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

Severe Lactic Acidosis Due to Inappropriate Use of Biktarvy in a Patient With AIDS

Bictegravir-emtricitabine-tenofovir alafenamide is an approved medication for the treatment of acquired immunodeficiency syndrome (AIDS). This medication, also called Biktarvy, includes an integrase strand inhibitor combined with nucleoside reverse transcriptase inhibitors (NRTIs) to prevent viral DNA synthesis and lead to improvements in disease progression and mortality in patients with AIDS. A rare but previously documented adverse effect of NRTIs present in Biktarvy is lactic acidosis. NRTIs can cause lactic acidosis through mitochondrial impairment, as mitochondria depend on DNA polymerase gamma for replication. This enzyme is very similar to HIV's reverse transcriptase. Inhibition of mitochondrial production results in increased anaerobic metabolism and lactic acid production. We present a case where an inappropriately high dosage of Biktarvy in a patient with septic shock led to persistent lactic acidosis despite clinical improvement. After a thorough medication review, Biktarvy was temporarily held, and the lactic acidosis resolved. This clinical presentation stresses the importance of maintaining wide differentials for lactic acidosis and thorough medication reconciliation.

Human immunodeficiency virus and antiretroviral therapy-mediated immune cell metabolic dysregulation in children born to HIV-infected women: potential clinical implications

Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+) has dramatically improved the health of HIV-infected women and their children, with the majority being of HIV-exposed children born uninfected (HEU). This success has led to an increasing population of HIV-infected women receiving ART during pregnancy and children exposed to ART in utero. Nonetheless, a small proportion of children are still infected with HIV (HEI) each year. HEI children suffer from reduced immunocompetence and host-defence, due to CD4+ T lymphocyte depletion, but also dysregulation of other immune cells including CD8+ T lymphocytes, natural killer (NK) cells, macrophages including B lymphocytes. Furthermore, although HEU children are uninfected, altered immune responses are observed and associated with increased vulnerability to infections. The mechanisms underlying immune dysregulation in HEU children remain poorly described. Building on early studies, emerging data suggests that HIV/ART exposure early in life affects cell metabolic function of HEU children. Prenatal HIV/ART exposure has been associated with dysregulation of mitochondria, including impaired DNA polymerase activity. Furthermore, dysregulation of oxidative phosphorylation (OXPHOS) causes a decreased generation of adenosine triphosphate (ATP) and increased production of reactive oxygen species (ROS), resulting in oxidative stress. These altered metabolic processes can affect immune cell viability and immune responses. Recent studies have indicated that immune-metabolic dysregulation may contribute to HIV-associated pathogenesis and clinical observations associated with HIV and ART exposure in HEU/HEI children. Given the critical role metabolic processes in immune cell functioning, immune-metabolic dysregulation in HEU and HEI children may have implications in effective host-defence responses against pathogens, as well as efficacy of standard ART regimens and future novel HIV cure approaches in HEI children. At the same time, targeting metabolic pathways of immune cells may provide safer and novel approaches for HIV cure strategies. Here, we review the current literature investigating immune-metabolic dysregulation in paediatric HIV pathogenesis.

Viral infections in critical care: a narrative review

Viral infections form a substantial part of the intensive care workload, even before the recent and ongoing COVID-19 pandemic. The growing availability of molecular diagnostics for viral infections has led to increased recognition of these pathogens. This additional information, however, provides new challenges for interpretation and management. As the SARS-CoV-2 pandemic has amply demonstrated, the emergence and global spread of novel viruses are likely to provide continued challenges for critical care physicians into the future. This article will provide an overview of viral infections relevant to the critical care physician, discussing the diagnosis and management of respiratory viral infections, blood borne and enteric viruses. We will also discuss herpesviridae complications, commonly seen due to reactivation of latent infections. Further, we explore some rarer and emerging viruses, including recognition of viral haemorrhagic fevers, and briefly discuss post-viral syndromes which may present to the intensive care unit. Finally, we will discuss infection control and its importance in preventing nosocomial viral transmission.

Mitochondrial changes associated with viral infectious diseases in the paediatric population

Infectious diseases occur worldwide with great frequency in both adults and children, causing 350,000 deaths in 2017, according to the latest World Health Organization reports. Both infections and their treatments trigger mitochondrial interactions at multiple levels: (i) incorporation of damaged or mutated proteins into the complexes of the electron transport chain; (ii) impact on mitochondrial genome (depletion, deletions and point mutations) and mitochondrial dynamics (fusion and fission); (iii) membrane potential impairment; (iv) apoptotic regulation; and (v) generation of reactive oxygen species, among others. Such alterations may result in serious adverse clinical events with considerable impact on the quality of life of the children and could even cause death. Herein, we use a systematic review to explore the association between mitochondrial alterations in paediatric infections including human immunodeficiency virus, cytomegalovirus, herpes viruses, various forms of hepatitis, adenovirus, T-cell lymphotropic virus and influenza. We analyse how these paediatric viral infectious processes may cause mitochondrial deterioration in this especially vulnerable population, with consideration for the principal aspects of research and diagnosis leading to improved disease understanding, management and surveillance.

