Penciclovir cream

The cream contains penciclovir, an antiviral agent active against herpes viruses for topical administration as a 1% white cream. Each gram of cream contains 10 mg penciclovir 

Place into kettle and heat to 70°C while stirring transfer the melted fatty mass under vacuum (-0.3 mm) through the inline sieve (mesh size 0.150 mm). After the addition, evacuate again to -0.3 atm, then stir for another 15 minutes and homogenize for 5 minutes under the same condition. 

Cool to 30°C. (The cooling should be within 4 hours.) When this temperature is reached, continue stirring until the ointent has reached 24°-26°C stop cooling. Then evacuate to -0.3 atm and stir for 5 minutes. 

Transfer the ointment in a mixer and mix for 5 minutes with electric mixture. Fill the ointment. 

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The guanosine analog penciclovir, the active metabolite of famciclovir, is available for topical use. Penciclovir cream (1%) is effective for the treatment of recurrent herpes labialis (Table 49-1). When applied within 1 hour of the onset of prodromal symptoms and continued every 2 hours during waking hours for 4 days, median time until healing was shortened by 17 hours compared with placebo. Adverse effects are uncommon, although application site reactions occur in about 1%. 

Lin L, Chen XS, Cui PG, et al. Topical application of penciclovir cream for the treatment of herpes simplex facialis/labialis a randomized, double-blind, multicentre, aciclovir-controlled trial. J Dermatolog Treat. 2002 13 67-72. 

Famciclovir is contraindicated in patients with known hypersensitivity to the product, or its components, or penciclovir cream (Denavir ). 

Pharmacokinetics Measurable penciclovir concentrations were not detected in plasma or urine of healthy male volunteers following single or repeat application of the 1% cream at a dose of 180 mg penciclovir daily (about 67 times the estimated usual clinical dose). 

Penciclovir (Denavir) [Antiviral] U e Herpes simplex (herpes labialis/ cold sores) Action Competitive inhibitor of DNA polym ase Dose Apply at 1st sign of lesions, then q2h while awake x 4 d Caution [B, /-] Contra Allergy, previous Rxn to famciclovir Disp Cream SE Erythema, HA EMS None OD Unlikely to cause life-threatening Sxs... 

Penciclovir Topical (1% cream) Recurrent herpes labialis Thin film covering lesion every 2 hours x 4 days... 

Topical acyclovir (Zovirax) is available as a 5% ointment topical penciclovir (Denavir), as a 1% cream for the treatment of recurrent orolabial herpes simplex virus infection in immunocompetent adults. Adverse local reactions to acyclovir and penciclovir may include pruritus and mild pain with transient stinging or burning. 

Penciclovir (Fig. 23.17) is closely related to ganciclovir in structure and has the same mechanism of action. Penciclovir has similar activity to aciclovir against herpes simplex infection. Its safety is similar to that of aciclovir due to its lack of effect on DNA synthesis in uninfected cells. A closer structural similarity to deoxyguanosine makes penciclovir a superior substrate in comparison to aciclovir for viral thymidine kinase, resulting in an enhancement of phosphorylation. This is offset by reduced activity of penciclovir triphosphate as an inhibitor of DNA synthesis. It has poor oral bioavailability and is used in the form of a cream (1% w/w) to treat labial herpes. Famciclovir (Fig. 23.17) is a prodmg of penciclovir which has good oral bioavailability (73%) and is deacetylated and oxidised (aldehyde oxidase) in the liver to penciclovir. The toxicity of famciclovir is low. It is administered three times a day by mouth, whereas treatment of herpes with aciclovir by the oral route requires five daily doses. 

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