Valacyclovir pharmacokinetics and exploratory pharmacodynamics in young adults with Epstein-Barr virus infectious mononucleosis

Valacyclovir or valganciclovir for cytomegalovirus prophylaxis: A randomized controlled trial in adult and pediatric kidney transplant recipients

BACKGROUND

Valganciclovir (valG), a cytomegalovirus (CMV) prophylactic agent, has dose-limiting side effects. The tolerability and effectiveness of valacyclovir (valA) as CMV prophylaxis is unknown.

METHODS

We conducted a randomized, open-label, single-center trial of valA versus valG for all posttransplant CMV prophylaxis in adult and pediatric kidney recipients. Participants were randomly assigned to receive valA or valG. Primary endpoints were the incidence of CMV viremia and side-effect related drug reduction with secondary assessment of incidence of EBV viremia.

RESULTS

Of the 137 sequential kidney transplant recipients enrolled, 26 % were positive and negative for CMV antibody in donor and recipient respectively. The incidence of CMV viremia (4 of 71 [6 %]; 8 of 67 [12 %] P = 0.23), time to viremia (P = 0.16) and area under CMV viral load time curve (P = 0.19) were not significantly different. ValG participants were significantly more likely to require side-effect related dose reduction (15/71 [21 %] versus 1/66 [2 %] P = 0.0003). Leukopenia was the most common reason for valG dose reduction and granulocyte-colony stimulating factor was utilized for leukopenia recovery more frequently (25 % in valG vs 5 % in valA: P = 0.0007). Incidence of EBV viremia was not significantly different.

CONCLUSIONS

ValA has significantly less dose-limiting side effects than valG. In our study population, a significant increase in CMV viremia was not observed, in adults and children after kidney transplant, compared to valG.

TRIAL REGISTRATION NUMBER

NCT01329185.

Prevention and Treatment of Persistent Epithelial Defects After Common Refractive Surgery Procedures

PURPOSE

To discuss the prevention and treatment of persistent epithelial defects after the most common refractive surgeries-photorefractive keratectomy, laser in situ keratomileusis, or small incision lenticule extraction.

METHODS

PubMed was used to search the medical literature.

RESULTS

Persistent epithelial defects are infrequent after photorefractive keratectomy, laser in situ keratomileusis, or small incision lenticule extraction. In the authors' opinion, any persistent epithelial defect present at 1 week or beyond after surgery should be treated aggressively with a properly fit bandage contact lens, lubrication with non-preserved artificial tears, and treatment of any eyelid abnormalities, including nocturnal lagophthalmos. Consideration should be given for presumptive treatment for herpes simplex virus or varicella zoster virus infection. If the persistent epithelial defect does not close within 2 weeks, then other measures should be considered, such as autologous serum drops, topical losartan, amniotic membranes, and topical human recombinant nerve growth factor to limit corneal scarring fibrosis and microbial infection.

CONCLUSIONS

Persistent epithelial defects are among the most feared complications of refractive surgery. Timely and aggressive treatment should be instituted to close the epithelium prior to the development of scarring fibrosis and/or microbial corneal infection. [J Refract Surg. 2024;40(2):e117-e124.].

Valacyclovir as Initial Treatment for Acute Retinal Necrosis: A Pharmacokinetic Modeling and Simulation Study

PURPOSE

Acute retinal necrosis (ARN) is a feared complication of infectious retinitis most commonly caused by varicella zoster virus (VZV). We performed a pharmacokinetic modeling and simulation study by integrating the existing understanding of physiology with previously published data to evaluate the vitreal penetration of oral valacyclovir for the treatment of ARN, under various dosing scenarios.

METHOD

We compared different oral valacyclovir dosing regimens with intravenous acyclovir. The vitreous compartment was modeled as a peripheral compartment, and paired serum and vitreal acyclovir concentrations were obtained from previously published data of adult patients with ARN undergoing vitrectomy. The efficacy threshold for vitreal acyclovir concentrations was based on the previously reported IC₅₀ values for VZV.

