Acyclovir-induced renal failure. Clinical course and histology

Discovery of Broad-Spectrum Herpes Antiviral Oxazolidinone Amide Derivatives and Their Structure-Activity Relationships

Herpesvirus infections are ubiquitous, with over 95% of the adult population infected by at least one strain. While most of these infections resolve without treatment in healthy individuals, they can cause significant morbidity and mortality in immunocompromised, stem cell, or organ transplant patients. Current nucleoside standards of care provide meaningful benefit but are limited due to poor tolerability, resistance, and generally narrow spectrum of activity. Herpesviruses share a conserved DNA polymerase, the inhibition of which is validated as an effective strategy to disrupt viral replication. By utilizing a non-nucleoside inhibitor of the viral DNA polymerase, we sought to develop agents covering multiple herpesviruses (e.g., CMV, VZV, HSV1/2, EBV, and HHV6). Herein is described the invention of an oxazolidinone class of broad-spectrum non-nucleoside herpes antiviral inhibitors. A lead compound (42) with potent biochemical and broad-spectrum cellular activity was found to be efficacious in murine models against both HSV-1 and CMV infection.

Simultaneous analysis of acyclovir and its metabolite using hydrophilic interaction liquid chromatography-tandem mass spectrometry

The antiviral drug acyclovir (ACV) may induce drug-induced neuropsychiatric symptoms as side effects. The detailed pathogenic mechanism remains unclear; however, it is hypothesized that 9-carboxymethoxymethylguanine (CMMG), a metabolite of ACV, is the causative compound. Therefore, the blood concentrations of ACV and CMMG should be analyzed in ACV toxicity studies. However, it is rare to find methods that can sufficiently separate the ACV and CMMG peaks during simultaneous analysis of both compounds. Therefore, we intended to develop a liquid chromatography-tandem mass spectrometry method with improved peak separation of analytes. Samples were deproteinized using methanol/acetonitrile solution (6:4, v/v). Analytes were separated on an InertSustain® Amide column (3 μm, 2.1 mm × 150 mm). The mobile phase consisted of acetonitrile/10 mM ammonium formate (5:95, v/v) (A) and acetonitrile/10 mM ammonium formate (95:5, v/v, pH 5.0) (B) and samples were eluted in the gradient mode. The separation of analytes was satisfactory and the peak shapes were good. Linear regression models weighted 1/x2 were obtained in the range of 0.25-10 μg/mL. The range of quality control (QC) bias was between 3.6% and 19.8%, and the within-run and between-run precisions of QC were within 13.5%. Recovery ranged from 83.6% to 103.7%, but ion suppression was observed. Samples from a patient with ACV encephalopathy were analyzed using this method. The resulting blood ACV and CMMG concentrations were 8.2 and 8.5 μg/mL, respectively. This method, with sufficient separation of ACV and CMMG, proved useful for use in ACV toxicity studies.

Acyclovir dosing in herpes encephalitis: A scoping review

BACKGROUND

Herpes encephalitis, a rare yet potentially fatal viral infection, is treated exclusively with acyclovir, the sole antiviral medication used for this condition. Acyclovir recommended dose is 10 mg/kg/dose intravenous every 8 hours; however, it is unclear what body weight should be utilized in obese patients. Using the ideal body weight may result in subtherapeutic ineffective concentrations, while utilizing the actual body weight might result in acyclovir induced adverse effects, either nephrotoxicity or neurotoxicity or both.

OBJECTIVE

The objective of this scoping review is to explore existing evidence regarding acyclovir dosing for obese patients afflicted with herpes encephalitis.

METHODS

MEDLINE, EMBASE, Scopus, Web of Science, and CINAHL databases were searched on 26 May 2023, with no language restrictions. Two independent reviewers utilized the Covidence software to carry out the screening and selection of the articles. A total of 22 articles were included in the current review.

RESULTS

The prevalence of acyclovir-associated nephrotoxicity ranged from 13% to 21%, while the prevalence of neurotoxicity was not clearly defined. However, there is lack of evidence regarding what may arise from subtherapeutic concentrations. An approach has been suggested to help clinicians to give the most appropriate acyclovir dose to herpes encephalitis patients. Patients with normal kidney function could receive the normal doses based on actual weight if normal weight and based on adjusted body weight if obese. On the other hand, if the patients are experiencing augmented renal clearance, they could receive up to the maximum recommended doses.

CONCLUSION

Overall, there is a lack of consistency on which body weight to use to calculate acyclovir dose in obese patients. So it is recommended that further studies compare the concentration of intravenous acyclovir between obese and nonobese patients and relating the resultant concentration with patient outcomes.

Acyclovir-Induced Nephrotoxicity and Neurotoxicity: A Report of Two Cases

Acyclovir is a widely used antiviral agent used to treat viral meningitis. Although well tolerated, on rare occasions, it can cause severe nephrotoxicity and neurotoxicity. It is recommended that the dose of intravenous acyclovir be calculated based on the ideal body weight for height rather than the actual weight in obese patients to avoid excessive dosage. We report two patients who developed severe acute kidney injury and neurological symptoms while on intravenous acyclovir therapy. The first patient was a 57-year-old obese woman known to have epilepsy who received a dose of intravenous acyclovir based on her actual weight of 80 kg and subsequently developed acyclovir-induced nephrotoxicity and increased seizure activity. The second patient was a 60-year-old, slightly overweight, man, who received a dose of intravenous acyclovir based on his actual weight of 80 kg and subsequently developed both acyclovir-induced nephrotoxicity and possible neurotoxicity. No other cause for the deterioration in renal function or neurological symptoms was identified, and there was rapid recovery within three days of stopping acyclovir therapy. This case report emphasizes the importance of monitoring renal function while patients are on intravenous acyclovir therapy and highlights the fact that even non-obese, overweight patients are at risk of toxicity when their actual body weight instead of their ideal body weight for height is used for intravenous acyclovir dose calculation.

