Famciclovir for treatment of herpesvirus infections

Pharmacovigilance study of famciclovir in the Food and Drug administration adverse event reporting system database

Famciclovir, mainly used to treat herpes zoster, is rapidly transforms into penciclovir when administered orally. Our study evaluated adverse events (AEs) associated with famciclovir by mining data from the publicly available Food and Drug Administration Adverse Event Reporting System (FAERS) database, providing a reference for clinical safety. Disproportionality analysis (including reported odds ratio and proportional reporting ratio) and Bayesian methods (including Bayesian Confidence Propagation Neural Network and Gamma-Poisson Shrinkage) were used to quantify the AE signals associated with famciclovir. A total of 17,652,186 case reports were obtained from the FAERS database, and 432 famiclovir-related AEs were identified. Nausea, headache, altered mental status, vomiting, and dizziness were found to be the most common Aes, corresponding to those reported in the Food and Drug Administration (FDA) drug labelling and clinical trials. Our study found some potential AEs of famciclovir that were not mentioned in the FDA drug labelling, such as toxic encephalopathy, encephalopathy, ataxia, dysarthria, dementia, cerebral infarction, tremor, purpura, skin ulcers, acute pancreatitis, rhabdomyolysis, muscle twitching, increased blood urea, lowered blood pressure, hepatitis, disease recurrence, drug interactions, and pancytopenia. Our study identified potential famciclovir AE signals, providing insights for physicians to reduce possible side effects and promote the safe implementation of the drug in clinical settings.

An Insight into Current Treatment Strategies, Their Limitations, and Ongoing Developments in Vaccine Technologies against Herpes Simplex Infections

Herpes simplex virus (HSV) infection, the most prevalent viral infection that typically lasts for a lifetime, is associated with frequent outbreaks of oral and genital lesions. Oral herpes infection is mainly associated with HSV-1 through oral contact, while genital herpes originates due to HSV-2 and is categorized under sexually transmitted diseases. Immunocompromised patients and children are more prone to HSV infection. Over the years, various attempts have been made to find potential targets for the prevention of HSV infection. Despite the global distress caused by HSV infections, there are no licensed prophylactic and therapeutic vaccines available on the market against HSV. Nevertheless, there are numerous promising candidates in the pre-clinical and clinical stages of study. The present review gives an overview of two herpes viruses, their history, and life cycle, and different treatments adopted presently against HSV infections and their associated limitations. Majorly, the review covers the recent investigations being carried out globally regarding various vaccine strategies against oral and genital herpes virus infections, together with the recent and advanced nanotechnological approaches for vaccine development. Consequently, it gives an insight to researchers as well as people from the health sector about the challenges and upcoming solutions associated with treatment and vaccine development against HSV infections.

Discovery, Chemistry, and Preclinical Development of Pritelivir, a Novel Treatment Option for Acyclovir-Resistant Herpes Simplex Virus Infections

When the nucleoside analogue acyclovir was introduced in the early 1980s, it presented a game-changing treatment modality for herpes simplex virus infections. Since then, work has been ongoing to improve the weaknesses that have now been identified: a narrow time window for therapeutic success, resistance in immunocompromised patients, little influence on frequency of recurrences, relatively fast elimination, and poor bioavailability. The present Drug Annotation focuses on the helicase–primase inhibitor pritelivir currently in development for the treatment of acyclovir-resistant HSV infections and describes how a change of the molecular target (from viral DNA polymerase to the HSV helicase–primase complex) afforded improvement of the shortcomings of nucleoside analogs. Details are presented for the discovery process leading to the final drug candidate, the pivotal preclinical studies on mechanism of action and efficacy, and on how ongoing clinical research has been able to translate preclinical promises into clinical use.

Efficacy of Intermittent, Oral Famciclovir Prophylaxis for Bortezomib-Induced Herpes Zoster in Multiple Myeloma Patients

Objective

To explore the efficacy and safety of intermittent, oral famciclovir prophylaxis for bortezomib-induced herpes zoster in multiple myeloma patients.

Method

We retrospectively analyzed the incidence of bortezomib treatment-related varicella-zoster virus reactivation in 719 newly-diagnosed multiple myeloma patients receiving intermittent oral famciclovir prophylaxis, continuous oral acyclovir prophylaxis or no prophylaxis. The definition of intermittent oral famciclovir prophylaxis was oral famciclovir at a dose of 250mg twice daily for 9 days after finishing the last dose of bortezomib therapy every cycle. Age, gender, stage per the International Staging System, type of M protein, baseline of absolute lymphocyte count, absolute neutrophil count, and absolute monocyte count were analyzed to find the potential factors that could predispose to herpes zoster infections.