RESULTS

Based on the minimum vitreal acyclovir concentrations (C_min) relative to the mean IC₅₀ for VZV, valacyclovir 1.5 g every 8 hours performed similarly to intravenous acyclovir 700 mg every 8 hours, with the minimum concentration (C_min) exceeding the mean IC₅₀ after the second dose. In contrast, the standard dosing regimen for herpes zoster, valacyclovir 1 g every 8 hours, performed inferiorly to the intravenous acyclovir regimen throughout the dosing interval.

CONCLUSIONS

Modeling and simulation data support oral valacyclovir for the treatment of ARN, although the required dosing exceeds the recommended FDA dose size for herpes zoster.

The Biology and Clinical Utility of EBV Monitoring in Blood

Epstein-Barr virus (EBV) DNA in blood can be quantified in peripheral blood mononuclear cells, in circulating cell-free (CCF) DNA specimens, or in whole blood. CCF viral DNA may be actively released or extruded from viable cells, packaged in virions or passively shed from cells during apoptosis or necrosis. In infectious mononucleosis, viral DNA is detected in each of these kinds of specimens, although it is only transiently detected in CCF specimens. In nasopharyngeal carcinoma, CCF EBV DNA is an established tumor marker. In EBV-associated Hodgkin lymphoma and in EBV-associated extranodal NK-/T-cell lymphoma, there is growing evidence for the utility of CCF DNA as a tumor marker.

The cycle of EBV infection explains persistence, the sizes of the infected cell populations and which come under CTL regulation

Previous analysis of Epstein-Barr virus (EBV) persistent infection has involved biological and immunological studies to identify and quantify infected cell populations and the immune response to them. This led to a biological model whereby EBV infects and activates naive B-cells, which then transit through the germinal center to become resting memory B-cells where the virus resides quiescently. Occasionally the virus reactivates from these memory cells to produce infectious virions. Some of this virus infects new naive B-cells, completing a cycle of infection. What has been lacking is an understanding of the dynamic interactions between these components and how their regulation by the immune response produces the observed pattern of viral persistence. We have recently provided a mathematical analysis of a pathogen which, like EBV, has a cycle of infected stages. In this paper we have developed biologically credible values for all of the parameters governing this model and show that with these values, it successfully recapitulates persistent EBV infection with remarkable accuracy. This includes correctly predicting the observed patterns of cytotoxic T-cell regulation (which and by how much each infected population is regulated by the immune response) and the size of the infected germinal center and memory populations. Furthermore, we find that viral quiescence in the memory compartment dictates the pattern of regulation but is not required for persistence; it is the cycle of infection that explains persistence and provides the stability that allows EBV to persist at extremely low levels. This shifts the focus away from a single infected stage, the memory B-cell, to the whole cycle of infection. We conclude that the mathematical description of the biological model of EBV persistence provides a sound basis for quantitative analysis of viral persistence and provides testable predictions about the nature of EBV-associated diseases and how to curb or prevent them.

Epstein-Barr virus (EBV) is a herpesvirus that establishes a lifelong persistent infection in virtually all human beings. This infection is a risk factor for the subsequent development of certain tumors and possibly also autoimmune diseases. In order to understand the origin of these diseases, it is necessary to first understand how EBV maintains persistent infection. We have used mathematical analysis to study this question. We find that the characteristic cycle of infected stages that EBV establishes in vivo allows it to persist stably at extremely low levels. This represents a consistent mathematical description of EBV infection and allows us to describe what must change to convert benign infection into pathogenic infection, as well as what kind of efficacy drugs and vaccines must have in order to be useful.

Acyclovir reduces the duration of fever in patients with infectious mononucleosis-like illness

