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

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.

Severe Lactic Acidosis Due to Acute Intoxication by Emtricitabine/Tenofovir Alafenamide

A 46-year-old female with a history of generalized anxiety disorder was admitted after intentional ingestion of an unknown amount of emtricitabine/tenofovir alafenamide (Descovy®) in a suicidal attempt. Patient was emergently intubated secondary to severe agitation and inability to protect airways. Patient developed severe lactic acidosis early in the admission, secondary as to a possible mitochondrial toxicity. Failed attempts to fluid resuscitation with Lactate Ringer®, eventually warranted to start the patient on norepinephrine infusion. Metabolic acidosis remained refractory to bicarbonate bolus and infusion. Hypothermia and hypoglycemia were corrected. Despite the initial approach, the patient remained acidotic, and the nephrology was consulted for emergent continuous renal replacement therapy (CRRT). After three days of intensive care unit stay and CRRT, the patient improved and was successfully decannulated. Her metabolic profile also showed remarkable improvement and the metabolic lactic acidosis resolved. The previous formulation of tenofovir with disoproxil fumarate is associated with severe lactic acidosis due to inhibition of mammalian mitochondrial DNA polymerase. Risk factors include liver cirrhosis, chronic kidney disease, hepatitis B and C coinfection, and metformin use. The new pharmaceutical formulation of tenofovir with alafenamide (TAF) has caused a significant decrease in the incidence of lactic acidosis. However, its real incidence and the usual plasma level to induce toxicity and mitochondrial dysfunction are unknown. The aim of this report is to highlight the risk of severe lactic acidosis with the use of TAF.

Tenofovir alafenamide associated fatal lactic acidosis in an autologous hematopoietic stem cell transplant recipient

Fatal lactic acidosis has been reported while on the treatment with Nucleoside/nucleotide analogues (NA) for the treatment of hepatitis B, C and HIV. No cases of such a complication have been reported in hematopoietic stem cell transplant (HSCT) recipients. We present a 65-year male who underwent autologous HSCT for the treatment of multiple myeloma. Prior to transplant he was started on single agent tenofovir alafenamide (TAF) for treatment of resolved hepatitis B infection. He presented few weeks later with severe lactic acidosis. Other causes of lactic acidosis were excluded. The patient died of multi-organ failure despite stopping TAF and aggressive supportive care. The case demonstrates the need for increased awareness of this potential complication of NA treatment in the course of transplantation.

Fatal lactic acidosis in hepatitis B virus-associated decompensated cirrhosis treated with tenofovir: A case report

RATIONALE

Recently tenofovir disoproxil fumarate (TDF) has been widely used as a first-line therapy for chronic hepatitis B (CHB) infection. Although TDF demonstrates successful viral suppression, the possibility of renal failure and lactic acidosis has been proposed with TDF administration, especially in human immunodeficiency virus co-infected patients. However, TDF induced lactic acidosis has never been reported in CHB mono-infected patients.

PATIENT CONCERNS

A 59-year-old man received TDF for hepatitis B associated with cirrhosis. After ten days of TDF administration, nausea, vomiting and abdominal pain developed. High anion gap acidosis with elevated lactate level (pH 7.341, pCO2 29.7 mmHg, HCO3- 15.6mmHg, lactate 3.2mmol/L, anion gap 15.4 mEq/L) was developed.

DIAGNOSIS

With no infection, normal diagnostic paracentesis, and urinalysis together with high anion gap and increased blood lactate levels suggested lactic acidosis.

INTERVENTIONS

TDF was stopped, and haemodialysis was performed to control lactic acidosis.

OUTCOMES

Although stopping TDF instantly and treating lactic acidosis using hemodialysis, the patient died.

LESSONS

Although, Fatal lactic acidosis is very rare in TDF patient, however, decompensated cirrhotic patients should be closely observed to keep the possibility of lactic acidosis in mind.

Drug safety evaluation of oral tenofovir disoproxil fumarate-emtricitabine for pre-exposure prophylaxis for human immunodeficiency virus infection

INTRODUCTION

Tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) are nucleoside reverse transcriptase inhibitors approved as pre-exposure prophylaxis (PrEP) against human immunodeficiency virus (HIV). Prophylactic TDF-based regimens have been shown to reduce the risk of HIV infection by 74 to 92% among participants with detectable drug levels. Adverse events observed in clinical trials include nausea, elevated creatinine and liver enzymes, and decreased bone mineral density.

