Severe toxicity associated with the combination of tenofovir and didanosine: case report and review

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.

[Diagnosis, treatment and prevention of renal diseases in HIV infected patients. Recommendations of the Spanish AIDS Study Group/National AIDS Plan]

The incidence of opportunistic infections and tumours in HIV-infected patients has sharply declined in the HAART era. At the same time there has been a growing increase of other diseases not directly linked to immunodeficiency. Renal diseases are an increasing cause of morbidity and mortality among HIV-infected patients. In the general population, chronic renal failure has considerable multiorgan repercussions that have particular implications in patients with HIV infection. The detection of occult or subclinical chronic kidney disease is crucial since effective measures for delaying progression exist. Furthermore, the deterioration in glomerular filtration should prompt clinicians to adjust doses of some antiretroviral agents and other drugs used for treating associated comorbidities. Suppression of viral replication, strict control of blood pressure, dyslipidemia and diabetes mellitus, and avoidance of nephrotoxic drugs in certain patients are fundamental components of programs aimed to prevent renal damage and delaying progression of chronic kidney disease in patients with HIV. Renal transplantation and dialysis have also special implications in HIV-infected patients. In this article, we summarise the updated clinical practice guidelines for the evaluation, management and prevention of renal diseases in HIV-infected patients from a panel of experts in HIV and nephrologists on behalf of the Spanish AIDS Study Group (GESIDA) and the National AIDS Plan.

[Toxicogenetics of antiretroviral treatment (II): neurotoxicity, hepatotoxicity, lactic acidosis, kidney damage, and other adverse effects of antiretroviral drugs]

Several pharmacogenetics studies have analyzed the influence of specific genetic polymorphisms on the toxicity of antiretroviral treatment. The present review describes some of the adverse effects of antiretroviral drugs in which a genetic predisposition may be involved: efavirenz-induced neurological toxicity, generally associated with the 516G>T polymorphism of liver enzyme cytochrome P450 2B6 (CYP2B6); hypersensitivity reactions to nevirapine, associated with specific alleles of major histocompatibility complex, mainly the HLA-DRB1*0101 allele, which, in combination with a high CD4 lymphocyte count, has been associated with systemic reactions and hepatitis in Caucasians, and the HLA-Cw8 allele, which is associated with hypersensitivity reactions in persons from the Italian island of Sardinia and from Japan; nevirapine-induced hepatotoxicity associated with the C>T polymorphism in position 3435T of the ABCB1 (MDR-1) gene codifying for glycoprotein P (lower risk); hyperbilirubinemia in patients exposed to atazanavir or indinavir carrying the UGT1A1*28 polymorphism; peripheral neuropathy with nucleoside analogues associated with haplogroup T of the mitochondrial genome (higher risk) and with the HFE C282Y genotype of the hemochromatosis gene (lower risk); the mutation in codon 964 (R964C) of the POLG gene that codifies the mitochondrial polymerase DNA gamma described in a Thai patient with lactic acidosis; the ABCC2 gene haplotypes associated with tenofovir-induced proximal tubulopathy, and the risk of pancreatitis in persons with mutations in the CFTR and SPINK-1 genes.

Amprenavir and didanosine are associated with declining kidney function among patients receiving tenofovir

OBJECTIVE

To examine the effect of antiretroviral agents and clinical factors on the development of tenofovir-associated kidney dysfunction.

METHODS

Observational cohort study of HIV-infected patients receiving tenofovir in an HIV clinic population. Patients' kidney function prior to initiating and while receiving tenofovir was evaluated in relation to other antiretroviral medications and demographic and clinical characteristics. Decline in kidney function was assessed by the glomerular filtration rate (GFR) as estimated by the Cockcroft-Gault (CG) equation, which incorporates weight. Logistic regression analysis was used to examine factors associated with GFR of > 90, 60-90, 30-60, and < 30 ml/min per 1.73 m(2) while on tenofovir. Secondary analyses used the simplified Modification of Diet in Renal Disease (MDRD) equation.

RESULTS

Among the 445 patients initiating tenofovir, 51 (11%) developed a decline in kidney function. In multivariate analysis, there was a significant association between decline in kidney function and concurrent use of amprenavir [odds ratio (OR) 3.6; P = 0.045] and didanosine (OR, 3.1; P = 0.006), age over 50 years (OR, 4.4; P = 0.03), and lower baseline weight (OR, 0.95/kg; P < 0.001). Patients identified with kidney dysfunction by the MDRD equation did not fully overlap with those identified by the CG equation.

