Chronic hyperlactatemia in HIV-infected patients taking antiretroviral therapy

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.

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.

Short communication: reversible mitochondrial respiratory chain impairment during symptomatic hyperlactatemia associated with antiretroviral therapy

Direct evidence confirming the hypothesis that a dysfunction of the mitochondrial respiratory chain (MRC) underlies the pathogenesis of hyperlactatemia associated with highly active antiretroviral therapy (HAART) is scarce. We studied mitochondrial DNA (mtDNA) content and MRC function in the skeletal muscle of an HIV-infected patient during an episode of symptomatic hyperlactatemia. Skeletal muscle biopsy was performed during the episode when the patient was symptomatic and 3 months later when the patient was clinically recovered. Assessment of mitochondria was performed using histological, polarographic, spectrophotometrical, and Southern blot and real time PCR DNA quantification methods. The histological study disclosed extensive mitochondrial impairment in the form of ragged-red fibers or equivalents on oxidative reactions. These findings were associated with an increase in mitochondrial content and a decrease in both mitochondrial respiratory capacity and MRC enzyme activities. Mitochondrial DNA content declined to 53% of control values. Mitochondrial abnormalities had almost disappeared later when the patient became asymptomatic. Our findings support the hypothesis that MRC dysfunction stands at the basis of HAART-related hyperlactatemia.

Factors associated with mitochondrial dysfunction in circulating peripheral blood lymphocytes from HIV-infected people

Nucleoside analogue reverse transcriptase inhibitor (NRTI)-associated mitochondrial toxicity is an important issue in the clinical management of HIV infection. The aim of this study was the detection of mitochondrial dysfunction by flow cytometry in lymphocytes from HIV-infected individuals and its association with blood lactate levels, clinical and virologic status, and the different NRTI-based therapies. Lower peripheral blood lymphocytes with mitochondrial dysfunction (PBLmd) percentages were observed in healthy controls (1.2, interquartile range [IQR] = 0.4-1.9) than in patients (2.2, IQR = 0.9-3.7; P < 0.01). Stavudine-containing therapy showed higher PBLmd percentages (3.0, IQR = 1.1-4.5) than no treatment (2.1, IQR = 0.8-2.8; P < 0.05) or zidovudine-based therapy (0.9, IQR = 0.3-1.4; P < 0.01). A significant inverse correlation was found between PBLmd and CD4 T-cell percentage and absolute count. Patients with an AIDS diagnosis had higher PBLmd percentage (2.7, IQR = 1.1-4.4) than HIV-positive non-AIDS patients (1.4, IQR = 0.6-3.0; P = 0.012). In multivariate analysis, use of stavudine (odds ratio [OR] = 5.86, 95% CI = 1.81-19.01, P = 0.003) and CD4 T-cell counts <200/microL (OR = 4.51, 95% CI = 1.38-14.70, P = 0.012) were independent predictors of high PBLmd percentage. This cross-sectional study shows that antiretroviral drugs can impair the in vivo mitochondrial function of PBLs.

Matched case-control study to evaluate risk factors for hyperlactataemia in HIV patients on antiretroviral therapy

BACKGROUND

Lactic acidosis is a life-threatening event during antiretroviral therapy (ART). Hyperlactataemia may be a prelude to acidosis. Our database study suggested that female gender, intercurrent illness and didanosine (ddI)-based regimens may increase risk of lactic acidosis. The aim of this matched case-control study was to identify risk factors for hyperlactataemia requiring screening.

METHODS

Cases were defined as patients with two consecutive lactate samples > or =3.5 mmol/L taken more than 1 week apart. Cases were matched to two controls on gender, use of ddI and total duration of therapy using a 6-month window on either side. Controls never had raised lactate >2.5 mmol/L. A conditional logistic regression analysis using the PHREG procedure in SAS (SAS Institute Inc, Cary, NC) was performed with a discreet logistic model stratified by matching variables.

RESULTS

Twenty-one cases were matched to 42 controls. In the univariate model, current use of stavudine (d4T), total cholesterol >5.3 mmol/L and glucose levels > or =5.2 mmol/L gave increased likelihood of persistent hyperlactataemia. The multivariate model showed current use of d4T to be a significant independent predictor of persistent hyperlactataemia.

CONCLUSIONS

The results of this case-control study indicate that, when controlling for ddI use, d4T use is an additional risk factor for hyperlactataemia.

Low efficacy and high frequency of adverse events in a randomized trial of the triple nucleoside regimen abacavir, stavudine and didanosine

BACKGROUND

Highly active antiretroviral therapy containing three nucleoside reverse transcriptase inhibitors has been somewhat successful, but the clinical efficacy is unclear.

METHODS

Randomized, controlled, open-label trial of 180 antiretroviral drug-naive HIV-infected patients allocated to a regimen of abacavir, stavudine and didanosine (A/S/D, n = 60), ritonavir and saquinavir (R/S 400/400 mg twice daily; n = 60) or nelfinavir and nevirapine (N/N 1250/200 mg twice daily; n = 60); the latter two in combination with lamivudine and zidovudine. The primary endpoint was HIV plasma RNA < or = 20 copies/ml after 48 weeks.

RESULTS

At baseline, the median CD4 cell count was 161 x 106 cells/l (range, 0-920) and the HIV RNA was 5.0 log10 copies/ml (range, 2.7-6.7). At 48 weeks, 43% in the A/S/D arm had a HIV RNA < or = 20 copies/ml, compared with 69% in the N/N arm (P < 0.01) and 62% in the R/S arm (P < 0.05). In a multivariate analysis, the A/S/D arm had an odds ratio of obtaining a viral load of < or = 20 copies/ml at week 48 of 0.25 [95% confidence interval (CI) 0.10-0.59] versus N/N and 0.53 (95% CI, 0.33-0.83) versus R/S. The A/S/D arm had a particularly poor outcome in patients with higher viral load and AIDS at baseline: 63% had to discontinue A/S/D (any drug). Side effects were more frequent in the A/S/D arm and included neuropathy 27%, suspicion of hypersensitivity 12%, and increase in lactate accompanied by systemic symptoms 8%.

