Valaciclovir:development, clinical utility and potential

Valacyclovir-associated acute kidney injury

A man in his 70s presented to hospital with an acute kidney injury. He recently had started taking valacyclovir for treatment of shingles. The valacyclovir was stopped and his acute kidney injury improved. Work-up for other causes of acute kidney injury was negative and he was diagnosed with valacyclovir-associated acute kidney injury. He was discharged home after four days in the hospital with improving renal function.

Comparing Prodrugs with Acyclovir for Treating Postherpetic Neuralgia among Herpes Zoster Patients: A Systematic Review and Meta-Analysis

Postherpetic neuralgia (PHN) is a common, painful, and long-term complication of herpes zoster (HZ). PHN increases the demand for healthcare services and, previous studies showed that patients who received antiviral agents were less likely to develop PHN. The objective of this study was to compare the efficacy of prodrugs and acyclovir in treating PHN among patients with HZ. The search included the PubMed, Medline, Embase, and Cochrane Center of Register of Controlled Trails databases through February 2022. Clinical trials and randomized controlled trials (RCTs) involving antiviral agent intervention for HZ patients diagnosed with PHN were eligible for inclusion. A meta-analysis was conducted to calculate pooled risk ratios (RRs) with 95% confidence intervals (CIs) with a fix-effect model. Five RCTs with 1147 HZ patients met our eligibility criteria. Our meta-analysis found that there was a significantly lower risk of PHN for members of the prodrugs group (famciclovir and valaciclovir) compared with those who received acyclovir (RR = 0.86, 95%, CI: 0.75 to 0.98, p = 0.03). The review of studies indicated that the efficacy of prodrugs was better than acyclovir for reliving PHN.

Neurotoxicity associated with acyclovir and valacyclovir: A systematic review of cases

WHAT IS KNOWN AND OBJECTIVE

Acyclovir and valacyclovir are commonly used antivirals with good general tolerance. Despite their good safety profile, they can cause systemic adverse effects, such as neurotoxicity, which are less frequent and known. The objective of this review was to collect all the reported cases of neurotoxicity associated with acyclovir and valaciclovir published in the literature and characterize their clinical course and interventions.

METHODS

A systematic review of cases was carried out following the guidelines established by "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA). The research was carried out using the PubMed-Medline and Embase databases, between July 1984 and March 2021.

RESULTS AND DISCUSSION

A total of 119 cases with neurotoxicity mainly related to acyclovir (n = 88; 73.9%), followed by valaciclovir (n = 35; 29.4%) were analysed. 49.6% (n = 59) were men with a mean age of 59.5 years ± 21.1 (0.5-88). In 83.3% of the cases, renal impairment was documented and 57.1% (n = 68) with end-stage renal disease. The administered dose was higher than the renal adjustment recommendations in 59.7% of the cases. The global mean of onset of symptoms was 3.1 days ± 4.3 (0.2-28) after the start of antivirals. The mean recovery time was 9.8 days ± 21.7 (0.2-180). 74.4% of the patients had a recovery of ≤7 days, 15.9% between 8 and 15 days and 9.8% > 15 days.

WHAT IS NEW AND CONCLUSION

The neurotoxicity induced by acyclovir and its derivative valacyclovir is a poorly known and rare adverse effect that can occur mainly in patients with advanced age and impaired renal function. The most characteristic symptoms are confusion, altered level of consciousness, hallucinations, agitation and dysarthria. The basis of treatment is the discontinuation of the antiviral, and in some cases, it may require additional clearance by dialysis.

Periodontal herpesvirus morbidity and treatment

Four billion individuals worldwide have a history of periodontitis, with the poorest people in society most affected. Periodontitis can lead to unsightly drifting of teeth and tooth loss that may interfere with the wellbeing of daily living and has also been linked to at least 57 medical diseases and disabilities. The etiology of severe periodontitis includes active herpesviruses, specific bacterial pathogens, and destructive immune responses, but herpesviruses seem to be the major pathogenic determinant. Periodontal herpesviruses that disseminate via the systemic circulation to nonoral sites may represent a major link between periodontitis and systemic diseases. Current treatment of periodontitis focuses almost exclusively on bacterial biofilm and will require revision. Periodontal therapy that targets both herpesviruses and bacterial pathogens can provide long-term clinical improvement and potentially reduces the risk of systemic diseases. Molecular diagnostic tests for periodontal pathogens may enable early microbial identification and preemptive therapy. This review details an efficient and reliable anti-infective treatment of severe periodontitis that can be carried out in minimal time with minimal cost.

