HSV-1(EC50=0.5 μg/mL);HSV-2(EC50=0.8 μg/mL)

With EC50s of 0.5, 0.8, 2.4, 52, 100, 1.2, 1.6, 0.9, >100 µg/ml for HSV-1 (HFEM), HSV-2 (MS), VZV (Ellen), CMV (AD-169), BHV-1 (Oxford 1964), BHV-2 (New York 1), EHV-1 (Quai Hals), FHV-1 (B927), and SVV, respectively, penciclovir (0-100 µg/ml) exhibits anti-herpesvirus activity.To human cells that are not infected, penciclovir (0-100 µg/ml) exhibits no toxicity[1].

Penciclovir (100 mg/kg; s.c.; daily for 5 days) preventes mortality in mouse[2].

Human breast cancer cell lines MCF-7 and MDA-MB-435, glioblastoma U87MG, and embryonic kidney cells 293T are cultured at 37°C in a humidified atmosphere containing 5% CO2 in Iscove’s modified Dulbecco medium or Leibovitz’s L-medium and 5% fetal bovine serum (FBS). The assays are performed with slight modifications. In brief, cells are seeded into 24-well plates (5×104 cells/well) and infected 48 h later with 103 particles per cell of unmodified virus (Adtk), PEGylated virus (PEG-Adtk), or RGD-PEG-modified virus (RGD-PEG-Adtk) in triplicates in culture medium with 2% FBS and incubated for 4 h at 37°C. The incubation medium is then replaced by normal medium and cells are further incubated for 48 h. Cells are harvested and lysed with 500 μL of TK lysis buffer that contained 0.5% Nonidet P-40 (NP-40), 20 mM N-(2-hydroxyethyl) piperazine-N′-(2-ethanesulfonic acid) (HEPES) (pH 7.6), 2 mM Mg(OAc)2, 1 mM dithiothreitol, and 50 μM thymidine. The supernatant is collected after centrifugation. The samples are kept at -80°C until use. The modified and unmodified adenovirus protein concentrations are determined by the Micro BCA assay. One microgram of cell extract is incubated with HSV1-tk substrate 8-3H-Penciclovir (8-3 H-PCV). The phosphorylated tracer is separated from unphosphorylated 8-3 H-PCV with DE-81 filters. TK activity is expressed as the percentage of conversion of substrate per minute per microgram protein.

Animal Model: Three-week-old female Balb/c mice[2]
Dosage: 100 mg/kg
Administration: S.c.; daily for 5 days
Result: decreased viral titres in the respiratory systems of mice infected with PR3 and W/t.

Absorption, Distribution and Excretion
Measurable penciclovir concentrations were not detected in plasma or urine of healthy male volunteers (n= 12) following single or repeat application of the 1% cream at a dose of 180 mg penciclovir daily.
Measurable penciclovir concentrations were not detected in plasma or urine of healthy male volunteers (n=12) following single or repeat application of the 1% cream at a dose of 180 mg penciclovir daily (approximately 67 times the estimated usual clinical dose).
There is no information on whether penciclovir is excreted in human milk after topical administration. However, following oral administration of famciclovir (the oral prodrug of penciclovir) to lactating rats, penciclovir was excreted in breast milk at concentrations higher than those seen in the plasma.
The ... pharmacokinetics of intravenously administered penciclovir (BRL 39,123A), a novel anti-herpes agent, were investigated in 15 healthy male subjects. The volunteers were divided into three groups, receiving either 10, 15 or 20 mg/kg penciclovir by a 60 min constant-rate infusion. Blood samples were taken sequentially up to 48 hr after the start of the infusion and urine collections made at appropriate intervals up to 72 hr. After a simple solid phase extraction, concentrations of penciclovir in plasma and urine were determined using HPLC with U.V. detection. Mean values of Cmax, corresponding usually with the end of infusion, and of AUC appeared to increase proportionately with dose. Furthermore, there was no evidence that dose significantly affected any individual pharmacokinetic parameter. Penciclovir was distributed into tissues with an overall mean volume of distribution of approximately 1.5 L.kg-1, i.e. approximately double that of body water. It was rapidly eliminated, with a mean total plasma clearance of 39.3 L.hr-1, and a mean terminal-phase half-life of 2.0 hr. The majority of the dose, approximately 70%, was excreted unchanged in the urine. Mean renal clearance of BRL 39,123 was 28.1 L.hr-1, which exceeds normal glomerular filtration rate and approaches renal plasma flow.
Following the oral administration of a single 500 mg dose of radiolabeled famciclovir to three healthy male volunteers, 73% and 27% of administered radioactivity were recovered in urine and feces over 72 hours, respectively. Penciclovir accounted for 82% and 6-deoxy penciclovir accounted for 7% of the radioactivity excreted in the urine. Approximately 60% of the administered radiolabeled dose was collected in urine in the first 6 hours.
For more Absorption, Distribution and Excretion (Complete) data for Penciclovir (15 total), please visit the HSDB record page.

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Metabolism / Metabolites
Hepatic
Following oral administration, famciclovir is deacetylated and oxidized to form penciclovir. Metabolites that are inactive include 6-deoxy penciclovir, monoacetylated penciclovir, and 6-deoxy monoacetylated penciclovir (5%, <0.5% and <0.5% of the dose in the urine, respectively). Little or no famciclovir is detected in plasma or urine. An in vitro study using human liver microsomes demonstrated that cytochrome P450 does not play an important role in famciclovir metabolism. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase.
Famciclovir is deacetylated and oxidized to penciclovir. Penciclovir is phosphorylated to penciclovir triphosphate (the active metabolite) in cells infected with HSV-1, HSV-2, or VZV. The inactive metabolite 6-deoxy penciclovir is converted to penciclovir by aldehyde oxidase. Famciclovir not metabolized by CYP enzymes.

