cholesterol and current stavudine were the only predictors of hyperlactataemia. Lactate levels were highly reproducible both for short-term (within 3 months) and long-term (>1 year) follow-up. During the study period, 16 subjects were identified with sustained hyperlactataemia; 12/16 remained asymptomatic after a median of 210 days (30–585), and four developed symptoms suggestive of lactic acidosis syndrome. In three of the four, asymptomatic hyperlactataemia had preceded the onset of symptoms by 18–122 days. A longitudinal model showed a rapid rise of lactate levels from 0 to 12 months on nucleoside reverse transcriptase inhibitor (NRTI) and then stabilization. Lactate levels did not correlate with baseline or on-study development of lipoatrophy.

Conclusions

Even when optimal methods of collection are used, asymptomatic hyperlactataemia does exist and could be sustained in a subset of NRTI-treated subjects for as long as 585 days. A subset of these subjects became symptomatic, after as long as 122 days of asymptomatic hyperlactataemia. Asymptomatic hyperlactataemia is not predictive of lipoatrophy. This work was partly presented at the 9th Conference on Retroviruses & Opportunistic Infections. Seattle, Wash., USA, February 2002.

Mitochondrial diabetes: molecular mechanisms and clinical presentation

Mutations in mitochondrial DNA (mtDNA) associate with various disease states. A few mtDNA mutations strongly associate with diabetes, with the most common mutation being the A3243G mutation in the mitochondrial DNA-encoded tRNA(Leu,UUR) gene. This article describes clinical characteristics of mitochondrial diabetes and its molecular diagnosis. Furthermore, it outlines recent developments in the pathophysiological and molecular mechanisms leading to a diabetic state. A gradual development of pancreatic beta-cell dysfunction upon aging, rather than insulin resistance, is the main mechanism in developing glucose intolerance. Carriers of the A3243G mutation show during a hyperglycemic clamp at 10 mmol/l glucose a marked reduction in first- and second-phase insulin secretion compared with noncarriers. The molecular mechanism by which the A3243G mutation affects insulin secretion may involve an attenuation of cytosolic ADP/ATP levels leading to a resetting of the glucose sensor in the pancreatic beta-cell, such as in maturity-onset diabetes of the young (MODY)-2 patients with mutations in glucokinase. Unlike in MODY2, which is a nonprogressive form of diabetes, mitochondrial diabetes does show a pronounced age-dependent deterioration of pancreatic function indicating involvement of additional processes. Furthermore, one would expect that all mtDNA mutations that affect ATP synthesis lead to diabetes. This is in contrast to clinical observations. The origin of the age-dependent deterioration of pancreatic function in carriers of the A3243G mutation and the contribution of ATP and other mitochondrion-derived factors such as reactive oxygen species to the development of diabetes is discussed.

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.