Antiviral drugs for viruses other than human immunodeficiency virus

Most viral diseases, with the exception of those caused by human immunodeficiency virus, are self-limited illnesses that do not require specific antiviral therapy. The currently available antiviral drugs target 3 main groups of viruses: herpes, hepatitis, and influenza viruses. With the exception of the antisense molecule fomivirsen, all antiherpes drugs inhibit viral replication by serving as competitive substrates for viral DNA polymerase. Drugs for the treatment of influenza inhibit the ion channel M(2) protein or the enzyme neuraminidase. Combination therapy with Interferon-α and ribavirin remains the backbone treatment for chronic hepatitis C; the addition of serine protease inhibitors improves the treatment outcome of patients infected with hepatitis C virus genotype 1. Chronic hepatitis B can be treated with interferon or a combination of nucleos(t)ide analogues. Notably, almost all the nucleos(t) ide analogues for the treatment of chronic hepatitis B possess anti-human immunodeficiency virus properties, and they inhibit replication of hepatitis B virus by serving as competitive substrates for its DNA polymerase. Some antiviral drugs possess multiple potential clinical applications, such as ribavirin for the treatment of chronic hepatitis C and respiratory syncytial virus and cidofovir for the treatment of cytomegalovirus and other DNA viruses. Drug resistance is an emerging threat to the clinical utility of antiviral drugs. The major mechanisms for drug resistance are mutations in the viral DNA polymerase gene or in genes that encode for the viral kinases required for the activation of certain drugs such as acyclovir and ganciclovir. Widespread antiviral resistance has limited the clinical utility of M(2) inhibitors for the prevention and treatment of influenza infections. This article provides an overview of clinically available antiviral drugs for the primary care physician, with a special focus on pharmacology, clinical uses, and adverse effects.

Adjuvant therapy for laryngeal papillomatosis

Respiratory papillomatosis affects the larynx in most cases. It is a relatively rare disease, with potentially devastating consequences for the patient. Many studies have proven the viral etiology of the disease. Surgery is the most successful mode of treatment. Adjuvant therapy is used in cases of aggressive disease. The most successful adjuvant drugs are interferon, various virostatics (e.g., acyclovir, valacyclovir, and cidofovir) and indole-3-carbinol. Vaccination with a quadrivalent vaccine against HPV will probably decrease the incidence of respiratory papillomatosis or help in the treatment of the disease in the future. The results of adjuvant therapy of laryngeal papillomatosis at the University Department of ORL & HNS in Ljubljana are comparable to the results in other centers around the world.

[Antiherpesviral activity of acycloguanosine H-phosphonate in experiments using laboratory animals]

A study of the antiherpesviral activity of acycloguanosine (ACG) H-phosphonate (ACG-P) on a model of fatal herpesvirus infection in inbred BALB/c albino mice has established that ACG-P reduces death rates in the animals, considerably increases their average lifespan, and significantly decreases brain virus titers with both 60% mortality in the control and 92% mortality in the control group. There was also a significant inhibition of herpes simplex virus type 1 (HSV-1) replication in the brain tissue of animals receiving ACG-P on a model of ACG-resistant HSV-1/L2/RACG(TK-).

Effect of ASP2151, a herpesvirus helicase-primase inhibitor, in a guinea pig model of genital herpes

ASP2151 is a herpesvirus helicase-primase inhibitor with antiviral activity against varicella zoster virus and herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). Here, we examined the potency and efficacy of ASP2151 against HSV in vitro and in vivo. We found that ASP2151 was more potent in inhibiting the replication of HSV-1 and HSV-2 in Vero cells in the plaque reduction assay and had greater anti-HSV activity in a guinea pig model of genital herpes than did acyclovir and valacyclovir (VACV), respectively. Oral ASP2151 given from the day of infection reduced peak and overall disease scores in a dose-dependent manner, resulting in complete prevention of symptoms at the dose of 30 mg/kg. The 50% effective dose (ED(50)) values for ASP2151 and VACV were 0.37 and 68 mg/kg, respectively, indicating that ASP2151 was 184-fold more potent than VACV. When ASP2151 was administered after the onset of symptoms, the disease course of genital herpes was suppressed more effectively than by VACV, with a significant reduction in disease score observed one day after starting ASP2151 at 30 mg/kg, whereas the therapeutic effect of VACV was only evident three days after treatment at the highest dose tested (300 mg/kg). This indicated that ASP2151 possesses a faster onset of action and wider therapeutic time window than VACV. Further, virus shedding from the genital mucosa was significantly reduced with ASP2151 at 10 and 30 mg/kg but not with VACV, even at 300 mg/kg. Taken together, our present findings demonstrated the superior potency and efficacy of ASP2151 against HSV.

