Lactic acidosis related to nucleoside therapy in HIV-infected patients

Severe lactic acidosis during tenofovir disoproxil fumarate and cobicistat combination for HIV patient

Lactic acidosis is a rare but serious side effect in individuals receiving nucleoside reverse transcriptase inhibitors. An underweight woman with HIV was admitted to our hospital because of nausea and diffuse myalgia. Her antiretroviral regimen had been changed to tenofovir disoproxil fumarate (TDF)/emtricitabine and darunavir/cobicistat 3 months prior, after which her renal function had gradually declined. After admission, she was diagnosed with lactic acidosis, and a liver biopsy suggested mitochondrial damage. Her plasma tenofovir levels were elevated at the onset of lactic acidosis. We hypothesise that the patient's low body weight, combined with the addition of cobicistat, induced renal dysfunction and led to elevated plasma tenofovir concentrations, resulting in mitochondrial damage and lactic acidosis. Careful monitoring of renal function and lactic acidosis is required during use of TDF-containing regimens for underweight HIV patients, particularly when combined with cobicistat.

Successful Treatment of Tenofovir Alafenamide-Induced Lactic Acidosis: A Case Report

Nucleoside or nucleotide analogues (NAs) have the potential to cause lactic acidosis by inhibiting DNA polymerase-γ of human mitochondria and impairing aerobic metabolism. Patients may be asymptomatic, have mild non-specific symptoms, or present in multisystem organ failure. There is a paucity of data to guide management of life-threatening lactic acidosis due to NA therapy. Here we describe a case of a 60-year old critically ill male with decompensated cirrhosis secondary to hepatitis B virus (HBV) infection who developed severe lactic acidosis (13.8 mmol/L) 2 days after initiation of tenofovir alafenamide (TAF). All other possible etiologies for the elevated lactate were ruled out. Lactic acidosis resolved rapidly with TAF discontinuation and supplementation with cofactors supporting mitochondrial oxidative phosphorylation, including coenzyme Q10, levocarnitine, riboflavin, and thiamine. This case highlights the ability of TAF to cause lactic acidosis early after therapy initiation, especially in susceptible hosts, and reviews the potential role for cofactor supplementation for drug-induced mitochondrial injury.

[Nephrotoxicity of antiretrovirals other than tenofovir]

The remarkable improvement of the outcome of HIV infection came with the price of substantial toxicity of some antiretrovirals. The first molecules used to treat HIV included an important nephrotoxicity. Zalcitabine, stavudine and didanosine can induce severe lactic acidosis. Lactate production is enhanced and the renal capacity to regulate pH is overwhelmed. However, this side effect is not due to a direct dysfunction of the kidneys. Zalcitabine was withdrawn from the market because of this risk. Indinavir, a protease inhibitor, is soluble only in very acidic solutions. Consequently, the small fraction that is excreted in the urine precipitates and can be responsible for uro-nephrolithiasis, leukocyturia, cristalluria, obstructive acute kidney failure, and acute or chronic interstitial nephritis. This is the reason why indinavir is almost not prescribed nowadays, even if it is still marketed. In addition to the direct nephrotoxicity of some antiretrovirals, anti-HIV treatment also includes a toxicity which pathophysiology is not completely elucidated. This nephrotoxicity is the consequence of organ accelerated ageing and of an increased vascular risk. Kidney vascularization (from renal arteries to capillaries) is essential to kidney function and all cardiovascular risks are also renal risks. It is now clearly established that combined antiretroviral treatment increases the vascular risk. A better comprehension of the links between HIV infection, its treatment and very long-term kidney risk is needed to improve the complex management of patients who have now cumulated several decades of HIV infection and treatment with various toxicities.

