Oral brivudin in comparison with acyclovir for herpes zoster: a survey study on postherpetic neuralgia

Efficacy and safety of brivudine for the treatment of herpes zoster: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Brivudine has been used in herpes zoster (HZ) treatment for years, but the safety and efficacy of brivudine are inconclusive. Here we perform a meta-analysis to assess the efficacy, safety, incidence of postherpetic neuralgia of brivudine.

METHODS

Data of randomized controlled Trials (RCTS) were obtained from the databases of both English (PubMed, Embase, and Cochrane Library) and Chinese (China National Knowledge Infrastructure, China Science Journal Database, and WanFang Database) literatures from inception to 12 September 2022. Meta-analyses of efficacy and safety of Brivudine for the treatment of herpes zoster for RCTS were conducted.

RESULTS

The analyses included seven RCTS (2095 patients in experimental group and 2076 patients in control group) in the treatment of HZ with brivudine. It suggested that the brivudine group was superior to the control group in terms of efficacy (p = .0002) and incidence of postherpetic neuralgia (p = .04). But the incidence of adverse reactions has no significant difference between the brivudine and the control groups (p = .22). In addition, subgroup analysis of adverse events also showed that brivudine was about the same safety as other modalities in the treatment of HZ (p > .05).

CONCLUSIONS

Brivudine is effective for HZ. However, the evidence on the safety of brivudine is insufficient.

Herpes Zoster in Four HIV Seropositive Patients and One Patient With Recurrent Carcinoma After Radiotherapy

Herpes zoster is a ubiquitous ultramicroscopic neurotropic virus that causes pruritic acute grouped vesicular eruptions and rashes, these vesicles rupture spontaneously resulting in pustules, crustations, which are pruritic in nature on the affected skin along the course of the dermatome resulting in scab. The scab withers off later leaving a permanent scar and pigmentation. The characteristic clinical finding was that vesicles or ulcers resulting from herpes zoster lesions never cross the midline. Two such reported cases of herpes zoster in seropositive HIV patients that resulted in extensive crustations and periorbital edema, left unilateral facial pain of burning quality in 25-year-old female patient and spontaneous exfoliation of a tooth in another 35-year-old patient, treated with drug therapy comprising acyclovir, gabapentin, amitriptyline are discussed here.

DNA polymerases of herpesviruses and their inhibitors

Human herpesviruses are large double-stranded DNA viruses belonging to the Herpesviridae family. The main characteristics of these viruses are their ability to establish a lifelong latency into the host with a potential to reactivate periodically. Primary infections and reactivations with herpesviruses are responsible for a large spectrum of diseases and may result in severe complications in immunocompromised patients. The viral DNA polymerase is a key enzyme in the replicative cycle of herpesviruses, and the target of most antiviral agents (i.e., nucleoside, nucleotide and pyrophosphate analogs). However, long-term prophylaxis and treatment with these antivirals may lead to the emergence of drug-resistant isolates harboring mutations in genes encoding viral enzymes that phosphorylate drugs (nucleoside analogs) and/or DNA polymerases, with potential cross-resistance between the different analogs. Drug resistance mutations mainly arise in conserved regions of the polymerase and exonuclease functional domains of these enzymes. In the polymerase domain, mutations associated with resistance to nucleoside/nucleotide analogs may directly or indirectly affect drug binding or incorporation into the primer strand, or increase the rate of extension of DNA to overcome chain termination. In the exonuclease domain, mutations conferring resistance to nucleoside/nucleotide analogs may reduce the rate of excision of incorporated drug, or continue DNA elongation after drug incorporation without excision. Mutations associated with resistance to pyrophosphate analogs may alter drug binding or the conformational changes of the polymerase domain required for an efficient activity of the enzyme. Novel herpesvirus inhibitors with a potent antiviral activity against drug-resistant isolates are thus needed urgently.

Current Drugs to Treat Infections with Herpes Simplex Viruses-1 and -2

Herpes simplex viruses-1 and -2 (HSV-1 and -2) are two of the three human alphaherpesviruses that cause infections worldwide. Since both viruses can be acquired in the absence of visible signs and symptoms, yet still result in lifelong infection, it is imperative that we provide interventions to keep them at bay, especially in immunocompromised patients. While numerous experimental vaccines are under consideration, current intervention consists solely of antiviral chemotherapeutic agents. This review explores all of the clinically approved drugs used to prevent the worst sequelae of recurrent outbreaks by these viruses.

