Famciclovir in treatment of acute herpes zoster: results of two post-marketing surveillance studies in Germany.

Sir, Post-marketing surveillance (PMS) supplies important information on the pro® t ± risk evaluation of a drug after its approval. Its importance derives from the fact that it is carried out in routine clinical everyday life and without the patient and investigator selection biases that result from controlled clinical studies. Herpes zoster is a common disease that affects up to 20% of the population (1). Most patients suffer from cutaneous lesions and acute-phase pain. In immunocompetent patients symptoms are usually self-limiting, resolving within 4 weeks after the onset of rash (2). However, up to 70% of herpes zoster patients develop post-herpetic neuralgia (PHN) (3), a debilitating pain that persists for a long time after the initial infection. Most notably up to 70% of elderly patients develop this complication, which is more severe and lasts considerably longer than in younger patients. Antiviral therapy, anti-in ̄ ammatory steroids, blockers of the sympathetic nerve system and analgesics are the main measures for prevention and treatment of PHN. In addition, tricyclic antidepressants are also used. However, the therapy of choice is antiviral agents applied early in the acute phase of zoster (4). An antiherpes agent which effectively reduces zoster-associated pain is famciclovir, the well-absorbed oral prodrug form (bioavailability 77%) of penciclovir (5), with activity against varicella-zoster virus, herpes simplex virus types 1 and 2, Epstein ± Barr virus and hepatitis B virus. Clinical trials have shown that famciclovir alleviates the symptoms of acute and chronic herpes zoster and reduces time to resolution of shingles-associated pain (6 ± 9). A prospective observational cohort study, including 5,949 evaluable patients, was conducted to assess famciclovir therapy in routine use in patients with acute herpes zoster. Further objectives were to collect epidemiological data and to reveal pre-therapy risk factors in ̄ uencing the clinical outcome in famciclovir-treated patients, especially in terms of persisting pain.