CONCLUSION

The A/S/D regimen had a low efficacy and a high frequency of adverse events and cannot be recommended.

Mitochondrial Toxicity in the Era of HAART: Evaluating Venous Lactate and Peripheral Blood Mitochondrial DNA in HIV-Infected Patients Taking Antiretroviral Therapy

Nucleoside analogs can induce mitochondrial toxicity by inhibiting the human DNA polymerase gamma. This can lead to a wide range of clinical toxicities, from asymptomatic hyperlactatemia to death. Despite their technical and physiological variability, we propose that random venous lactate measurements can be useful to monitor the development of nucleoside-related mitochondrial toxicity. Recently, we have developed an assay that can measure changes in mitochondrial DNA levels in peripheral blood cells. Using this assay we have characterized changes in mitochondrial DNA (mtDNA) relative to nuclear DNA (nDNA) in peripheral blood cells of patients with symptomatic nucleoside-induced hyperlactatemia. Our results demonstrate that symptomatic hyperlactatemia was associated with markedly low mtDNA/nDNA ratios, which were on average 69% lower than HIV-uninfected controls and 45% lower than HIV-infected asymptomatic/antiretroviral naive controls. A statistically significant (p = .016) increase in mtDNA/nDNA ratio was observed following discontinuation of antiretroviral therapy. The mtDNA/nDNA ratio remained stable among selected patients who reintroduced antiretroviral therapy with stavudine (d4T)-sparing regimens. Of note, the decline in mtDNA preceded the increase in venous lactate levels. More recently we have evaluated changes in the mtDNA/nDNA ratio in relation to selected antiretroviral drug regimens in a cross-sectional study on a non-random sample of participants within the British Columbia Centre for Excellence in HIV/AIDS Drug Treatment Program. Eligible patients had continuously received saquinavir plus ritonavir with either nevirapine (n = 20), lamivudine (n = 15), d4T (n = 53) or lamivudine + d4T (n = 69), for 4 to 30 months. d4T-sparing regimens were associated with a higher median mtDNA/nDNA ratio than d4T-containing regimens (p = .016), despite the fact that study patients had received d4T-containing regimens for a shorter median time than patients taking d4T-sparing regimens (13 versus 25 months, p = .002). In summary, mtDNA levels are significantly decreased among patients who develop symptomatic, nucleoside-related hyperlactatemia, an effect reversed upon therapy discontinuation. Furthermore, mtDNA/nDNA ratios were statistically significantly lower in patients taking d4T-containing regimens than in those taking selected d4T-sparing regimens in a population setting. These results suggest that measurement of this parameter should be investigated as a potential clinical management tool.

Hyperlactatemia in human immunodeficiency virus-infected children receiving antiretroviral treatment

BACKGROUND

Hyperlactatemia and lactic acidosis occur in HIV-infected adults receiving antiretroviral treatment. Our objective was to determine the incidence, course and risk factors for hyperlactatemia in our HIV-infected pediatric patients.

DESIGN

A prospective observational study of venous lactate concentrations during a 28-month period in 80 HIV-infected children, most of whom were receiving antiretrovirals.

METHODS

Venous blood lactate concentrations were measured every 6 months under optimal sample-obtaining conditions. Alanine values from the same blood sample were performed when lactate concentrations were elevated. Hyperalaninemia is observed only when mitochondrial oxidative phosphorylation is chronically disturbed.

RESULTS

Twenty-three patients (29%) were identified with hyperlactatemia, in 9 of the cases with normal alaninemia, probably caused by difficult venous punctures. The other 14 children (17%) had pathologic alanine concentrations with a mean lactate peak of 2.67 mmol/l (range, 2.05 to 4.9 mmol/l); none of them showed metabolic acidosis, and they were all symptom-free. Treatment was continued in all cases, and lactate has progressed spontaneously to normal values in 5 patients.

CONCLUSIONS

Symptom-free hyperlactatemia was observed in HIV-infected children receiving nucleoside analog reverse transcriptase inhibitors. In our study, only a younger age at the beginning of antiretroviral treatment was a statistically significant risk factor for hyperlactatemia. Random measurements of blood lactate concentrations should be included in the clinical follow-up of those HIV-infected children <3 years of age who are treated with nucleoside analog reverse transcriptase inhibitors, symptomatic or not.

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

OBJECTIVE

To investigate potential mitochondrial toxicity in HIV-uninfected infants exposed to highly active antiretroviral therapy (HAART) in utero and/or neonatal zidovudine.

DESIGN

A prospective observational study performed in a tertiary referral center for HIV-infected women and their infants and children.

METHODS

Plasma lactate was measured repeatedly during the first 6 months of life in a consecutive cohort of infants exposed to HAART in utero and/or neonatal zidovudine. Maternal CD4, HIV RNA concentration, antiretroviral and substance use histories, mode of delivery, infant gender, cord pH, Apgar score and birth weight were collected.

RESULTS

The plasma lactate was above normal on at least 1 occasion in 35 of 38 (92%) infants and reached levels > or =5 mmol/l in 10 (26%) infants. Overall 78 of 117 (68%) lactate measurements were elevated, with 11 (10%) in the serious (> or =5 mmol/l) range. None of the infants received antiretrovirals beyond 6 weeks, yet elevated lactates persisted up to age 6 months. Two infants had reversible symptoms consistent with those of lactic acidemia. No association was found between the infant peak lactate and the type of therapy during pregnancy, its duration or maternal substance use.