Herpes Zoster (Shingles) Patient-Centered Wound Outcomes: A Literature Review

GENERAL PURPOSE

To present a comprehensive review of patient-centered outcomes of topical or systemic interventions applied to those with shingles or postherpetic neuralgia to inform clinical practice and identify related research needs.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will be able to:1. Explain the importance of early diagnosis and treatment of herpes zoster (HZ).2. Identify interventions that have resulted in documented improvement of validated patient-centered outcomes in patients with HZ or postherpetic neuralgia.3. Recognize the average per patient medical costs of HZ in the US.

Emergence of varicella-zoster virus resistance to acyclovir: epidemiology, prevention, and treatment

Introduction: Acyclovir has led to the development of successful systemic therapy for herpes simplex virus and varicella-zoster virus (VZV) infection, and the use of valacyclovir and famciclovir has improved treatment. Additionally, the use of a helicase-primase (HP) inhibitor (HPI), amenamevir, is changing the treatment of herpes zoster (HZ).Area covered: VZV infection is prevented by vaccines and is treated with antiviral agents. Acyclovir and penciclovir are phosphorylated by viral thymidine kinase and work as chain terminators. Improvements in the management of immunocompromised patients have reduced severe and prolonged immunosuppression and chronic VZV infection with acyclovir-resistant mutants has become rarer. The HP is involved in the initial step of DNA synthesis and amenamevir has novel mechanisms of action, efficacy to acyclovir-resistant mutants, and pharmacokinetic characteristics. The literature search for PUBMED was conducted on 10 April 2020 and updated on 4 November 2020.Expert opinion: Amenamevir has been used to treat HZ in Japan. Although the number of patients with VZV infection will decrease owing to the use of vaccines, the addition of HPI will improve treatment and treatment options for resistant viruses. The clinical use of HPIs in addition to current nucleoside analogs opens a new era of antiherpes therapy.

Antiviral Drugs Against Herpesviruses

The discovery of the nucleoside analogue, acyclovir, represented a milestone in the management of infections caused by herpes simplex virus and varicella-zoster virus. Ganciclovir, another nucleoside analogue, was then used for the management of systemic and organ-specific human cytomegalovirus diseases. The pyrophosphate analogue, foscarnet, and the nucleotide analogue, cidofovir, have been approved subsequently and constitute the second-line antiviral drugs. However, the viral DNA polymerase is the ultimate target of all these antiviral agents with a possible emergence of cross-resistance between these drugs. Recently, letermovir that targets the viral terminase complex was approved for the prophylaxis of human cytomegalovirus infections in hematopoietic stem cell transplant recipients. Other viral targets such as the protein kinase and the helicase-primase complex are also evaluated for the development of novel potent inhibitors against herpesviruses.

[S2k guideline for the diagnosis and therapy of zoster and post-zoster neuralgia]

Diese Leitlinie richtet sich an Dermatologen, Ophthalmologen, HNO-Ärzte, Pädiater, Neurologen, Virologen sowie Infektiologen, Anästhesisten und Allgemeinmediziner in Klinik und Praxis und dient zur Information für andere medizinische Fachrichtungen, die an der Behandlung des Zoster beteiligt sind. Darüber hinaus soll die Leitlinie Kostenträgern und politischen Entscheidungsträgern zur Orientierung dienen. Die Leitlinie wurde im formellen Konsensusverfahren (S2k) von Dermatologen, Virologen/Infektiologen, Ophthalmologen, HNO-Ärzten, Neurologen, Pädiatern und Anästhesisten/Schmerzmedizinern erstellt.

Die Leitlinie stellt einen Überblick über die klinische und molekulare Diagnostik sowie den Antigennachweis, die Antikörperkultur und Viruskultur dar. Diagnostisch besondere Situationen und komplizierte Verläufe der Erkrankung finden ebenfalls Berücksichtigung. Die antivirale Therapie des Zoster und der Postzosterneuralgie wird im Allgemeinen und für besondere Situationen dargelegt. Detaillierte Angaben zur Schmerzbehandlung finden Erwähnung und sind in einer Übersicht dargestellt. Ebenso werden die lokaltherapeutischen Maßnahmen thematisiert.