Lactic acidosis and hyperlactatemia associated with lamivudine accumulation and sepsis in a kidney transplant recipient-a case report and review of the literature

Background

We report a case of sudden, lethal metabolic acidosis in a 70-year-old man on long-term nucleoside reverse transcriptase inhibitor (NRTI) -based antiretroviral therapy (ART) who had developed atypical necrotizing fasciitis 1 month after kidney transplantation.

Case presentation

The HIV infection of the patient was treated for the last four months with an integrase strand inhibitor (dolutegravir 50 mg/d) plus a NRTI backbone including lamivudine (150 mg/d) and abacavir (600 mg/d). In this renal transplant patient we hypothesize that the co-existence of sepsis, renal failure and an accumulation of lamivudine led to the development of fatal metabolic acidosis and hyperlactatemia. Although lamivudine is only rarely associated with hyperlactatemia, there is evidence that overdose may be a risk factor for developing it. In our patient the lamivudine concentration two days after stopping and during hemodiafiltration was more than 50 times higher than therapeutic target trough concentrations. Likely reasons for this were renal impairment and concurrent treatment with trimethoprim, known to inhibit the renal elimination of lamivudine.

Conclusions

NRTIs could trigger the development of hyperlactatemia in septic patients. The use of NRTI sparing regimens might be considered in the presence of this critical condition.

Intentional overdose of dolutegravir/abacavir/lamivudine (Triumeq) in a 26-year-old man

Triumeq is a single-tablet regimen for patients with HIV infection comprising dolutegravir, abacavir and lamivudine. Overdoses with Triumeq have not been reported previously. We present a case of a 26-year-old man who presented to our hospital after intentionally ingesting 30 tablets of Triumeq. An intoxication with Triumeq can lead to several side effects. An overdose of abacavir and lamivudine can cause mitochondrial toxicity and lactic acidosis. An intoxication with dolutegravir appears to be relatively harmless. As Triumeq will be used on a regular basis as treatment for patients with HIV-1 infection, these intoxications are expected to be encountered more often.

[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.

Development of peptide inhibitors of HIV transmission

Treatment of HIV has long faced the challenge of high mutation rates leading to rapid development of resistance, with ongoing need to develop new methods to effectively fight the infection. Traditionally, early HIV medications were designed to inhibit RNA replication and protein production through small molecular drugs. Peptide based therapeutics are a versatile, promising field in HIV therapy, which continues to develop as we expand our understanding of key protein-protein interactions that occur in HIV replication and infection. This review begins with an introduction to HIV, followed by the biological basis of disease, current clinical management of the disease, therapeutics on the market, and finally potential avenues for improved drug development.

Life-Threatening Complications of HIV Infection

Few modern diseases have experienced as rapid and dramatic change in prognosis and treatment as HIV infection. The introduction of active antiretroviral therapy (ART) and effective prophylaxis of opportunistic infections ushered in a new era in the treatment of HIV infection and changed dramatically the natural history of this disease. The rates of admission to the intensive care unit (ICU) and intensive care mortality in patients with HIV infection have shifted repeatedly during the AIDS epidemic, influenced by attitudes of patients and providers toward utility of care. In the ART era, patients with HIV infection admitted to the ICU fall into 3 general categories: those with AIDS-related opportunistic infections, those who are experiencing complications related to ART, and those with medical problems unrelated to HIV infection. In this article, the authors provide a review of the most common life-threatening complications in patients with HIV infection.

Fatal Tenofovir-Associateacd Lactic Acidosis: A Case Report

Introduction:

The introduction of highly active antiretroviral therapy (HAART), in 1996, has resulted in marked reductions in the rate of illness and death, due to HIV infection. The HAART has transformed HIV infection into a manageable chronic disease. However, although many regimens lower plasma viral load, to below the limit of detection, in most patients, maintaining viral load suppression remains challenging, because of adverse effects and toxicity in the long term, which can lead to non-adherence, virologic failure and drug resistance. Although rare, lactic acidosis often develops fatal complications, as reported in several human immunodeficiency virus infected patients treated with nucleoside reverse transcriptase inhibitors (NRTIs). The purpose of this paper is to report a case of tenofovir induced lactic acidosis and review the literature.

Case Presentation:

A 52-year-old Malay gentleman, with hepatitis C virus and HIV infection was admitted to the intensive care unit for severe lactic acidosis, with concurrent Escherichia coli bacteremia with multiorgan dysfunction. The patient was started on highly active antiretroviral therapy, which included tenofovir, 5 weeks before presentation. Antimicrobial therapy, continuous veno-venous hemofiltration, and other supportive treatments were instituted. However, the patient eventually succumbed to his illness.