[Efficacy of FilmArray® ME panel for the rapid diagnosis of meningitis and encephalitis]

Microbial tests are essential for appropriate management for acute meningitis and encephalitis, but it often takes several days to identify the results of culture tests or PCR. BioFire FilmArray® meningitis/encephalitis panel (ME panel) is a rapid multiplex PCR assay that targets 14 bacteria, viruses, and yeast in 1 hour. In this single-center retrospective study, we reviewed adult patients who underwent ME panel test in parallel with conventional microbial tests from January to August 2021. Eighteen of 70 patients (26%) tested positive by ME panel, of which 8 patients (11%) were helpful in altering treatment strategy. Fifty-two patients (74%) could stop empirical treatment such as acyclovir or antibiotics due to negative results on ME panel. All results of ME panel were same as traditional assays. Use of ME panel can contribute to early diagnosis and treatment.

The Impact of Antiviral Resistance on Herpetic Keratitis

ABSTRACT

Herpes simplex keratitis resistance to antiviral treatment presents a growing concern. The herpes simplex virus has many different mechanisms of resistance to antiviral treatment, which have been well described. Resistance to acyclovir occurs because of mutations in the viral thymidylate kinase and DNA polymerase that decrease this enzyme's affinity for its substrate. This article discusses factors that explain the prevalence of this resistance, the ability for recurrences in immunocompromised populations, current treatments for acyclovir-resistant herpes simplex keratitis, and novel therapies for this growing concern.

Acute retinal necrosis: pathophysiological aspects, diagnosis, and treatment

Acute retinal necrosis (ARN) is a devastating viral infection commonly associated with varicella zoster virus (VZV) and herpes simplex virus types 1 and 2 (HSV-1, HSV-2). Typically, ARN affects individuals without immune status disorders between the ages of 50-70. In two-thirds of the cases, one-eye involvement is observed and the inflammation can be presented as panuveitis. The most characteristic clinical manifestations are vitreitis, occlusion of the retinal arterioles, and peripheral necrotizing retinitis. Retinitis presents with the appearance of deep, multifocal, yellowish-white foci, typically localized in the peripheral retina. Systemic antivirals are the first treatment of choice for ARN. The goal of the therapy is to stop the viral replication and disease progression in the affected eye, as well as to prevent involvement of the healthy eye. The other eye can be attacked in an interval of 5 days to 30 years. The visual prognosis after illness is poor. Early diagnosis and timely initiation of treatment play an important role in maintaining visual acuity and preventing the other eye from being affected.

Pathophysiology of Acute Kidney Injury in Critical Illness: A Narrative Review

Acute kidney injury (AKI) is a syndrome that entails a rapid decline in kidney function with or without injury. The consequences of AKI among acutely ill patients are dire and lead to higher mortality, morbidity, and healthcare cost. To prevent AKI and its short and long-term repercussions, understanding its pathophysiology is essential. Depending on the baseline kidney histology and function reserves, the number of kidney insults, and the intensity of each insult, the clinical presentation of AKI may differ. While many factors are capable of inducing renal injury, they can be categorized into a few processes. The three primary processes reported in the literature are hemodynamic changes, inflammatory reactions, and nephrotoxicity. The majority of patients with AKI will suffer from more than one during their development and/or progression of AKI. Moreover, the development of one usually leads to the instigation of another. Thus, the interactions and progression between these mechanisms may determine the severity and duration of the AKI. Other factors such as organ crosstalk and how our concurrent therapies interact with these mechanisms complicate the pathophysiology of the progression of the AKI even further. In this narrative review article, we describe these three main pathophysiological processes that lead to the development and progression of AKI. © 2022 American Physiological Society. Compr Physiol 12: 1-14, 2022.

Central Composite Design for Formulation and Optimization of Solid Lipid Nanoparticles to Enhance Oral Bioavailability of Acyclovir

Treatment of herpes simplex infection requires high and frequent doses of oral acyclovir to attain its maximum therapeutic effect. The current therapeutic regimen of acyclovir is known to cause unwarranted dose-related adverse effects, including acute kidney injury. For this reason, a suitable delivery system for acyclovir was developed to improve the pharmacokinetic limitations and ultimately administer the drug at a lower dose and/or less frequently. In this study, solid lipid nanoparticles were designed to improve the oral bioavailability of acyclovir. The central composite design was applied to investigate the influence of the materials on the physicochemical properties of the solid lipid nanoparticles, and the optimized formulation was further characterized. Solid lipid nanoparticles formulated from Compritol 888 ATO resulted in a particle size of 108.67 ± 1.03 nm with an entrapment efficiency of 91.05 ± 0.75%. The analyses showed that the optimum combination of surfactant and solid lipid produced solid lipid nanoparticles of good quality with controlled release property and was stable at refrigerated and room temperature for at least 3 months. A five-fold increase in oral bioavailability of acyclovir-loaded solid lipid nanoparticles was observed in rats compared to commercial acyclovir suspension. This study has presented promising results that solid lipid nanoparticles could potentially be used as an oral drug delivery vehicle for acyclovir due to their excellent properties.

Pediatric onco-nephrology: time to spread the word : Part I: early kidney involvement in children with malignancy

Onco-nephrology has been a growing field within the adult nephrology scope of practice. Even though pediatric nephrologists have been increasingly involved in the care of children with different forms of malignancy, there has not been an emphasis on developing special expertise in this area. The fast pace of discovery in this field, including the development of new therapy protocols with their own kidney side effects and the introduction of the CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy, has introduced new challenges for general pediatric nephrologists because of the unique effects of these treatments on the kidney. Moreover, with the improved outcomes in children receiving cancer therapy come an increased number of survivors at risk for chronic kidney disease related to both their cancer diagnosis and therapy. Therefore, it is time for pediatric onco-nephrology to take its spot on the expanding subspecialties map in pediatric nephrology.