Antiviral Drugs Against Alphaherpesvirus

The discovery of acyclovir and penciclovir has led to the development of a successful systemic therapy for treating herpes simplex virus infection and varicella-zoster virus infection, and the orally available prodrugs, valacyclovir and famciclovir, have improved antiviral treatment compliance. Acyclovir and penciclovir are phosphorylated by viral thymidine kinase and are incorporated into the DNA chain by viral DNA polymerase, resulting in chain termination. Helicase-primase plays an initial step in DNA synthesis to separate the double strand into two single strands (replication fork) and is a new target of antiviral therapy. The helicase-primase inhibitors (HPIs) pritelivir and amenamevir have novel mechanisms of action, drug resistance properties, pharmacokinetic characteristics, and clinical efficacy for treating genital herpes. The clinical study of amenamevir in herpes zoster has been completed, and amenamevir has been submitted for approval for treating herpes zoster in Japan. The clinical use of HPIs will be the beginning of a new era of anti-herpes therapy.

European consensus-based (S2k) Guideline on the Management of Herpes Zoster - guided by the European Dermatology Forum (EDF) in cooperation with the European Academy of Dermatology and Venereology (EADV), Part 2: Treatment

Herpes zoster (HZ, shingles) is a frequent medical condition which may severely impact the quality of life of affected patients. Different therapeutic approaches to treat acute HZ are available. The aim of this European project was the elaboration of a consensus-based guideline on the management of patients who present with HZ, considering different patient populations and different localizations. This interdisciplinary guideline aims at an improvement of the outcomes of the acute HZ management concerning disease duration, acute pain and quality of life of the affected patients and at a reduction in the incidence of postherpetic neuralgia (PHN) and other complications. The guideline development followed a structured and pre-defined process, considering the quality criteria for guidelines development as suggested by the AGREE II instrument. The steering group was responsible for the planning and the organization of the guideline development process (Division of Evidence-Based Medicine, dEBM). The expert panel was nominated by virtue of clinical expertise and/or scientific experience and included experts from the fields of dermatology, virology/infectiology, ophthalmology, otolaryngology, neurology and anaesthesiology. Recommendations for clinical practice were formally consented during the consensus conference, explicitly considering different relevant aspects. The guideline was approved by the commissioning societies after an extensive internal and external review process. In this second part of the guideline, therapeutic interventions have been evaluated. The expert panel formally consented recommendations for the treatment of patients with HZ (antiviral medication, pain management, local therapy), considering various clinical situations. Users of the guideline must carefully check whether the recommendations are appropriate for the context of intended application. In the setting of an international guideline, it is generally important to consider different national approaches and legal circumstances with regard to the regulatory approval, availability and reimbursement of diagnostic and therapeutic interventions.

Advances in the antiviral therapy of herpes virus infection in children

Herpes viruses are ubiquitous and primary infections, with many of these viruses common during childhood. In general, children tolerate primary infection well, with only mild symptoms, but in the immunocompromised, including the newborn, infection can be associated with serious morbidity and mortality. Drug treatment for many of the herpes infections is available but is often associated with serious side effects. In the pediatric age group, treatment is further hindered by a lack of information on suitable dosing regimes, unavailability of oral solutions and a lack of clinical trials specifically investigating response to treatment in this group of patients. This article will review current evidence regarding the pharmacokinetics and dosing of the most commonly used antiherpetic agents and will look specifically at the treatment of the more common herpes virus infections in children.

Prevention of shingles by varicella zoster virus vaccination

Herpes zoster is caused by reactivation from previous varicella zoster virus (VZV) infection, and affects millions of people worldwide. It primarily affects older adults and those with immune system dysfunction, most likely as a result of reduced or lost VZV-specific cell-mediated immunity. Complications include post-herpetic neuralgia, a potentially debilitating and chronic pain syndrome. Current treatment of herpes zoster and post-herpetic neuralgia involves antiviral agents and analgesics, and is associated with significant economic cost. Results from several clinical trials have determined that a live, attenuated VZV vaccine using the Oka/Merck strain (Zostavax) is safe, elevates VZV-specific cell-mediated immunity, and significantly reduces the incidence of herpes zoster and post-herpetic neuralgia in people over 60 years of age. Regulatory approval has recently been obtained and once launched, it is expected that this vaccine will significantly reduce the morbidity and financial costs associated with herpes zoster. Durability of vaccine response and possible booster vaccination will still need to be determined.

