Famciclovir

Famciclovir is an oral prodrug of penciclovir [1].

Famciclovir is an oral prodrug of anti- herpesvirus drug penciclovir since penciclovir is poorly absorbed when given orally to rodents. Famciclovir is a diester derivative of 6-deoxy-penciclovir. It can be quickly absorbed and converted to the antiviral drug efficiently both in rat tissues and fluids and in human tissues and fluids. Besides that, famciclovir is relatively stable in the duodenal contents and can give consistent levels of penciclovir in blood. Currently, famciclovir is approved to be used for the treatment of herpes zoster, herpes labialis, genital herpes in immunocompetent adult patients and HSV in immunocompromised adults [1, 2].

References:
[1] Hodge R A V, Sutton D, Boyd M R, et al. Selection of an oral prodrug (BRL 42810; famciclovir) for the antiherpesvirus agent BRL 39123 [9-(4-hydroxy-3-hydroxymethylbut-l-yl) guanine; penciclovir]. Antimicrobial agents and chemotherapy, 1989, 33(10): 1765-1773.
[2] Sáez-Llorens X, Yogev R, Arguedas A, et al. Pharmacokinetics and safety of famciclovir in children with herpes simplex or varicella-zoster virus infection. Antimicrobial agents and chemotherapy, 2009, 53(5): 1912-1920.

Clinical study in genital herpes: natural Gene-Eden-VIR/Novirin versus acyclovir, valacyclovir, and famciclovir.[Pubmed:27621592]

Drug Des Devel Ther. 2016 Aug 29;10:2713-22.

BACKGROUND: This paper reports the results of a clinical study that tested the effect of suppressive treatment with the botanical product Gene-Eden-VIR/Novirin on the number of genital herpes outbreaks. The results in this study were compared to those published in clinical studies of acyclovir, valacyclovir, and Famciclovir. METHODS: The framework was a retrospective chart review. The population included 139 participants. The treatment was one to four capsules of Gene-Eden-VIR/Novirin per day. The duration of treatment was 2-48 months. The study included three controls recommended by the US Food and Drug Administration (FDA): baseline, no treatment, and dose response. RESULTS: The treatment decreased the number of outbreaks per year in 90.8% of the participants. The treatment also decreased the mean number of outbreaks per year from 7.27 and 5.5 in the control groups to 2.39 (P<0.0001 and P<0.001, respectively). The treated participants reported no adverse experiences. Out of the 15 tests that compared Gene-Eden-VIR/Novirin to the three drugs, Gene-Eden-VIR/Novirin had superior efficacy in eight tests, inferior efficacy in three tests, and comparable efficacy in four tests. Gene-Eden-VIR/Novirin also had superior safety. CONCLUSION: The clinical study showed that the natural Gene-Eden-VIR/Novirin decreases the number of genital herpes outbreaks without any side effects. The study also showed that the clinical effects reported in this study are mostly better than those reported in the reviewed studies of acyclovir, valacyclovir, and Famciclovir.

A famciclovir + celecoxib combination treatment is safe and efficacious in the treatment of fibromyalgia.[Pubmed:28260944]

J Pain Res. 2017 Feb 22;10:451-460.

OBJECTIVE: Infections and other stressors have been implicated in the development of fibromyalgia. We hypothesized that these stressors could result in recurrent reactivations of latent herpes virus infections, which could lead to the development of fibromyalgia. This study evaluated a Famciclovir + celecoxib drug combination (IMC-1), active against suspected herpes virus reactivation and infection, for the treatment of fibromyalgia. METHODS: A total of 143 fibromyalgia patients were enrolled at 12 sites in a 16-week, double-blinded, placebo-controlled proof-of-concept trial. Randomized patients received either IMC-1 or placebo in a 1:1 ratio. Outcome measures included a 24-hour recall pain Numerical Rating Scale, the Revised Fibromyalgia Impact Questionnaire (FIQ-R), the Patient's Global Impression of Change (PGIC) questionnaire, the Multidimensional Fatigue Inventory, the NIH Patient-Reported Outcomes Measurement Information System (PROMIS), and the Beck Depression Inventory-II conducted at baseline and weeks 6, 12, and 16 of the study. RESULTS: A significant decrease in fibromyalgia-related pain was observed for patients on IMC-1 treatment versus placebo. PGIC response rates were significantly improved with IMC-1 treatment. Overall, patient self-reported functioning, as measured by the FIQ-R, was significantly improved. Fatigue was also significantly improved as measured by the PROMIS fatigue inventory. The safety profile was encouraging. Despite the celecoxib component of IMC-1, gastrointestinal and nervous system treatment emergent adverse events were reported less frequently in the IMC-1 group, and study completion rates favored IMC-1 treatment. CONCLUSION: IMC-1 was efficacious and safe in treating symptoms of fibromyalgia, supporting the hypothesis that herpes virus infections may contribute to this syndrome. Improved retention rates, decreased adverse event rates, and evidence of efficacy on a broad spectrum of outcome measures are suggestive that IMC-1 may represent an effective, novel treatment for fibromyalgia.

