Methods
Participants
This clinical protocol and patient consent forms were designed following
the revised Declaration of Helsinki and the Good Clinical Practice of
the International Conference on Harmonization (ICH-GCP) and approved by
the Ethics Committee of the School of Pharmaceutical Sciences of
Ribeirão Preto and the School of Medicine of Ribeirão Preto, University
of São Paulo (USP) (CAAE: 34175314.3.0000.5403). Thirty-two patients
were invited to participate and provided written informed consent. The
study was registered in Clinicaltrials.gov under the identifier
NCT03047278.
Eligible subjects were adult patients (n=32), from 18 to 59 years old,
with neuropathic pain with pain scores ≥ 4 on VAS. All patients were
recruited from the Pain Ambulatory or Diabetes Ambulatory of the
Clinical Hospital of the School of Medicine of Ribeirão Preto,
University of São Paulo (FMRP-USP) or from the Health Basic Unity (UBS)
Cuiabá of the FMRP-USP. The diagnosis of neuropathic pain was based on
the presence of daily moderate to severe chronic pain in the extremities
for more than 90 days and a score of 4 cm (or greater than 4 cm) on a 10
cm visual analogue pain scale (0 = no pain; 10 = worst possible pain)
[45,46]. The diagnosis of diabetes was based on the criteria by the
American Diabetes Association [18]. Only participants with DM2
diagnosis for more than 6 months were included. Exclusion criteria were
creatinine clearance ≤ 30 mL/min, gastrointestinal diseases, history of
alcohol or drug abuse and chronic use of medicines that interact with
GBP. Three patients were excluded from the final analysis due to
incomplete data.