Acute hepatitis due to brivudin: a case report

BACKGROUND/AIMS

Brivudin is licensed in several European countries for the treatment of herpetic infections, and is considered safe (approximately 1% of patients with transient elevation of liver enzymes) in large multicenter trials.

METHODS

We report a case of acute brivudin hepatitis documented with a liver biopsy in detail.

RESULTS

Liver biopsy demonstrated acute liver injury with a predominant cytolytic pattern and features suggestive of a drug-induced immunoallergic hepatitis. Elevated ALT levels returned to normal within weeks.

CONCLUSIONS

This is the first published case of acute immunoallergic hepatitis due to brivudin.

Recommendations for the management of herpes zoster

The objective of this article is to provide evidence-based recommendations for the management of patients with herpes zoster (HZ) that take into account clinical efficacy, adverse effects, impact on quality of life, and costs of treatment. Systematic literature reviews, published randomized clinical trials, existing guidelines, and the authors' clinical and research experience relevant to the management of patients with HZ were reviewed at a consensus meeting. The results of controlled trials and the clinical experience of the authors support the use of acyclovir, brivudin (where available), famciclovir, and valacyclovir as first-line antiviral therapy for the treatment of patients with HZ. Specific recommendations for the use of these medications are provided. In addition, suggestions are made for treatments that, when used in combination with antiviral therapy, may further reduce pain and other complications of HZ.

Viral infections affecting the skin in organ transplant recipients: epidemiology and current management strategies

Viral skin infections are common findings in organ transplant recipients. The most important etiological agents are the group of human herpesviruses (HHV), human papillomaviruses (HPV), and molluscum contagiosum virus. HHV that are important in this group of patients are herpes simplex virus (HSV) types 1 and 2, varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), HHV-6 and -7, and HHV-8, which causes Kaposi sarcoma (KS). HSV infections are characterized by their ability to establish latency and then reactivate at a later date. The most common manifestations of HSV infection in organ transplant recipients are mucocutaneous lesions of the oropharynx or genital regions. Treatment is usually with acyclovir, valaciclovir, or famciclovir. Acyclovir resistance may arise although the majority of acyclovir-resistant strains have been isolated from AIDS patients and not organ transplant recipients. In such cases, alternatives such as foscarnet, cidofovir, or trifluridine may have to be considered. VZV causes chickenpox as well as herpes zoster. In organ transplant recipients, recurrent herpes zoster can occur. Acute chickenpox in organ transplant patients should be treated with intravenous acyclovir. CMV infection occurs in 20-60% of all transplant recipients. Cutaneous manifestations, which include nonspecific macular rashes, ulcers, purpuric eruptions, and vesiculobullous lesions, are seen in 10-20% of patients with systemic infection and signify a poor prognosis. The present gold standard for treatment is ganciclovir, but newer drugs such as valganciclovir appear promising. EBV is responsible for some cases of post-transplant lymphoproliferative disorder, which represents the greatest risk of serious EBV disease in transplant recipients. HHV-6 and HHV-7 are two relatively newly discovered viruses and, at present, the body of information concerning these two agents is still fairly limited. KS is caused by HHV-8, which is the most recently discovered lymphotrophic HHV. Iatrogenic KS is seen in solid-organ transplant recipients, with a prevalence of 0.5-5% depending on the patient's country of origin. HPV is ubiquitous, and organ transplant recipients may never totally clear HPV infections, which are the most frequently recurring infections in renal transplant recipients. HPV infection in transplant recipients is important because of its link to the development of certain skin cancers, in particular, squamous cell carcinoma. Regular surveillance, sun avoidance, and patient education are important aspects of the management strategy.

Linear Darier disease with herpes zoster superinfection treated successfully by brivudine

We report the case of a human immunodeficiency virus-positive patient presenting linear Darier disease with varicella-zoster virus superinfection following the lines of Blaschko. The lesions healed after treatment with brivudine.