An extract of Stephania hernandifolia, an ethnomedicinal plant, inhibits herpes simplex virus 1 entry

Stephania hernandifolia (Nimukho), an ethnomedicinal herb from rural Bengal, has been used traditionally for the management of nerve, skin, urinary, and digestive ailments. Here, we attempted to confirm the antiviral potential of aqueous, methanol, and chloroform extracts of S. hernandifolia against herpes simplex virus type 1 (HSV-1), the causative agent of orolabial herpes in humans, and decipher its underlying mechanism of action. The bioactive extract was standardized and characterized by gas chromatography-mass spectroscopy, while cytotoxicity and antiviral activity were evaluated by MTT and plaque reduction assay, respectively. Two HSV strains, HSV-1F and the clinical isolate VU-09, were inhibited by the chloroform extract (CE) with a median effective concentration (EC₅₀) of 4.32 and 4.50 µg/ml respectively, with a selectivity index (SI) of 11. Time-of-addition assays showed that pre-treatment of virus-infected cells with the CE and its removal before infection reduced the number of plaques without lasting toxicity to the cell, indicating that the CE affected the early stage in the viral life cycle. The number of plaques was also reduced by direct inactivation of virions and by the addition of CE for a short time following attachment of virions. These results together suggest that modification of either the virion surface or the cell surface by the CE inhibits virus entry into the host cell.

Transdermal drug delivery systems for fighting common viral infectious diseases

Transdermal drug delivery systems (TDDS) have many advantages and represent an excellent alternative to oral delivery and hypodermic injections. TDDS are more convenient and less invasive tools for disease and viral infection treatment, prevention, detection, and surveillance. The emerging development of microneedles for TDDS has facilitated improved skin barrier penetration for the delivery of macromolecules or hydrophilic drugs. Microneedle TDDS patches can be fabricated to deliver virus vaccines and potentially provide a viable alternative vaccine modality that offers improved immunogenicity, thermostability, simplicity, safety, and compliance as well as sharp-waste reduction, increased cost-effectiveness, and the capacity for self-administration, which could improve vaccine distribution. These advantages make TDDS-based vaccine delivery an especially well-suited option for treatment of widespread viral infectious diseases including pandemics. Because microneedle-based bioassays employ transdermal extraction of interstitial fluid or blood, they can be used as a minimally invasive approach for surveying disease markers and providing point-of-care (POC) diagnostics. For cutaneous viral infections, TDDS can provide localized treatment with high specificity and less systemic toxicity. In summary, TDDS, especially those that employ microneedles, possess special attributes that can be leveraged to reduce morbidity and mortality from viral infectious diseases. In this regard, they may have considerable positive impact as a modality for improving global health. In this article, we introduce the possible role and summarize the current literature regarding TDDS applications for fighting common cutaneous or systemic viral infectious diseases, including herpes simplex, varicella or herpes zoster, warts, influenza, measles, and COVID-19.

Characteristics and outcome of varicella-zoster virus central nervous system infections in adults

We conducted an observational retrospective study of all adults hospitalized for documented varicella-zoster virus (VZV) meningitis or encephalitis during years 2000-2015 in one referral centre. Thirty-six patients (21 males, 15 females) were included, with meningitis (n = 21), or meningoencephalitis (n = 15). Median age was 51 years [interquartile range, 35-76], and 6 patients (17%) were immunocompromised. Aciclovir was started in 32 patients (89%), with a median dose of 11 mg/kg/8 h [10-15]. No patient died, but 12 (33%) had neurological sequelae at discharge. Age was the only variable associated with adverse outcome (OR 1.98 [1.17-3.35] per 10-year increment, P = 0.011).

Acute kidney injury following intravenous acyclovir in children

OBJECTIVE

The objective of this study was to describe the incidence of acute kidney injury (AKI) in children receiving intravenous acyclovir and determine risk factors that may be associated with it.

DESIGN

This was a retrospective cohort study, conducted by chart review.

SETTING

The study was conducted across two paediatric hospitals.

PATIENTS

All inpatients that received intravenous acyclovir in records from January 2015 to December 2015 were reviewed. Only patients with creatinine measurements taken before and after starting acyclovir were included in the study.

MAIN OUTCOME MEASURES

The main outcome measure was the development of AKI following intravenous acyclovir administration, with AKI defined according to change in serum creatinine.

RESULTS

150 patients were included in the analysis. Patients' ages ranged from 2 days to 18.6 years. 27 children (18%) developed at least stage 1 AKI. Children receiving cancer treatment developed AKI more frequently than children with other diagnoses; 29.3% vs 10.9% (OR 3.4, 95% CI 1.5 to 8.2, p=0.008). The baseline estimated glomerular filtration rate (eGFR) was higher in those children who developed AKI. 34% of children had an eGFR >120 mL/min/1.73 m² prior to acyclovir use. 31% of these children developed AKI compared with only 11% of those with a normal baseline eGFR (OR 3.6, 95 CI 1.3 to 10.1, p=0.02). Baseline eGFR was a significant predictor of AKI in a multivariable analysis that included cumulative dose and treatment duration (OR 1.02, p=0.013).

CONCLUSION

AKI following intravenous acyclovir exposure is common in children. This study raises the possibility that glomerular hyperfiltration is a previously unrecognised risk factor for acyclovir-induced AKI.

Successful treatment of elephant endotheliotropic herpesvirus infection in an Asian elephant (Elephas maximus) calf by oral acyclovir medication: Case report

Elephant endotheliotropic herpesvirus (EEHV) is a major cause of death in Asian elephant (Elephas maximus) calves. A 2-year, 11-month-old female, captive Asian elephant presented with facial edema and a mild fever. Blood samples were collected and showed EEHV1A positivity with a high viral load by real time PCR. Heterophil toxicity also was reported for the first time in this case. The calf was treated orally with acyclovir, 45 mg/kg tid for 28 days, which reduced the EEHV1A viral load to undetectable levels within 9 days and the calf survived. A successful outcome with oral acyclovir administration provides another and affordable option to treat EEHV hemorrhagic disease in Asian elephants, and one that is easier to administer in untrained calves.