Safety of antiviral medication for the treatment of herpes during pregnancy

QUESTION

One of my patients is a pregnant woman in her first trimester with a history of recurrent genital herpes. She is concerned about whether use of her antiviral medication will adversely affect her baby. What should I tell her?

ANSWER

Studies have shown that the use of acyclovir or valacyclovir is not associated with an increase in birth defects. Limited data exist for famciclovir and therefore it would not be considered a first-line choice for treatment of herpes during pregnancy.

Biotransformation of the antiviral drugs acyclovir and penciclovir in activated sludge treatment

The biotransformation of the two antiviral drugs, acyclovir (ACV) and penciclovir (PCV), was investigated in contact with activated sludge. Biodegradation kinetics were determined, and transformation products (TPs) were identified using Hybrid Linear Ion Trap- FT Mass Spectrometry (LTQ Orbitrap Velos) and 1D (1H NMR, 13C NMR) and 2D (1H,1H-COSY, 1H-(13)C-HSQC) NMR Spectroscopy. ACV and PCV rapidly dissipated in the activated sludge batch systems with half-lives of 5.3 and 3.4 h and first-order rate constants in relation to the amount of suspended solids (SS) of 4.9±0.1 L gss(-1) d(-1) and 7.6±0.3 L gss(-1) d(-1), respectively. For ACV only a single TP was found, whereas eight TPs were identified for PCV. Structural elucidation of TPs exhibited that transformation only took place at the side chain leaving the guanine moiety unaltered. The oxidation of the primary hydroxyl group in ACV resulted in the formation of carboxy-acyclovir (Carboxy-ACV). For PCV, transformation was more diverse with several enzymatic reactions taking place such as the oxidation of terminal hydroxyl groups and β-oxidation followed by acetate cleavage. Analysis of different environmental samples revealed the presence of Carboxy-ACV in surface and drinking water with concentrations up to 3200 ng L(-1) and 40 ng L(-1), respectively.

Herpes simplex virus type 2 suppressive therapy with acyclovir or valacyclovir does not select for specific HIV-1 resistance in HIV-1/HSV-2 dually infected persons

Recent in vitro studies suggest that acyclovir may directly inhibit HIV-1 replication and can select for a specific HIV-1 reverse transcriptase mutation (V75I) with concomitant loss of an anti-HIV-1 effect. We tested for HIV-1 genotypic resistance at reverse transcriptase codon 75 in plasma from 168 HIV-1-infected persons from Botswana, Kenya, Peru, and the United States taking daily acyclovir or valacyclovir for between 8 weeks and 24 months. No V75I cases were detected (95% confidence interval, 0%-2.2%). These prospective in vivo studies suggest that standard-dose acyclovir or valacyclovir does not select for HIV-1 resistance.

Can herpes simplex virus type 2 suppression slow HIV disease progression: a study protocol for the VALacyclovir In Delaying Antiretroviral Treatment Entry (VALIDATE) trial

BACKGROUND

Although highly active antiretroviral therapy (HAART) has dramatically decreased HIV-related morbidity and mortality, the associated costs, toxicities, and resistance risks make the potential delay of HAART initiation an attractive goal. Suppression of herpes simplex virus type 2 (HSV-2) may be a novel strategy for achieving this goal because HSV-2 is associated with clinically significant increases in HIV viral load, the primary driver of HIV disease progression.

METHODS/DESIGN

The VALacyclovir In Delaying Antiretroviral Treatment Entry (VALIDATE) trial is a multicentre, randomized, fully blinded, clinical trial of twice daily valacyclovir 500 mg versus placebo for delaying the need for initiating HAART among HIV-1, HSV-2 co-infected HAART-naïve adults. 480 participants from Canada, Brazil and Argentina will undergo quarterly clinical follow-up until reaching the composite primary endpoint of having a CD4+ T-cell count ≤ 350 cells/mm(3) or initiation of HAART for any reason, whichever occurs first. The primary analysis will use a proportional hazards model, stratified by site, to estimate the relative risk of progression to this endpoint associated with valacyclovir. Secondary analyses will compare the rates of change in CD4 count, median log10 HIV viral load, drug-related adverse events, frequency of HSV reactivations, rate of acyclovir-resistant HSV, and quality of life between study arms.