Actualización en el tratamiento del herpes zóster

The systemic treatment of herpes zoster shortens the healing process, and prevents or alleviates pain and other acute or chronic complications, especially when it is administered in the first 72 hours after symptoms appear. This treatment is especially indicated in patients over the age of 50 and in those who, regardless of age, have head and neck involvement, especially in herpes zoster ophthalmicus. The drugs approved in Europe for the systemic treatment of herpes zoster are aciclovir, valaciclovir, famciclovir and brivudine. Brivudine shows greater effectiveness against the varicella-zoster virus than aciclovir and its derivatives, and can be given just once a day for seven days, compared to multiple doses of the latter. As opposed to the others, brivudine is a non-nephrotoxic drug that should not be administered to immunodepressed patients or to those being treated with 5-fluorouracil. The treatment of herpes zoster to reduce pain should be combined with analgesics and neuroactive agents (amitriptyline, gabapentin, etc). While corticosteroids are of dubious efficacy in the treatment of post-herpes neuralgia, the intensity and duration of the pain can be reduced with some topical treatments (capsaicin, lidocaine patches, etc). Finally, this review discusses treatment guidelines for special locations (cranial nerves) and different subpopulations (children, pregnant women, immunodepressed patients, etc).

Current management of herpes zoster: the European view

The overall incidence of herpes zoster in Europe is approximately 3 per 1000 people per year and more than 10 per 1000 people per year in those aged >80 years. Post herpetic neuralgia (PHN) is a common debilitating complication of herpes zoster, particularly in patients aged >50 years, in persons with severe pain or rash at presentation, and in those with significant prodromal symptoms. Antiviral drugs can effectively control acute symptoms and, if used early enough in the course of the illness, can help prevent the development of PHN and other complications. However, despite this, many patients do not receive such treatment. The economic impact of zoster and PHN is largely underestimated in Europe. Furthermore, there is considerable variation throughout Europe in the management of herpes zoster. Use of antiviral therapy including the newer potent antiviral agents such as brivudin, which requires less frequent administration than acyclovir, is improving patient outcomes in some European countries. However, in many countries, patient awareness of herpes zoster and, as a result, overall antiviral use is low. Guidelines recommending the use of antiviral agents, particularly in patients at risk of developing PHN, are available but are not widely used. More needs to be done to educate the general public and increase awareness among primary healthcare providers of the benefits of timely and appropriate pharmacological therapy in patients with herpes zoster.

Management of herpes zoster (shingles) and postherpetic neuralgia

Herpes zoster (HZ) results from recrudescence of varicella zoster virus latent since primary infection (varicella). The overall incidence of HZ is approximately 3/1000 of the population per year rising to 10/1000 per year by 80 years of age. Approximately 50% of individuals reaching 90 years of age will have had HZ. In approximately 6%, a second attack may occur (usually several decades after the first). Patients with HZ can transmit the virus to a non-immune individual causing varicella. HZ is not contracted from individuals with varicella or HZ. Reduced cell-mediated immunity to HZ occurs with ageing, explaining the increased incidence in the elderly and from other causes such as tumours, HIV and immunosuppressant drugs. Diagnosis is usually clinical from typical unilateral dermatomal pain and rash. Prodromal symptoms, pain, itching and malaise, are common. The most common complication of HZ is postherpetic neuralgia (PHN), defined as significant pain or dysaesthesia present >or= 3 months after HZ. PHN results from damage and secondary changes within components of the nervous system subserving pain. Some motor deficit is common; severe and long-lasting paresis may rarely accompany HZ. More than 5% of elderly patients have PHN at 1 year after acute HZ. Predictors of PHN are, greater age, acute pain and rash severity, prodromal pain, the presence of virus in peripheral blood as well as adverse psychosocial factors. Therapy for acute HZ is intended to reduce acute pain, hasten rash healing and reduce the risk of PHN and other complications. Antiviral drugs are close to achieving these aims but do not entirely remove risk of PHN. Oral steroids show no protective effect against PHN. Adequate analgesia during the acute phase may require strong opioid drugs. Nerve blocks and tricyclic antidepressants (TCAs) may reduce the risk of PHN although firm evidence is lacking. PHN requires thorough evaluation and development of a management strategy for each individual patient. Initial therapy is with TCAs (e.g., nortriptyline) or the anticonvulsant gabapentin. Topical lidocaine patches frequently reduce allodynia. Strong opioids are sometimes required. Topical capsaicin cream is beneficial for a small proportion of patients but is poorly tolerated. NMDA antagonists have not proved beneficial with the exception of ketamine. Transcutaneous Electrical Nerve Stimulation (TENS) may be effective in some cases. HZ is a common condition. Severe complications such as stroke, encephalitis and myelitis are relatively rare whereas sight threatening complications of ophthalmic HZ are more common. PHN is common, distressing and often intractable. Good management improves outcome.

