title: Efficacy of gabapentin for prevention of postherpetic neuralgia: study protocol for a randomized controlled clinical trial.
abstract: Postherpetic neuralgia (PHN) is a chronic neuropathic pain that results from alterations of the peripheral nervous system in areas affected by the herpes zoster virus. The symptoms include pain, paresthesia, dysesthesia, hyperalgesia, and allodynia. Despite the availability of pharmacological treatments to control these symptoms, no treatments are available to control the underlying pathophysiology responsible for this disabling condition.
  
  
  
  Patients with herpes zoster who are at least 50 years old and have a pain score of 4 or higher on a visual analogue scale (VAS) will be recruited. The aim is to recruit 134 patients from the practices of general physicians. Participants will be randomized to receive gabapentin to a maximum of 1800 mg/day for 5 weeks or placebo. Both arms will receive 1000-mg caplets of valacyclovir three times daily for 7 days (initiated within 72 h of the onset of symptoms) and analgesics as needed. The primary outcome measure is the percentage of patients with a VAS pain score of 0 at 12 weeks from rash onset. The secondary outcomes measures are changes in quality of life (measured by the SF-12 questionnaire), sleep disturbance (measured by the Medical Outcomes Study Sleep Scale), and percentage of patients with neuropathic pain (measured by the Douleur Neuropathique in 4 Questions).
  
  
  
  Gabapentin is an anticonvulsant type of analgesic that could prevent the onset of PHN by its antihypersensitivity action in dorsal horn neurons.
  
  
  
  ISRCTN Registry identifier: ISRCTN79871784 . Registered on 2 May 2013.
authors.affiliation: Pollença Health Care Centre, Baleares Health Services (IB-Salut), 07460, Pollença, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Rullán
authors.affiliation: Son Espases Hospital, Baleares Health Services (IB-Salut), 07010, Palma, Spain.
authors.forename: Oana
authors.initials: O
authors.lastname: Bulilete
authors.affiliation: Primary Care Research Unit of Mallorca, Baleares Health Services (IB-Salut), 07005, Palma, Spain. aleiva@ibsalut.caib.es.|Instituto de Investigación Sanitaria de Palma (IdISPa), 07010, Palma, Spain. aleiva@ibsalut.caib.es.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Leiva
authors.affiliation: Primary Care Research Unit of Mallorca, Baleares Health Services (IB-Salut), 07005, Palma, Spain.|Instituto de Investigación Sanitaria de Palma (IdISPa), 07010, Palma, Spain.
authors.forename: Aina
authors.initials: A
authors.lastname: Soler
authors.affiliation: Son Serra-La Vileta Health Care Centre, Baleares Health Services (IB-Salut), 07013, Palma, Spain.
authors.forename: Antonia
authors.initials: A
authors.lastname: Roca
authors.affiliation: Manacor Health Care Centre, Baleares Health Services (IB-Salut), 07500, Manacor, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: González-Bals
authors.affiliation: Calvià Health Care Centre, Baleares Health Services (IB-Salut), 07184, Calvià, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Lorente
authors.affiliation: Primary Care Research Unit of Mallorca, Baleares Health Services (IB-Salut), 07005, Palma, Spain.|Instituto de Investigación Sanitaria de Palma (IdISPa), 07010, Palma, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Llobera
mesh_terms: D000212:Acyclovir / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000588:Amines / Q000009:adverse effects / Q000627:therapeutic use*; D000700:Analgesics / Q000009:adverse effects / Q000627:therapeutic use*; D000998:Antiviral Agents / Q000009:adverse effects / Q000627:therapeutic use*; D002985:Clinical Protocols; D003509:Cyclohexanecarboxylic Acids / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D000077206:Gabapentin; D006562:Herpes Zoster / Q000175:diagnosis / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D051474:Neuralgia, Postherpetic / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control* / Q000821:virology; D010147:Pain Measurement; D011788:Quality of Life; D012107:Research Design; D012890:Sleep; D013030:Spain; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D000077483:Valacyclovir; D014633:Valine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005680:gamma-Aminobutyric Acid / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000588:Amines; D000700:Analgesics; D000998:Antiviral Agents; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D014633:Valine; D000077483:Valacyclovir; D000212:Acyclovir
keywords: Gabapentin; Herpes zoster; Postherpetic neuralgia; Prevention; Primary health care