Valaciclovir

IC50 Value: 2.9 microg/ml (for HSV-1 W)[4]. Valacyclovir, the metabolic precursor of , is now approved for treatment and prevention of genital infection with herpes simplex viruses [1]. in vitro: VACV uptake was concentration dependent and saturable with a Michaelis-Menten constant and maximum velocity of 1.64 +/- 0.06 mM and 23.34 +/- 0.36 nmol/mg protein/5 min, respectively. A very similar Km value was obtained in hPEPT1/CHO cells and in rat and rabbit tissues and Caco-2 cells, suggesting that hPEPT1 dominates the intestinal transport properties of VACV in vitro [5]. in vivo: For treatment of a first episode of genital herpes, a large comparative trial has shown that valacyclovir (1 g twice a day) is as effective as acyclovir (200 mg five times a day) when given for 10 days. For treating recurrences, two trials show that valacyclovir is as effective as acyclovir (200 mg five times a day) with a treatment period of 5 days. A daily dose of 1 g of valacyclovir is as effective as 2 g daily. Valacyclovir can be administered once a day[1]. The concentrations of acyclovir in serum and CSF were measured at steady state after 6 days of oral treatment with 1,000 mg of valacyclovir three times a day [2]. EC50 values of PE and AC in 3T3 cells were 0.02 and 0.01 ug/ml, while values in BHK cells were 0.2 and 0.03 ug/ml. Treatment of infected immunosuppressed mice and FA and VA (b.i.d., 5.5 days) reduced the proportion with erythema from 100% to 24% and 38%, and eliminated ear paralysis, ear lesions (vesicles, etc) and death. Virus was absent from ear and brainstem by day 6, but reappeared after discontinuation in mice treated with VA [3]. Clinical trial: Evaluation of Valaciclovir in Patients with Chickenpox. Phage3

Prophylactic Efficacy Against Herpes Zoster and Costs Difference Between Acyclovir and Valaciclovir in Hematological Patients.[Pubmed:27566094]

In Vivo. 2016 09-10;30(5):701-5.

BACKGROUND: Immunocompromised hematological patients are at increased risk of herpes zoster (HZ). We examined the efficacy of acyclovir and Valaciclovir in preventing HZ. We also created a simulation to reduce prophylactic medicine costs. PATIENTS AND METHODS: We retrospectively evaluated 573 hematological patients who received chemotherapy, and assessed the difference in the costs between the acyclovir (Zovirax(R)) and Valaciclovir (Valtrex(R)) groups. RESULTS: Forty-four out of the 573 patients (7.7%) developed HZ. Out of them, there were 37 patients (84.1%) who received corticosteroids. Moreover, in total, there were 67 patients receiving acyclovir prophylaxis and 42 patients receiving Valaciclovir prophylaxis, out of which one from each group occurred with HZ. The total 5-year cost of acyclovir and Valaciclovir was yen2,869,917 and yen4,809,952, respectively. Therefore, by changing from Valaciclovir to acyclovir, medical costs could be reduced by 28.3%. Additionally, switching to generic inexpensive acyclovir would possibly reduce them to 15.0%. CONCLUSION: Chemotherapy, including corticosteroids, is associated with a high incidence of HZ. Additionally, there was no prophylactic difference between acyclovir and Valaciclovir. We expect that use of generic acyclovir could reduce prophylaxis costs by 85.0%.

Efficacy of interferon in recurrent valaciclovir-refractory erythema multiforme in a patient not infected with hepatitis C virus.[Pubmed:27334053]

Clin Exp Dermatol. 2016 Aug;41(6):648-50.

Recurrent erythema multiforme (EM) is rare and is most typically related to infections with herpes simplex virus. Prophylactic administration of Valaciclovir is the first-line treatment, but there is no agreement about second-line treatment in cases of ineffectiveness. We present a 31-year-old man who was not infected with hepatitis C virus (HCV), and had a history of severe and recurrent EM, unresponsive to Valaciclovir, colchicine and hydroxychloroquine. The patient noticed that an intermittent flu-like illness seemed to have abrogated an EM flare. Because of this observation, the next EM flares were treated with short courses of interferon, which gave rapid and complete efficacy. Efficacy of interferon in EM has only been reported in two previous patients, in whom the drug was administered to treat HCV infection. Efficiency was attributed to treatment of the underlying HCV infection, which was thought to be the origin of EM in both cases. This is the first case, to our knowledge, reporting a dramatic response to interferon-alfa in a patient who was not infected with HCV.

Valaciclovir to prevent Cytomegalovirus mediated adverse modulation of the immune system in ANCA-associated vasculitis (CANVAS): study protocol for a randomised controlled trial.[Pubmed:27450392]

Trials. 2016 Jul 22;17(1):338.

BACKGROUND: The ANCA-associated vasculitides (AAV) are systemic autoimmune inflammatory disorders characterised by necrotising inflammation affecting small to medium-sized blood vessels. Despite improvements in survival, infection and cardiovascular disease remain leading causes of morbidity and mortality. Considerable evidence suggests that CD4 + CD28null T-cell expansions, predominantly seen in Cytomegalovirus (CMV) seropositive individuals, are associated with systemic dysregulation of immune function leading to a heightened risk of infection and cardiovascular disease. In patients with AAV, CD4 + CD28null expansions are driven by CMV and are associated with an increased risk of infection and mortality. The aim of this study is to explore in detail the ways in which CMV modulates the immune system and to determine whether treatment with Valaciclovir blocks subclinical CMV reactivation in CMV seropositive AAV patients and ameliorates the CMV-induced adverse effects on the immune system. METHODS/DESIGN: CANVAS is a single-centre prospective open-label randomised controlled proof-of-concept trial of 50 adult CMV seropositive patients with stable AAV. Participants will be randomly allocated to receive Valaciclovir orally (2 g QDS or reduced according to renal function) or no additional treatment for 6 months with an additional 6-month follow-up period. The primary outcome is the proportion of patients with CMV reactivation, as assessed by measurable viral load on quantitative blood and urine CMV polymerase chain reaction. The secondary outcomes are safety, change in the proportion of CD4+ CMV-specific T-cell population (defined as CD4 + CD28null cells) and change in soluble markers of inflammation from baseline to 6 months. Further tertiary and exploratory outcomes include persistence of the effect of Valaciclovir on the proportion of CD4 + CD28null cells at 6 months post completion of treatment, change in the immune phenotype of CD4+ T cells and change in blood pressure and arterial stiffness parameters from baseline to 6 months. DISCUSSION: The results of this study will enable larger studies to be conducted to determine whether by controlling subclinical CMV reactivation, we can improve clinical endpoints such as infection and cardiovascular disease. The potential impact of this study is not limited to AAV, as CD4 + CD28null cells have been linked to adverse outcomes in other inflammatory conditions and in the context of an ageing immune system. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01633476 (registered 29 June 2012).