Evidenzbasierte Therapie von Herpes-Virus-Erkrankungen der Haut

Six questions regarding varicella-zoster virus-related skin diseases are addressed. The Cochran Library, MEDLINE, Clinical Evidence and several guideline providers were searched for evidence. The level of evidence in papers was appraised according to the Oxford Centre for Evidence-based Medicine Levels of Evidence. The current evidence for antiviral therapy of chickenpox in immunocompetent children, adults and pregnancy, recommendation of varicella vaccination, effect of time of initiation of antiviral therapy in acute zoster as well as route of treatment with regard to onset of post-zoster neuralgia are covered.

(E)-5-(2-bromovinyl)-2?-deoxyuridine (BVDU)

(E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU, Brivudin, Zostex, Zerpex, Zonavir), now more than 20 years after its discovery, still stands out as a highly potent and selective inhibitor of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) infections. It has been used in the topical treatment of herpetic keratitis and recurrent herpes labialis and the systemic (oral) treatment of herpes zoster (zona, shingles). The high selectivity of BVDU towards HSV-1 and VZV depends primarily on a specific phosphorylation of BVDU to its 5'-diphosphate (DP) by the virus-encoded thymidine kinase (TK). After further phosphorylation (by cellular enzymes), to the 5'-triphosphate (TP), the compound interferes as a competitive inhibitor/alternate substrate with the viral DNA polymerase. The specific phosphorylation by the HSV- and VZV-induced TK also explains the marked cytostatic activity of BVDU against tumor cells that have been transduced by the viral TK genes. This finding offers considerable potential in a combined gene therapy/chemotherapy approach for cancer. To the extent that BVDU or its analogues (i.e., BVaraU) are degraded (by thymidine phosphorylase) to (E)-5-(2-bromovinyl)uracil (BVU), they may potentiate the anticancer potency, as well as toxicity, of 5-fluorouracil. This ensues from the direct inactivating effect of BVU on dihydropyrimidine dehydrogenase, the enzyme that initiates the degradative pathway of 5-fluorouracil. The prime determinant in the unique behavior of BVDU is its (E)-5-(2-bromovinyl) substituent. Numerous BVDU analogues have been described that, when equipped with this particular pharmacophore, demonstrate an activity spectrum characteristic of BVDU, including selective anti-VZV activity.

Brivudin compared with famciclovir in the treatment of herpes zoster: effects in acute disease and chronic pain in immunocompetent patients. A randomized, double-blind, multinational study

OBJECTIVE

This was a double-blind, randomized multicentre trial comparing efficacy and safety of brivudin (125 mg, once a day) and famciclovir (250 mg, three times a day), both given orally for 7 days, in the treatment of herpes zoster.

METHODS

A total of 2027 immunocompetent zoster patients>or=50 years with zoster-related pain at presentation were included. Outcome measures embraced prevalence of postherpetic neuralgia (PHN), defined as at least moderate pain 3 months after treatment initiation, duration of PHN, prevalence and duration of zoster-associated pain (ZAP), duration of vesicle formation and rash healing.

RESULTS

The prevalence of PHN at month 3 was 11.3% with brivudin and 9.6% with famciclovir [per-protocol (PP) population]. Equivalence of the two drugs could be demonstrated (P=0.01, PP and intention-to-treat analysis). The median duration of PHN was 46.5 days with brivudin and 58 days with famciclovir (P=0.54, PP analysis). Prevalence and duration of ZAP did not differ significantly between treatment groups. The prevalence of PHN was higher in patients>or=65 years (brivudin: 16.4%, famciclovir: 16.4%), and in patients with severe rash (brivudin: 13.4%, famciclovir: 15.7%), without significant differences between treatment groups. In patients>or=65 years, median duration of PHN was shorter with brivudin than with famciclovir (39.5 vs. 57.5 days), although the difference was not statistically significant. The two drugs had equivalent efficacy in being able to accelerate the stop of vesicle formation, and lesion healing. Adverse events were similar in nature and prevalence among groups.

