Condition category
Nervous System Diseases
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Postherpetic neuralgia is thought to be nerve damage caused by herpes zoster virus. The damage causes nerves in the affected area of the skin to send abnormal electrical signals to the brain. The aim of this study is to analyse the efficacy of a drug gabapentin in patients 50 years old or above with moderate to severe pain during the acute phase of the herpes zoster in the prevention of the postherpetic neuralgia. The study's findings should help to reduce the percentage of patient that show postherpetic neuralgia during an episode of herpes zoster.

Who can participate?
Men and women aged 50 or above diagnosed or uncomplicated Herpes zoster within 72 hours of onset of the rash in patients with acute herpes zoster and with moderate/severe pain.

What does the study involve?
Participants are randomly allocated to take either gabapentin or placebo (dummy drug) for 5 weeks. At the end of the study, the prevalence of postherpetic neuralgia is compared in the placebo and gabapentin groups.

What are the possible benefits and risks of participating?
Gabapentin is an drug authorised by the European and American drugs agencies for the treatment of epilepsy and postherpetic neuralgia, both agencies has evaluated the safety of the gabapentin for the treatment of epilepsy and is not expected to be less safer in those patients with Herpes zoster. Patients treated with gabapentin for 5 weeks in the acute herpes zoster period plus valacyclovir and analgesic will reduce the incidence of postherpetic neuralgia by 25% compared to placebo.

Where is the study run from?
Primary Care Management of Mallorca

When is the study starting and how long is it expected to run for?
May 2013 to November 2015.

Who is funding the study?
Institute of Health Carlos III (Spain)

Who is the main contact?
Manel Rullán

Trial website

Contact information



Primary contact

Mr Manuel Rullan


Contact details

Centro de Salud de Pollença; C/ BISBE DESBACH

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Efficacy and safety of gabapentin versus placebo to prevent the incidence of PostHerpetic Neuralgia: a double-blinded clinical trial



Study hypothesis

Patient treated with gabapentin for 5 weeks in the acute herpes zoster period plus valacyclovir and analgesic will reduce the incidence of postherpetic neuralgia by 25% when compared to placebo plus valacyclovir and analgesic.

Ethics approval

Illes Balears ethics committee - approval pending

Study design

Phase III multi-centre double-blind placebo randomized clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Postherpetic neuralgia


Antiviral therapy is first-line treatment and should be initiated within 72 hours of rash onset to increase the rate of healing and decrease pain, valacyclovir is also effective in the prevention of the postherpetic neuralgia, placebo and gabapentin groups will receive 1g/8h the first week.

Pain management: The WHO three-step "ladder" will be used for pain management.
If pain occurs, there should be prompt oral administration of drugs in the following order: non opioids (aspirin and paracetamol); then, as necessary, mild opioids (codeine); then strong opioids such as morphine, until the patient is free of pain.

Gabapentin or placebo treatment: effective dose should be individualized according to patient response and tolerability. The treatment should be started at a dose of 900 mg/d (300 mg/d on day 1, 600 mg/d on day 2, and 900 mg/d on day 3), then every 2 or 3 day an increase of 300mg depending up to a maximum doses of 3600mg/day. The treatment will end at 5 weeks, in the last week gabapentin or placebo will be gradually tapered.

Intervention type



Phase III

Drug names

Gabapentin, valacyclovir

Primary outcome measure

Prevalence of postherpetic neuralgia, assessed using the Visual Analog Scale (VAS >0) at 12 weeks

Secondary outcome measures

1. Prevalence of postherpetic neuralgiaa, assessed using the Visual Analog Scale (VAS >0) at 6 weeks
2. Percentage of patients with a reduction of at least 50% in the VAS scale

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Patient aged 50 or above, either sex
2. Patient diagnosed or uncomplicated herpes zoster within 72 hours of onset of the rash in patients with acute herpes zoster and with moderate/severe pain (Analogic visual scale ≥ 4)

Participant type


Age group




Target number of participants

254 patients

Participant exclusion criteria

1. Patients taking gabapentin
2. Patients diagnosed of severe hepatic impairment, hypersensitivity to gabapentin or excipients, acute renal failure or renal impairment (Clcr <79ml/min)
3. Patients with evidence of cutaneous or visceral dissemination of herpes zoster infection (cutaneous dissemination is defined as 20 discrete lesions outside adjacent dermatomes) or ocular dissemination
4. Immunocompromised state and/or interferon treatment in the last 4 weeks
5. Patient taking tricyclic antidepressants or corticoids in the inclusion or treatment period

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Centro de Salud de Pollença; C/ BISBE DESBACH, S/N

Sponsor information


Primary Care Management of Mallorca (Gerencia de Atención Primaria de Mallorca) (Spain)

Sponsor details

C/Reina Esclaramunda n 9
Palma de Mallorca

Sponsor type




Funder type

Hospital/treatment centre

Funder name

Instituto de Salud Carlos III (ref: PI12_01813)

Alternative name(s)

Institute of Health Carlos III, Carlos III Health Institute, ISCIII

Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government



Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2017 protocol in:

Publication citations

Additional files

Editorial Notes

16/01/2017: Publication reference added.