GaPP2 Trial

Eight UK endometriosis centres are running a clinical trial to find out if gabapentin reduces pelvic pain in women, where no cause for their pain has been found. They are also investigating whether the drug could improve these women’s quality of life.


Chronic pelvic pain (CPP) affects >1 million UK women. It accounts for 20% of gynaecological consultations and was highlighted in the Chief Medical Officer’s Annual Report in 2009 as a key area of unmet need. Evidence-based treatments for CPP are limited, and management is often unsatisfactory. If no pathology is identified, the pain is much more difficult to treat and a drug called gabapentin, which has been used safely and successfully to treat other chronic pain conditions is being increasingly prescribed.

There is currently no evidence to show whether it is effective or not for CPP. We will investigate the effectiveness of gabapentin in women with CPP. In addition, we want to understand whether changes in the central nervous system of women with CPP are responsible for their symptoms and whether these can predict response to gabapentin. The main aim of the study is to demonstrate whether a reduction in daily pain can be achieved with the treatment of gabapentin.

The study will invite 300 women with CPP where no cause has been found, to participate in a clinical trial where they are allocated at random to gabapentin or placebo (dummy capsules). They will collect information on pain, physical and emotional wellbeing at the beginning of the study and after 12 weeks of optimal treatment. They will also ask a subset of 50 women (from Scottish sites) to undergo a functional magnetic resonance imaging (fMRI) scan to look at brain activity before and during treatment.


Women who are admitted to a gynaecology clinic who fulfill all the following criteria will be eligible to be randomised into the trial if they match the following criteria:


  • Women aged between 18-50 years
  • Chronic pelvic pain (non-cyclical with or without dysmenorrhoea or dyspareunia) of >3 months duration
  • Pain located within the true pelvis or between and below anterior iliac crests
  • Associated functional disability
  • No obvious pelvic pathology at laparoscopy (laparoscopy must have taken place at least 2 weeks ago, but no more than 36 months prior to screening)
  • Using or willing to use effective contraception if necessary to avoid pregnancy
  • Able to give informed consent


Which hospitals are taking part?


• Aberdeen Royal Infirmary

• Birmingham Women’s NHS Foundation Trust

• Edinburgh Royal Infirmary

• University Hospitals of Leicester NHS Trust

• University College London

• James Cook University Hospital, Middlesborough

• John Radcliffe Hospital, Oxford

• Southampton General Hospital


For more information about the hospitals recruiting and how to get involved, please visit the trial website.