A diagnostician's field guide to crystalline nephropathies

The kidney's role in filtration of blood and production of urine occurs via a combination of size and charge filtration at the glomerular basement membrane and resorption and excretion of molecules through a complex tubular system embedded within an ion gradient. This delicate system provides the kidney with a unique propensity for substrate saturation and crystal nucleation within the nephron. While crystalline nephropathies may seem exotic to the uninitiated, they are comprised of easily recognizable morphologies and generally lack complicated classification schemas. Additionally, unlike many intrinsic kidney diseases, crystalline nephropathies are often associated with systemic conditions that, upon further investigation, may elucidate critically important information. This review focuses on practical, diagnostically relevant and high yield information that can be utilized by diagnosticians. Our hope is to equip the reader who reviews renal tissue with a practical toolkit that they feel empowered to use when faced with crystal formation in a kidney biopsy, pre-implantation biopsy, or nephrectomy specimen. Short Abstract The kidney's role in filtration of blood and production of urine provides a unique propensity for substrate saturation and crystal nucleation within the nephron. While crystalline nephropathies may seem exotic to the uninitiated, they are comprised of easily recognizable morphologies and generally lack complicated classification. Additionally, crystalline nephropathies are often associated with systemic conditions that, upon further investigation, may elucidate critically important information.

Nephrotoxicity of Antimicrobials and Antibiotics

Medication-induced nephrotoxicity remains one of the most common causes of acute kidney injury (AKI) among hospitalized patients. Within the extensive group of medications associated with AKI, antibiotics and other antimicrobials are well recognized triggers of structural and functional renal impairment. Clinical manifestations range from mild forms of tubular injury to significant deterioration of kidney function requiring acute renal replacement therapy. Several mechanisms are described, although the most frequent are acute interstitial nephritis, acute tubular necrosis, intratubular crystal deposition, and proximal/distal tubulopathy with electrolyte wasting abnormalities. General risk factors for antimicrobial-induced AKI include pre-existing chronic kidney disease, and concomitant use of medication with nephrotoxic potential. Prevention and early recognition of AKI represent the standard approach to mitigate AKI and avoid morbidity.

Risk Evaluation for Acute Kidney Injury Induced by the Concomitant Use of Valacyclovir, Analgesics, and Renin-Angiotensin System Inhibitors: The Detection of Signals of Drug-Drug Interactions

Background: Drug-related acute kidney disease is a common side effect of valacyclovir (VACV) treatment. Although analgesics are frequently administered concomitantly with VACV to treat the pain of herpes zoster, the differences between nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen in relation to VACV-related acute kidney injury (AKI) are unclear. The risk for AKI with concomitant use of VACV and renin–angiotensin system (RAS) inhibitors that can cause AKI via a similar mechanism to NSAIDs is also unknown. We therefore evaluated the association between concomitant use of these drugs and VACV-related AKI, which was characterized according to the Japanese Adverse Drug Event Report (JADER) database.

Methods: We analyzed data from the JADER database, which is a spontaneous reporting system. The reporting odds ratio was used to evaluate the signals of AKI.

Results: A high proportion of VACV-related AKI cases occurred in summer. There was an increase in AKI signal in cases with concomitant use of VACV and NSAIDs, while no increase was detected in cases with concomitant use of VACV and acetaminophen. AKI events in cases with concomitant use of VACV and NSAIDs were more frequent in older and female patients and those with hypertension. Additionally, a signal increase for VACV-related AKI was observed with concomitant use of RAS inhibitors, with or without NSAIDs.

Conclusions: We identified a seasonal variation in VACV-related AKI. Additionally, our findings indicate that acetaminophen might represent a safer analgesic than NSAIDs with respect to VACV-related AKI. We also identified candidate risk factors for AKI with concomitant use of NSAIDs, such as older age, female sex, and hypertension. Although further studies are warranted, our findings highlight the need to consider concomitant drug use and seasonal factors that lead to urinary output loss so that VACV-related AKI can be avoided.

The incidence, risk factors, and clinical outcomes of acute kidney injury (staged using the RIFLE classification) associated with intravenous acyclovir administration

Intravenous (IV) acyclovir is commonly administered medication for viral infection but is well known for its nephrotoxicity. However, there was no study for incidence, risk factors, and clinical outcomes of acute kidney injury (AKI) associated with IV acyclovir administration. We retrospectively reviewed the medical records of 287 patients who were medicated IV acyclovir from January 2008 to May 2013 in Gyeongsang National University Hospital. All had documented medical histories and underwent medical review. Demographic data, risk factors, concomitant drugs, laboratory findings and outcome were gathered from the medical records and analyzed. AKI occurred in 51 patients (17.8%). As per RIFLE classification, renal injury was graded as either at risk of renal dysfunction (62.7%), renal injury (15.6%), and renal failure (21.6%). There was no significant difference in age, sex, total dose, drug duration, and presence of hydration between AKI and non-AKI group. However, systolic pressure, underlying diabetes, concomitant vancomycin and non-steroidal anti-inflammatory drugs (NSAIDs) use was positively correlated with AKI occurrence (p = .04, p < .001, 0.01, and 0.04, respectively). Two patients underwent hemodialysis and these patients died. Higher mortality was observed in AKI patients (p < .001). Multivariate analysis also presented that presence of diabetes, concomitant NSAIDs, and vancomycin use was independent risk factor of acyclovir associated with AKI (p = .001, OR 3.611 (CI: 1.708–7.633), p = .050, OR 2.630 (CI: 1.000–6.917), and p = .009, OR 4.349 (CI: 1.452–13.022), respectively). AKI is relatively common in patients administrating acyclovir injection. Physicians should attempt to prevent, detect, and manage acyclovir associated AKI in patients prescribing acyclovir due to possible association of poor prognosis.

Impact of Obesity on Acyclovir-Induced Nephrotoxicity

Background

Obesity is a major medical issue nationally, with rates continually increasing. In obese patients, minimal data exist for appropriate dosing of acyclovir to decrease the rates of nephrotoxicity. The purpose of this study was to determine the prevalence of and risk factors associated with acyclovir-induced nephrotoxicity.

Methods

A retrospective case-control of patients who received intravenous acyclovir for >48 hours at the University of Mississippi Medical Center over a 4-year period were evaluated to elucidate the prevalence of acyclovir-induced nephrotoxicity. Additionally, risk factors for the development of nephrotoxicity, including the effect of obesity and dosing strategy, were assessed.