Results

Varicella-zoster virus infection occurred in 96 patients (13.4%) during bortezomib treatment. The incidence of herpes zoster was significantly higher in the non-prophylaxis group compared with the prophylaxis group (22.9% vs 8.2% P<0.001), while the rate was similar between the intermittent oral famciclovir group and the continuous oral acyclovir group (8.4% vs 7.9% P=0.835). Hepatic and renal toxicity were observed in 12% and 2.8% of the patient respectively in the intermittent famciclovir group, which was similar in the continuous acyclovir group (18.1% and 4.2%). The prophylactic use of antiviral agents is a predictive factor for varicella-zoster virus reactivation.

Conclusion

Intermittent famciclovir prophylaxis is effective and safe in preventing herpes zoster development and can markedly reduce the duration of oral medicine treatment compared with continuous acyclovir prophylaxis.

Synthesis of Novel Acyl Derivatives of 3-(4,5,6,7-Tetrabromo-1H-benzimidazol-1-yl)propan-1-ols-Intracellular TBBi-Based CK2 Inhibitors with Proapoptotic Properties

Protein kinase CK2 has been considered as an attractive drug target for anti-cancer therapy. The synthesis of N-hydroxypropyl TBBi and 2MeTBBi derivatives as well as their respective esters was carried out by using chemoenzymatic methods. Concomitantly with kinetic studies toward recombinant CK2, the influence of the obtained compounds on the viability of two human breast carcinoma cell lines (MCF-7 and MDA-MB-231) was evaluated using MTT assay. Additionally, an intracellular inhibition of CK2 as well as an induction of apoptosis in the examined cells after the treatment with the most active compounds were studied by Western blot analysis, phase-contrast microscopy and flow cytometry method. The results of the MTT test revealed potent cytotoxic activities for most of the newly synthesized compounds (EC50 4.90 to 32.77 µM), corresponding to their solubility in biological media. We concluded that derivatives with the methyl group decrease the viability of both cell lines more efficiently than their non-methylated analogs. Furthermore, inhibition of CK2 in breast cancer cells treated with the tested compounds at the concentrations equal to their EC50 values correlates well with their lipophilicity since derivatives with higher values of logP are more potent intracellular inhibitors of CK2 with better proapoptotic properties than their parental hydroxyl compounds.

Current Antivirals and Novel Botanical Molecules Interfering With Herpes Simplex Virus Infection

Herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent within the human population and are characterized by lifelong infections and sporadic recurrences due to latent neuron infection. Upon reactivations, HSVs may manifest either, symptomatically or asymptomatically and be shed onto others through mucosae body fluids. Although, HSVs can produce severe disease in humans, such as life-threatening encephalitis and blindness, the most common symptoms are skin and mucosal lesions in the oro-facial and the genital areas. Nucleoside analogs with antiviral activity can prevent severe HSV infection, yet they are not very effective for treating skin manifestations produced by these viruses, as they only reduce in a few days at most the duration of lesions. Additionally, HSV variants that are resistant to these antivirals may arise, especially in immunosuppressed individuals. Thus, new antivirals that can reduce the severity and duration of these cutaneous manifestations would certainly be welcome. Here, we review currently available anti-herpetic therapies, novel molecules being assessed in clinical trials and new botanical compounds reported in the last 20 years with antiviral activities against HSVs that might represent future treatments against these viruses.

Selected nucleos(t)ide-based prescribed drugs and their multi-target activity

Nucleos(t)ide analogues play pivotal roles as antiviral, cytotoxic or immunosuppressive agents. Here, we review recent reports of nucleoside analogues that exhibit broad-spectrum activity towards multiple life-threatening RNA and DNA viruses. We also present a discussion about nucleoside antimetabolites-approved antineoplastic agents-that have recently been shown to have antiviral and/or antibacterial activity. The approved drugs and drug combinations, as well as recently identified candidates for investigation and/or experimentation, are discussed. Several examples of repurposed drugs that have already been approved for use are presented. This strategy can be crucial for the first-line treatment of acute infections or coinfections and for the management of drug-resistant strains.

