bio.uniurb.it

Acyclovir is an acyclic guanine analog with a considerable activity against herpes simplex viruses. We studied the antiherpetic activity of acyclovir in macrophages and fibroblast cell lines. Utilising a plaque reduction assay we found that acyclovir potently inhibited the HSV-1 replication in macrophages (EC50) = 0.0025 microM) compared to Vero (EC50 = 8.5 microM) and MRC-5 (EC50 = 3.3 microM) cells. The cytotoxicity of acyclovir was not detected at concentrations < or = 20 microM, thus the selective index in macrophages was >8000. This marked difference in antiherpetic activity between macrophages and fibroblasts was not observed with Foscarnet and PMEA. We suggest that this potent antiviral effect of acyclovir is mainly due to a proficient phosphorylation of the drug and/or a favourable dGTP/acyclovir triphosphate ratio in macrophage cells.

Online pharmacy ref source - acyclovir: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11521752&dopt=Abstract acyclovir Zovirax

hsp.santpau.es

The in vitro susceptibility to acyclovir of 204 herpes simplex virus isolates from 165 immunocompromised patients treated at our hospital was determined by the cytopathic effect reduction assay. Approximately 95% of herpes simplex virus 1 and 73% of herpes simplex virus 2 isolates were inhibited by acyclovir at concentrations of <2 microgram/mL. From 8 patients (5%), an isolate with low susceptibility to acyclovir (50% inhibitory dose, >3 microgram/mL) was recovered. Medical records of 83 patients were reviewed. Lesions resolved in most of the patients, independent of treatment. Treatment failures were not always associated with isolation of an in vitro-resistant virus. On the contrary, when a virus with low susceptibility to acyclovir was isolated, resolution of the lesion was the rule. In 9 of 10 patients with subsequent recurrent episodes of disease, the susceptibility of the viruses isolated was similar to that of the first episode. Routine susceptibility testing in our geographic area is not encouraged because of the low incidence of acyclovir-resistant herpes simplex viruses.

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swipnet.se

BACKGROUND: The efficacy of oral acyclovir, a purine nucleoside analogue with activity against human herpes viruses, is limited as a result of its low bioavailability. Valacyclovir, the L-valyl ester of acyclovir, has been developed as a pro-drug to improve the bioavailability. The aim of the present study was to compare the pharmacokinetics of acyclovir after intravenous administration and after oral administration of valacyclovir. PROCEDURE: The pharmacokinetics of acyclovir were studied in 18 children aged 1.4-18.1 years (median: 6.9 years; 9 females) after intravenous infusion (1 hr; median dose: 10.5 mg/kg). In 10 of the children the pharmacokinetics of acyclovir were also studied after oral administration of valacyclovir (median dose: 34.1 mg/kg). Quantification of acyclovir in serum was performed by reversed-phase liquid chromatography with fluorometric detection. The pharmacokinetic analysis was performed by pharmacokinetic modelling. RESULTS: The serum concentration versus time curves of acyclovir were described by the two compartment model after intravenous administration and by the one compartment model with a zero- or first-order absorption phase after oral administration of valacyclovir. The bioavailability of acyclovir after oral administration of valacyclovir was 45% (median value; 95% CI: 37-55%). CONCLUSION: It is possible to substitute intravenous acyclovir therapy by oral valacyclovir therapy in children with leukopenia and mucositis after chemotherapy. This finding can at present not be fully implemented in clinical practice, since a commercial pharmaceutical formulation of valacyclovir aimed for children not able to swallow intact tablets is lacking. Crushed valacyclovir tablets have a very unpleasant taste, but can be administered to children through nasogastric tubes. Copyright 2002 Wiley-Liss, Inc.

