# E-DRUG: E-drug: acyclovir or valacyclovir **URL:** \ **Category:** e-drug\ **Created:** [November 12, 1998, 5:58am UTC](https://talk.edrugplus.org/t/e-drug-e-drug-acyclovir-or-valacyclovir/3815 "1998-11-12T05:58:34Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Sigurdur\_Helgason](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Sigurdur\_Helgason](https://talk.edrugplus.org/u/Sigurdur_Helgason)\ **Post date:** [November 12, 1998, 5:58am UTC](https://talk.edrugplus.org/t/e-drug-e-drug-acyclovir-or-valacyclovir/3815/1 "1998-11-12T05:58:34Z")
E-drug: Acyclovir or valazyclovir? (3) -------------------------------------- Dear colleagues, in response to Dr Michel LALOGE. I only know of one comparative trial (RCT) comparing acyclovir to the prodrug valacyclovir. (1) The Prescrire international published recently a review of valacyclovir (2). The advantage of the slightly cheaper valacyclovir is three times a day dosing. Efficacy is similar to acyclovir although the serum conc. is significantly higher after valacyclovir. The effects are mainly on the acute phase although the industry claims effects on post herpetic neuralgia (it depends heavily on how PHN is defined or wheather we use zoster associated pain (ZAP) as an endpoint). A major flaw in many of the RCT's on antivirals for zoster in immunocompetent adults is that no distinction is made between mild (clinically insignificant in many cases) and moderate or severe pain. (3) A superb study (3) done a few years ago showed no effect on PHN in \>350 elderly patients. The study has been eliminated by most reviews or metanalysis on the grounds that all pt. were not followed for 6 months. My own study on the prognosis of zoster showed (5) that in patients painfree at 3 months reappearance of pain later was extremely rare. Blanket reccommendations that all patients over certain age (\>50) are unfounded. Other clinical parameters should be taken into account. Other cheap modalities like amitriptyline or nortriptylin are underused as adjunctive therapy for pain from the start. Another good review is (6) (1) Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ. Valacyclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults. Antimicrob Agents Chemother 1995;39:1546-53. (2) Valaciclovir. Prescrire International 1997;7:72-73 (Rev Prescr March 1997;17(171):156-158. (3) Dworkin RH, Carrington D, Cunningham A, Kost RG, Levin MJ, Mckendrick MW, Oxman MN, Rentier B, Schmader KE, Tappeiner G, Wassilew SW, Whitley RJ. Assessment of pain in herpes zoster: lessors learned from antiviral trials. Antiviral Research 1997; 33:73-85. (4)McKendrick MW, McGill JI, Wood MJ. Lack of effect of acyclovir on postherpetic neuralgia. BMJ 1989;298:431. (5) Helgason S, Sigurdsson JA, Gudmundsson S. The clinical course of herpes zoster: a prospective study in primary care. Eur J Gen Pract 1996;2:12-6. (6) Lancaster T, Silagy C, Gray S. Primary care management of acute herpes zoster: systematic review of evidence from randomized controlled trials. British Journal of General Practice 1995;45:39-45.    Sincerely Sigurdur Helgason MD Heilsug�slust�din Arbae Hraunb� 102, Reykjav�k 110 Fax (354)-5671183 Phone (354)-5671500 e-mail sh@centrum.is -- Send mail for the `E-Drug' conference to `e-drug@usa.healthnet.org'. Mail administrative requests to `majordomo@usa.healthnet.org'. For additional assistance, send mail to: `owner-e-drug@usa.healthnet.org'.