Study to Investigate the Safety, Tolerability and Pharmacokinetics of AZD1940

Inclusion Criteria: * A diagnosis of Chronic Low Back Pain according to Quebec Task force Class 1-3 and an average pain intensity score of 3-9 on NRS(0-10) during the past week. * Clinical normal physical findings, including blood pressure, pulse rate \> 45bpm, ECG (with normal QTcF interval \<450msec and without any additional risk factors for Torsades de Pointes) and laboratory assessments, as judged by investigator * Body Mass Index (BMI) ≥18 to ≤32 kg/m2 inclusive and body weight ≥50 to ≤100 kg Exclusion Criteria: * History of somatic disease/condition which may interfere with the objectives of the study, with the exception of Chronic Low Back Pain * History of previous or ongoing psychiatric disease/condition including psychosis, affective disorder, anxiety disorder, borderline state and personality disorder * Clinically significant illness with the exception of Chronic Low Back Pain