Famvir
Synthesis and evaluation of 2-amino-9-(3-acyloxymethyl-4-alkoxycarbonyloxybut-1-yl)purines and 2-amino-9-(3-alkoxycarbonyloxymethyl-4-alkoxycarbonyloxybut-1- yl)purines as potential prodrugs of penciclovir.

Kim DK, Lee N, Ryu DH, Kim YW, Kim JS, Chang K, Im GJ, Choi WS, Cho YB, Kim KH, Colledge D, Locarnini S.

Life Science Research Center, SK Chemicals, Kyungki-Do, Korea. dkkim skchemicals.com

A series of 2-amino-9-(3-acyloxymethyl-4-alkoxycarbonyloxybut-1-yl)purin es (1-8) and 2-amino-9-(3-alkoxycarbonyl-oxymethyl-4-alkoxycarbonyloxybut -1-yl)purines (9-12) were synthesized as potential prodrugs of penciclovir. Treatment of 6-deoxypenciclovir with trimethyl orthoacetate or triethyl orthopropionate (1.2 equiv) in DMF in the presence of p-TsOH.H2O (0.1 equiv) followed by quenching with excess H2O gave the corresponding mono-O-acetyl or mono-O-propionyl compound, 17 or 18, in excellent yields of 95 and 92%, respectively. Reactions of 17 or 18 with an appropriate alkyl (Me, Et, n-Pr, and i-Pr) 4-nitrophenyl carbonate (1.2 equiv) in pyridine in the presence of a catalytic amount of DMAP (0.1 equiv) at 80 degrees C afforded the monoacyl, monocarbonate derivatives of 6-deoxypenciclovir, 1-8, in 86 94% yields. Similar reactions of 6-deoxypenciclovir with 2.1 equiv of alkyl 4-nitrophenyl carbonate produced the dicarbonate derivatives 9 12 in 81-83% yields. Of the prodrugs tested in rats, 2-amino-9-(3-acetoxymethyl-4-isopropoxycarbonyloxybut-1-yl)purine (4) achieved the highest mean urinary recovery of penciclovir (36%), followed in order by compounds 2 (35%), 6 (35%), 7 (34%), 10 (34%), 8 (32%), 3 (32%), and famciclovir (31%). The mean urinary recovery of penciclovir and concentrations of penciclovir in the blood from 4 in mice were also slightly higher than those from famciclovir. The in vivo antiviral efficacy of 4 in HSV-1-infected normal BALB/c mice was higher than those of famciclovir and valaciclovir in terms of mortality (100, 80, and 40%) and mean survival time ( > 21, 13+/-5.0 (SEM), and 13+/-1.6 days). Compound 4 demonstrated an effective anti-hepadnaviral response with intrahepatic viral load being reduced by 90%, the viral supercoiled DNA levels reduced by 70% and Pre-S expression inhibited by 30% against duck hepatitis B virus (DHBV) in vivo, and did not cause any significant hepatotoxicity after 4 weeks of treatment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10482463&dopt=Abstract famciclovir Famvir



Famvir
Differential effects of famciclovir and valaciclovir on the pathogenesis of herpes simplex virus in a murine infection model including reactivation from latency.

Thackray AM, Field HJ.

Centre for Research in Veterinary Science, Cambridge University Veterinary School, United Kingdom.

The ability of famciclovir and valaciclovir to affect the establishment and maintenance of latency in mice with a cutaneous herpes simplex type 1 (HSV-1) infection was examined. Mice were treated via drinking water starting at various times between days 1 and 5 and terminating on day 10 after inoculation. Clinical signs and viral replication in the target tissues were monitored. Three to four months later, trigeminal and dorsal root ganglia were explanted from groups of 16 mice and examined for latent virus by cocultivation. The two compounds differed in their effects on the acute neural infection, and ganglia explanted from famciclovir-treated mice were markedly reduced in their ability to reactivate virus, although neither drug affected latency if treatment was delayed for several months. The difference between the compounds is likely to reflect differences in the metabolism of their respective products, penciclovir and acyclovir, in infected neurons.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8568288&dopt=Abstract famciclovir Famvir



Famvir
Comparison of effects of famciclovir and valaciclovir on pathogenesis of herpes simplex virus type 2 in a murine infection model.