AREAS COVERED

This article reviews the pharmacology, pharmacokinetics, and the safety profile of TDF and FTC used as PrEP for HIV infection.

EXPERT OPINION

TDF-FTC can have a large impact in preventing HIV infections among high risk individuals when taken daily. Although TDF-FTC is associated with adverse events, they can be minimized with clinician-guided monitoring.

[Tenofovir nephrotoxicity]

Tenofovir is currently the only commercially available nucleotidic reverse-transcriptase inhibitor of human immunodeficiency virus (HIV). It is overall very well tolerated and is prescribed to millions of patients-without any specific monitoring in developing countries. However a significant nephrotoxicity has been described. Acute nephrotoxicity is well characterized. Tenofovir is excreted in urine by proximal tubular epithelial cells. In case of cytoplasmic accumulation, tenofovir inhibits mitochondrial DNA polymerase γ, which causes a dysfunction of the respiratory chain, and in turn an alteration of the energy-deprived cells. Fanconi syndrome is the clinical expression of tenofovir acute toxicity, with sometimes an associated acute kidney failure. These abnormalities are usually reversible, at least partially, when tenofovir is discontinued. Tenofovir chronic toxicity has been debated but seems now well established by several cohort studies, even though it pathophysiology has yet to be understood. It manifests as an accelerated glomerular filtration rate decline in treated patients with no other renal abnormalities. The identification of this chronic toxicity was probably blurred by multiple cofactors, usually excluded from clinical trials. Simple measures such as dose adaptation to kidney function, identification of risk factors, and plasmatic tenofovir concentration monitoring can help decrease the risk of nephrotoxicity.

Tenofovir effect on the kidneys of HIV-infected patients: a double-edged sword?

Tenofovir disoproxil fumarate (TDF), the first nucleotidic inhibitor of HIV reverse transcription, became available in 2001. It has been extensively used worldwide and is now the most prescribed antiretroviral (ARV) drug. Its high antiviral activity and favorable metabolic profile are responsible for its success. Furthermore, TDF has been associated with other ARVs to form new combined antiretroviral treatments in only one tablet once-a-day, which increases treatment adherence. Fears of potential nephrotoxicity that tenofovir would have in common with two other drugs from the same family (adefovir, used to treat hepatitis B, and cidofovir, used to treat cytomegalovirus infections) were alleviated by the early clinical trials. Yet, in 2001, the first case of TDF-induced acute nephrotoxicity was published. Numerous cases have been published since then, and it is now established that TDF presents a tubular toxicity risk. Some facilitating factors have been identified, such as co-prescription of didanosine or boosted protease inhibitor, preexisting CKD, low body weight, and associated diabetes mellitus. Conversely, whether TDF is nephrotoxic in the long term is a highly debated question. Some studies suggest a decreased GFR when TDF is prescribed for a long period, while others indicate that TDF is safe for the kidneys even after many years of use. Here we review the differences in patient characteristics, study designs, and measured outcomes that can possibly explain these conflicting findings. We conclude with rational recommendation for appropriate TDF prescription.

Clinical management of drug interaction with antiretroviral agents

PURPOSE OF REVIEW

Combination antiretroviral therapy has improved the morbidity and mortality of HIV-infected patients worldwide. As patients live longer, management of HIV infection extends to treatment of a wide spectrum of co-morbid conditions. Pharmacokinetic interactions are common among antiretroviral drugs when they are used in combination and along with treatments for other conditions. This review discusses the clinical significance of drug interactions among antiretroviral drugs and other medications, resources to use in assessing drug interaction potential, and some key principles to follow when managing patients prescribed potentially interacting drugs.

RECENT FINDINGS

Targeted pharmacokinetic drug interaction studies and extrapolations on the basis of potential mechanism of interactions provide an initial basis for recommendations regarding use of certain drug combinations. Some unexpected interactions have emerged in the literature through case reports in which untoward effects were observed.