Results

One hundred fifteen patients were included in the study. A total of 24 (21%) patients developed nephrotoxicity after acyclovir exposure and were in the Risk (9.6%), Injury (4.3%), and Failure (7%) categories, defined by the RIFLE criteria. Neither acyclovir dosage, fluid status, nor baseline characteristics, other than obesity, varied between those who developed nephrotoxicity vs those who did not. Independent predictors of nephrotoxicity were obesity (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.19-8.67) and receipt of vancomycin (OR, 4.73; 95% CI, 1.57-14.25). No differences in vancomycin dosing or concentrations were observed between the patients who developed nephrotoxicity and those who did not.

Conclusions

In this study, nephrotoxicity occurred in 21% of patients receiving acyclovir. Concomitant vancomycin receipt and obesity led to higher rates of toxicity. Efforts should be made to target obese patients on acyclovir plus vancomycin and discontinue therapy in patients not warranting antiviral coverage to minimize chances of toxicity.

Meeting report of the "Symposium on kidney stones and mineral metabolism: calcium kidney stones in 2017"

A symposium on kidney stones and mineral metabolism held on December 2017 in Brussels, Belgium was the first international multidisciplinary conference of the International Collaborative Network on Kidney Stones and Mineral Metabolism. This meeting addressed epidemiology, underlying pathophysiological mechanisms, genetics, pathological, as well as clinical and research topics. The participants included clinicians and recognized experts in the field from Europe and the United States interacted closely during the symposium which promoted a chance to explore new frontiers in the field of kidney stone disease. This manuscript summarizes some of the major highlights of the meeting.

Renal Complications Following Lung Transplantation and Heart Transplantation

Renal complications are common following heart and/or lung transplantation and lead to increased morbidity and mortality. Renal dysfunction is also associated with increased mortality for patients on the transplant wait list. Dialysis dependence is a relative contraindication for heart or lung transplantation at most centers, and such patients are often listed for a simultaneous kidney transplant. Several factors contribute to the impaired renal function in patients undergoing heart and/or lung transplantation, including the interplay between cardiopulmonary and renal hemodynamics, complex perioperative issues, and exposure to nephrotoxic medications, mainly calcineurin inhibitors.

Incidence and predictors of intravenous acyclovir-induced nephrotoxicity

To assess the incidence, predictive factors, and prognosis of acyclovir-induced nephrotoxicity. We conducted a historical prospective cohort study of patients treated with intravenous acyclovir in North Denmark Region from 2009 to 2016. Information on baseline demographics, co-morbidities, plasma creatinine, and treatment was obtained from the medical records. The primary outcome was an increase of ≥ 40 μmol/L in plasma creatinine level from baseline. We included 276 patients treated with intravenous acyclovir of which 29 (10.5%) met the primary outcome. In 14 cases, the treating physician considered acyclovir the main reason for nephrotoxicity, whereas a potential competing cause of renal impairment was present among the 15 remaining patients. Hypertension was the only predictive factor associated with nephrotoxicity (risk ratio (RR), 2.77; 95% confidence interval (CI), 1.41-5.46), while having no co-morbidities was protective (RR, 0.32; CI, 0.16-0.63). In all cases, the nephrotoxicity was reversible following rehydration and dose reduction or discontinuation of the drug. However, the normalized plasma creatinine upon treatment was significantly higher between cases with acyclovir-induced nephrotoxicity than cases with a potential competing cause (median [interquartile range (IQR)], 93.5 μmol/L [85-108] vs 75 μmol/L [66.5-88]; p = 0.019). Acyclovir-induced, reversible nephrotoxicity was observed in 5.1-10.5% of patients. It is difficult to predict who will develop acyclovir-induced nephrotoxicity; it may occur late in treatment and hypertension was the only independent predictive factor, while the absence of co-morbidities was protective. Ensuring hydration, frequent evaluations of renal function, and corresponding dose adjustment of intravenous acyclovir treatment seem prudent.

Acute kidney injury (AKI) associated with intravenous aciclovir in adults: Incidence and risk factors in clinical practice

OBJECTIVES

This study sought to identify the incidence of, and risk factors for, acute kidney injury (AKI) in adults treated with parenteral aciclovir.

METHODS

A single-centre retrospective cohort study of prospectively acquired electronic clinical, pharmacy and laboratory data was performed with approval of the Caldicott guardian. AKI was defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria, prior to analysis of baseline patient and treatment-related risk factors.

RESULTS

269 aciclovir treatment episodes were identified in 268 patients. Overall incidence of AKI was 13%. Half of AKI episodes were KDIGO grade 2/3. In univariate analysis, AKI occurred more frequently in patients with pre-existing chronic kidney disease (CKD), diabetes, and in patients treated with higher daily doses of aciclovir. There was also a trend to increased age in patients with AKI. In a binomial logistic regression model only CKD and daily dose remained significant independent factors.

CONCLUSIONS

AKI is an important side effect of parenteral aciclovir, the incidence of which is comparable to established nephrotoxic drugs such as aminoglycosides. Patients with pre-existing chronic kidney disease or receiving higher total doses are at greatest risk, reinforcing the clinical importance of appropriate dose adjustment for ideal body weight and baseline renal function.

Acute Kidney Failure as a Single Complication of Varicella Virus Infection in an Adult Patient

BACKGROUND

Varicella zoster virus (VZV) is distributed worldwide and is highly contagious. In adults and immunosuppressed patients of any age, the clinical course is much more severe. The most severe complications are pneumonia (the main cause of lethal outcomes in this infection), encephalitis, and very rarely Reye syndrome and hepatitis.

CASE PRESENTATION

We present a 59-year-old man who came to the emergency department due to varicella and diarrhea. During initial evaluation acute kidney failure (AKF) was diagnosed, and the patient was admitted to the intensive care unit. Continuous renal replacement therapy was applied, and the patient was treated with acyclovir in adjusted doses; renal biopsy revealed acute tubular necrosis. Complete renal function recovery was established after 12 days.

CONCLUSION

VZV infection occurs in a range of clinical scenarios, sometimes presenting only with mild symptoms, but in some other setting it can result in severe AKF even in healthy kidneys. Acute VZV infection can lead to isolated, clinically significant kidney failure. The administration of continuous renal replacement therapy and adjusted doses of acyclovir has a favorable effect on the course of the infection, with complete recovery of kidney function.