CONCLUSIONS

The study demonstrated equivalent efficacy of brivudin and famciclovir in the treatment of herpes zoster regarding the prevention of chronic pain and the resolution of signs and symptoms of acute herpes zoster. Compared with famciclovir, brivudin provides equivalent efficacy and safety at a more convenient once-daily dose schedule.

[Varicella-zoster virus infections]

The primary infection with varicella-zoster virus (VZV) is manifest clinically as varicella. It is a common very contagious disease, normally appearing in childhood. VZV is a ubiquitous virus with a high prevalence. Clinically it is characterized by pleomorphic skin lesions. Normally antiviral therapy is necessary only in severe cases, in adults or in immunosuppressed patients. Herpes zoster, also caused by (VZV), is a neurodermal disease representing the endogenous relapse of the primary varicella infection. Herpes zoster is characterized by lesions concentrated in the innervation region of a cranial or spinal nerve. One of the most feared manifestations of herpes zoster is pain. Several antiviral drugs are approved and many studies have shown that antiviral therapy, started early in the course of disease, can significantly reduce risk and duration of postherpetic neuralgia in elderly patients. Therefore, antiviral therapy in combination with an adequate pain management should be given to all elderly patients as soon as herpes zoster is diagnosed.

Discovery and development of BVDU (brivudin) as a therapeutic for the treatment of herpes zoster

This Commentary is dedicated to the memory of Dr. Jacques Gielen, the late Editor of Biochemical Pharmacology, whom I have known as both an author and reviewer for the Journal for about 25 years. This is, quite incidentally, about the time it took for bringing brivudin (BVDU) [(E)-5-(2-bromovinyl)-2'-deoxyuridine] from its original description as an antiviral agent to the market place (in a number of European countries, including Germany and Italy) for the treatment of herpes zoster in immunocompetent persons. BVDU is exquisitely active and selective against varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV-1). BVDU owes this high selectivity and activity profile to a specific phosphorylation by the virus-encoded thymidine kinase, followed by a potent interaction with the viral DNA polymerase. The (E)-5-(2-bromovinyl)-substituent can be considered as the hallmark for the activity of BVDU against VZV and HSV-1. Extensive clinical studies have indicated that BVDU as a single (oral) daily dose of 125 mg (for no more than 7 days) is effective in the treatment of herpes zoster, as regards both short-term (suppression of new lesion formation) and long-term effects (prevention of post-herpetic neuralgia). In this sense, BVDU is as efficient and/or convenient, if not more so, than the other drugs (acyclovir, valaciclovir, famciclovir) that have been licensed for the treatment of herpes zoster. There is one caveat; however, BVDU should not be given to patients under 5-fluorouracil therapy, as the degradation product of BVDU, namely (E)-5-(2-bromovinyl)uracil (BVU), may potentiate the toxicity of 5-fluorouracil, due to inhibition of dihydropyrimidine dehydrogenase, the enzyme involved in the catabolism of 5-fluorouracil.

Brivudin (Bromovinyl Deoxyuridine)

Brivudin is an oral thymidine analogue indicated for the early treatment of acute herpes zoster in immunocompetent adults. It has high, selective activity against varicella zoster virus (VZV), inhibiting VZV replication, possibly through competitive inhibition of viral DNA polymerase, or by acting as an alternative substrate to deoxythymidine triphosphate, causing viral DNA strand breakage. In a large, 7-day, phase III trial in immunocompetent patients with herpes zoster, once-daily brivudin 125mg was significantly more effective than oral acyclovir 800mg five times daily in reducing the mean time from start of treatment to last vesicular eruption, and was as effective as acyclovir at healing lesions and alleviating acute zoster-related pain. The likelihood of developing post-herpetic neuralgia (PHN) in immunocompetent patients aged > or =50 years was significantly lower with brivudin than with acyclovir. Brivudin was as effective as oral famciclovir 250mg three times daily in terms of the prevalence of PHN, the time to last vesicular eruption and lesion healing in another large, 7-day, phase III study in immunocompetent patients with herpes zoster. Oral brivudin is generally well tolerated, with a similar tolerability profile to those of oral acyclovir or famciclovir. Nausea was the most commonly reported adverse event.