CONCLUSIONS

Didanosine and amprenavir use, increased age, and lower baseline weight were significantly associated with risk for kidney dysfunction among patients receiving tenofovir. GFR results using the MDRD equation were inconsistent with those using CG, which highlights the impact of including weight in the estimation of GFR among HIV-infected patients.

CD4+ T cell evolution and predictors of its trend before and after tenofovir/didanosine backbone in the presence of sustained undetectable HIV plasma viral load

BACKGROUND

Tenofovir with full-dose didanosine has been associated with paradoxical CD4 + T cell decrease despite virological suppression. We investigated whether tenofovir plus didanosine at a weight-adjusted dosage could be responsible for such an effect, and factors associated with CD4 + T cell count evolution under this combination.

METHODS

This was a prospective observational multicohort study (Italian MASTER and Spanish Hospital Carlos III HIV cohorts). Patients with HIV plasma viral load suppression for >/= 6 months who switched to an antiretroviral combination including tenofovir plus didanosine were studied, as long as virological success was maintained. CD4 + T cell count variations over time (slopes) were compared before and after switching to tenofovir plus didanosine using linear mixed models and segmented regression analysis.

RESULTS

Annual time-weighted CD4 + T cell count slope did not change significantly after the prescription of tenofovir plus didanosine: it was 14 cells/mm(3) [95% confidence interval (CI) - 7 to 35] from month - 24 to month - 12, 12 cells/mm(3) (95% CI - 14 to 38) from month - 12 to the time of switching, 30 cells/mm(3) (95% CI 5-55) from switching to month + 12 and 15 cells/mm(3) (95% CI - 8 to 39) from month + 12 to month + 24 after switching to tenofovir plus didanosine. No significant change in the slope of the segment after the switch to tenofovir plus didanosine-containing regimens when compared with the segment preceding the intervention was found (CD4 + T cell count slope change: 24 cells/mm(3); 95% CI - 10 to 58). Similar results were obtained using CD4 + T cell percentage over total lymphocytes. The significant independent predictors of lower CD4 + T cell count slope were older age (P = 0.006), lower nadir CD4 + T cell count (P < 0.001) and positive hepatitis C virus antibody (P = 0.03). Moreover, reduced estimated creatinine clearance was an additional independent predictor of lower CD4 + T cell count slope (P = 0.02), but only after excluding nadir CD4 + T cell count.

CONCLUSIONS

Tenofovir plus didanosine (weight-adjusted dosage) was not associated with paradoxical CD4 + T cell decrease in our patients maintaining undetectable HIV plasma viral load for a maximum of 24 months after switching. Several factors could explain variability in CD4 + T cell count evolution in these patients.

Evaluation and management of early virological failure

PURPOSE OF REVIEW

To describe the causes, evaluation, and management of early virological failure in patients treated with their first antiretroviral regimen.

RECENT FINDINGS

Combination antiretroviral therapy predictably induces a rapid virological response, with the majority of patients achieving an undetectable HIV-RNA load by week 24. In clinical trials and cohorts, rates of virological suppression have improved over time. Poor adherence to therapy remains the most common cause of virological failure, and genotype resistance testing is a critical step in evaluating the optimal subsequent approach. Most studies suggest that transient HIV-RNA elevations do not warrant changing treatment, and may be a consequence of laboratory variation. For those who experience virological failure, resistance to individual components of the antiretroviral regimen is dependent on the initial choice of treatment. Once virological failure is confirmed and adherence issues addressed, a prompt change in treatment is warranted to limit the selection of further drug resistance.

SUMMARY

Resistance that occurs with early virological failure follows typical patterns, with limited resistance to most antiretroviral agents in the nucleoside reverse transcriptase and protease inhibitor classes. The likelihood of achieving virological suppression with subsequent regimens should be high so long as adherence can be assured.

Symptomatic hyperlactataemia precipitated by the addition of tetracycline to combination antiretroviral therapy

Hyperlactataemia in the setting of combination antiretroviral therapy for HIV infection occurs on a spectrum ranging from common, asymptomatic laboratory abnormalities to rare, potentially life-threatening lactic acidosis. Some other medications, including the biguanides, tetracycline, and even linezolid, have rarely been reported to cause lactic acidosis. Recently, cases of lactic acidosis or hyperlactataemia have been reported in patients receiving combination antiretroviral therapy that have been precipitated by the addition of other medications-eg, metformin or ribavirin. We report a case of symptomatic hyperlactataemia in a patient on combination antiretroviral therapy that was likely precipitated by the addition of tetracycline and discuss the broader implications of other medications with the potential to cause hyperlactataemia in the setting of combination antiretroviral therapy.