Drugs influencing acid base balance and bicarbonate concentration readings

Serum bicarbonate dosage is sensitive to pharmacological interferences. However, elevated bicarbonate concentration reflects chronic hypoventilation and has been proposed as a simple marker for screening patients with Obesity Hypoventilation Syndrome (OHS), a currently underdiagnosed multimorbid and high mortality disease. We provide a practical overview of the different drugs acting on the acid-base equilibrium to aid clinicians to interpret bicarbonate concentration readings. Little is known about the chronic impact of the usual doses of these drugs on serum bicarbonate concentration and further studies are needed. It is essential to take into account drugs that could interfere with this parameter to avoid misinterpretation of serum bicarbonate levels.

Changes in first-line cART regimens and short-term clinical outcome between 1996 and 2010 in The Netherlands

OBJECTIVES

Document progress in HIV-treatment in The Netherlands since 1996 by reviewing changing patterns of cART use and relating those to trends in patients' short-term clinical outcomes between 1996 and 2010.

DESIGN AND METHODS

1996-2010 data from 10,278 patients in the Dutch ATHENA national observational cohort were analysed. The annual number of patients starting a type of regimen was quantified. Trends in the following outcomes were described: i) recovery of 150 CD4 cells/mm(3) within 12 months of starting cART; ii) achieving viral load (VL) suppression ≤1,000 copies/ml within 12 months of starting cART; iii) switching from first-line to second-line regimen within three years of starting treatment; and iv) all-cause mortality rate per 100 person-years within three years of starting treatment.

RESULTS

Between 1996 and 2010, first-line regimens changed from lamivudine/zidovudine-based or lamivudine/stavudine-based regimens with unboosted-PIs to tenofovir with either emtricitabine or lamivudine with NNRTIs. Mortality rates did not change significantly over time. VL suppression and CD4 recovery improved over time, and the incidence of switching due to virological failure and toxicity more than halved between 1996 and 2010. These effects appear to be related to the use of new regimens rather than improvements in clinical care.

CONCLUSION

The use of first-line cART in the Netherlands closely follows changes in guidelines, to the benefit of patients. While there was no significant improvement in mortality, newer drugs with better tolerability and simpler dosing resulted in improved immunological and virological recovery and reduced incidences of switching due to toxicity and virological failure.

Dynamic lactate indices as predictors of outcome in critically ill patients

Introduction

Dynamic changes in lactate concentrations in the critically ill may predict patient outcome more accurately than static indices. We aimed to compare the predictive value of dynamic indices of lactatemia in the first 24 hours of intensive care unit (ICU) admission with the value of more commonly used static indices.

Methods

This was a retrospective observational study of a prospectively obtained intensive care database of 5,041 consecutive critically ill patients from four Australian university hospitals. We assessed the relationship between dynamic lactate values collected in the first 24 hours of ICU admission and both ICU and hospital mortality.

Results

We obtained 36,673 lactate measurements in 5,041 patients in the first 24 hours of ICU admission. Both the time weighted average lactate (LAC_TW24) and the change in lactate (LAC_Δ24) over the first 24 hours were independently predictive of hospital mortality with both relationships appearing to be linear in nature. For every one unit increase in LAC_TW24 and LAC_Δ24 the risk of hospital death increased by 37% (OR 1.37, 1.29 to 1.45; P < 0.0001) and by 15% (OR 1.15, 1.10 to 1.20; P < 0.0001) respectively. Such dynamic indices, when combined with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, improved overall outcome prediction (P < 0.0001) achieving almost 90% accuracy. When all lactate measures in the first 24 hours were considered, the combination of LAC_TW24 and LAC_Δ24 significantly outperformed (P < 0.0001) static indices of lactate concentration, such as admission lactate, maximum lactate and minimum lactate.

Conclusions

In the first 24 hours following ICU admission, dynamic indices of hyperlactatemia have significant independent predictive value, improve the performance of illness severity score-based outcome predictions and are superior to simple static indices of lactate concentration.

Relative hyperlactatemia and hospital mortality in critically ill patients: a retrospective multi-centre study

Introduction

Higher lactate concentrations within the normal reference range (relative hyperlactatemia) are not considered clinically significant. We tested the hypothesis that relative hyperlactatemia is independently associated with an increased risk of hospital death.