CONCLUSION

Transient lactic acidemia was observed in the majority of HIV uninfected infants exposed to HAART in utero and/or zidovudine neonatally. We hypothesize that the hyperlactatemia is a consequence of persistent, primarily subclinical, mitochondrial toxicity from the transplacental and neonatal exposure to antiretrovirals and of impaired hepatic lactate clearance. Although the clinical relevance of our findings is unknown, we recommend lactate monitoring in these infants, considering discontinuation of neonatal zidovudine in symptomatic infants with lactate > or =5 mmol/l and careful long term follow up of these children.

Lactic acidosis related to nucleoside therapy in HIV-infected patients

The incidence of nucleoside analogue-related lactic acidosis has been estimated in 0.57 - 8.5 cases/1000 person years of antiretroviral therapy. The onset of lactic acidosis is usually insidious and patients complain of nausea, vomiting, abdominal pain, fatigue and weight loss. When lactate levels are high enough, a catastropic clinical situation develops, resulting in multiorgan failure. The mortality rate of patients with lactic acidosis related to nucleoside therapy is very high, 33 - 60%. Although all nucleoside analogues have been implicated in lactic acidosis, most cases are associated with stavudine. At present, there are no controlled trials to evaluate the treatment of nucleoside-induced lactic acidosis. Therapy is based on supportive measures and discontinuation of all antiretroviral drugs. Administration of essential vitamin coenzymes, electron acceptors and L-carnitine may be useful in some cases.

Lactic acidosis in HIV infected patients: a systematic review of published cases

OBJECTIVE

To describe the clinical, epidemiological, and biochemical characteristics of published cases of lactic acidosis (LA) and to generate hypotheses concerning risk factors associated with this complication.

METHODS

Systematic review of cases reported in the medical literature.

RESULTS

217 published cases were identified, 90 of which fulfilled the study definition and had sufficient individual data on potential risk factors to be included. The 90 patients had a mean age of 40.1 years (range 16-69) and 53% were female. All 90 patients were taking nucleoside reverse transcriptase inhibitors (NRTI) at the time of the episode. Among the 83 patients with details of their antiretroviral therapy (ART) regimen 51 patients were taking stavudine, 29 zidovudine, 27 didanosine, and 25 lamivudine. Around 50% of the patients had abdominal pain, nausea, or vomiting. Hepatic steatosis was consistently reported (53/90) and in 36 (68%) there was histological evidence. The case fatality rate was 48%. Six cases were rechallenged with NRTI and three developed a further LA episode. Using data on the numbers of HIV infected individuals receiving care in the United States, we estimate that the risk of LA could be 2.5 times higher for women than men.

CONCLUSIONS

NRTI use and female sex appear to be risk factors for the development of LA. What other factors are involved is still not clear but might include duration of NRTI therapy, specific drug use, and genetic predisposition. A case-control study is needed to better define risk factors for severe LA.

Fatal nucleoside-associated lactic acidosis in an obese woman with human immunodeficiency virus type 1 infection on a very low-calorie diet

This study reports the case of an obese woman with human immunodeficiency virus type 1 (HIV-1) infection who developed fatal nucleoside-associated lactic acidosis 10 d after she started a weight-loss dietary regimen containing 600 kcal/d. This case suggests that very low-calorie diets may be life threatening for HIV-infected patients receiving nucleoside analogues.

Lactate levels in children with HIV/AIDS on highly active antiretroviral therapy

A total of 251 venous lactate levels were obtained from 127 children with HIV/AIDS; 104 on highly active antiretroviral therapy, and 23 not on therapy. Asymptomatic hyperlactatemia (> 2 mmol/l) was found in 41 children; no hepatic dysfunction or life-threatening lactic acidosis occurred. Asymptomatic hyperlactatemia is associated with treatment with nucleoside reverse transcriptase inhibitors or protease inhibitors and with undetectable viral loads regardless of treatment regimen, suggesting that elevated lactate levels are useful in evaluating adherence.

Frequency, risk factors, and outcome of hyperlactatemia in HIV-positive persons: implications for the management of treated patients

BACKGROUND

The nucleoside reverse transcriptase inhibitors used for the treatment of HIV-positive persons are now clearly associated with metabolic disorders. We determined the prevalence of and risk factors for hyperlactatemia in HIV-positive persons to assess the relevance of lactate venous blood concentrations during antiretroviral therapy.

METHODS

We conducted a prospective cross-sectional study of venous lactate determinations with 282 consecutive HIV-positive persons who, in addition to a physical examination, had blood samples taken every 3-4 months for routine biochemical, immunologic, and viral assessment. The frequencies of hyperlactatemia and lactic acidosis were determined, and the risk factors were analyzed by a multivariate logistic regression model. The effect of modification of antiretroviral therapy in patients with moderate hyperlactatemia was also assessed.

RESULTS

From 782 blood lactate determinations, we identified 65 (23%) patients with moderate hyperlactatemia and 5 (1.8%) with lactate concentrations >5 mmol/L (2 with severe lactic acidosis; 0.7%). Older age, drug regimens containing stavudine [adjusted odds ratio (OR) = 2.5] or a combination of stavudine-didanosine (adjusted OR = 3.1), and the use of buprenorphine (adjusted OR = 14.7) were independent predictors of hyperlactatemia. Among 65 patients with moderate hyperlactatemia, 39 did not have their treatments changed, and 26 had a new combination therapy that was associated with a clinical improvement and a more pronounced decrease in lactate (-1.66 vs -0.99 mmol/L; P <0.05).

CONCLUSIONS

Chronic compensated and moderate hyperlactatemia was common in our population study. Measurement of lactate, under standardized conditions, may be useful in optimizing management of HIV-positive persons on antiretroviral therapy.