Conclusions:

It is essential for clinicians to be able to recognize the signs and symptoms of lactic acidosis in NRTIs treated HIV patients, as an early diagnosis is important to institute treatment.

Effects of mid-respiratory chain inhibition on mitochondrial function in vitro and in vivo

Schematic showing the toxicological and adaptive effects of drug-induced respiratory chain inhibition in vivo; also highlighting unanticipated differences from observations made in vitro (in red).

Relating the in vitro mitochondrial effects of drug candidates to likely in vivo outcomes remains challenging. Better understanding of this relationship, alongside improved methods to assess mitochondrial dysfunction in vivo, would both guide safer drug candidate selection and better support discovery programmes targeting mitochondria for pharmacological intervention. The aim of this study was to profile the in vivo effects of a compound with suspected complex III electron transport chain (ETC) inhibitory activity (GSK932121A) at doses associated with clinical signs, and relate findings back to in vitro data with the same compound. Control liver mitochondria or HepG2 cells were treated in vitro with GSK932121A to assess mitochondrial effects on both calcium retention capacity (CRC) and oxygen consumption rate (OCR) respectively. The same assessments were then performed on liver mitochondria isolated from Crl:CD(SD) rats, 5 hours following intraperitoneal (IP) administration of GSK932121A. Lactate/pyruvate assessment, hepatic microscopy, blood gas analysis, glutathione profiling and transcriptomics were used to characterise the acute toxicity. In vivo, GSK932121A caused hypothermia, increased levels of hepatocellular oxidative stress and a metabolic shift in energy production, resulting in an increased lactate/pyruvate ratio, liver steatosis and glycogen depletion, together with gene expression changes indicative of a fasted state. As would be expected of an ETC inhibitor, GSK932121A reduced the CRC of liver mitochondria isolated from naive control animals and the OCR of HepG2 cells when treated directly in vitro. In contrast, mitochondria isolated from animals treated with GSK932121A in vivo unexpectedly showed an increase in CRC and basal OCR. Whilst seemingly contradictory, these differences likely reflect an adapted state in vivo resulting from the initial insult in combination with compensatory changes made by the tissue to maintain energy production. Only the initial, unconfounded, response is observable in vitro. These findings improve current understanding of the toxicological and molecular consequences of ETC inhibition. Furthermore, this work highlights key differences in the way that mitochondrial perturbation is manifest in vivo versus in vitro in terms of functional endpoints and helps guide endpoint selection for future studies with potential mitochondrial toxicants or drugs designed to modulate mitochondrial function for therapeutic benefit.

Etiologies, clinical features and outcome of cardiac arrest in HIV-infected patients

BACKGROUND

Compared to many other cardiovascular diseases, there is a paucity of data on the characteristics of successfully resuscitated cardiac arrest (CA) patients with human immunodeficiency virus (HIV) infection. We investigated causes, clinical features and outcome of these patients, and assessed the specific burden of HIV on outcome.

METHODS

Retrospective analysis of HIV-infected patients admitted to 20 French ICUs for successfully resuscitated CA (2000-2012). Characteristics and outcome of HIV-infected patients were compared to those of a large cohort of HIV-uninfected patients admitted after CA in the Cochin Hospital ICU during the same period.

RESULTS

99 patients were included (median CD4 lymphocyte count 233/mm(3), viral load 43 copies/ml). When compared with the control cohort of 1701 patients, HIV-infected patients were younger, with a predominance of male, a majority of in-hospital CA (52%), and non-shockable initial rhythm (80.8%). CA was mostly related to respiratory cause (n=36, including 23 pneumonia), cardiac cause (n=33, including 16 acute myocardial infarction), neurologic cause (n=8) and toxic cause (n=5). CA was deemed directly related to HIV infection in 18 cases. Seventy-one patients died in the ICU, mostly for care withdrawal after post-anoxic encephalopathy. After propensity score matching, ICU mortality was not significantly affected by HIV infection. Similarly, HIV disease characteristics had no impact on ICU outcome.

CONCLUSIONS

Etiologies of CA in HIV-infected patients are miscellaneous and mostly not related to HIV infection. Outcome remains bleak but is similar to outcome of HIV-negative patients.

L-carnitine supplementation in patients with HIV/AIDS and fatigue: a double-blind, placebo-controlled pilot study

Background

The purpose of this study was to determine the effect of L-carnitine supplementation on fatigue in patients with terminal human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS).