Exploitation of new structurally diverse d-glucuronamide-containing N-glycosyl compounds: synthesis and anticancer potential

The synthesis and anticancer evaluation of novel N-glycosyl derivatives containing N-substituted glucuronamide moieties, as nucleoside analogs or as prospective mimetics of glycosyl phosphates or of nucleotides, is reported. These compounds comprise N-anomerically-linked nucleobases or motifs that are surrogates of a phosphate group, such as sulfonamide or phosphoramidate moieties. 1-Sulfonamido glucuronamides containing N-benzyl, N-propargyl or N-dodecyl carboxamide units were synthesized through glycosylation of methanesulfonamide with tetra-O-acetyl glucuronamides. 1-Azido glucuronamides were accessed by microwave-assisted reactions of tetra-O-acetyl glucuronamides with TMSN₃ and were further converted into N-glycosylphosphoramidates by treatment with trimethyl phosphite. Potential glucuronamide-based nucleotide mimetics comprising both an anomeric sulfonamide/phosphoramidate group and a benzyltriazolylmethyl amide system at C-5, as nucleobase mimetics, were synthesized via 'click' cycloaddition of N-propargyl glucuronamide derivatives with benzyl azide. N-Dodecyl tetra-O-acetyl glucuronamides were converted into uracil and purine nucleosides via N-glycosylation of the corresponding silylated nucleobases. Biological screening revealed significant antiproliferative activities of the N-dodecyl glucuronamide-containing sulfonamide, phosphoramidate and nucleosides in K562 and MCF-7 cells. The highest effect was exhibited by the N⁹-linked purine nucleoside in the breast cancer cell MCF-7 with a GI₅₀ value similar to that of clinically used 5-fluorouracil. Immunoblotting and cell cycle analysis of K562 cells treated with the most active compound as well as evaluation of the effect of this nucleoside on the activities of caspases 3 and 7 showed induction of apoptosis as the mechanism of cell death.

Valacyclovir in the Treatment of Herpes Simplex, Herpes Zoster, and other Viral Infections

Background:

Genital herpes and herpes labialis are prevalent, physically and pychologically painful, and often disabling. Herpes zoster is often very painful and may result in months or years of postherpetic neuralgia (PHN). Over the past two decades, the treatment of these conditions has been transformed by guanosine nucleoside antivirals such as valacyclovir (Valtrex®), a highly bioavailable prodrug of acyclovir (Zovirax®), and famciclovir (Famvir®), a highly bioavailable prodrug of penciclovir (Denavir®).

Objective:

We describe the pharmacology, pharmacokinetics, and clinical efficacy of valacyclovir for the treatment of herpes simplex, herpes zoster, and other viral infections. Valacyclovir is also compared with acyclovir and famciclovir.

Methods:

All published literature containing the word “valacyclovir” was reviewed and summarized.

Results:

Valacyclovir is the only oral antiviral agent approved for therapy of herpes labialis, the only antiviral drug approved for a 3-day course in the episodic treatment of recurrent genital herpes, as well as the only antiviral drug approved for once daily dosing for suppressive therapy. In herpes zoster, valacyclovir is more effective than acyclovir and equally effective as famciclovir at hastening the healing of zoster-associated pain and PHN.

Conclusion:

Valacyclovir is safe and effective in the therapy of patients with herpes simplex and herpes zoster and may be useful in other viral infections.

Review of antiviral therapy for herpes labialis, genital herpes and herpes zoster

Acyclovir (Zovirax) was approved for the treatment of herpesvirus infections almost two decades ago. It was the first agent in a novel group of antiviral medications that now include valacyclovir (Valtrex), penciclovir (Denavir and famciclovir (Famvir). These agents have made a dramatic impact on the morbidity associated with herpes simplex virus infections and herpes zoster. Topical and oral antiviral use have shown modest but statistically significant efficacy in treating herpes labialis with most studies demonstrating a significant reduction in episode length and/or healing time. Oral acyclovir, valacyclovir and famciclovir are efficacious and safe for the treatment of the first episode and recurrent genital herpes and are useful as suppressive therapy for individuals with frequent genital herpes recurrences. In addition, high doses of oral acyclovir, valacyclovir and famciclovir have been shown to speed the healing of herpes zoster, and data suggests that these agents also decrease associated acute and chronic pain in people of 50 years of age or older. Further research is required to clarify the safety of these agents in pregnant women with genital herpes, the role of antiviral therapy in decreasing the sexual transmission of genital herpes, and the efficacy and cost-effectiveness of these agents in treating herpes zoster in people below the age of 50 years.