Acyclovir is known for its antiviral activity against some pathogenic viruses such as the Epstein-Barr virus (EBV) that causes infectious mononucleosis (IM) and IM-like illness. Therefore, we empirically administered acyclovir to patients with suspected EBV-IM and IM like-illness, upon their admission to our hospital. We admitted 25 patients, who were hospitalized for fever and lymphadenopathy, to the Tohoku University Hospital Infectious Disease Ward. As part of treatment, 8 of these patients were given acyclovir (750 mg/day) with their consent and were assigned to the acyclovir group; the remaining 17 patients were assigned to the control group. The mean age of acyclovir patients (all men) was 42±5.2 years, and that of control patients (13 men and 4 women) was 31±3.0 years. The cause of illness was confirmed as EBV-IM in 6 patients (1, acyclovir; 5, control), and remained unknown for the other 19 IM-like illness patients (7, acyclovir; 12, control). A shorter duration of hospitalization and fever was observed in the acyclovir compared to that in the control patients (hospitalization duration: 16±3.7 vs. 27±7.7 days, P=0.36; fever duration: 4.5±1.8 vs. 18±6.5 days, P=0.04). Additionally, serum amyloid A (SAA) levels were lower in acyclovir than that in control patients (98±37 vs. 505±204 µg/mL, P=0.02). Therefore, we propose that acyclovir is a potential therapeutic agent for both EBV-IM and IM like-illnesses. Future studies should further examine its mechanism of action.

Current diagnosis and management of infectious mononucleosis

PURPOSE OF REVIEW

Infectious mononucleosis is a common, usually self-limited disease. However, infectious mononucleosis may present with severe manifestations. Complications may also occur. Consequently, diagnostic and treatment issues regarding infectious mononucleosis are of major importance.

RECENT FINDINGS

In this review, we focus on the evaluation of articles providing diagnosis and treatment data for infectious mononucleosis, published during the past 2 years. Twelve studies, deriving from extended search in PubMed, were included. Nine studies provided diagnosis data. The evaluated diagnostic methods were real-time PCR (RT-PCR), IgM/IgG antibodies measured with different assays [measurement of Epstein-Barr virus viral load (EBV-VL) in peripheral blood, neutrophil/lymphocyte/monocyte counts, C-reactive protein values, and monospot test]. The sensitivities reported for RT-PCR were high. The available treatment data were scarce (three studies). Two of them suggested that antivirals (mainly acyclovir and valacyclovir) may have a role in the treatment of infectious mononucleosis with complications, whereas the remaining study presented novel potential therapeutic patents including 5-substituted uracyle, azacytosine derivatives, and peptides inhibiting EBV-mediated membrane fusion.

SUMMARY

RT-PCR and measurement of EBV-VL may provide useful tools for the early diagnosis of infectious mononucleosis in cases with inconclusive serological results. Antiviral agents may provide a useful treatment option in patients with severe infectious mononucleosis.

High-dose valacyclovir HSV-2 suppression results in greater reduction in plasma HIV-1 levels compared with standard dose acyclovir among HIV-1/HSV-2 coinfected persons: a randomized, crossover trial

BACKGROUND

Standard-dose HSV-2 suppressive therapy (acyclovir 400 mg twice daily) reduces plasma HIV-1 levels by 0.25-0.50 log(10) copies/mL. It is not known if higher doses might further suppress HIV-1 levels.

METHODS

We enrolled 32 HIV-1/HSV-2 dually infected Kenyan individuals who were not on antiretroviral therapy (ART) into a randomized, crossover trial of 2 dosing regimens of HSV-2 suppression: valacyclovir 1.5 g vs acyclovir 400 mg, both twice daily for 12 weeks, then a 2-week washout, and then the alternative for 12 weeks. Weekly plasma HIV-1 RNA quantity was measured (ClinicalTrials.gov number NCT01026454).

RESULTS

Mean plasma HIV-1 levels were significantly lower on valacyclovir compared with acyclovir: 2.94 vs 3.56 log(10) copies/mL, an average difference of 0.62 log(10) copies/mL (95% confidence interval [CI]: -0.68, -0.55; P < .001), a 76% decrease. Valacyclovir resulted in a 1.23 log(10) copies/mL decrease compared with baseline HIV-1 levels without HSV-2 suppression. Adherence was similar (99.4% of dispensed study tablets taken), and high-dose valacyclovir was well tolerated.

CONCLUSIONS

High-dose valacyclovir reduced plasma HIV-1 viral levels by 0.62 log(10) copies/mL compared with standard-dose acyclovir. The potential for higher-dose HSV-2 suppressive therapy to slow HIV-1 disease progression and reduce HIV-1 infectiousness among HIV-1/HSV-2 coinfected persons not yet eligible for ART warrants further evaluation.