Thackray AM, Field HJ.

Centre for Veterinary Science, Cambridge University Veterinary School, United Kingdom.

The effects of famciclovir (FCV) and valaciclovir (VACV) were compared in a cutaneous infection model for herpes simplex virus type 2 (HSV-2). The compounds were administered orally from day 1 to day 5 postinfection. Both compounds reduced local inflammation and virus replication in the skin. FCV markedly reduced mortality and virus replication in the nervous system. On the cessation of therapy after 5 days, when the levels of infectious virus in the tissues were reduced to below the level of detection, there followed a rebound of virus replication in the ganglia and brain stems of mice that had been treated with VACV. The recurrence of infection in the brain stem occurred on three separate occasions. No such recurrences were observed following FCV treatment. When ganglia were explanted from survivors 6 weeks later, latent virus was shown to be reactivated in all 10 of 10 control, untreated mice. The number of mice whose ganglia yielded virus was reduced to 60% in mice that had been treated with VACV, whereas no mice that had been treated with FCV had evidence of latent infection by this test.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8849238&dopt=Abstract famciclovir Famvir



Famvir
Drug treatment of common STDs: part I. Herpes, syphilis, urethritis, chlamydia and gonorrhea.

Woodward C, Fisher MA.

West Virginia University Hospitals, Morgantown 26506-8045, USA.

In 1998, the Centers for Disease Control and Prevention released guidelines for the treatment of sexually transmitted diseases. Several treatment advances have been made since the previous guidelines were published. Part I of this two-part article describes current recommendations for the treatment of genital ulcer diseases, urethritis and cervicitis. Treatment advances include effective single-dose regimens for many sexually transmitted diseases and improved therapies for herpes infections. Two single-dose regimens, 1 g of oral azithromycin and 250 mg of intramuscular ceftriaxone, are effective for the treatment of chancroid. A three-day course of 500 mg of oral ciprofloxacin twice daily may be used to treat chancroid in patients who are not pregnant. Parenteral penicillin continues to be the drug of choice for treatment of all stages of syphilis. Three antiviral medications have been shown to provide clinical benefit in the treatment of genital herpes: acyclovir, valacyclovir and famciclovir. Valacyclovir and famciclovir are not yet recommended for use during pregnancy. Azithromycin in a single oral 1-g dose is now a recommended regimen for the treatment of nongonococcal urethritis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10524484&dopt=Abstract famciclovir Famvir



Famvir
Famciclovir therapy for recurrent hepatitis B virus infection after liver transplantation.

Haller GW, Bechstein WO, Neuhaus R, Raakow R, Berg T, Hopf U, Neuhaus P.

Department of Surgery, Virchow Clinic, Humboldt University of Berlin, Germany.

Between November 1993 and June 1995 18 patients received oral famciclovir (3 x 500 mg) for treatment of hepatitis B virus (HBV) reinfection after liver transplantation. Reinfection was defined as the reoccurrence of HBsAg in the serum. In the first 15 patients, famciclovir therapy was initiated after clinical signs of graft hepatitis, whereas the last 3 patients received treatment immediately after HBV-DNA was detected. Famciclovir was well-tolerated in all patients. HBV-DNA values were decreased to undetectable levels in 8 out of 18 patients. Clinical status improved in 7 patients, whereas 5 patients remained unchanged and 6 patients progressed to deteriorating graft function and death. When famciclovir was initiated early after reinfection, a response rate of approximately 66% was observed. Late onset of therapy in patients with fulminant hepatitis generally failed to provide any clinical benefit.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8959829&dopt=Abstract famciclovir Famvir