DISCUSSION

Although HIV treatment guidelines continue to evolve, with some authorities recommending earlier HAART among asymptomatic individuals, the potential delay of HAART remains a clinically relevant goal for many. If shown to be of benefit, implementation of the VALIDATE intervention will require careful consideration of both individual patient-level and public health implications.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN66756285. ClinicalTrials.gov NCT00860977.

[Neurotoxicity of valacyclovir in a peritoneal dialysis patient]

The patient was a 67-year-old man with a 2-year history of peritoneal dialysis for end-stage renal disease due to hypertensive nephropathy. He presented to a dermatologist with a complaint of pain in the right femoral region. He was diagnosed as having herpes zoster and valacyclovir, 1,000 mg/day, was prescribed. After 5 days of taking valacyclovir orally, he felt fretful and hallucinations appeared. He was admitted to our hospital and was hospitalized in our urology ward. We diagnosed his condition as neurotoxicity caused by an overdose of valacyclovir. As his general condition was stable, he was treated only by continuation of peritoneal dialysis. After 7 days of hospitalization, the neurotoxicity completely disappeared and he left the hospital. His serum acyclovir concentration at admission was 20.20 μg/l, and was reduced to 0.7 μg/l when he left the hospital. This supported our diagnosis of valacyclovir-induced neurotoxicity. In this case, valacyclovir should have been reduced to 500 mg/day, considering his renal function. Although we could treat the patient only by continuation of peritoneal dialysis, hemodialysis seems to be an effective treatment method in the case of unstable general condition or severe adverse effects, because it can eliminate the serum acyclovir.

Use of acyclovir, valacyclovir, and famciclovir in the first trimester of pregnancy and the risk of birth defects

CONTEXT

Herpes simplex and herpes zoster infections are common and often treated with antiviral drugs including acyclovir, valacyclovir, and famciclovir. Safety of these antivirals when used in the first trimester of pregnancy is insufficiently documented.

OBJECTIVE

To investigate associations between exposure to acyclovir, valacyclovir, and famciclovir in the first trimester of pregnancy and risk of major birth defects.

DESIGN, SETTING, AND PARTICIPANTS

Population-based historical cohort study of 837,795 live-born infants in Denmark from January 1, 1996, to September 30, 2008. Participants had no diagnoses of chromosomal aberrations, genetic syndromes, birth defect syndromes with known causes, or congenital viral infections. Nationwide registries were used to ascertain individual-level information on dispensed antiviral drugs, birth defect diagnoses (categorized according to a standardized classification scheme), and potential confounders.

MAIN OUTCOME MEASURE

Prevalence odds ratios (PORs) of any major birth defect diagnosed within the first year of life by exposure to antiviral drugs.

RESULTS

Among 1804 pregnancies exposed to acyclovir, valacyclovir, or famciclovir in the first trimester, 40 infants (2.2%) were diagnosed with a major birth defect compared with 19,920 (2.4%) among the unexposed (adjusted POR, 0.89; 95% confidence interval [CI], 0.65-1.22). For individual antivirals, a major birth defect was diagnosed in 32 of 1561 infants (2.0%) with first-trimester exposure to acyclovir (adjusted POR, 0.82; 95% CI, 0.57-1.17) and in 7 of 229 infants (3.1%) with first-trimester exposure to valacyclovir (adjusted POR, 1.21; 95% CI, 0.56-2.62). Famciclovir exposure was uncommon (n = 26), with 1 infant (3.8%) diagnosed with a birth defect. Exploratory analyses revealed no associations between antiviral drug exposure and 13 different subgroups of birth defects, but the number of exposed cases in each subgroup was small.

CONCLUSION

In this large nationwide cohort, exposure to acyclovir or valacyclovir in the first trimester of pregnancy was not associated with an increased risk of major birth defects.

Neutropenia related to valacyclovir and valganciclovir in 2 renal transplant patients and treatment with granulocyte colony stimulating factor: a case report

OBJECTIVES

Posttransplant leukopenia is frequently observed in renal transplant. Granulocyte colony-stimulating factor controls the production of functional neutrophils and their release into peripheral blood. Granulocyte colony-stimulating factor has been widely and frequently used for many conditions and disorders in the field of hematology and oncology.

MATERIALS AND METHODS

We present the cases of valacyclovir-related and valganciclovir-related neutropenia in 2 renal transplant recipients.