Oral administration of famciclovir for treatment of spontaneous ocular, respiratory, or dermatologic disease attributed to feline herpesvirus type 1: 59 cases (2006-2013).[Pubmed:27556267]

J Am Vet Med Assoc. 2016 Sep 1;249(5):526-38.

OBJECTIVE To evaluate outcomes for cats treated with orally administered Famciclovir 3 times/d for clinical signs attributed to naturally occurring feline herpesvirus type 1 (FHV-1) infection and to assess variables related to owner satisfaction with the treatment. DESIGN Retrospective case series. ANIMALS 59 client-owned cats. PROCEDURES Medical records were reviewed to identify cats treated for presumed FHV-1 infection from 2006 through 2013 with >/= 1 follow-up visit. Signalment, duration of clinical signs, prior treatment, examination findings, diagnostic test results, concurrent treatments, and outcome data were recorded. Owners were asked to complete a survey regarding patient- and treatment-related variables. Data were compared between cats that received low (approx 40 mg/kg [18 mg/lb]) and high (approx 90 mg/kg [41 mg/lb]) doses of Famciclovir, PO, 3 times/d. RESULTS Patient age ranged from 0.03 to 16 years. Conjunctivitis (51/59 [86%]), keratitis (51 [86%]), blepharitis (19 [32%]), nasal discharge or sneezing (10 [17%]), and dermatitis (4 [7%]) were common findings. Clinical improvement was subjectively graded as marked in 30 (51%) cats, mild in 20 (34%), and nonapparent in 9 (15%). Median time to improvement was significantly shorter, and degree of improvement was significantly greater in the highdose group than in the low-dose group. Adverse effects potentially attributable to Famciclovir administration were reported for 10 cats. On the basis of survey responses, most (29/32 [91%]) owners were satisfied with their cat's treatment. CONCLUSIONS AND CLINICAL RELEVANCE Famciclovir at the prescribed dosages was associated with improved clinical signs in cats with presumed FHV-1 infection, and few adverse effects were attributed to the treatment. Further studies are needed to assess whether a Famciclovir dosage of 90 versus 40 mg/kg, PO, 3 times/d would result in increased efficacy and shorter treatment time.

Comparison of Acyclovir and Famciclovir for Ramsay Hunt Syndrome.[Pubmed:28221283]

Otol Neurotol. 2017 Jun;38(5):754-758.

OBJECTIVE: Although antiviral agents are widely used to treat Ramsay hunt syndrome (RHS), their relative effectiveness has not been assessed. This study retrospectively compared clinical outcomes in patients with RHS treated with the antiviral agents acyclovir and Famciclovir. PATIENTS AND METHODS: This study involved 227 patients diagnosed with RHS from 2003 to 2015. Patients were treated with prednisolone plus acyclovir (n = 102) or Famciclovir (n = 125). Patient outcomes were measured using the House-Brackmann scale according to age, initial severity of disease, electroneurography, and underlying disease. RESULTS: Based on complications (p = 0.019) and disease severity (p = 0.013), the overall complete recovery rate was significantly higher with Famciclovir than with acyclovir, whereas rates of recovery in patients with severe (p = 0.111) and initially moderate (grades III-IV; p = 0.070) facial palsy were similar. Electroneurography also showed no difference in remission rate between the two groups (p = 0.692). Complete recovery rates in patients with hypertension and/or diabetes mellitus were similar in the two groups. However, the complete recovery rate of patients without hypertension and diabetes was significantly higher in patients treated with Famciclovir than acyclovir (p = 0.018). CONCLUSION: Recovery rates in patients with RHS were higher following treatment with steroid plus Famciclovir than with steroid plus acyclovir, especially in patients without hypertension and diabetes mellitus.