Methods

This observational study examined a prospectively obtained intensive care database of 7,155 consecutive critically ill patients admitted to the Intensive Care Units (ICUs) of four Australian university hospitals. We assessed the relationship between ICU admission lactate, maximal lactate and time-weighted lactate levels and hospital outcome in all patients and also in those patients whose lactate concentrations (admission n = 3,964, maximal n = 2,511, and time-weighted n = 4,584) were under 2 mmol.L^-1 (i.e. relative hyperlactatemia).

Results

We obtained 172,723 lactate measurements. Higher admission and time-weightedlactate concentration within the reference range was independently associated with increased hospital mortality (admission odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3 to 3.5, P = 0.01; time-weighted OR 3.7, 95% CI 1.9 to 7.00, P < 0.0001). This significant association was first detectable at lactate concentrations > 0.75 mmol.L^-1. Furthermore, in patients whose lactate ever exceeded 2 mmol.L^-1, higher time-weighted lactate remained strongly associated with higher hospital mortality (OR 4.8, 95% CI 1.8 to 12.4, P < 0.001).

Conclusions

In critically ill patients, relative hyperlactataemia is independently associated with increased hospital mortality. Blood lactate concentrations > 0.75 mmol.L^-1 can be used by clinicians to identify patients at higher risk of death. The current reference range for lactate in the critically ill may need to be re-assessed.

Use of Tris-hydroxymethyl aminomethane in severe lactic acidosis due to highly active antiretroviral therapy: a case report

BACKGROUND

Lactic acidosis is a rare, yet life-threatening adverse drug effect of highly active antiretroviral therapy (HAART), specifically stavudine and lamivudine. These nucleoside analogue reverse transcriptase inhibitors (NRTIs) are commonly used to treat patients infected with the human immunodeficiency virus (HIV).

CASE

We report the use of Tris-hydroxymethyl aminomethane (THAM) to treat severe lactic acidosis due to HAART in a 50-year-old African-American woman. NRTIs can cause hyperlactinaemia by interfering with mitochondrial oxidative phosphorylation function, which normally removes H(+) generated by the hydrolysis of adenosine triphosphate. This side-effect is associated with a high mortality in patients infected with HIV. One explanation for this high mortality is that lactic acidosis is typically refractory to treatment with commonly used buffering agents.

CONCLUSION

THAM generates serum bicarbonate, and reduces the level of carbon dioxide in arterial blood. Both of these qualities appear to make THAM an ideal agent for treating lactic acidosis caused by HAART.

Management of antiretroviral treatment-related complications

Antiretroviral therapy for HIV restores immune function, controls viral replication, decreases opportunistic infections, and extends lifespan to near-normal for infected individuals. However, successful HIV therapy has been accompanied by the emergence of treatment-related complications, with an impact not yet fully understood. This article reviews six common complications of antiretroviral therapy, including hyperlactatemia/lactic acidosis, hypersensitivity reactions, abnormal glucose metabolism, dyslipidemia, body composition changes, and cardiovascular disease. A comprehensive approach to management of antiretroviral-related complications includes awareness of (1) risk factors for adverse reactions, (2) clinical syndromes suggestive of an evolving complication, and (3) evidence-based monitoring and treatment strategies. Fluency in options for preventing and managing complications can provide maximal opportunity to balance treatment effects with quality of life.

Monitoring oxygen transport and tissue oxygenation

PURPOSE OF REVIEW

To review recent publications in the field of oxygen delivery and tissue oxygenation. With few exceptions, we restricted our selection to clinical studies published in the English literature.

RECENT FINDINGS

No major breakthroughs have occurred in the past decade in the diagnosis or treatment of tissue hypoxia. There is renewed interest in goal-directed resuscitation when applied early in the course of treatment. Monitoring metabolic markers of tissue hypoxia continues to hold great clinical interest, in particular, tissue PCO2, near infrared spectroscopy, base deficit and blood lactate concentration. Technical issues, however, seem to restrict the widespread use of many of these techniques.