Methods

In this randomized, double-blind, placebo-controlled, parallel-group study, patients who had end-stage HIV/AIDS with carnitine deficiency and fatigue received 3 g of oral L-carnitine or placebo for 2 weeks, followed by a 2-week, open-label phase with the same amount of L-carnitine for all patients. The primary outcome was the degree of fatigue according to the Brief Fatigue Inventory. Secondary outcomes included serum carnitine and lactate levels, physical, emotional, social, and functional well-being, performance status, mood, and CD4 count.

Results

Eighteen patients in the treatment arm and 17 in the placebo arm completed the trial. At the end of the double-blind phase, total and free carnitine levels in the treatment arm rose from 28±9 to 48±17 nM/L (P<0.001) and from 24±8 to 40±13 nM/L (P<0.001) respectively, with no changes in the placebo arm. The primary outcome, ie, fatigue measured at the end of the blinded phase, did not improve. Secondary outcomes of function, quality of life, and mood did not show improvement either. The secondary outcome of serum lactate decreased from baseline in the treatment group (1.45±0.76 to 1.28±0.52 mmol/L) and increased in the placebo group (1.38±0.62 to 1.84±0.74 mmol/L; P<0.005).

Conclusion

Our study suggests that 3 g of oral L-carnitine supplementation for 2 weeks in terminally ill HIV/AIDS patients does not improve fatigue. This study might help to determine the dose and duration of treatment used in future clinical trials, as higher doses and/or longer periods of supplementation might be needed in order to detect an improvement. The reduction in serum lactate levels suggests a potential role for L-carnitine supplementation in patients undergoing certain types of antiretroviral therapy. This study contributes evidence-based data to the field of alternative and complementary medicine, a multibillion dollar industry in which controlled studies are not the norm.

Evaluation of adverse drug reactions in HIV positive patients in a tertiary care hospital

CONTEXT

The advancement and development of new drugs and treatment strategies increase the risk of unusual Adverse Events (AEs) in HIV patients.

AIMS

The objective of our study was to assess the incidence, types and nature of AEs in HIV positive subjects.

SETTINGS AND DESIGN

Patients with WHO stage IV disease irrespective of the CD4 cell count, or WHO stage III disease with a CD4 cell count <350 cell/cu. Mm, or, WHO stage I or II disease with a CD4 cell count of <200 cells/cu. mm, and on prior anti-retroviral therapy for not more than six months preceding the observation date, were included in the study. After initiation of therapy, the patients were examined for the occurrence any adverse events including the type and severity, or any other abnormal laboratory findings. Causality assessment of the adverse events was done using the Naranjo's scale.

RESULTS

Out of 327 patients studied prospectively, 43 patients developed AEs. Out of these, 23 (53.5%) were males and 20 (46.5%) were females. A total of 53 (16.21%) AEs were reported. Antitubercular drugs caused the maximum AEs (28.3%) followed by zidovudine (20.7%), nevirapine (15.0%) and efavirenz (5.6%). Stavudine, ethambutol, sulfamethoxazole and trimethoprim, and atazanavir were also responsible for 3.7% of AEs individually. Causality assessment done according to the Naranjo's scale revealed that 66.04% AEs were 'probable' and 33.96% were 'possible'.

CONCLUSIONS

Anemia, hepatitis and dermatological adverse effects are the most common AEs. Antitubercular drugs contributed significantly for the incidence of AEs in these patients. Frequency of AEs was slightly more in males compared to females.

Type B lactic acidosis secondary to thiamine deficiency in a child with malignancy

Type B lactic acidosis is an underrecognized clinical entity that must be distinguished from type A (hypoxic) lactic acidosis. We present the case of a 4-year-old boy with medulloblastoma who presented with lactic acidosis in the setting of septic shock. His hyperlactatemia persisted to high levels even after his hemodynamic status improved. After administration of intravenous thiamine, his lactate level rapidly normalized and remained stable. It was determined that his total parenteral nutrition was deficient in vitamins due to a national shortage. Because thiamine is an important cofactor for pyruvate dehydrogenase, he was unable to use glucose through aerobic metabolism pathways. We briefly review type A versus type B lactic acidosis in this case report.

Peripheral blood mitochondrial DNA/nuclear DNA (mtDNA/nDNA) ratio as a marker of mitochondrial toxicities of stavudine containing antiretroviral therapy in HIV-infected Malawian patients