Hyperlactataemia syndromes associated with HIV therapy

Hyperlactataemia is seen in 8-18.3% of HIV-infected patients taking nucleoside-analogue reverse transcriptase inhibitors (NRTIs). Recent epidemiological studies suggest that most episodes are transient and subclinical. However, symptomatic and occasionally life-threatening cases accompanied by metabolic acidosis and hepatic steatosis (ie, lactic acidosis syndrome) have also been described. Though yet to be fully elucidated, the proposed mechanism is NRTI-induced inhibition of mitochondrial DNA polymerase culminating in derangements in oxidative phosphorylation and lactate homeostasis. Signs and symptoms range from mild hyperlactataemia accompanied by nausea, abdominal discomfort, and weight loss to severe, intractable lactic acidosis complicated by coma and multi-organ failure. Significant progress has recently been made with regard to the natural history of NRTI-related hyperlactataemia. However, other important aspects of the disorder, such as its pathogenesis, predisposing conditions, and management, remain poorly understood. This article reviews the current published work on these issues, identifies areas of controversy, and addresses directions for future research.

Human Immunodeficiency Virus Infection: A Focus on Women

Nearly half of all HIV infections worldwide occur in women, and 20% of AIDS cases in the United States are women. Differences in HIV virologic and immunologic markers occur between men and women and have been studied to determine the effect on disease progression, mortality, and treatment. Certain adverse clinical events associated with highly active retroviral therapy (HAART), such as drug rashes and lipodystrophy, may affect women more than men. Depressive symptoms and low mental health quality of life occur commonly in HIV-infected women and can influence whether a woman will use HAART. Substance abuse among HIV-infected women is common, which can play a factor in coinfection rate with other infectious diseases and adherence to therapy. Also, HIV-infected women are at risk for increased severity and prevalence of human papillomavirus, which can be associated with cervical cancer. As demographics of HIV infection change, medical, psychological, and social problems must be addressed.

Bench-to-bedside review: severe lactic acidosis in HIV patients treated with nucleoside analogue reverse transcriptase inhibitors

Nucleoside reverse transcriptase inhibitors (NRTIs) are effective antiretroviral therapy for the treatment of HIV-infected patients. NRTIs can induce mitochondrial impairment that leads to a number of adverse events, including symptomatic lactic acidosis. In the present review, we describe the underlying mechanism of NRTI-induced toxicity and the main clinical features of this infrequent, but severe, emerging complication. We also summarise experimental data and clinical observations that support the use of L-carnitine supplementation to reverse NRTI-induced mitochondrial impairment.

Natural history of hyperlactataemia in human immunodeficiency virus-1-infected patients during highly active antiretroviral therapy

A study on the course of hyperlactataemia during highly active antiretroviral therapy (HAART) and the association between hyperlactataemia and antiretroviral drugs was conducted at the outpatient department, Rigshopitalet, Copenhagen. Lactate levels were monitored in 848 patients during a study period of 1 y. Longitudinal analysis was performed on all human immunodeficiency virus-1-infected patients who had plasma lactate > 2.1 mM. Hyperlactataemia was found in 178 patients (21%), of whom 7 patients needed treatment modification, owing to symptomatic hyperlactataemia in 3 and neuropathy in 4 patients, while 171 remained on unchanged therapy. Lactate levels increased in 20 patients during the study period, but the increases were modest with a mean of 0.6 mM (range 0.1-1.7 mM). The association between antiretroviral drugs and hyperlactataemia was studied using logistic regression in 263 patients with data on their treatment regimen available in electronic form. Only stavudine and ritonavir were significantly associated with hyperlactataemia, with odds ratios of 5.1 and 2.6, respectively. In conclusion, symptomatic hyperlactataemia is uncommon, while asymptomatic hyperlactataemia is a frequent and apparently benign condition unlikely to progress to lactic acidosis. A significant association between stavudine and hyperlactataemia was confirmed. The unexpected association between ritonavir and hyperlactataemia will need confirmation in future studies.

Risk factors for lactic acidosis in HIV-infected patients treated with nucleoside reverse-transcriptase inhibitors: a case-control study

A case-control study was undertaken to determine risk factors for lactic acidosis in human immunodeficiency virus-infected patients treated with nucleoside reverse-transcriptase inhibitors (NRTIs). From May 1996 to June 2000, 9 patients with lactic acidosis (defined as a plasma lactic acid level of >5 mM and plasma pH of <7.38) were identified. Control patients were randomly selected from among a large cohort of patients who initiated a dual NRTI regimen in 1996 or after. Two factors were associated with an increased risk of lactic acidosis: first, a creatinine clearance of <70 mL/min before lactic acidosis (OR, 15.8 [range, 3.0-86.5], P<10(-4)), and, second, a low nadir CD4+ T lymphocyte count before the inception of NRTI therapy (OR, 8.4 [range, 1.2-infinity], P=.03). The total cumulative exposure to NRTIs was not associated with an increased risk of lactic acidosis, nor was the cumulative exposure to any of the 4 NRTIs studied. According to these results, monitoring of creatinine clearance, especially in patients with a low nadir CD4+ T lymphocyte count, could lead to modifications in antiretroviral therapy in order to diminish the risk of occurrence of lactic acidosis.

Could antioxidant supplementation reduce antiretroviral therapy-induced chronic stable hyperlactatemia?

OBJECTIVE

To determine if asymptomatic stable chronic hyperlactatemia in human immunodeficiency virus (HIV)-infected patients under highly active antiretroviral therapy (HAART, including nucleoside analog reverse transcriptase inhibitors (NRTI)) could be improved by antioxidant supplementation.