Acute retinal necrosis: a national population-based study to assess the incidence, methods of diagnosis, treatment strategies and outcomes in the UK

AIM

To determine the incidence, methods of diagnosis, treatment strategies and outcomes for acute retinal necrosis (ARN) in the UK.

METHODS

A 12-month active case ascertainment study was carried out between March 2001 and March 2002 to record cases of ARN presenting to ophthalmologists via the British Ophthalmological Surveillance Unit (BOSU) reporting system. Questionnaires were sent to the reporting consultants, requesting data on patient characteristics, presentation, clinical findings, investigations and treatment. Diagnosis was made using the American Uveitis Society diagnostic criteria. Further questionnaires were sent at 2 weeks and 6 months to assess outcome and therapies.

RESULTS

74 cases of ARN were reported by 58 consultants between March 2001 and March 2002. Questionnaires were returned for 49 cases (66.2%), of which 18 (36.7%) were excluded. Of the 31 cases included, 22 (71.0%) were male and 9 (29.0%) were female. The age range was 13 to 85 years (mean 54.3 years). 28 cases (90.3%) were unilateral, with 3 patients (9.7%) presenting with bilateral ARN. An aqueous or vitreous biopsy was performed in only 18 patients, with one patient having both. Herpes viral DNA analysis was performed on all 19 biopsies, with identification of the viral DNA in 16; results from 3 biopsies were not documented. Varicella zoster virus (VZV) was the commonest cause identified in 10 patients (56%). Of the 31 subjects, 27 (87.1%) were treated for ARN with systemic antiviral treatment: with intravenous antiviral in 23 cases (85.2%) and oral antiviral in 4 cases (14.8%). 21 of these patients went on to receive oral antiviral maintenance therapy. In addition to antiviral treatment, systemic steroids were given to 16 subjects (51.6%). Surgical intervention for retinal detachment was performed on 5 patients.

CONCLUSIONS

During the 12-month study period, 31 cases of ARN met the diagnostic criteria set by the American Uveitis Society. The incidence in the UK based on this study is approximately 1 case per 1.6 to 2.0 million population per year. We have ascertained that the management of ARN throughout the UK is variable, suggesting that national guidelines would be of benefit.

Valacyclovir for the treatment of genital herpes

Genital herpes is the most prevalent sexually transmitted infection in the USA. While sometimes mild in severity, it can be a distressing and painful chronic condition. Likewise, herpes labialis and herpes zoster can be both physically and psychologically painful. While there is no cure for these conditions, treatment to alleviate symptoms, suppress recurrences and reduce transmission has been drastically improved over the past 20 years with the use of guanine nucleoside antivirals, such as valacyclovir hydrochloride (Valtrex), GlaxoSmithKline) the highly bioavailable prodrug of acyclovir (Zovirax((R)), GlaxoSmithKline), and famciclovir (Famvir, Novartis), a highly bioavailable prodrug of penciclovir (Denavir, Novartis). Clinical trials involving approximately 10,000 patients (including patients from nongenital herpes studies, such as herpes zoster) have assessed the safety and efficacy of valacyclovir in the treatment of initial genital herpes outbreaks, episodic treatment of recurrent episodes and daily suppressive therapy. It was shown that valacyclovir has similar efficacy to acyclovir in the episodic and suppressive treatment of genital herpes. Valacyclovir is the only antiviral drug approved for a once-daily dose of suppressive therapy for genital herpes, as well as the only antiviral drug US FDA approved for a 3-day regimen of episodic treatment of recurrent genital herpes. In addition, valacyclovir is also indicated in the reduction of the sexual transmission of herpes simplex virus infection and for the treatment of herpes labialis. In herpes zoster, valacyclovir is more effective than acyclovir or placebo (and as equally effective as famciclovir) in shortening the length and severity of herpes zoster-associated pain and postherpetic neuralgia. Valacyclovir has an acceptable safety profile in patients with herpes simplex and herpes zoster. The less frequent dosing regimen makes it an attractive option in the treatment of genital herpes and other viral infections, and may contribute to increased patient adherence to therapy.

Valacyclovir in the treatment of herpes simplex, herpes zoster, and other viral infections

BACKGROUND

Genital herpes and herpes labialis are prevalent, physically and psychologically painful, and often disabling. Herpes zoster is often very painful and may result in months or years of postherpetic neuralgia (PHN). Over the past two decades, the treatment of these conditions has been transformed by guanosine nucleoside antivirals such as valacyclovir (Valtrex, a highly bioavailable prodrug of acyclovir (Zovirax, and famciclovir (Famvir), a highly bioavailable prodrug of penciclovir (Denavir).