Mitochondrial toxicity is a major concern related to nucleoside reverse transcriptase inhibitors. Common manifestations are peripheral neuropathy and lipodystrophy. Depletion of mitochondria has been associated with mitochondrial dysfunction. We investigated whether mitochondria DNA (mtDNA) levels in peripheral blood can be used as biomarker of stavudine-associated mitochondrial toxicities. We enrolled 203 HIV-infected Malawian adult patients on stavudine-containing ART and 64 healthy controls of Bantu origin in a cross-sectional study. Total DNA was extracted from whole blood.The glyceraldehyde-3-phosphate dehydrogenase gene was used to estimate nuclear DNA (nDNA) levels and the ATP synthase-8 mitochondrial DNA gene to estimate mtDNA levels, from which mtDNA/nDNA ratios were determined. MtDNA subhaplogroups were established by sequencing. Among patients, peripheral neuropathy was present in 21% (43/203), lipodystrophy in 18% (20/112), elevated lactate level (>2.5 mmol/L) in 17% (19/113). Healthy controls had a higher median mtDNA/nDNA ratio when compared to HIV/AIDS patients (6.64 vs. 5.08; p=0.05), patients presenting with peripheral neuropathy (6.64 vs. 3.40, p=0.039), and patients with high lactate levels (6.64 vs. 0.68, p=0.024), respectively. Significant differences in median mtDNA/nDNA ratios were observed between patients with high and normal lactate levels (5.88 vs. 0.68, p=0.018). The median mtDNA/nDNA ratio of patients in subhaplogroup L0a2 was much lower (0.62 vs. 8.50, p=0.01) than that of those in subhaplogroup L2a. Our data indicate that peripheral blood mtDNA/nDNA ratio is a marker of mitochondrial toxicities of stavudine and is associated with elevated lactate levels and mtDNA subhaplogroups. This could open the prospect to select a substantial group of patients who will not have problematic side effects from stavudine, an affordable and effective antiretroviral drug that is being phased out in Africa due to its toxicity.

Lactic acidosis occurrence during exercises in the smoke chamber in a 53-year-old firefighter with no significant medical history

Lactic acidosis is a form of metabolic acidosis with a high anion gap, reduced rate of arterial blood pH under 7.35 mmol/l, and lactic acid concentration over 7 mmol/l. In the literature we can find some descriptions of the cases of lactic acidosis in patients with severe systemic diseases (cancer, acquired immunodeficiency syndrome, sepsis, diabetes with cardiovascular disease and after organ transplantations). We present the case of lactic acidosis in a patient with no chronic disease — a firefighter in whom lactic acidosis has developed during standard exercises in the smoke chamber.

Mitochondria as a target of environmental toxicants

Enormous strides have recently been made in our understanding of the biology and pathobiology of mitochondria. Many diseases have been identified as caused by mitochondrial dysfunction, and many pharmaceuticals have been identified as previously unrecognized mitochondrial toxicants. A much smaller but growing literature indicates that mitochondria are also targeted by environmental pollutants. We briefly review the importance of mitochondrial function and maintenance for health based on the genetics of mitochondrial diseases and the toxicities resulting from pharmaceutical exposure. We then discuss how the principles of mitochondrial vulnerability illustrated by those fields might apply to environmental contaminants, with particular attention to factors that may modulate vulnerability including genetic differences, epigenetic interactions, tissue characteristics, and developmental stage. Finally, we review the literature related to environmental mitochondrial toxicants, with a particular focus on those toxicants that target mitochondrial DNA. We conclude that the fields of environmental toxicology and environmental health should focus more strongly on mitochondria.

Performance of Clinical Criteria for Screening of Possible Antiretroviral Related Mitochondrial Toxicity in HIV-Infected Children in Accra

Mitochondrial damage is implicated in highly active antiretroviral therapy (HAART) toxicity. HIV infection also causes mitochondrial toxicity (MT). Differentiating between the two is critical for HIV management. Our objective was to test the utility of the Mitochondrial Disease Criteria (MDC) and the Enquête Périnatale Française (EPF) to screen for possible HAART related MT in HIV-infected children in Ghana. The EPF and MDC are compilations of clinical symptoms, or criteria, of MT: a (+) score indicates possible MT. We applied these criteria retrospectively to 403 charts of HIV-infected children. Of those studied, 331/403 received HAART. Comparing HAART exposed and HAART naïve children, the difference in EPF score, but not MDC, approached significance (P = 0.1). Young age at HIV diagnosis or at HAART initiation was associated with (+) EPF (P ≤ 0.01). Adherence to HAART trended toward an association with (+) EPF (P = 0.09). Exposure to nevirapine, abacavir, or didanosine increased risk of (+) EPF (OR = 3.55 (CI = 1.99-6.33), 4.76 (2.39-9.43), 4.93 (1.29-18.87)). Neither EPF nor MDC identified a significant difference between HAART exposed or naïve children regarding possible MT. However, as indicators of HAART exposure are associated with (+) EPF, it may be a candidate for prospective study of possible HAART related MT in resource-poor settings.

