The active medical ingredient penciclovir is used as a virostatic agent for the therapy of herpes infections. When viewed chemically, it is a compound that has functional and structural similarities to guanine. Penciclovir is approved in the United States and Europe, including German-speaking countries (Germany, Austria, Switzerland).
What is penciclovir?
Penciclovir is an analog of guanine. This means that, from a chemical and pharmacological point of view, penciclovir is very similar in function and structure to the nucleic base guanine. These similarities have implications for the mechanism of action. Penciclovir is used as a virostatic agent to treat simplex-type herpes infections. The drug has a morale mass of 253.26 g/mol, corresponding to a chemical molecular formula of C 10 – H 15 – N 5 – O 3. The substance, which is solid at regular room temperature, is soluble in water and is usually marketed as an ointment for external use on the face only. In Europe, penciclovir is subject to compulsory pharmacy sales. Medicines containing the active ingredient can therefore only be purchased from licensed pharmacies. However, penciclovir is not subject to prescription. Since the manufacturer Novartis, a Swiss pharmaceutical company based in Basel, is the sole owner of the patent, there are no generics. Sales are therefore handled exclusively by Novartis. Nevertheless, different trade names are used, which vary according to dosage and country of distribution (e.g., Fenivir, Denavir, or Fenistil).
Pharmacologic effects on the body and organs
The effect of penciclovir can be described as antiviral. Consequently, the substance is effective in targeting and killing certain viruses that cause infectious diseases. Due to these effects, penciclovir belongs to the group of antivirals. However, it can only be used against the herpes simplex viruses, as there is no relevant efficacy against other forms of the virus. In addition, penciclovir is a so-called prodrug. Accordingly, the drug itself is not directly effective. Rather, it is metabolized in the body into the related substance penciclovir triphosphate, which then produces the antiviral effects. Penciclovir triphosphate inhibits viral DNA replication by preventing DNA polymerase. From a pharmacological perspective, it should also be emphasized that penciclovir has a much longer half-life compared to other herpes drugs such as aciclovir. It has been shown in the literature that penciclovir, when used properly, is able to reduce the symptoms of herpes infection (e.g., lesions on the lip) within half a day.
Medicinal use and use for treatment and prevention.
Penciclovir is marketed exclusively for topical use in the form of ointments or creams. These are applied directly to the cold sores. However, application must be exclusively to the face. The exact dosage depends on numerous factors, which is why it may not always be identical. As a rule, however, an application every two hours is advisable. It is important to apply the medication with fingers that are as clean as possible to prevent further infections. The average duration of treatment is four days. The preparations sold in German-speaking countries are subject to pharmacy regulations, but not to prescription requirements. They can therefore be purchased without a prior medical prescription.
Risks and side effects
Since penciclovir is a medical drug, there may be risks and side effects even with proper use of the cream or ointment. In principle, however, the active substance is considered very safe. In numerous studies, the substance was tested on well over 1,000 test subjects. It was found that some patients showed skin reactions after application. These were manifested by redness, a stinging sensation, local (non-transient) numbness, and a moderate to severe burning sensation. If these side effects occur, the application should be discontinued. A doctor should be contacted to agree on the further course of action. Interactions between penciclovir and other medicines are not known. The attending physician should nevertheless be informed about all medications taken.Furthermore, penciclovir must not be taken if there is a contraindication. A contraindication is when treatment with the active ingredient should be avoided from a doctor’s point of view because there are contraindications that lead to dangers. This is the case with penciclovir if an allergy or intolerance is known. Also, the cream is only suitable for external treatment of the face. Penciclovir should therefore not be applied to the eyes or genital area.