DESIGN

To match two groups of patients taking NRTI for at least 24 months: 15 without and 15 with antioxidant supplementation (vitamin E, beta-carotene, N-acetylcysteine, selenium, Gingko biloba extracts and nutritional supplements). For both the groups, the supplementation by antioxidants or its lack was carefully assessed. Venous lactatemia, blood oxidative stress markers (plasma lipid peroxidation, enzymatic and non-enzymatic antioxidants), CDC revisited classification, CD4 count and viral load, NRTI (with or without stavudine) and other antiretroviral drugs used, lipoatrophy, central fat accumulation were assessed.

RESULTS

Patients were not statistically different with respect to the CDC classification, CD4 count, viral load and characteristics of antiretroviral therapy. Blood oxidative stress markers, i.e. vitamin E, vitamin A and beta-carotene tended to be higher in the supplemented group. The difference observed in venous lactate concentration between the two groups was significant (1.37 +/- 0.10 vs. 1.82 +/- 0.19 mmol/l in the supplemented and non-supplemented groups, respectively P = 0.04).

CONCLUSION

Antioxidant supplementation improves the asymptomatic stable chronic hyperlactatemia observed in HIV-infected patients taking HAART including NRTI for a long time. Controlled studies are needed to demonstrate the efficacy of this supplementation on mitochondrial toxicity observed during HAART and the possible usefulness of its combination with mitochondrial cofactors like carnitine, riboflavine, coenzyme Q, alpha-lipoic acid.

Antiretroviral-associated liver injury

ART-related hepatotoxicity can manifest in a variety of ways. Although benign, asymptomatic LEEs predominate, liver injury occurring in the context of either hypersensitivity or hyperlactatemia, represents a medical emergency and mandates immediate cessation of ART. Underpinning this broad spectrum of presentations are several, as yet poorly understood, mechanisms of liver damage that reflect contributions by constituents of HAART and host factors. Thus far, the most significant predisposing condition to emerge from clinical studies is chronic viral hepatitis. A more precise understanding, however, of the processes and factors that underlie ART-related hepatotoxicity is critical not only to the management of liver injury from current antiretroviral drugs but also to the design of safer drugs in the future.

Lactic acidemia in infection with human immunodeficiency virus

Lactic acidosis in patients infected with the human immunodeficiency virus was initially identified as a rare complication of therapy with nucleoside analog reverse transcriptase inhibitors (NRTIs). The only patient group that appears to be at greater risk is pregnant women. More recently, milder elevations in lactate (i.e., lactic acidemia or hyperlactatemia) have been found to be more common and to be associated with numerous illnesses. Mild asymptomatic lactic acidemia is common, but it appears to lead to more severe illness only rarely. This suggests that routine measurement of plasma lactate should be limited to patients with previous acidemia who reinitiate NRTI therapy and to pregnant women. For symptomatic lactic acidemia (generally >5 mmol/L), NRTIs and other antiretroviral therapy should be ceased. Currently, asymptomatic lactic acidemia should not be treated and should not lead to a change in antiretroviral therapy.

Persistent non-gastrointestinal metabolic acidosis in pediatric HIV-1 infection

OBJECTIVES

To determine the incidence and to identify the clinical parameters associated with non-gastrointestinal renal tubular and high anion gap acidosis in a cohort of HIV-1-infected children.

METHODS

Records of 202 HIV-1-infected children were reviewed to identify patients with metabolic acidosis. Serum and urine chemistries of those children with persistent non-gastrointestinal acidosis were then studied prospectively. Serum and urinary anion gaps (SAG and UAG) were calculated. Those with acidosis (group 1) were compared with children without acidosis (group 2). Associations were determined with Pediatric HIV classification, height, weight, antiretroviral therapy, and Pneumocystis carinii pneumonia prophylaxis.

RESULTS

Persistent acidosis was noted in 34 out of 202 children (17%): 16 out of 34 (47%, group 1A) had elevated SAG acidosis, and 18 out of 34 (53%) had normal SAG acidosis with a positive UAG (distal renal tubular) acidosis (group 1B). Those with acidifying defects more often received P. carinii pneumonia prophylaxis (P = 0.02 and 0.01 for groups 1 and 1A, respectively) independently of HIV-1 classification. This group was shorter in height than group 2 (P = 0.007). Differences in weight were not significant (P = 0.1). However, acidotic subjects were more immunocompromised than those in group 2 (multivariate P < 0.001 for HIV classification C3).

CONCLUSIONS

Elevated SAG acidosis and renal tubular acidosis are not uncommon among HIV-infected children with advanced disease. These disorders may be associated with height growth failure and prophylaxis with sulfur/sulfone containing antibiotics. HIV infection and/or its associated therapies may cause renal tubular damage. The causes of elevated SAG acidosis require further investigation.

Hyperlactataemia during antiretroviral therapy: incidences, clinical data and treatment

Lactic acidosis is a serious complication of antiretroviral therapy. Symptomatic hyperlactataemia is a milder form of this syndrome, but its incidence is unclear. In this prospective ongoing observational study of a large cohort of HIV-infected adults, hyperlactataemia was diagnosed in 64 patients. Incidences were 18.3/1000 person-years with antiretroviral therapy, and 35.8/1000 person-years for stavudine (d4T) regimens. Ten of the 64 patients developed lactic acidosis during the first 13 months of treatment (incidence 2.9/1000 treated person-years). In four of ten patients, symptoms were absent or mild. More patients on d4T first-line therapy developed lactic acidosis than patients previously treated with other drugs (p = 0.008). Despite the occurrence of one death, the subsequent outcome for the remaining patients was favourable after antiretroviral therapy was stopped and supportive treatment with vitamins and antioxidants initiated. The early diagnosis of cases was the result of great vigilance and, combined with routine measurements of the anion gap, might be the most crucial factor explaining the low mortality rate observed here.