Fatal lactic acidosis in a kidney transplant recipient on combination antiretroviral therapy after initiation of tacrolimus therapy

In general, kidney transplantation is safe and efficacious in patients receiving treatment for HIV. Although multiple drug interactions between antiviral and immunosuppressive treatments exist, few patients experience serious adverse reactions. We report a case of fatal lactic acidosis in a healthy kidney transplant recipient with stable HIV infection who had previously received treatment for and cleared hepatitis C virus infection. Death occurred less than one month following the initiation of tacrolimus therapy. Based on predicted drug interactions, appropriate tacrolimus dosing was calculated prior to its commencement, yet plasma tacrolimus levels were initially unexpectedly high. The patient subsequently developed lactic acidosis and hepatic steatosis, presumably due to mitochondrial toxicity from the antiretroviral regimen on which he had previously been stable. We suspect CYP2C19*2 (poor metaboliser) genotype status and concomitant treatment with lansoprazole, tacrolimus, and antiretroviral (ARV) medications resulted in hepatic decompensation. This highlights the importance of careful interaction screening for all new drugs administered to patients with HIV who have complex treatment regimens as well as heightened clinical vigilance for unexpected toxicities.

Treatment of lactic acidosis: appropriate confusion

BACKGROUND

Lactic acidosis (LA) is common in hospitalized patients and is associated with poor clinical outcomes. There have been major recent advances in our understanding of lactate generation and physiology. However, treatment of LA is an area of controversy and uncertainty, and the use of agents to raise pH is not clearly beneficial.

AIM AND METHODS

We reviewed animal and human studies on the pathogenesis, impact, and treatment of LA, published in the English language and available through the PubMed/MEDLINE database. Our aim was to clarify the physiology of the generation of LA, its impact on outcomes, and the different treatment modalities available. We also examined relevant data regarding LA induced by medications commonly prescribed by hospitalists: biguanides, nucleoside analog reverse-transcriptase inhibitors (NRTIs), linezolid, and lorazepam.

RESULTS/CONCLUSIONS

Lactic acid is a marker of tissue ischemia but it also may accumulate without tissue hypoperfusion. In the latter circumstance, lactic acid accumulation may be an adaptive mechanism-a novel possibility quite in contrast to the traditional view of lactic acid as only a marker of tissue ischemia. Studies on the treatment of LA with sodium bicarbonate or other buffers fail to show consistent clinical benefit. Severe acidemia in the setting of LA is a particularly poorly studied area. In the settings of medication-induced LA, optimal treatment, apart from prompt cessation of the offending agent, is still unclear.

Cost-effectiveness of tenofovir as first-line antiretroviral therapy in India

BACKGROUND

World Health Organization guidelines for antiretroviral treatment (ART) in resource-limited settings recommend either stavudine or tenofovir as part of initial therapy. We evaluated the clinical outcomes and cost-effectiveness of first-line ART using tenofovir in India, compared with current practice using stavudine or zidovudine.

METHODS

We used a state-transition model of human immunodeficiency virus (HIV) disease to examine strategies using different nucleoside reverse-transcriptase inhibitors, combined with lamivudine and nevirapine, compared with no ART: (1) stavudine, (2) stavudine with substitution by zidovudine after 6 months, (3) zidovudine, and (4) tenofovir. Data were from the Y. R. Gaitonde Centre for AIDS Research and Education in Chennai, India, and published studies. Results. Discounted mean per person survival was 36.9 months (40.2 months undiscounted) with no ART, 115.5 months (145.3) with stavudine-containing ART, 115.7 months (145.6) with stavudine and 6-month zidovudine substitution, 115.8 months (145.6) with zidovudine-containing ART, and 125.8 months (162.0) with initial tenofovir. Discounted lifetime medical costs were $610 with no ART and ranged from $5580 with stavudine-containing ART to $5720 with zidovudine-containing ART. Initial tenofovir had an incremental cost-effectiveness ratio of $670 per year of life saved, compared with no ART, and was more economically efficient than the other regimens.

RESULTS

were most sensitive to variations in the costs of first-line tenofovir, access to additional ART after treatment failure, and quality of life adjustment.

CONCLUSIONS

Using tenofovir as part of first-line ART in India will improve survival, is cost-effective by international standards, and should be considered for initial therapy for HIV-infected patients in India.

A review of nucleoside reverse transcriptase inhibitor use to prevent perinatal transmission of HIV

Worldwide, women comprise > 50% of all people living with HIV and the vast majority of these women are of childbearing age. In fact, a significant proportion of these women are identified as HIV-infected during pregnancy. Preventing perinatal transmission has been one of the greatest prevention successes of the HIV epidemic with < 2% of live births resulting in an HIV-infected infant. The strategic use of combination antiretroviral therapy has been a critical component of this reduction. With more antiretroviral agents available for HIV, the appropriate selection of therapy is often based on provider familiarity with the various agents. Although benefits of antiretroviral use in pregnancy tremendously outweigh the risks, concerns regarding short- and long-term toxicity in mothers and their children, in addition to the risk of the development of HIV resistance, remain subjects of discussion. The choice of antiretroviral 'backbone' is supported by extensive data showing efficacy in the prevention of HIV vertical transmission. Co-formulated zidovudine/lamivudine is the most commonly used combination in pregnancy. Long-term consequences of in utero exposure to antiretroviral agents are not fully understood. In this article, we review the data regarding nucleoside reverse transcriptase inhibitors with a focus on tenofovir.