RESULTS

Both cases had renal transplants from live donors. The first one was an 18-year-old man. Laboratory investigations revealed his leukocyte count as 1.7 x 10(9)/L. The patient was using mycophenolate mofetil, cyclosporine, and valganciclovir. Mycophenolate mofetil was stopped because he had neutropenia, and later, valganciclovir was also stopped because the neutropenia persisted. Because the neutropenia did not recover after we discontinued valganciclovir, the patient was administered granulocyte colony-stimulating factor. The neutrophil count increased to 2.2 x 10(9)/L (leucocyte count to 6.5 x 10(9)/L) after 24 hours. The second case was a 37-year-old man and was using mycophenolic acid, tacrolimus, and valacyclovir. Laboratory investigations revealed his leukocyte count to be 1.3 x 10(9)/L. Mycophenolic acid and valganciclovir were stopped owing to neutropenia. The patient was administered granulocyte colony-stimulating factor, and the neutrophil count increased to 3.8 x 10(9)/L (leucocyte count to 5.8 x 10(9)/L). The kidney functions did not deteriorate in either patient, and the patients' kidney functions were similar to baseline levels 12 months after surgery.

CONCLUSIONS

We conclude that granulocyte colony-stimulating factor can be used safely and effectively in renal transplant patients.

Mycotic pulmonary artery aneurysm due to Aspergillus infection in a patient with leukemia: case report and review of the literature

We present a case of a patient with hairy cell leukemia and pulmonary aspergillosis who developed a cycotic pulmonary artery aneurysm despite prolonged antifungal therapy. A review of the literature in regards to incidence, etiology, clinical manifestations and treatment options is included.

Eruptive neutrophilic xanthomas

Cutaneous eruptive xanthomas are characteristics lesions of hyperlipidemia. Rarely,these lesions may present with prominent leukocytoclasis as seen in papular neutrophilic xanthomas, which have been described in HIV positive and immunocompromised patients. Herein we describe a patient with eruptive neutrophilic xanthomas with neither hyperlipidemia nor immunocompromise. Moreover, these lesions improved with sun and UV light exposure.

Bioequivalence studies of two different film-coated tablet formulations of valacyclovir of two different strengths in healthy volunteers

These studies were conducted in order to assess the bioequivalence of two film-coated formulations containing 250 mg and 1000 mg of valacyclovir (INN: valaciclovir; CAS 124832-26-4), which is the L-valyl ester and a pro-drug of the antiviral drug acyclovir (INN: aciclovir). In the study with valacyclovir 250 mg, 36 healthy subjects were enrolled in a randomized, single-dose, open-label, 2-way crossover study, with a washout period of 10 days. In the study with valacyclovir 1000 mg, 46 healthy subjects were enrolled in a randomized, single-dose, open-label, 2-way crossover study, with a washout period of 7 days. Plasma samples were collected up to 36 h postdose for both studies. Valacyclovir levels were determined by liquid chromatography with tandem mass detection (ie, the LC/MS/MS method) (lower limit of quantification: 0.50 ng/ mL for valacyclovir and 9.93 ng/mL for acyclovir for the 250 mg study and 1.00 ng/mL for valacyclovir and 20.00 ng/ mL for acyclovir for the 1000 mg study). Pharmacokinetic parameters used for bioequivalence assessment were the area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(0-t)) and from time zero to infinity (AUC(0-inf) and maximum observed concentration (C(max)). These parameters were determined from the valacyclovir concentration data using non-compartmental analysis. In the tained by analysis of variance (ANOVA) for valacyclovir were 107.54-124.26% for C(max), 95.45-103.46% for AUC(0-Inf) and 95.53-103.63% for AUC(0-t) whereas for acyclovir the 90% confidence intervals obtained were 103.19-117.02% for C(max), 99.61-106.92% for AUC(0-Inf) and 99.58-106.94% for AUC(0-t). In the study with valacyclovir 1000 mg formulations, the 90% confidence intervals obtained for valacyclovir were 93.20-107.35% for C(max), 90.87-96.27% for AUC(0-inf) and 90.87-96.27% for AUC(0-t) whereas for acyclovir the 90% CIs obtained were 95.98-104.94% for C(max), 97.13-103.94% for AUC(0-inf) and 97.14-104.09% for AUC(0-t). All the 90% confidence intervals obtained for all the parameters assessed were within the predefined range (80-125%). Based on these results, it can be concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.