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peds.uab.edu

Herpes simplex virus (HSV) infections are ubiquitous. Children are infected with HSV resulting in totally asymptomatic acquisition to life-threatening disease. Therapy of HSV diseases of children can be considered according to severity and time of acquisition. Neonatal herpes simplex virus infections take one of three forms--disease localized to skin, eye, or mouth (SEM), encephalitis, or multiorgan disseminated disease. Treatment consists of intravenous (IV) administration of acyclovir. Supportive care for patients with life-threatening disease is an integral component of patient management. Mucocutaneous HSV infections in the immunocompromised host can be treated with either intravenous acyclovir or one of the orally bioavailable antiviral therapies. For hospitalized patients, therapy consists of IV acyclovir at 5 mg/kg every 8 hours for 7 to 14 days. For ambulatory patients, therapy is tailored according to age. For children less than 12 years of age, oral acyclovir is administered at a dosage of 20 mg/kg every eight hours. Although no controlled studies have been performed with valaciclovir or famciclovir, the pharmacokinetics of these medications would suggest superiority over acyclovir. Dosage recommendations have not been established for young children. For postpubertal children, dosage should mirror that of adults. Valaciclovir is administered at 500 mg twice daily. Famciclovir is administered at 125 mg three times daily. Herpes simplex keratoconjunctivitis is treated with topical triflurothymidine. Two drops are applied to the infected eye five times daily until resolved. Recurrences are managed in a similar manner. Some physicians administer oral acyclovir at the doses noted above in order to prevent frequent recurrences. Genital HSV infections can be treated with acyclovir, valaciclovir, or famciclovir. Episodic treatment of recurrent episodes is usually not necessary in childhood. Importantly, all data on the use of these compounds for these conditions have been generated in adults. Physician judgment is required for the management of recurrent herpes labialis, erythema multiforme, and herpes gladitorum. No controlled studies have been performed in children, although experience with acyclovir, valaciclovir, and famciclovir have resulted in their use.

Online pharmacy ref source - acyclovir: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11931730&dopt=Abstract acyclovir Zovirax[PubMed - as supplied by publisher]




J Chromatogr B Analyt Technol Biomed Life Sci. 2002 Jun 5;772(2):327-34.
Determination of acyclovir in maternal plasma, amniotic fluid, fetal and placental tissues by high-performance liquid chromatography.

Brown SD, White CA, Chu CK, Bartlett MG.

Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, GA 30602-2352, USA.

Acyclovir [9-[(2-hydroxyethoxy)-methyl]-guanosine, Zovirax, ACV] is a synthetic purine nucleoside analog active against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella zoster virus. Acyclovir has frequently been used in HSV-2 seropositive mothers to prevent prenatal transmission of herpes virus to their unborn children. A fast and reproducible HPLC method for the determination of the highly polar acyclvoir in maternal rat plasma, amniotic fluid, placental tissue, and fetal tissue has been developed and validated. Plasma and amniotic fluid samples were prepared by protein precipitation using 2 M perchloric acid and syringe filtering. Tissue samples were homogenized in distilled water, centrifuged, and extracted using a C(18) solid-phase extraction method prior to analysis. Baseline resolution was achieved for acyclovir and the internal standard gancyclovir, an anti-viral of similar structure to acyclovir, using an Agilent Eclipse XDB C(8) column (150 x 2.1 mm, 5 microm). The mobile phase used for the plasma and amniotic fluid was 10 mM acetate/citrate buffer-3.7 mM aqueous octanesulfonic acid (87.5:12.5, v/v) at a flow-rate of 0.2 ml/min. The mobile phase used for the tissue samples was 30 mM acetate/citrate buffer with 5 mM octanesulfonic acid-acetonitrile (99:1, v/v). Both aqueous mobile phase portions were pH adjusted to 3.08. All separations were done using an Agilent 1100 Series HPLC system with UV detection of 254 nm. The assay was validated for each matrix over a range of 0.25-100 microg/ml over 3 days using five replicates of three spiked concentrations. The relative standard deviation and percent error for each validation data set was <15% for middle and high quality control (QC) points and <20% for all low QC points. All calibration curves showed good linearity with an R(2)>0.99. The extraction efficiency for recovery of acyclovir from all matrices was >80%.

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