SUMMARY

Management of patients on multiple drug therapy can be a challenge. The key to safe and effective therapy relies on the clinician's vigilance in their ongoing assessment of interaction potential among drugs prescribed to each patient, the significance for such interactions, the need for modification to therapy, and close follow up to assess safety and toxicity.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

In vitro cytotoxicity and mitochondrial toxicity of tenofovir alone and in combination with other antiretrovirals in human renal proximal tubule cells

We assessed the in vitro toxicity of tenofovir (TFV) and compared it with those of zidovudine (AZT), didanosine (ddI), ritonavir (RTV), and lopinavir (LPV) alone and in combination in human renal proximal tubule epithelial cells (RPTECs). The cells were treated with various concentrations and combinations of the tested antiretrovirals for up to 22 days, and cytotoxicity was determined. In addition, we assessed the levels of mitochondrial DNA (mtDNA) and cytochrome oxidase II (COII) mRNA in RPTECs treated with reverse transcriptase inhibitors. TFV alone was not associated with significant cytotoxicity. ddI showed pronounced cytotoxicity that was greater than those of AZT (P = 0.002) and TFV (P = 0.0001). The combination of 10 muM RTV and 40 muM LPV significantly reduced RPTEC viability (P < 0.0001), and TFV tended to partially reduce this effect. TFV alone affected neither mtDNA nor COII mRNA levels, whereas ddI caused a profound depletion of mtDNA and a parallel reduction in COII mRNA expression. The effects of ddI, but not those of AZT, on mtDNA and COII mRNA were further enhanced in the presence of TFV, a finding consistent with the inhibition of ddI clearance by TFV. The addition of TFV to ddI or AZT appeared to slightly increase the COII mRNA/mtDNA ratio relative to that in cells treated with ddI or AZT alone. Together, these in vitro results indicate that combination with other antiretrovirals does not significantly increase the toxic potential of TFV in RPTECs.

Exploring Mitochondrial Nephrotoxicity as a Potential Mechanism of Kidney Dysfunction among HIV-Infected Patients on Highly Active Antiretroviral Therapy

Background

Tenofovir (TDF) exposure has been associated with renal dysfunction. Mitochondrial nephrotoxicity was investigated as an underlying mechanism. Given the interaction between TDF and didanosine (ddI), their concurrent use was also investigated.

Design

Relative kidney biopsy mitochondrial DNA (mtDNA) to nuclear DNA ratios were measured retrospectively. HIV+ individuals on TDF within 6 months preceeding the biopsy (HIV+/TDF+, n=21) were compared to HIV+ individuals who never received TDF (HIV+/TDF-, n=10) and to HIV uninfected controls (HIV–, n=22). Twelve of the HIV+/TDF+ individuals received concurrent ddI, 10 of those once at unadjusted ddI dosage. Tubular mitochondria morphology was also examined by electron microscopy. Statistical analyses were done on log-transformed mtDNA/nDNA, using non-parametric tests.

Results

Kidney mtDNA levels were different among the three groups ( P=0.046). mtDNA ratios were lower in HIV+/TDF+ subjects (7.5 [2.0–12.1]) than in HIV- ones (14.3 [6.0–16.5], P=0.014), but not lower than HIV+/TDF-controls (6.4 [2.8–11.9], P=0.82). Among HIV+ subjects, there was a difference between TDF-, TDF+/ddI- and TDF+/ddI+ ( P=0.005), with concurrent TDF/ddI use associated with lower mtDNA (2.1 [1.9–5.5], n=12) than TDF+/ddI- (13.8 [7.5–16.4], n=9, P=0.003). No TDF–/ddI+ biopsies were available. In regression analyses, only HIV infection ( P=0.03), and TDF/ddI use ( P=0.003) were associated with lower mtDNA. At the ultrastructural level, abnormal tubular mitochondria was more prevalent in HIV+/TDF+ biopsies than HIV+/TDF- and HIV- ones together ( P<0.001) but not more so in TDF+/ddI+ biopsies than TDF+/ddI- ones ( P=0.67).

Conclusions

Renal dysfunction in this population may be mediated through mitochondrial nephrotoxicity that involves more than one drug and/or pathogenesis. Kidney mtDNA depletion was associated with HIV infection and concurrent TDF/ddI therapy but not TDF use alone, while kidney ultrastructural mitochondrial abnormalities were seen with TDF use. The interaction between TDF and ddI may be relevant in the kidney where both drugs are cleared. The clinical relevance of our findings needs to be evaluated given the current recommendation for reduced doses of ddI when used in conjunction with TDF.