SUMMARY

There is an urgent need to develop methods to accurately and rapidly identify patients with tissue hypoxia. Perhaps the combination of gastric tonometry, near-infrared spectroscopy, urinary PO2 and continuous measures of mixed (or central) venous O2 saturation may provide the answer. An even more formidable task is that of developing effective therapy to correct tissue hypoxia while avoiding harm to the patient.

Systematic review of clinical trials evaluating low doses of stavudine as part of antiretroviral treatment

Stavudine is a nucleoside analogue used for the treatment of HIV-1 infection, as part of highly active antiretroviral treatment. In developing countries, stavudine is used widely, owing to low cost and inclusion in generic fixed-dose combinations. In developed countries, stavudine is now rarely used, although it is highly effective. This is because newer drugs show lower rates of mitochondrial toxicities, such as lipoatrophy, peripheral neuropathy and lactic acidosis. In the development of stavudine, there was evidence that a dosage of 20-30 mg b.i.d. was effective, but the 40-mg b.i.d. dose gained regulatory approval. This review analyses the clinical trials conducted before and after the regulatory approval of stavudine, and shows that the dose of 30 mg b.i.d. has equivalent antiviral efficacy (given the caveats of meta-analysis), with some evidence of lower rates of peripheral neuropathy and lipoatrophy. With limited resources for HIV-1 treatment in developing countries, and only 25% of eligible patients receiving highly active antiretroviral treatment, low-cost treatment options such as stavudine still need to be pursued, if safety can be improved by dose optimisation.

Carnitines and its congeners: a metabolic pathway to the regulation of immune response and inflammation

Carnitine and its congeners may regulate the immune networks, and their influence on functions of immune cells predominantly or exclusively relies on carnitine-dependent energy production from fatty acids. A reduced pool of carnitines has been demonstrated in either serum or tissues, or both, from patients with a wide spectrum of disorders characterized by unregulated or impaired immune responses ranging from sepsis syndrome to systemic sclerosis, infection with human immunodeficiency virus, and chronic fatigue syndrome. Furthermore, experimental studies have consistently reported that the deranged immune responses and the less efficient inflammation towards infectious organisms associated with aging may be enhanced or modulated by treatment with carnitines. There is also evidence that carnitine deprivation could adversely affect the course of the sepsis syndrome, at least in experimental models, and preliminary studies suggest that carnitine deficiency is ultimately implicated in the pathophysiology of endotoxin-mediated multiple organ failure. Several data indicate that carnitine deficiency is a contributing factor to the progression of infection with human immunodeficiency virus, and carnitine therapy in those patients could counteract the unregulated process of lymphocyte apoptosis and improve CD4 counts. Some case reports have suggested the use of carnitine for the treatment of the severe lactic acidosis that complicates in some patients the use of reverse transcriptase inhibitors.

Fatal Lactic Acidosis Associated with Coadministration of Didanosine and Tenofovir Disoproxil Fumarate

Lactic acidosis is an uncommon but potentially life-threatening adverse effect of didanosine. When given concomitantly with tenofovir disoproxil fumarate (DF), the area under the concentration-time curve of didanosine is increased by 48-60%. A 63-year-old man with human immunodeficiency virus (HIV) infection tolerated several didanosine-containing antiretroviral regimens. He developed generalized weakness, loss of appetite, weight loss, nausea, and vomiting 1.5 years after tenofovir DF was added to his didanosine-containing regimen. He was diagnosed with lactic acidosis and died after a 13-day hospital stay, when his lactate level increased to 189.7 mg/dl and his arterial blood gas pH value fell to 6.75. Health care providers should maintain a high index of suspicion for lactic acidosis in patients with HIV infection who receive didanosine and tenofovir DF concurrently. For patients receiving antiretroviral regimens containing this drug combination, it would be prudent to monitor lactate levels periodically. This is especially important when patients experience symptoms suggestive of lactic acidosis, such as weakness, abdominal pain, weight loss, nausea and vomiting, and shortness of breath.