Left ventricular dysfunction in human immunodeficiency virus infection

The relationship between human immunodeficiency virus (HIV) infection and cardiovascular disease is still under debate, but it appears that the risk of myocardial infarction in those with HIV infection who are receiving highly active antiretroviral therapy (HAART) is increased. There has been less focus, however, on the effect of HIV and HAART on left ventricular function. Evidence from the past 20 years in both Westernized and developing countries has indicated that subclinical left ventricular dysfunction in HIV-infected individuals with and without well-controlled HIV infection is prevalent and may represent emerging cardiac disease. The specific roles of HIV infection and HAART are unclear, but they may exert independent direct and indirect effects on the myocardium. These effects may include chronic inflammation, metabolic complications (ie, insulin resistance, lipotoxicity, dyslipidemia), and mitochondrial toxicity. The objective of this article is to review the evidence for HIV- and HAART-related left ventricular dysfunction in persons infected with HIV.

Metabolic acidosis in AIDS patients

BACKGROUND AND AIMS

Metabolic acidosis (MA) is a frequent and serious complication in HIV-infected patients. The aim of the study is to compare patients with and without MA associated with HIV.

METHODS

Patients were retrospectively studied involving all HIV-infected patients with blood gas analysis performed during hospital stay admitted to a single hospital between April 2004 and July 2006. Statistical analysis was performed using SPSS 10.0 for Windows.

RESULTS

Included in the study were 159 HIV patients, 72 cases (45.3%) with MA and 87 cases (54.7%) without. The comparison of both groups showed a mean arterial pH of 7.24 +/- 0.08 vs. 7.44 +/- 0.05, HCO(3) 12 +/- 5.7 vs. 21 +/- 5.1 mEq/L, serum urea 81 +/- 68 mg/dL vs. 39 +/- 46 mg/dL and serum creatinine 2.7 +/- 2.6 mg/dL vs. 1.2 +/- 1.9 mg/dL in MA-HIV and non-MA-HIV, respectively (p <0.05). Antiretroviral therapy (ART) was being administered to 38 subjects (52.8%) in MA-HIV group and 45 (51.7%) in non-MA-HIV group (p = 0.57). There was no association between the use of ART and MA. Mortality was higher in patients with acidosis (52.7 vs. 17.2%, p <0.0001).

CONCLUSIONS

In the present study, MA was associated with acute kidney injury and increased mortality. There was no association between the use of ART and MA.

Severe Hyperlactataemia Complicating Stavudine First-Line Antiretroviral Therapy in South Africa

Background

In the public sector antiretroviral therapy (ART) programme in South Africa the standardized first-line regimen includes stavudine (d4T). Severe symptomatic hyperlactataemia (SHL) is a potentially life- threatening complication of d4T.

Methods

GF Jooste Hospital is a referral centre for six ART clinics. We retrospectively reviewed cases referred with lactate levels ≥5 mmol/l that were attributed to nucleoside reverse transcriptase inhibitors from August 2003 to November 2005. We calculated cumulative ART exposure in patients attending these clinics to derive a referral rate.

Results

In total, 75 patients were referred with severe SHL (71 female). All had been on d4T and on ART for a median of 10 months. The referral rate for severe SHL was 17.5 cases per 1,000 patient-years. In 53 patients (71%), lactic acidosis (standard bicarbonate [SHCO3]<20 mmol/l) was confirmed, resulting in a referral rate of 12.3 cases per 1,000 patient-years. Twelve patients (16%) died during acute admission (≤30 days). SHCO3<15 mmol/l and pH<7.2 were the only factors associated with acute mortality (odds ratio [OR] 22.5, 95% confidence interval [CI] 2.8–1,045.7 and OR 13.9, 95% CI 2.7–86.9, respectively). A total of 30 less severe cases were rechallenged with zidovudine without recurrence of SHL.

Conclusions

This study confirms a high incidence of severe SHL in Africa, which has been shown in previous studies. Rechallenge with zidovudine in less severe cases was found to be safe.

Potential risks and benefits of HIV treatment simplification: a simulation model of a proposed clinical trial

BACKGROUND

In recent studies, subjects who had achieved suppression of the human immunodeficiency virus (HIV) RNA level while receiving an initial 3-drug antiretroviral regimen successfully maintained suppression while receiving treatment with a "boosted" protease inhibitor (PI) alone. We projected the long-term outcomes of this treatment simplification strategy to inform the design of a proposed multicenter, randomized clinical trial.