Tests for mitochondrial function and DNA: potentials and pitfalls

PURPOSE OF REVIEW

In the past few years, mitochondria have been carefully studied to ascertain whether and how in patients affected by HIV antiretroviral therapy is able to alter their functionality and exert a toxic effect on immune cells, as well as on cells present in other districts.

RECENT FINDINGS

A variety of in-vivo and ex-vivo models have been developed to investigate the functionality of mitochondria and DNA during a variety of physiopathological situations, including HIV infection and its treatment. Numerous technologies are available to study at the single-cell or at the single-organelle level a variety of parameters, such as membrane potential, the activity of respiratory chain enzymes, and DNA content or its sequence. As far as in-vitro studies are concerned, a substantial homogeneity of data exists, and several changes in different mitochondrial parameters have been described that depend upon the drug used, the cell model and the parameter investigated. On the other hand, different results have been reported on biological material collected from HIV-positive patients and immediately analysed. Ex-vivo studies showed that changes in mitochondrial DNA content or in the functionality of the organelle exist in some tissues or cells, but not in others.

SUMMARY

One of the possible causes of the discrepancies is the technologies used to investigate mitochondria, and this paper summarizes some of the pros and cons of the main methods used to study mitochondrial function or DNA.

K65R with and without S68: A New Resistance Profile in Vivo Detected in Most Patients Failing Abacavir, Didanosine and Stavudine

Antiretroviral treatment with three nucleoside reverse transcriptase inhibitors (NRTIs) is widely used, but the combination of abacavir, didanosine and stavudine has never been investigated.

We describe the surprising and consistent genotypic and phenotypic outcome in patients failing this combination. As part of a Danish multicentre study, 60 antiretroviral-naive patients were randomized to treatment with abacavir, didanosine and stavudine. Failure was defined as one HIV-1 RNA >400 copies/ml. Genotyping was performed using TrueGene™ HIV-1 assay (Visible Genetics, London, UK). Phenotypic susceptibilities were determined with the Virco Antivirogram assay.

Eight patients failed treatment with a median viral load of 2.980 copies/ml (range 478-5.950).

At baseline, five patients were wild-type. Three patients harboured nucleoside excision mutations (NEMs), but phenotypic susceptibilities were within normal range.

All five patients with wild-type virus developed K65R and four of these patients also acquired the S68G mutation. Phenotypic susceptibility decreased towards abacavir (median 8.9-fold) and didanosine (median 3.2-fold), while susceptibility towards stavudine was unchanged (median 0.8-fold). Susceptibility towards lamivudine and tenofovir decreased median 14.2- and 4.0-fold, respectively. In two patients with baseline resistance mutations, further accumulation of NEMs and V75T or L74V was observed. One patient developed Q151M.

Failure of a triple NRTI regimen is possible and frequent with only the K65R mutation. Under adequate selection pressure K65R can easily emerge in vivo and may compromise several future treatment options including newer NRTIs. The unexpected high incidence of S68G suggests a functional role of this mutation in viruses harbouring K65R.

Metabolic complications of antiretroviral therapy in children

Survival in HIV-infected children has greatly improved with the introduction of highly active antiretroviral therapy. Children are more vulnerable than adults to metabolic side effects of therapy because of its potential impact on growth and the children's likely greater cumulative exposure. This review summarizes the epidemiology and management of lipodystrophy, dyslipidemia, insulin resistance, hyperlactatemia, osteopenia and growth failure in HIV-infected children.

Mitochondrial DNA replication, nucleoside reverse-transcriptase inhibitors, and AIDS cardiomyopathy

Nucleoside reverse-transcriptase inhibitors (NRTIs) in combination with other antiretrovirals (HAART) are the cornerstones of current AIDS therapy, but extensive use brought mitochondrial side effects to light. Clinical experience, pharmacological, cell, and molecular biological evidence links altered mitochondrial (mt-) DNA replication to the toxicity of NRTIs in many tissues, and conversely, mtDNA replication defects and mtDNA depletion in target tissues are observed. Organ-specific pathological changes or diverse systemic effects result from and are frequently attributed to HAART in which NRTIs are included. The shared features of mtDNA depletion and energy depletion became key observations and related the clinical and in vivo experimental findings to inhibition of mtDNA replication by NRTI triphosphates in vitro. Subsequent to those findings, other observations suggested that mitochondrial energy deprivation is concomitant with or the result of mitochondrial oxidative stress in AIDS (from HIV, for example) or from NRTI therapy itself.

Metabolic acidosis and hepatic steatosis in two HIV-infected patients on stavudine (d4T) treatment

Nucleoside analog reverse transcriptase inhibitors (NRTI) have been used to treat HIV-infected patients for >10 years. Some severe adverse events have been attributed to mitochondrial dysfunction. Since 1991, cases of severe lactic acidosis have been reported in association with nucleoside therapy. Our objective was to report two cases of metabolic acidosis and hepatic steatosis in patients receiving stavudine (d4T) and to review the literature. A male and a female, 47 and 45 years of age, respectively, presented with abdominal pain, nausea, vomiting, and weakness after 9 and 6 months, respectively, of treatment with stavudine. At presentation, both patients had severe metabolic acidosis and liver failure. Ultrasonography showed hepatic steatosis (confirmed by biopsy in one case). All antiretroviral drugs were withdrawn and patients were treated with bicarbonate. Both patients developed fulminant liver dysfunction and multiple organ failure. We reviewed the literature and found 75 cases of lactic acidosis and hepatic steatosis associated with use of NRTI; 57 of these patients received d4T (76%). Of all cases reported in association with nucleoside therapy, 63% were females and mortality was 47%. General weakness, hepatic enzyme elevation, and liver steatosis are data that should alert physicians to this serious adverse event and to respond with prompt interruption of antiretroviral drugs and measurement of lactic acid in plasma. It is important to report serious adverse events in commercially released drugs to know prevalence in an exposed population. Physicians should be aware of risk and early signs of this serious adverse event.