OBJECTIVE

We describe the pharmacology, pharmacokinetics, and clinical efficacy of valacyclovir for the treatment of herpes simplex, herpes zoster, and other viral infections. Valacyclovir is also compared with acyclovir and famciclovir.

METHODS

All published literature containing the word "valacyclovir" was reviewed and summarized.

RESULTS

Valacyclovir is the only oral antiviral agent approved for therapy of herpes labialis, the only antiviral drug approved for a 3-day course in the episodic treatment of recurrent genital herpes, as well as the only antiviral drug approved for once daily dosing for suppressive therapy. In herpes zoster, valacyclovir is more effective than acyclovir and equally effective as famciclovir at hastening the healing of zoster-associated pain and PHN.

CONCLUSION

Valacyclovir is safe and effective in the therapy of patients with herpes simplex and herpes zoster and may be useful in other viral infections.

Valacyclovir in the treatment of genital herpes and herpes zoster

Genital herpes is prevalent and sometimes debilitating. Likewise, herpes zoster ('shingles') can be painful and often disabling. The treatment of these conditions has been advanced over the past two decades by the introduction of guanosine nucleoside antivirals such as valacyclovir (Valtrex), Glaxo Wellcome), the highly bioavailable prodrug of acyclovir (Zovirax), Glaxo Wellcome). This review describes the pharmacology, pharmacokinetics, clinical efficacy and tolerability of valacyclovir and considers its clinical attributes in the context of those of the antivirals, acyclovir and famciclovir (Famvir), SmithKline Beecham). The data demonstrate that valacyclovir is more effective than placebo and as effective as other antivirals in the episodic and suppressive treatment of recurrent genital herpes. Valacyclovir is the only antiviral shown to be effective with a short (3-day) course in the episodic treatment of recurrent genital herpes, as well as with once-daily dosing for daily suppressive therapy. In herpes zoster, valacyclovir is as effective as famciclovir and more effective than either placebo or acyclovir at facilitating cutaneous healing and healing of zoster-associated pain and post-herpetic neuralgia. Valacyclovir is well tolerated, with convenient dosing frequencies for the treatment of genital herpes or herpes zoster, it also has the option for use as a short course therapy in the episodic treatment of recurrent genital herpes, all of which are important benefits in the management of these conditions.

In vitro and in vivo metabolism and pharmacokinetics of bis [(t-butyl)-S-acyl-2-thioethyl]-beta-L-2',3'-dideoxy-5-fluorocytidine monophosphate

Exposure to 10 &M L-FddCMP-bisSATE led to formation of intracellular L-FddCTP levels of 410.1(+/-) +/- 46.2 and 242.1 +/- 13.2 pmol/10(6) cells in unstimulated and PHAstimulated PBM cells, respectively; whereas, exposure of cells to the parent nucleoside, L-FddC, generated 5-10-fold less L-FddCTP. In Hep-G2 cells and EGF/HGF stimulated and unstimulated primary cultured hepatocytes, the active metabolite reached 113 +/- 29, 23.9 +/- 15.6, and 20.6 +/- 10.5 pmol/10(6) cells. Three other metabolites, L-FddCMP-monoSATE, L-FddCMP-SH, and M I, were detected intracellularly and extracellularly in all cell types examined. Intravenous administered dose of 3 mg/kg L-FddCMP-bisSATE to rhesus monkeys resulted in plasma concentration levels of 2.06 +/- 1.00 and 0.39 +/- 0.15 &M of L-FddCMP-monoSATE and L-FddC, respectively, while the prodrug was completely cleared metabolically within 15 min. Following oral administration of an equivalent dose, the absolute oral bioavailability of L-FddC derived from L-FddCMP-bisSATE administration was 65%.

Clinical management of selected oral fungal and viral infections during HIV-disease

The purpose of this review is to describe current possibilities of management of selected fungal and viral oral opportunistic infections including oral candidiasis, herpes simplex type 1 and 2-related lesions (HSV1,2), oral hairy leukoplakia (OHL) and oral lesions associated with human papilloma viruses (HPV). Less common diseases such as cytomegalovirus infection or human herpes virus type 8 associated with Kaposi's sarcoma and others are not considered. In a number of instances lifelong therapy or prophylaxis has to be instituted. Antiretroviral combination therapy, also called highly active antiretroviral therapy (HAART), has considerably changed the frequency of oral lesions caused by opportunistic agents. A short description of the antiretroviral agents available including respective side-effects is presented.