Progress in meeting today's demands in genital herpes: an overview of current management

Treatment of genital herpes requires accurate diagnosis, patient support, and effective treatment. Diagnosis is usually straightforward for classic presentations characterized by vesicular lesions but can be challenging for atypical presentations, which are more common. Diagnosis of asymptomatic infection requires access to molecular technology or type-specific serologic assays. Misconceptions about herpes simplex infection are common and patient education is essential. Patient concerns extend beyond disease frequency and severity-the psychological impact should not be underestimated. Antiviral therapy is relevant at all stages of infection. Acyclovir, valacyclovir, and famciclovir are effective and well tolerated for genital herpes treatment. Continuous suppressive therapy controls all symptoms of recurrent disease and helps to relieve disease complications. The prodrugs valacyclovir and famciclovir offer easier, less-frequent dosing than required for acyclovir. Valacyclovir achieves effective suppression when taken once a day. Interventions to prevent genital herpes transmission and to control the global problem are urgently required.

Valaciclovir: a review of its use in the management of herpes zoster

Varicella zoster virus (VZV), the pathogen responsible for herpes zoster, belongs to the herpesvirus family and is sensitive to the antiviral drug aciclovir. However, the low oral bioavailability of aciclovir has to some extent limited its efficacy in the treatment of herpes zoster and has prompted the development of the more readily absorbed oral prodrug valaciclovir. In a large comparative study valaciclovir, (1000 mg 3 times daily for 7 days) was at least as effective as aciclovir (800 mg 5 times daily for 7 days) in controlling the symptoms of acute herpes zoster. Importantly, valaciclovir alleviated zoster-associated pain and postherpetic neuralgia significantly faster than aciclovir. A 14-day regimen of valaciclovir showed no significant advantage over the 7-day regimen. A smaller trial in Japanese patients focusing primarily on the cutaneous (rash) signs of herpes zoster confirmed the similar efficacy of valaciclovir and aciclovir in the 7-day regimen. This study did not follow all patients for a formal analysis of postherpetic neuralgia. Valaciclovir and aciclovir demonstrated similar efficacy for the control of cutaneous lesions and ocular complications in patients with zoster ophthalmicus. Preliminary results of a large controlled trial indicate that valaciclovir 1000 mg 3 times daily and famciclovir (the prodrug of penciclovir) 500 mg 3 times daily are of similar efficacy in speeding resolution of acute herpes zoster rash and shortening the duration of postherpetic neuralgia. Starting treatment later than 72 hours after rash onset did not significantly reduce the beneficial effect of valaciclovir on duration of zoster-associated pain (a continuum of pain that encompasses both acute pain and postherpetic neuralgia) in a large observational study, suggesting that valaciclovir might be effective when given later than previously thought. However, valaciclovir should ideally be given as soon as possible after symptoms appear. With the recommended regimen for the treatment of herpes zoster (1000 mg 3 times daily for 7 days) valaciclovir was well tolerated, with nausea and headache being the most commonly reported adverse events. The adverse events profile of the agent was similar to that seen with aciclovir or famciclovir.

CONCLUSION

The efficacy of valaciclovir for the treatment of herpes zoster has been confirmed and extended by follow-up studies in herpes zoster ophthalmicus, in Japanese patients, and in the wider primary care setting. Valaciclovir is at least equivalent to, and better in certain parameters than, aciclovir and appears to have similar efficacy to famciclovir 500 mg 3 times daily. Valaciclovir is a well tolerated first-line therapy with an established place in the treatment of immunocompetent patients with herpes zoster.