Drug-Induced Kidney Stones and Crystalline Nephropathy: Pathophysiology, Prevention and Treatment

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favour crystallisation in the urine. Among them, drugs used for the treatment of patients with human immunodeficiency, namely atazanavir and other protease inhibitors, and sulphadiazine used for the treatment of cerebral toxoplasmosis, are the most frequent causes. Besides these drugs, about 20 other molecules may induce nephrolithiasis, such as ceftriaxone or ephedrine-containing preparations in subjects receiving high doses or long-term treatment. Calculi analysis by physical methods including infrared spectroscopy or X-ray diffraction is needed to demonstrate the presence of the drug or its metabolites within the calculi. Some drugs may also provoke heavy intra-tubular crystal precipitation causing acute renal failure. Here, the identification of crystalluria or crystals within the kidney tissue in the case of renal biopsy is of major diagnostic value. The second group includes drugs that provoke the formation of urinary calculi as a consequence of their metabolic effects on urinary pH and/or the excretion of calcium, phosphate, oxalate, citrate, uric acid or other purines. Among such metabolically induced calculi are those formed in patients taking uncontrolled calcium/vitamin D supplements, or being treated with carbonic anhydrase inhibitors such as acetazolamide or topiramate. Here, diagnosis relies on a careful clinical inquiry to differentiate between common calculi and metabolically induced calculi, of which the incidence is probably underestimated. Specific patient-dependent risk factors also exist in relation to urine pH, volume of diuresis and other factors, thus providing a basis for preventive or curative measures against stone formation.

Antiherpetic Drugs in Equine Medicine

Since vaccination may not prevent disease, antiherpetic drugs have been investigated for the therapy of several equine herpesviruses. Drug efficacy has been assessed in horses with disease, but most evidence is in vitro, in other species, or empirical. Oral valacyclovir is most often administered in the therapy of equine herpesvirus type-1 (EHV-1) to protect adult horses from equine herpesvirus myeloencephalopathy, while oral acyclovir is frequently administered for EHV-5 infection in the therapy of equine multinodular pulmonary fibrosis. Other antiherpetic drugs are promising but require further investigation. Several topical drugs are also empirically used in the therapy of equine viral keratitis.

Safety of High-dose Acyclovir in Infants With Suspected and Confirmed Neonatal Herpes Simplex Virus Infections

BACKGROUND

Acyclovir is used to treat herpes simplex virus disease in infants. Treatment with high-dose acyclovir, 60 mg/kg/d, is recommended; however, the safety of this dosage has not been assessed in the past 15 years, and this dosage is not currently approved for infants by the US Food and Drug Administration.

METHODS

We included infants with neonatal herpes simplex virus disease treated with ≥14 days of intravenous acyclovir starting in the first 120 days of life admitted to 1 of 42 neonatal intensive care units managed by the Pediatrix Medical Group between 2002 and 2012. We determined the frequency and proportion of infants with clinical and laboratory adverse events (AEs) as well as the number and proportion of infant days with laboratory AEs occurring during acyclovir exposure.

RESULTS

We identified 89 infants during the study period with 1658 days of acyclovir exposure. Almost all received high-dose acyclovir therapy (79/89, 89%). The most common clinical AEs were hypotension and seizure, both occurring in 9% of infants. Thrombocytopenia was the most common laboratory AE occurring in 25% of infants and on 9% of infant-days. Elevated creatinine occurred in 2% of infants and 0.2% of infant-days and no infants developed renal failure requiring dialysis. Overall, 45% of infants had ≥1 AE.

CONCLUSIONS

In this cohort of infants treated during the high-dose acyclovir era, AEs were common but usually not severe. Many of the AEs reported in this cohort may be related to the underlying infection rather than due to acyclovir exposure.

Acyclovir-induced thrombotic microangiopathy

Acyclovir is a commonly used antiviral drug. Acute kidney injury (AKI) due to intratubular crystal precipitation and interstitial nephritis is well known. Here we present a case of acyclovir induced AKI in a 61 year old male with herpes zoster, which presented like thrombotic microangiopathy with acute interstitial nephritis. This is the first case report on acyclovir causing thrombotic microaniopathy with partial improvement in renal function after plasmapharesis.

Acute renal injury induced by valacyclovir hydrochloride: A case report

Acyclovir has been a frequently used antiviral agent in the clinical treatment of leukemia, acute encephalitis, malignant tumor and herpes simplex. The adverse effects of this drug have been widely described in clinical practice. In the present study, a case of a 35-year-old female patient diagnosed with herpes simplex, who developed acute renal injury following treatment with valacyclovir hydrochloride, is described. Kidney biopsy, light microscopy and laboratory examination were performed, and all findings revealed the signs of evident vacuolar degeneration of capillary endothelial and renal tubular epithelial cells, erythrocyte aggregation in partial renal tubule and microvilli exfoliation from epithelial cells. Renal interstitial edema was clearly identified. The clinical evidence observed from this female patient indicated that renal functions should be closely monitored during valacyclovir hydrochloride administration. A variety of effective measures, such as hydration, alkalizing urine, promoting the discharge of medication and the use of antagonists are recommended following the administration of antiviral agents.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

Acute Kidney Injury in Hematopoietic Stem Cell Transplantation: A Review

Hematopoietic stem cell transplantation (HSCT) is a highly effective treatment strategy for lymphoproliferative disorders and bone marrow failure states including aplastic anemia and thalassemia. However, its use has been limited by the increased treatment related complications, including acute kidney injury (AKI) with an incidence ranging from 20% to 73%. AKI after HSCT has been associated with an increased risk of mortality. The incidence of AKI reported in recipients of myeloablative allogeneic transplant is considerably higher in comparison to other subclasses mainly due to use of cyclosporine and development of graft-versus-host disease (GVHD) in allogeneic groups. Acute GVHD is by itself a major independent risk factor for the development of AKI in HSCT recipients. The other major risk factors are sepsis, nephrotoxic medications (amphotericin B, acyclovir, aminoglycosides, and cyclosporine), hepatic sinusoidal obstruction syndrome (SOS), thrombotic microangiopathy (TMA), marrow infusion toxicity, and tumor lysis syndrome. The mainstay of management of AKI in these patients is avoidance of risk factors contributing to AKI, including use of reduced intensity-conditioning regimen, close monitoring of nephrotoxic medications, and use of alternative antifungals for prophylaxis against infection. Also, early identification and effective management of sepsis, tumor lysis syndrome, marrow infusion toxicity, and hepatic SOS help in reducing the incidence of AKI in HSCT recipients.