METHODS

We used published studies to estimate the efficacy, adverse effects, and cost of a sequence of HIV drug regimens for the simplification strategy, compared with those outcomes for the current standard-of-care (SOC) strategy. Using a published simulation model of HIV disease, we projected life expectancy, discounted quality-adjusted life expectancy (QALE), and discounted lifetime medical costs for each strategy.

RESULTS

Subjects who have not developed PI-resistant HIV infection at the time of failure of the simplification regimen have a greater life expectancy (27.9 vs. 27.1 years) and QALE (14.9 vs. 14.7 years), compared with SOC subjects, because they receive an additional line of therapy without negative consequences for future treatment options. The QALE for the simplification strategy remains higher than that for the SOC, unless a large proportion of patients experiencing virologic failure while receiving the simplification regimen develop PI resistance. Depending on the probability of simplification regimen failure, the advantage is maintained even if HIV develops PI resistance in 42%-70% of subjects. Projected lifetime costs are $26,500-$72,400 per person lower for the simplification strategy than for the SOC strategy.

CONCLUSIONS

An HIV treatment simplification strategy involving use of a boosted PI alone may lead to longer survival overall at lower cost, compared with the SOC combination therapy, because the simplification strategy potentially adds an additional line of therapy. The risk of emergence of PI resistance during treatment with a simplified regimen is a critical determinant of the viability of this strategy.

Fluorescent HIV-1 Dimerization Initiation Site: design, properties, and use for ligand discovery

The HIV-1 Dimerization Initiation Site (DIS) is an intriguing, yet underutilized, viral RNA target for potential antiretroviral therapy. To study the recognition features of this target and to provide a quantitative, rapid, and real-time tool for the discovery of new binders, a fluorescence-based assay has been constructed. It relies on strategic incorporation of 2-aminopurine, an isosteric fluorescent adenosine analogue, into short hairpin RNA constructs. These oligomers self-associate to form a kissing loop that thermally rearranges into a more stable extended duplex, thereby mimicking the association and structural features of the native RNA sequence. We demonstrate the ability of two fluorescent DIS constructs, DIS272(2AP) and DIS273(2AP), to report the binding of known DIS binders via changes in their emission intensity. Binding of aminoglycosides such as paromomycin to DIS272(2AP) results in significant fluorescence enhancement, while ligand binding to DIS273(2AP) results in fluorescence quenching. These observations are rationalized by comparison to the sequence-analogous bacterial A-site, where the relative emission of the fluorescent probe is dependent on the placement of the flexible purine residues inside or outside the helical domain. Analysis of binding isotherms generated using DIS272(2AP) yields submicromolar EC50 values for paromomycin (0.5 +/- 0.2 microM) and neomycin B (0.6 +/- 0.2 microM). Other neomycin-family aminoglycosides are less potent binders with neamine, the core pharmacophore, displaying the lowest affinity of 21 +/- 1 microM. Screening of additional aminoglycosides and their derivatives led to the discovery of new, previously unreported, aminoglycoside binders of the HIV DIS RNA, among them butirosin A (5.5 +/- 0.6 microM) and apramycin (7.6 +/- 1.0 microM). A conformationally constrained neomycin B analogue displays a rather high affinity to the DIS (1.9 +/- 0.2 microM). Among a series of nucleobase aminoglycoside conjugates, only the uracil derivatives display a measurable affinity using this assay with EC50 values in the 2 microM range. In addition, similarity between the solution behavior of HIV-1 DIS and the bacterial decoding A-site has been observed, particularly with respect to the intra- and extra-helical residence of the conformationally flexible A residues within the bulge. Taken together, the observations reported here shed light on the solution behavior of this important RNA target and are likely to facilitate the design of new DIS selective ligands as potential antiretroviral agents.

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

BACKGROUND

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

INVESTIGATION

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

DIAGNOSIS

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

MANAGEMENT

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

Lactic acidosis: from sour milk to septic shock

Lactic acidosis is frequently encountered in the intensive care unit. It occurs when there is an imbalance between production and clearance of lactate. Although lactic acidosis is often associated with a high anion gap and is generally defined as a lactate level >5 mmol/L and a serum pH <7.35, the presence of hypoalbuminemia may mask the anion gap and concomitant alkalosis may raise the pH. The causes of lactic acidosis are traditionally divided into impaired tissue oxygenation (Type A) and disorders in which tissue oxygenation is maintained (Type B). Lactate level is often used as a prognostic indicator and may be predictive of a favorable outcome if it normalizes within 48 hours. The routine measurement of serum lactate, however, should not determine therapeutic interventions. Unfortunately, treatment options remain limited and should be aimed at discontinuation of any offending drugs, treatment of the underlying pathology, and maintenance of organ perfusion. The mainstay of therapy of lactic acidosis remains prevention.

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.