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Biological Half-Life
2 hours
Elimination half-life of penciclovir after oral administration of famciclovir 1.6-3 hours. Intracellular half-life of penciclovir triphosphate in cells infected with herpes simplex virus (HSV)-1 or HSV-2 is 10 and 20 hours, respectively; intracellular half-life in varicella zoster virus (VZV)-infected cells is 7-14 hours.
The ... pharmacokinetics of intravenously administered penciclovir (BRL 39,123A), a novel anti-herpes agent, were investigated in 15 healthy male subjects. A mean terminal-phase half-life of 2.0 hr /was reported/.
The plasma elimination half-life of penciclovir was 2.0 + or - 0.3 hours after intravenous administration of penciclovir to 48 healthy male volunteers and 2.3 + or - 0.4 hours after oral administration of 500 mg famciclovir to 124 healthy male volunteers. The half-life in 17 patients with herpes zoster was 2.8 + or - 1.0 hours and 2.7 + or - 1.0 hours after single and repeated doses, respectively.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Although there is no published experience with penciclovir during breastfeeding, infant side effects are unlikely with maternal topical application to small areas of the mother's body away from the breast. Only water-miscible cream or gel products should be applied to the breast because ointments may expose the infant to high levels of mineral paraffins via licking.[1]
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Less than 20%.

[1]. Penciclovir: a review of its spectrum of activity, selectivity, and cross-resistance pattern. Antiviral Chemistry and Chemotherapy, 1993, (1): 3-11.

[2]. The acyclic nucleoside analogue penciclovir is a potent inhibitor of equine herpesvirus type 1 (EHV-1) in tissue culture and in a murine model. Antiviral Res. 1992 May;18(1):77-89.

Therapeutic Uses
Antiviral Agents; Reverse Transcriptase Inhibitors
Denavir (penciclovir cream) is indicated for the treatment of recurrent herpes labialis (cold sores) in adults and children 12 years of age and older. /Included in US product label/

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Drug Warnings
Denavir should only be used on herpes labialis on the lips and face. Because no data are available, application to human mucous membranes is not recommended. Particular care should be taken to avoid application in or near the eyes since it may cause irritation. Lesions that do not improve or that worsen on therapy should be evaluated for secondary bacterial infection. The effect of Denavir has not been established in immunocompromised patients.
FDA Pregnancy Risk Category: B /NO EVIDENCE OF RISK IN HUMANS. Adequate, well controlled studies in pregnant women have not shown increased risk of fetal abnormalities despite adverse findings in animals, or, in the absence of adequate human studies, animal studies show no fetal risk. The chance of fetal harm is remote but remains a possibility./
There is no information on whether penciclovir is excreted in human milk after topical administration. However, following oral administration of famciclovir (the oral prodrug of penciclovir) to lactating rats, penciclovir was excreted in breast milk at concentrations higher than those seen in the plasma. Therefore, a decision should be made whether to discontinue the drug, taking into account the importance of the drug to the mother.
In 74 patients >/=65 years of age, the adverse events profile was comparable to that observed in younger patients.
For more Drug Warnings (Complete) data for Penciclovir (9 total), please visit the HSDB record page.

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Pharmacodynamics
Penciclovir is the active metabolite of the oral product famciclovir. The more favorable results observed with topical penciclovir versus topical acyclovir for the treatment of herpes labialis may be due to the longer intracellular half-life of penciclovir in HSV-infected cells. The activated drug inhibits the viral DNA polymerase. This impairs the ability of the virus to replicate within the cell.

C10H15N5O3

253.26

253.117

C, 47.42; H, 5.97; N, 27.65; O, 18.95

39809-25-1

Penciclovir-d4;1020719-72-5;Penciclovir sodium;97845-62-0

135398748

White crystalline solid from water (monohydrate) ... also reported as colorless matted needles

1.7±0.1 g/cm3

636.7±65.0 °C at 760 mmHg

275-277°C

338.9±34.3 °C

0.0±2.0 mmHg at 25°C

1.749

-3.58

4

5

5

18

344

0

O([H])C([H])([H])C([H])(C([H])([H])O[H])C([H])([H])C([H])([H])N1C([H])=NC2C(N([H])C(N([H])[H])=NC1=2)=O

JNTOCHDNEULJHD-UHFFFAOYSA-N

InChI=1S/C10H15N5O3/c11-10-13-8-7(9(18)14-10)12-5-15(8)2-1-6(3-16)4-17/h5-6,16-17H,1-4H2,(H3,11,13,14,18)

2-amino-9-[4-hydroxy-3-(hydroxymethyl)butyl]-3H-purin-6-one

BRL-39123; BRL 39123; BRL39123; VSA 671; VSA671; VSA-671; Penciclovir; Denavir, Vectavir and Fenivir.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : 25~34 mg/mL (98.71~134.24 mM)
H2O : ~2 mg/mL (~7.90 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.87 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (9.87 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (9.87 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 10% DMSO+40% PEG300+5% Tween-80+45% Saline: ≥ 2.5 mg/mL (9.87 mM)

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 (Please use freshly prepared in vivo formulations for optimal results.)