[Severe lactic acidosis in HIV-infected patients treated with nucleosidic reverse transcriptase analogs: a report of 9 cases]

PURPOSE

Symptomatic lactic acidosis requiring intensive care is a rare and severe adverse event related to the mitochondrial toxicity of the nucleoside analog reverse transcriptase inhibitors (NRTIs).

METHOD

We retrospectively investigated the clinical and biological features of HIV-infected patients who developed severe lactic acidosis syndrome at the University teaching hospital of Bordeaux and the regional community hospital, during 1996-2000.

RESULTS

Nine patients were identified (incidence: 0,9/1000 NRTI treated patient-years), 4 men and 5 women with a median age of 36 years. They had a moderate immunodeficiency (median CD4+ T lymphocyte counts: 197/mm(3)) and only one of them presented a virological failure. The causes of hospital admission were abdominal pain (n = 6), dyspnea (n = 6), asthenia (n = 5), jaundice (n = 4), and vomiting (n = 2). Hepatomegaly was present in 6 patients. Lactic acidosis was found in all cases: median pH: 7.28, bicarbonate: 12 mmol/l, anion gap: 27 mEq/l, plasma lactic acid: 13 mmol/l. Cytolysis (n = 8), cholestasis (n = 6), hepatic failure (n = 4), rhabdomyolysis (n = 4) and pancreatitis (n = 2), were also present. Despite medical intensive care, seven patients died. The only two post-mortem examinations revealed severe hepatic steatosis. Median duration of NRTI therapy was 4 years. At presentation, five patients were receiving lamivudine, five didanosine, four stavudine and three zidovudine. Six patients were coinfected by HCV and/or HBV, four had chronic renal failure and five an immediately preceding infectious disease.

CONCLUSION

The prognosis of lactic acidosis is severe. Nucleosid-analog therapy needs clinical and biological monitoring, specially in patients with comorbidities.

Prevalence, risk factors and outcome of hyperlactataemia in HIV-infected patients

OBJECTIVE

We describe the prevalence, risk factors and outcome of hyperlactataemia (HL) in a cohort of 140 HIV-infected patients.

PATIENTS AND METHODS

Patients were enrolled consecutively within a 3-month period (July to September 1999) and followed until 31 October 2000. One hundred and forty HIV-infected patients had venous plasma lactate levels measured. HL was defined at baseline by two consecutive lactate levels > 2.1 mmol/L (upper limit of normal). We compared baseline demographic characteristics, immuno-virological parameters, antiretroviral therapy and outcome between patients with HL (cases) or without HL (controls). We described the clinical features of patients with HL.

RESULTS

Among 129 patients included in the analysis, HL was found in 11 patients (8.5%), all of whom were receiving nucleoside reverse transcriptase inhibitors (NRTIs). Cases were more likely than controls to receive didanosine or stavudine (82% vs. 19%, P= 2.7 x 10(-6) and 82% vs. 48%, P= 0.03, respectively). Only 4/11 cases (36%) had symptoms consistent with HL. After a median follow-up of 15 months, lactate level returned to normal in all three patients who discontinued NRTIs, but in only 2/8 patients who did not (P = 0.06). Only one case experienced lactic acidosis and died during follow-up. Mortality rate was similar in cases and controls.

CONCLUSION

HL is associated with NRTI use, in particular didanosine and stavudine, and discontinuation of NRTIs seems to be associated with rapid resolution of HL. Lactic acidosis remains rare and the long-term outcome of patients with HL does not seem to be poorer than controls.

Lipodystrophy in a cohort of human immunodeficiency virus-infected Asian patients: prevalence, associated factors, and psychological impact

We investigated the prevalence of and factors associated with lipodystrophy in a cohort of human immunodeficiency virus (HIV)-infected patients in Singapore. A standardized questionnaire was administered to 410 consecutive patients (mainly Chinese men), and blood samples were obtained for metabolic measurements for fasting patients. Peripheral fat loss was reported by 46% of subjects, central fat gain was reported by 32%, and 8% of patients overall had a mixed clinical presentation. Levels of total cholesterol, triglycerides, glucose, and lactate were elevated in 19%, 38%, 12%, and 16% of patients, respectively. A mixture of drug-related and non-drug-related factors was associated with these changes. The body-shape changes affected the mood of 36% of patients and the work and/or social activity of 23% of patients, but only <1% of affected subjects reported a desire to stop receipt of antiretroviral therapy because of these changes. We conclude that the prevalence of and factors associated with body-shape changes and metabolic abnormalities in HIV-infected Asian patients are similar to those reported for Western cohorts, but the changes did not appear to have a major psychosocial impact on this patient population.

Increased long-term mitochondrial toxicity in combinations of nucleoside analogue reverse-transcriptase inhibitors

BACKGROUND

Some nucleoside analogue reverse transcriptase inhibitors (NRTI) may cause depletion of mitochondrial (mt) DNA in liver by inhibiting polymerase-gamma. mtDNA depletion may contribute to lactic acidosis, steatohepatitis and liver failure.

OBJECTIVE

To evaluate the long-term mitochondrial toxicity of NRTI combinations.

METHODS

The HepG2 human hepatoma cell line was cultivated in the presence of zalcitabine (ddC), didanosine (ddI), stavudine (d4T), lamivudine (3TC), zidovudine (ZDV) and efavirenz at concentrations equivalent to steady-state peak plasma levels (C ), and also in one-third and 10 times C. The NRTI were added to the medium alone or in combination. Control cells were incubated without any NRTI or with efavirenz. Cell growth, lactate production, intracellular lipid droplets, mtDNA and the mtDNA-encoded respiratory chain subunit COX II were monitored over a period of up to 30 days.