A metabolic profiling analysis of the nephrotoxicity of acyclovir in rats using ultra performance liquid chromatography/mass spectrometry

Acyclovir (ACV) exposure is a common cause of acute kidney injury (AKI). The toxicity mechanism of ACV has always been a matter of debate. The present study investigated into the time-effect relationship and dose-effect relationship of ACV-induced nephrotoxicity in rats using metabonomics. Twenty-four rats were randomly divided into four groups: a 0.9% NaCl solution group, and 100, 300, and 600mg/kg ACV-treated groups; the ACV or vehicle solution was administered with a single intravenous injection. Urine was collected at different time periods (12h before administration, and 0-6h, 7-12h, and 13-24h after administration). Routine urinalysis was conducted by a urine automatic analyzer. Renal markers, including urine urea nitrogen, urine creatinine, and urinary N-acetyl-β-d-glucosaminidase (NAG) activity, were determined using established protocols. Urinary metabolites were evaluated using ultra performance liquid chromatography/mass spectrometry (UPLC/MS). In the ACV-treated rats, increased levels of protein (PRO), occult blood (BLD), white blood cell (WBC), and NAG activity in urine were observed, while the urine creatinine and urea nitrogen levels showed a decrease compared with the control. Moreover, urine metabolites significantly changed after the treatment with ACV, and all the effects induced by ACV were dose-time dependent. Finally, 4 metabolites (guanine, 4-guanidinobutyric acid, creatinine, and urea) were identified, which can be used for further research on the mechanism of ACV-induced nephrotoxicity.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

Herpetic infections have plagued humanity for thousands of years, but only recently have advances in antiviral medications and supportive treatments equipped physicians to combat the most severe manifestations of disease. Prompt recognition and treatment can be life-saving in the care of patients with herpes simplex-1 virus encephalitis, the most commonly identified cause of sporadic encephalitis worldwide. Clinicians should be able to recognize the clinical signs and symptoms of the infection and familiarize themselves with a rational diagnostic approach and therapeutic modalities, as early recognition and treatment are key to improving outcomes. Clinicians should also be vigilant for the development of acute complications, including cerebral edema and status epilepticus, as well as chronic complications, including the development of autoimmune encephalitis associated with antibodies to the N-methyl-D-aspartate receptor and other neuronal cell surface and synaptic epitopes. Herein, we review the pathophysiology, differential diagnosis, and clinical and radiological features of herpes simplex virus-1 encephalitis in adults, including a discussion of the most common complications and their treatment. While great progress has been made in the treatment of this life-threatening infection, a majority of patients will not return to their previous neurologic baseline, indicating the need for further research efforts aimed at improving the long-term sequelae.

Dosing Practices of Intravenous Acyclovir for Herpes Encephalitis in Obesity: Results of a Pharmacist Survey

BACKGROUND

Dosing of intravenous acyclovir for herpes encephalitis in obese patients is recommended to be based on ideal body weight. However, limited data support this recommendation, and recent data suggest this may lead to underdosing.

OBJECTIVE

To determine national dosing practices of intravenous acyclovir across a range of patient weights.

METHODS

A survey was distributed to members of the American College of Clinical Pharmacy Critical Care and Infectious Diseases Practice & Research Networks listservs. Data collected included demographic information and dosing of acyclovir, given consistent patient cases with varying patient weight.

RESULTS

A total of 264 pharmacists participated in the survey, with 240 (90.9%) participants completing the survey. Participants were predominately clinical pharmacists. As patient weight increased, respondents were more apt to dose based on an adjusted body weight, with dosing in the obese and morbidly obese showing a clear lack of consistency.

CONCLUSIONS

Intravenous dosing of acyclovir for herpes encephalitis is variable, especially in obese patients, and does not reflect recommendations. Limited data provide conflicting recommendations for dosing in obese patients, and future studies are necessary to optimize patient outcomes and prevent toxicity.

Interdisciplinary Systems-Based Intervention to Improve IV Hydration during Parenteral Administration of Acyclovir

BACKGROUND

Intravenous (IV) hydration is considered a protective factor in reducing the incidence of acyclovir-induced nephrotoxicity. A systems-based review of cases of acyclovir-associated acute kidney injury can be used to examine institution-, care provider-, and task-related factors involved in administering the drug and can serve as a basis for developing a quality improvement intervention to achieve safer administration of acyclovir.

OBJECTIVES

To explore the effectiveness of the study institution's inter-disciplinary quality improvement intervention in increasing the dilution of acyclovir before IV administration.

METHODS

After conducting a systems-based review for intervention development, a retrospective analysis was undertaken to compare IV administration of acyclovir in the 6-month periods before and after implementation of the intervention. The study population was a sequential sample of all patients over 18 years of age who were seen in the emergency department or admitted to a ward and who received at least one IV dose of acyclovir at the study institution. The primary outcome was the volume in which each acyclovir dose was delivered. The secondary outcomes were the hourly rate of fluid administration, the frequency of an increase in hourly hydration rate, and the incidence of acute kidney injury.

RESULTS

Eighty-four patients (44 in the pre-intervention period and 40 in the post-intervention period) received IV acyclovir and had evaluable data for the primary outcome. The median volume in which the acyclovir dose was administered was significantly higher in the post-intervention group (250 mL versus 100 mL, p < 0.001).

CONCLUSIONS

In this study, an easily implemented intervention significantly increased the volume of IV fluid administered to patients receiving acyclovir. Adequately powered prospective studies are suggested to investigate the effectiveness of this intervention on the clinically relevant incidence of acyclovir-induced nephrotoxicity.

