Does Pregabalin Change Serum Levels of iNOS and NO in Diabetic Patients With Neuropathic Pain? A Quasi-experimental Study

Abstract

Background Pregabalin (PGB) has been approved for the treatment of diabetic peripheral neuropathic pain (DPNP), but the mechanism of the PGB effect in this situation is not precisely known. Would it be via the reduction of inducible Nitric‏ ‏Oxide ‎Synthase (iNOS) and thus the decrease of Nitric Oxide (NO) in type 2 diabetic patients? The current clinical trial was conducted to answer this question. Methods Twenty Seven diabetic patients with DPNP > 4, assessed by Visual Analogue Scale (VAS), were enrolled in this study. They received placebo/Bd for ten days as a washout period, then a starting dose of 75 mg/Bd PGB for one week and 150 mg/Bd for the next seven weeks. We took a fasting blood sample at baseline, before starting the treatment (BT) with PBG, then one month after the treatment (OMT), and also at the end of two months (TMT). The iNOS and NO serum levels were measured using the ELISA kit and the Griess method, respectively. Results Significant time-dependent reduction of iNOS of serum and DPNP intensities observed (P < 0.05). However, the serum levels of NO reduced significantly in OMT compared to BT (P < 0.05), but no significant differences were seen between OMT and TMT (P > 0.05). Conclusions Our study revealed a direct correlation between serum levels of iNOS and NO with the treatment of DPNP by PGB, thus introducing a possible mechanism for pain-relieving properties of PGB. Trial registration: This study was approved by the ethics committee of our University of Medical ‎Sciences, (ethical code: IR.SBMU.MSP.REC.1395.41) and registered in our ‎Registry of Clinical Trials (at 14/03/2016) and approved in 19/07/2017, the registration number is: (IRCT2017012932277N1). The study was conducted in the Diabetes Clinic of a teaching ‎Hospital on 22/07/2017 till 18/03/2018.‎ We have explained the study objectives and protocols to the subjects and obtained written informed ‎consent before they participated in the study.‎