RESULTS

Time- and dose-dependent mtDNA depletion was observed with ddC > ddI > d4T and mtDNA depletion preceded or coincided with a decline in COX II expression, a decrease in cell growth, increased lactate production and increased intracellular lipids. 3TC and efavirenz did not affect any measurement. ZDV increased lactate moderately and cell growth was inhibited, despite normal mtDNA and COX II levels. The negative effects on some measurements were more pronounced in the 3TC-ZDV and ddC-d4T combinations, than in the single-NRTI incubations. The combination of ddI-d4T was not more toxic than ddI alone. Mitochondrial damage by ZDV, d4T, ddI, and ddC did not reach steady-state by day 25. Using a Southern blot technique, mtDNA deletions were never observed.

CONCLUSION

The data indicate additive or synergistic long-term mitochondrial toxicity in some NRTI combinations.

Mitochondrial damage associated with long-term antiretroviral treatment: associated alteration or causal disorder?

Combination of antiretroviral drugs has dramatically improved the prognosis of human HIV infection but is also associated with many adverse effects, the mitochondrial origin of which is discussed. In this study using extensive diagnostic procedures set up for inherited mitochondrial disorders, we analyzed HIV patients under active antiretroviral therapy who complained of severe adverse symptoms unexplained by HIV. All these patients had been treated for at least 5 years. They all had significant mitochondrial damage as evidenced by the diverse combination of lactate accumulation in blood or cerebrospinal fluid, mitochondrial morphologic alterations in muscle, and biochemical defects in muscle and liver, which designated mitochondrial DNA (mtDNA) as the main target of the toxic mechanisms. Southern blot and/or polymerase chain reaction -based analyses disclosed multiple deletions of the muscle mtDNA and reduction of the muscle and/or liver mtDNA copy number in a majority of the patients. In opposition to muscle and liver, blood mononuclear cells were devoid of significant biochemical or genetic alterations. Whether the mitochondrial toxicity is directly responsible for the patients' adverse symptoms remains disputable, because the investigations were transversal. Its severity argues for its clinical relevance, however. The skewed tissue distribution of mitochondrial alterations indicates potential pitfalls in the needed future prospective studies.

Management of metabolic complications associated with antiretroviral therapy for HIV-1 infection: recommendations of an International AIDS Society-USA panel

OBJECTIVE

Alterations in glucose and lipid metabolism, lactic acidemia, bone disorders, and abnormal body fat distribution have been recognized recently as frequent complications associated with HIV-1 infection and potent antiretroviral therapy, but limited data are available regarding the appropriate management of these disorders. These recommendations were developed to guide physicians actively involved in HIV care in the management of metabolic complications that occur primarily within the context of potent antiretroviral therapy.

PARTICIPANTS

A 12-member panel representing international expertise in HIV-1 patient care, antiretroviral therapy, and endocrine and metabolic disorders was selected in the spring of 2000 by the International AIDS Society-USA, a not-for-profit physician education organization. Panel members met in closed meetings beginning in May 2000. All work was funded by the International AIDS Society-USA; the panel members are not compensated for their participation.

EVIDENCE

The panel reviewed published results of clinical, epidemiologic, and basic science studies and data and abstracts presented at research conferences, primarily from 1997 to 2002. The panel also considered studies of the pathophysiology and treatment of similar metabolic abnormalities in noninfected persons. Emphasis was placed on results from prospective, randomized, controlled clinical trials when available.

PROCESS

For each metabolic complication, 1 or more member(s) reviewed and presented all available evidence to the panel, and then wrote a summary of the evidence and preliminary recommendations. Final recommendations were determined by full group consensus. The summaries were combined into a single working document and all panel members edited and approved all subsequent drafts.

CONCLUSIONS

Carefully controlled studies to determine the incidence, etiology, risk factors, and most appropriate treatments for metabolic complications in HIV-1 infection are urgently needed. In the absence of these data, and to prevent acute illness and mitigate long-term risks, the panel recommends routine assessment and monitoring of glucose and lipid levels and assessment and monitoring of lactic acidemia and bone abnormalities if clinical signs or symptoms are detected. With the exception of body fat distribution abnormalities, specific treatments for these complications are also recommended. Successful long-term antiretroviral therapy will require diligent monitoring and preemptive treatment of metabolic complications to optimize the risk-benefit ratio of antiretroviral therapies.

[Symptomatic hyperlactatemia associated with the use of antiretroviral agents]

Lactic acidosis has been reported as a rare but potentially fatal complication of anti-retroviral therapy in HIV-infected patients, mostly with nucleoside analogues. Two cases of lactic acidosis with a favorable prognosis are here reported. So far, no distinct risk factors associated with the development of lactic acidosis have been identified which were associated with the use of anti-retroviral agents, apart from female sex, obesity, and the prolonged use of necleoside reverse transcriptase inhibitors. Currently, there is no specific treatment for this condition, apart from drug discontinuation and hydro-electrolytic support. Several therapies based upon the pathophysiology of this entity have been tested, but none of them has been validated so far.

[Report of three cases of hyperlactacidemiae/lactic acidosis after treatment of hepatitis C with pegylated interferon and ribavirin in HIV coinfected patients]

The hepatitis C infection is highly prevalent among HIV-infected patients. As a direct consequence of the increased survival of these patients in the HAART era, liver disease and its long-term complications have became a genuine health problem in these patients. The treatment of chronic HCV hepatitis is associated with several secondary effects, hiperlactacidemiae/lactic acidosis is one of the most dangerous. It appears to be related with the association of ribavirin and ddI, d4T or AZT. These are three cases of hiperlactacidemiae/lactic acidosis collected during the first twelve months of treatment with pegylated interferon and ribavirin in University Hospital of Guadalajara.