Acute kidney injury induced by antimicrobial agents in the elderly: awareness and mitigation strategies

The use of antimicrobial agents has increased in recent years as treatments have diversified and resistant bacteria have appeared. With increased use of antimicrobial agents, elderly patients are prone to adverse drug reactions (ADRs) as a result of factors such as drug-drug interactions, polypharmacy, long-term use, and over- or under-dosage. In particular, elderly patients using antimicrobials are at increased risk to develop drug-induced acute kidney injury (AKI), which is the most common severe ADR in such patients. AKI is a serious problem that is associated with mortality amongst hospitalized patients. Antimicrobial-induced AKI can be classified into three different types: acute tubular necrosis (ATN), acute interstitial nephritis (AIN), and renal tubule lumen obstruction. AKI can generally be prevented by proper maintenance of fluid balance. To design dosage regimens that ensure efficient drug excretion via the kidney, it is necessary to accurately estimate renal function; however, the kidney undergoes age-dependent structural and functional alterations over time. Therefore, proper management of antimicrobial agents by an antimicrobial stewardship team may lead to decreased incidence of AKI. This article reviews antimicrobial-induced AKI and discusses potential strategies for increasing awareness of AKI and mitigating its clinical effects.

Topical iontophoretic delivery of ionizable, biolabile aciclovir prodrugs: A rational approach to improve cutaneous bioavailability

The objective was to investigate the topical iontophoretic delivery of a series of amino acid ester prodrugs of aciclovir (ACV-X, where ACV=aciclovir and X=Arg, Gly, Ile, Phe, Trp and Val) as a means to enhance cutaneous delivery of ACV. The newly synthesized prodrugs were characterized by (1)H NMR and high resolution mass spectrometry. Analytical methods using HPLC-UV were developed for their quantification and each method was validated. Investigation of solution stability as a function of pH showed that all ACV-X prodrugs were relatively stable in acid conditions at pH 2.0 and pH 5.5 for up to 8h but susceptible to extensive hydrolysis at pH 7.4 and under alkaline conditions (pH 10). No ACV-X hydrolysis was observed after contact for 2h with the external surface of porcine stratum corneum. However, there was significant hydrolysis following contact with the dermal surface of dermatomed porcine skin, in particular, for ACV-Arg. Passive transport of ACV and ACV-X prodrugs from aqueous solution after 2h was below the limit of detection. Iontophoresis of ACV at 0.5 mA/cm(2) for 2h led to modest ACV skin deposition (QDEP,ACV) of 4.6 ± 0.3 nmol/cm(2). In contrast, iontophoresis of ACV-X prodrugs under the same conditions produced order of magnitude increases in cutaneous deposition of ACV species, that is, QDEP,TOTAL=QDEP,ACV+QDEP,ACV-X. QDEP,TOTAL for ACV-Gly, ACV-Val, ACV-Ile, ACV-Phe, ACV-Trp and ACV-Arg was 412.8 ± 44.0, 358.8 ± 66.8, 434.1 ± 68.2, 249.8 ± 81.4, 156.1 ± 76.3, 785.9 ± 78.1 nmol/cm(2), respectively. The extent of bioconversion of ACV-X to ACV in the skin was high and the proportion of ACV present ranged from 81% to 100%. The skin retention ratio, a measure of the selectivity of ACV species for deposition over permeation after iontophoretic delivery of ACV-X prodrugs, was dependent on both the rate of transport and the susceptibility to hydrolysis of the prodrugs. Skin deposition of ACV and its six prodrugs were investigated further as a function of current density (0.125, 0.25 and 0.5 mA/cm(2)); the effect of duration of current application (5, 10, 30, 60 and 120 min) was evaluated using ACV-Arg and ACV-Ile. Iontophoresis of ACV-Arg and ACV-Ile at 0.25 mA/cm(2) for only 5 min resulted in the deposition of appreciable amounts of ACV (36.4 ± 5.7n mol/cm(2) and 40.3 ± 6.1 nmol/cm(2), respectively), corresponding to supra-therapeutic average concentrations in skin against HSV-1 or HSV-2. The results demonstrated that cutaneous bioavailability of ACV could be significantly improved after short-duration iontophoresis of ionizable, biolabile ACV-X prodrugs.

Intravenous acyclovir and renal dysfunction in children: a matched case control study

OBJECTIVES

A cluster of children receiving intravenous (IV) acyclovir for meningoencephalitis developed acute renal failure in April-May 2008, which prompted a retrospective case-control study to determine the rate of and risk factors for acute nephrotoxicity during IV acyclovir treatment in children.

STUDY DESIGN

The percentage decrease in glomerular filtration rate in children receiving IV acyclovir who had ≥ 1 creatinine measurement after acyclovir initiation from October 2006 to January 2009 was classified as renal risk, injury, or failure according to modified Pediatric Risk Injury, Failure, Loss, End-Stage Renal Disease criteria. Univariate and multivariate matched analyses were conducted to identify risk factors contributing to nephrotoxicity.

RESULTS

In the selected study group, renal dysfunction was seen in 131 of 373 (35%) treatment courses studied: 81 of 373 (22%) risk, 36 of 373 (9.7%) injury, and 14 of 373 (3.8%) failure. Most renal dysfunction occurred within 48 hours of the initiation of acyclovir. Renal function returned to the normal range but not to baseline in most cases during the follow-up period. Risk factors for renal dysfunction included acyclovir dose >15 mg/kg (OR 3.81, 95% CI 1.55-9.37) for risk; cumulative exposure greater than calculated cumulative exposure based on 500 mg/m(2)/dose (OR 6.00, 95% CI 1.95-18.46) for injury; and age >8 years (OR 21.5, 95% CI 2.2, >1000) and ceftriaxone coadministration (OR 19.3, 95% CI 1.8, >1000) for failure.

CONCLUSIONS

Nephrotoxicity associated with IV acyclovir is common and necessitates renal function monitoring. Risk factors include greater dose, older age, and concomitant ceftriaxone administration. Outside the neonatal period, renal dysfunction may be minimized by dosing IV acyclovir below thresholds associated with nephrotoxicity (ie, ≤ 500 mg/m(2)/dose or ≤ 15 mg/kg/dose), particularly in older patients.